Flashcards in Water And Carbon Deck (864):
What does the availability and quantity of water help tie together
The Earths lands, oceans and atmosphere into an integrated physical system
What is the most important greenhouse gas
What does the poor understanding of the water cycles interactions and processes at a variety of scale lead to
Bad representation in model predications
Where is carbon stored
Everywhere: in the oceans, rocks and soil, in all forms of life and our atmosphere
What does the well-bring and functioning of our planet depend on
Carbon and how it cycles through the Earths system
How does the carbon cycle play a key role in regulating the global temperature and climate change
By controlling the amount of another greenhouse gas, carbon dioxide, in the atmosphere
What is a flow/transfer
A form of linkage between one store/component and another that involved movement of energy or mass
What is an input
The addition of matter and/or energy into a system
What is a store/ component
A part of the system where energy/ mass is stored or transformed
What is a system
A set of interrelated components working towards some kind of process
Why do geographers attempt to simplify aspects of the Earth
It is highly complex.
They want relationships between components to be better understood.
What are simplifications of highly complex processes called
Models such as the water cycle or the demographic transition model
What is a type of model that is widely used
What are the three properties of systems
What are elements in the system
The things that make up the system
What are attributes of a system
The perceived characteristics of the elements
What are the relationships in a system
Descriptions of how the various elements (and their attributes) work together to carry out some kind of process
What are the four common characteristics of systems
- structure that lies within in a boundary.
- generalisations of reality, removing incidental detail that obscures fundamental relationships.
- they function by having inputs and outputs of material that is processes within the components causing it to change.
- involve the flow of material between components.
What are the three classifications of systems
What are isolated systems
They have no interaction with anything outside the system boundary. No inputs or outputs of energy. Many controlled lab experiments are this type of systems but they are rare in nature.
What is a closed system
Transfers of energy both into and beyond the system boundary but not transfer of matter
What are open systems
Matter and energy transferred from the system across the boundary into the surrounding environment. Most ecosystems are an example of this.
Specific example of an open system
A drainage basin hydrological system
When is a system said to be in a state of dynamic equilibrium
Where there is a balance between the inputs and outputs
What is feedback
When one of the inputs increases without any corresponding change in the outputs - the stores changes
What are the two types of feedback
What is positive feedback
Where the effects of an action are amplified or multiplied by subsequent knock-on or secondary effects (for example increase in carbon dioxide)
What is negative feedback
Where the effects of an action are nullified by subsequent knock-on effects (for example the increased use of fossil fuels)
Example of positive feedback in the carbon cycle system
More Co2 in the atmosphere.
(This acts as a greenhouse gas)
Global temperature rise.
(This warms the ocean)
Increased oceanic temperatures.
(Warm water less able to dissolve gas)
Dissolved Co2 release by warmer oceans.
(Co2 back into the atmosphere)
More Co2 in the atmosphere.
Example of negative feedback in the carbon cycle
Increased use of fossil fuels.
Increased in atmospheric Co2.
Global temperature increase.
More plant growth.
Increased take up of Co2.
Reduces atmospheric Co2.
This has dampening effect and reduce global temperature.
How does energy come into the system
Form of solar energy
What is the energy coming into systems in the form of solar energy balanced by
Radiant energy lost by the Earth
What is ‘Spaceship Earth’
A term to express the concern over the use of limited resources available on Earth and encouraging everyone on it to act as a harmonious crew working towards the greater good
What are the four major subsystems at a global level on the Earth
What is a cascading system
An open system that forms part of a chain such as the four major subsystems on Earth
What has a profound effect on the Earths climate and climate change
Interlocking relationships amount the atmosphere, lithosphere, hydrosphere and biosphere
What is vital to life on Earth
The availability and quantity of water
What is the global water cycle driven by
Many complex processes and interactions at a variety of scales
What is atmospheric water
Water found in the atmosphere; mainly water vapour with some liquid water (cloud and rain droplets) and ice crystals
What is cryospheric water
The water locked up in the Earths surface as ice
What is the hydrosphere
A discontinuous layer of water at or near the Earths surface. It includes all liquid and frozen surface waters, groundwater held in soil and rock and atmospheric water vapour
What is oceanic water
The water contained in the Earths oceans and seas but not including such inland seas as the Caspian Sea
What is terrestrial water
This consists of groundwater, soil moisture, lakes, wetlands and rivers
Who said ‘Water is life’s matter, mother and medium’
Albert Szent-Gyorgyi, 1937 Nobel Prize acceptance speech
Percentage of all water on earth
3% fresh water
What are the percentages of stores in fresh water
Ice caps and glaciers 79%
Easily accessible surface fresh water 1%
What are the percentage of stores in easily accessible surface fresh water
Soil moisture 38%
Atmospheric water vapour 8%
Water within living organisms 1%
Important percentages to know for all water on plent earth
3% is fresh water
Of this, 1% is easily accessible
Of this, 52% is lakes, 38% is soil moisture
What is the general agreement that scientists have come to on the amount of water in the hydrosphere
Estimated at 1.338 x 10^9 km^3
Examples of cryospheric water
Examples of terrestrial water
How much water vapour is found in the atmosphere
12,900km^3 which is a global average of 26kg/m^2 for each column of air on the surface of the earth
What percentage of water on earth is atmospheric water
0.4% and is has a profound effect on our lives at present
What is the amount of water in the stores in a state of
Dynamic equilibrium with changes at a range of timescales from diurnal to geological
In the future, what could changes in the amount of atmospheric water cause
Important effects on climate change
What do the figure of the amount of water in the ocean range from
1,320,000,000 to 1,370,000,000km^3 with an average depth of 3,682m.
What percentage of the planets surface does oceanic water cover
What is oceanic water customarily divided into
Several principal oceans and smaller seas
While the ocean contains 97% of the worlds water, how much have oceanographers stated have been explored
Why does oceanic water taste salty
Because it contains dissolved salts
What do the salts in oceanic water allow
It to stay as liquid water even below 0*C
What is the pH of oceanic water
Alkaline with an average pH of about 8.14
What has the pH fallen from in the last 250 years
Fallen from 8.25 to 8.14 and is destined to continue falling
What is the change in the pH of oceanic water linked to
The increase in atmospheric carbon
What may the change in pH have an influence on
Example of sea ice
The Ross Ice Shelf
Example of an ice cap
The Iceland Ice Cap
Example of an ice sheet
The Greenland ice sheet
Example of alpine glacier
Mer de Glacé, France
Example of permafrost
The Alaska North Slope
Why does the amount of water frozen In Arctic Ocean change
It grows in winter and shrinks in summer, same is true for the waters in Antarctica
What is much of the Arctic Ocean
When does sea ice form
When water in the oceans is cooled to temperatures below freezing
Why does sea ice not raise sea levels when it melts
Because it forms from the ocean waters
Why are scientists concerned about the recent decline of sea ice
It is closely linked with our planets climate
What are ice shelves
Platforms of ice that form where ice sheets and glaciers move out into the oceans
Where do Ice shelves mainly exist
In Antarctica and Greenland, as well as in the Arctic near Canada and Alaska
What are icebergs
Chunks of ice that break off glaciers and ice shelves and drift in the ocean
When do Ice burgs raise sea levels
When they first leave land and push into the water, but not when they melt in the water
What is an ice sheet
A mass of glacial land ice extending more than 50,000km^2
What do the two major ice sheets on Earth today cover
Most of Greenland and Antarctica
During the last advance, where did ice sheets cover
Along with Greenland and Antarctica
Together, how much of freshwater on earth is contained in the Antarctica and Greenland ice sheets
How far does the Antarctic Ice sheet extend
14 million km^2 - roughly the area of the United States and Mexico combined
How much ice does the Antarctica ice sheet contain
30 million km^3
How far does the Greenland Ice sheet extend
About 1.7 million km^2, covering most of the island of Greenland
Where do Ice sheets form
In seas where snow that falls in the winter does not melt entirely over the summer
How do ice sheets form
Over thousands of years, the layers of snow pile up into thick masses of ice, growing thicker and denser as the weight of new snow and ice layers compresses the older layers
How are Ice sheets constantly in motion
They are slowly flowing downhill under their own weight
Near the coast, how do most ice sheets nice
Through relatively fast-moving outlets called ice streams
Where are Ice sheets significant and why
In the Antarctic
How big can Ice sheets get in the Antarctic
Hundreds of kilometres King
What conditions are needed for an ice sheet to remain stable
As long as an ice sheet accumulated the same mass of snow as it loses to the sea
If the Greenland ice sheet melted, what do scientists estimate that sea levels would rise by
If the Antarctic Ice sheet melted, what do scientists predict the rise in sea level would be
What are ice caps
Hick layers of ice on land that are smaller than 50,000km^2
Where are ice caps usually found
Mountainous areas, They are usually centred over the highest point of an upland area
What shape are ice caps
How do ice caps flow
Outwards, covering almost everything in their path becoming a major source for glaciers
Where do ice caps occur in the world
All over - from the polar regions to mountainous ones such as the Himilayas, the Andes and the Southern Alps of New Zealand
What is Africa’s only remaining ice cap
The Furtwangler Glacier In Kilimanjaro at 60,000m^2. It is melting rapidly and any soon disappear
What are Alpine glaciers
Thick masses of ice
Where are alpine glaciers found
In deep valleys or upland hollows
What are most valley glaciers fed by
Ice from ice caps or smaller corrie glaciers
Why are alpine flavoured important in the Himalayas
15,000 Himalayan glaciers form a unique reservoir which supports perennial rivers which are the lifeline of millions of people in south Asian countries
What are perennial rivers in the Himalayas
Examples of South Asian countries
What ring the Arctic Ocean
Frozen ground and permafrost while glaciers , snow and ice cover the nearby land including Greenland
What is permafrost
Ground (soil or rock and included ice or organic material) that remains at or below 0*C for at least two consecutive years
What does the thickness of permafrost vary between
Less than 1 metre to more than 1,500m
When did most of the permafrost existing today form
During cold glacial periods and has persisted through warmer interglacial periods, including the Holocene.
What is the Holocene
The last 10,000 years
When did some relatively shallow permafrost (30 to 70m) forms
During the second part of the Holocene (last 6,000 years) and some during the Little Ice Age (from 400 to 150 years ago)
When was the Little Ice Age
From 400 to 150 years ago
When does Subsea permafrost occur
At close to 0*C over large areas of the Arctic continental shelf, where it formed during the last glacial period on the exposed shelf landscapes when sea levels were lower
Where is permafrost found
Beneath the ice-free regions of the Antarctica continent and also beneath areas in which the ice sheet is frozen to its bed
Why has permafrost begun to melt
As climate warms
How does melting permafrost affect global climates
Because it releases large amounts of carbon dioxide and methane
What are the four broad classes terrestrial water falls into
What is surface water
The free-flowing water of rivers as well as the water of ponds and lakes
What do rivers act as
Both a store and a transfer of water
How are rivers a store and a transfer of water
Streams of water within a defined channel.
Transfer water from the ground, from soils and from the atmosphere to a store
What may the store that rivers transfer water to be
What percentage of all rivers do rivers make up
What is the overall volume and span of all rivers
1,000,000km^3 span and 2,120km^3 volume
Which River is the largest river by discharge of water in the world
The Amazon in South America
What is the discharge of the Amazon river
209,000m3/s, greater than the next seven largest independent rivers combined
What area approximately does the Amazon river drain
How much of the worlds total river flow does the Amazon account for
How big is the Amazon drainage basin in Brazil
The portion of the rivers drainage basin in Brazil alone is larger than any other rivers basin
How much of the Amazons final discharge into the Atlantic Ocean enters Brazil
Only one fifth, yet it has already a greater flow than the discharge of any other river
What are mailed
Collections of fresh water
Where are lakes found
In hollows in the land surface
How big are lakes
Greater than 2 hectare season in area
What is a standing body of water smaller than 2 hectares termed
What are the majority of lakes on earth
Where do most lakes on earth lie
In the Northern Hemisphere at high altitudes
How many lakes that are larger than 3km^2 does Canada have
How many lakes does Canada have overall
Estimated total of at least 2 million
How many lakes does Finland have
187,888 that are 500km^2 or larger, of which 56,000 are large (10,000m^2)
What is the largest lake and how big is it
The Caspian Sea at 78,200km^3
How old is the Caspian Sea
As it is a remnant of an ancient ocean it is about 5.5 million years old
What is the Caspian Sea generally
Fresh water though it becomes more saline in the south where there are few rivers flowing into it
What is the deepest lake in the world
Lake Baikal in Siberia with a mean depth of 749m and a deepest point at 1,637n
What are does the Ramsar Convention define Wetlands
The Ramsar Convention defines them as ‘areas of marsh, fen, peatland or water whether natural or artificial, permanent or temporary, with water that is static or flowing where there is a dominance by vegetation’
Simple definition of wetlands
Areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season
What does water saturation determine
How the soil develops and the types of plant and animal communities living in and on the soil
What species may wetlands support
Both aquatic and terrestrial
What does the prolonged presence of water in wetlands create
Conditions that favour the growth of specially adapted plants and promotes the development of characteristic wetlands soils
What are the 7 reasons wetlands vary widely
Because of regional and local differences in soils.
Other factors like human disturbance.
Where are wetlands found
From the polar regions to the tropics and on every continent except Antarctica
Example of a wetland
The Pantanal of South America, often referred to as the worlds largest freshwater wetlands systems
How far does the Pantanal of South America extend
Through millions of hectares of central western Brazil, eastern Bolivia and eastern Paraguay
What is the Pantanal of South America
A complex system of marshlands, flood plains, lagoons and interconnected drainage lines
How does the Pantanal of South America provide economic benefits
It is a huge area for water purification and groundwater discharge and recharge, climate stabilisation, water supply, flood abatement and an extensive transport system
What are the main ecosystems in the Arctic
What covers nearly 60% of the Arctic
Peatland, rivers, lakes and shallow bays
What do Arctic wetlands store
Enormous amounts of greenhouse gases
What are Arctic wetlands critical for
What is groundwater
Water that collects underground in the lite spaces of rock
What have scientists said is the depth of groundwater
4,000m but it is known there are large quantities of water blow that
What was found in Northern Russia
A very deep borehole in the Kola Peninsula, found huge quantities of hot mineralised water at a depth of 13km
What is the water table
The depth at which soil purr spaces of fractures and voids in rocks become completely saturated with water
What eventually happens to groundwater
It is recharged from and eventually flows to the surface.
Sometimes natural discharge can occur at springs and seeks and can form oases or wetlands.
Why is the amount of groundwater reducing rapidly
Due to extensive extraction for use in irrigating agricultural land in dry area
What is soil water
That which is held together with air in unsaturated upper weathered layers of the earth
What is soil water of fundamental importance to
Many hydrological, biological and biogeochemical processes
What 6 things does soil water affect
Weather and climate.
Run-off potential and flood control.
Soil erosion and slope failure.
What is soil moisture a key variable in
Controlling the exchange of water and heat energy between the land surface and the atmosphere through evaporation and plant transpiration
What does soil moisture play an important role in
The development of weather patterns and the production of precipitation
What is biological water
Constitutes the water stored in all the biomass
What does biological water around the globe depend on
He vegetation cover and type
Where stores more biological water than a desert
Areas of dense rainforest
What is the role of animals as a water store
How do trees take in water
Via their roots
How is water transported in trees
Transported or stored in the trunk and branches of the tree
How is water lost in trees
By the process of transpiration through stomata in the leaves
What does the storage of water in trees provide
A reservoir of water that helps maintain some climatic environments
If the vegetation is destroyed, what happens to the biological water
The store is lost to the atmosphere and he climate can become more desert-like
How much water are many plants adapted to store
How do Cacti gather water
Via their extensive root system and then very slowly use it until the next rainstorm
Why does the baobab tree store water
To strengthen the structure of the tree rather than to be used in tree growth
What states does atmospheric water exist in
All three states
What is the most common atmospheric water
Gas; water vapour
What is water vapour
A clear, colourless and odourless gas
Why is atmospheric water important
It absorbs, reflects and scatters incoming solar radiation, keeping the atmosphere at a temperature that can maintain life
What does the amount of water vapour that can be held by the air depebd in
Why is the air in the poles quite dry, whereas air in the tropics is very humid
Because cold air cannot hold as much water vapour as warm air
What will a small increase in water vapour lead to
An increase in atmospheric temperatures
How does an increase in water vapour in the atmosphere become positive feedback
A small increase in global temperatures would lead to a rise in global water vapour levels, thus further enhancing the atmospheric warming
What is a cloud
A visible mass of water droplets or ice crystals suspended in the atmosphere
What is cloud formation the result of
Air in the lower layers of the earths atmosphere becoming saturated due to either or big of two processes: cooling of the air and an increase in water vapour
What happens when cloud droplets grow
They can eventually fall as rain
What are the 3 factors driving the change in magnitude of water stores
What is it called when water vapour is turned to liquid
Condensation, releasing latent heat of vaporisation
What’s the process of liquid to solid
Freezing, releasing latent heat of fusion
What’s the process of ice to water
Sublimation, absorbing latent heat of sublimation
What’s the process of gas to solid
Deposition, releasing latent heat of sublimation
What’s the process of ice to liquid
Melting, absorbing latent heat of fusion
What’s the process of water to gas
Evaporation, absorbing latent heat of vaporisation
What happens to energy, in the form of latent heat, in the phases of water and the phase changes
It is either absorbed or released depending on the process
Where is energy in the form of latent heat particularly important
In atmospheric processes such as cloud or precipitation formation
When does evaporation occur
When energy from solar radiation hits the surface of water or land and causes liquid water to change state from a liquid to a gas
What 4 factors does the rate of evaporation depend on
Amount of solar energy.
Availability of water (e.g more evaporation than a pond then a grassy field).
Humidity of the air (closer the air is to saturation point, the slower the rate of evaporation).
Temperature of the air (warmer air can hold more water than cold air).
What do all terrestrial plants lose water through
What is transpiration
Water is transported from the roots of a plant to its leaves and then lost through pores on the lead surfaces
What can water trapped on leaves be
Evaporated before t reaches the soil
When water evaporates why does it cool its surroundings
It uses energy in the form of latent heat
Explain the process of condensation
As air cools it is able to hold less water vapour.
This means that if it is cooled sufficiently then it will get to a temperature at which it becomes saturated.
This is known as the dew point temperature.
Excess water in the air will then be converted to liquid water in the process of condensation.
What do water molecules need in the process of condensation
Something to condense on
What can water molecules condenser on
Tiny particles like smoke, salt, dust etc that are collectively called condensation nuclei or surfaces like leaves, grass stems and windows that are blow the dew point temperature
What does sublimates mean
Changing directly from gas to solid in the form of hoar frost, done when the surface the vapour is condensing in is below freezing point
What is condensation the direct form of
All forms of precipitation
When does condensation take place
When the temperature of air is reduced to dew point but it’s volume remains constant.
When the volume of air increases but there is no addition of heat.
What is adiabatic cooling
During condensation, when the volume of air increases but there is no addition of heat
When does adiabatic cooling occur
When air rises and expands in the lower pressure of the upper atmosphere
When does the temperature of the air reduce to dew point while the volume remains constant
Warm moist air passes over a cold surface.
On a clear winters night heat is radiated out to space and the ground gets colder, cooling the air directly in contact with it.
When 3 effects cause adiabatic cooling to occur
Relief or orographic effect.
What is relief or orographic effect
Air is forced to rise over hills
What is the frontal effect
Masses of air of different temperatures and densities meet. The less dense warm air rises over the denser cold air
When does the convectional effect occur
When localised warm surfaces heat the air above, this expands and become less dense and rises
What are the two cryospheric processes
What is there thought to have been in Earths history
5 major glacial periods
When did the most recent glacial period start
2.58 million years ago and continues today
What is the most recent glacial period called
The Quaternary glaciation
During the Quaternary period what was there
Glacial periods when , due to the volume of ice on land, sea level was approx 120m lower than present and continental glaciers covered large parts of Europe and North America. This represents an interruption in the global hydrological cycle.
Interglacial periods when global ablation exceeds accumulation and the hydrological cycle as we know it today returns.
Over the past 740,000 years how many glacial cycles has there been
When is permafrost formed
When air temperatures are so low that they freeze any soil and groundwater present.
Why does permafrost rarely occur under ice
Because the temperatures are not low enough
What is the driving force behind global cloud formation and precipitation
The global atmospheric circulation model
Global atmospheric circulation model summary
At the equator high temperatures result in high rates of evaporation. The warm, moist air rises, cools and condensers to form towering banks of cloud and heavy rainfall in a low pressure zone called the ITCZ:
In the mid latitudes, cloud formation is driven by the convergence of warm air from the tropics and cold air from the Arctic. The boundary of these two distinct air masses - the polar front - results in rising air and cloud (and rain) formation. Strong upper-level winds (the jet stream) drive here unstable weather systems across mid latitudes, establishing the largely changeable conditions experienced in the Uk.
Cloud formation can occur on a more localised scale. The formation of thunderstorms from intense convection activity is somewhat ‘hit and miss’, but it does clearly demonstrate the variations in both time and space of water cycle transfer processes.
On a glacier what does the equilibrium line mark
The altitude where annual accumulation and melting are equal
What is the ITCZ
Inter-Tropical Convergence Zone
What could the total melting of all the polar sheets result in
A 60m rise in sea level
How are rising sea levels a positive feedback in the rate of removal of glacial ice
They can destabilise glaciers and ice shelves leading to accelerated rates of iceberg calving
What are cryospheric processes
Processes that affect the total mass of ice at any scale from local patches of frozen ground to global ice amounts. This includes accumulation (build up of ice mass) and ablation (the loss of ice mass)
What is a drainage basin
The area of land drained by a river and its tributaries. It includes water found in the surface, in the soil and in near-surface geology
What is energy provided by and aided by to cause evaporation
Provided by the sun and aided by the wind
What is evapotranspiration
The total output of water from the drainage basin directly back into the atmosphere
What is groundwater flow
The slow movement of water through underlying rocks
What is infiltration
The downward movement of water from the surface into soil
What is interception storage
The precipitation that falls on the vegetation surfaces of human-made cover and is temporarily stored in these surfaces. Intercepted water can either be evaporated directly to the atmosphere, absorbed by the canopy surfaces or ultimately transmitted to the ground surface
What is overland flow
The tendency of water to flow horizontally across land surfaces when rainfall has exceeded the infiltration capacity of the soil and all surfaces stored are full to overflowing
What is percolation
The downward movement of water within the rock under the soil surface. Rates vary depending on the nature of the rock
What is run-off
All the water that enters a river channel and eventually flows out of the drainage basin
What is saturated
This applies to any water store that has reached its maximum capacity
What is the stem flow
The portion of precipitation intercepted by the canopy that reaches the ground by flowing down stems, stalks or tree bole
What is a storm event
An individual storm is defined as a rainfall period seperated by dry intervals of at least 24 hours (Hamilton)
What is a rainfall event
Defined as a rain fall period separated by dry intervals of at least 4 hours (Hamilton)
What is throughfall
The portion of the precipitation that reaches the ground directly through gaps in the vegetation canopy and drips from leaves, twigs and stems
When does throughfall occu
When the canopy-surface rainwater storage exceeds its storage capacity
What is throughflow
The movement of water down-slope through the subsoil under the influence of gravity.
When is throughflow particularly effective
When underlying permeable rock prevents further downward movement
What is transpiration
The loss of water from vegetation through pores (stomata) on their surfaces
What is the water balance
Balance between inputs (precipitation) and outputs (run off, evapotranspiration, soil and groundwater storage) in a drainage basin
What is a useful way of looking at drainage basins
Consider them as cascading systems - they are a series of open systems hat link together so that the output of one is the input of the next
What supplies a river with it’s supply of water
A drainage basin
What are drainage basins seperated from one another by
High land called a watershed
What is the input to a drainage basin
What has a direct bearing on what happens when the water hits the ground
The nature, intensity and longevity of the precipitation
On a hill slope what happens to precipitation
It lands on the bare surface or more likely vegetation cover.
The vegetation provides an interception store.
What does the density of vegetation mean
That interception store is more
What have studies shown of forests made up of needle-leaf trees
They capture 22% of rainfall
What have studies shown about broad-lead deciduous forests
They intercept 19% of rainfall
What is the difference in rainfall capture between needle-leaf trees and deciduous tree because rid
Density of the vegetation cover rather than the structure of the leaves
What do some tropical rainforests intercept
As much as 58% of the rainfall
What happens to a lot of the water captured by vegetation surfaces
It is evaporated back into the atmosphere
What is the infiltration rate
The rate of infiltration
What is the movement of water into soil controlled by
Soil porosity (most important)
What is a soils porosity controlled by
It's texture, structure and organic content
What do coarse textured soils have
Larger spores and fissures than fine grained soil and allow for more water flow
What can pores and fissures in soil be made larger through
A number of factors that enhance internal soil structure. For example, the burrowing of worms and penetration of plant roots csn increase the size and number of macro and micro-channels within the soil
When does the rate of infiltration normally decline rapidly
During the early part of a rainstorm event
When does infiltration rates reach a constant value
During a rainstorm event after several hours of rainfall
What are 3 reasons for the phenomenon of infiltration dates declining rapidly and then reaching a constant value during a rainstorm event
Filling of pores on the soil surface reduces the ability of capillary forces to actively move water into the soil.
As soil moistens, clay particles absorb water causing them to expand. This expansion reduces the size of soil pores.
Raindrop impact breaks larger soil clumps into smaller particles, these then clog soil surface pores reducing movement of water into soil.
What is soil storage
The amount of water stored in the soil
What does soil consist of
Solid particles with pore spaces between them
What can soil pore spaces be filled with
Air as well as water
How much do the pores in a clay soil account for of the total volume
40 to 60 %
How much do the pores in fine sand account for of the total volume
20 to 45%
What is vegetation storage
Plans removing water from the soil and storing it in the structure of the plant
What happens if rainfall institutions is greater than the infiltration rate
The soil will have reached infiltration capacity and the soil will be saturated
What is surface storage
Water building up on the surface usually in the form of puddles
Where is surface storage common
In man-made environments
What is the infiltration rate usually greater than in natural environments
Greater than the rate of precipitation
When does water build up on the surface
After a long period of rain
An intense rainstorm
Impermeable surface such as an impacted foot path or a frozen surface
Why is the total amount of evaporated water referred to evapotranspiration
Because it is difficult to separate evaporation from transpiration so the total amount outputted is called this
When does overland flow/ sheet flow occur
When the surface stores are full then these will occur on slopes
How fast is overland flow
Very fast flow, rapidly reaching the newest channel
What tends to be much slower than overland flow
What happens to throughflow in a very vegetated area
It has a faster rate becsuse it is aided by root channels in the soil
What is the vertical transfer that happens after infiltration
Percolation which can then be held in pore spaces in the rocks as groundwater
What is groundwater flow
Groundwater passing slowly into the zone of saturated rock where it can then more vertically and laterally by this process, very slow movement
What can groundwater flow feed
Rivers through long periods of drought
What is an aquifer
Rocks that are able to store a lot of water, especially if they are porous
What do the sum of all the movements and stores of water add up to form
The drainage basin hydrological cycle
How do rivers transfer water
By channel flow
What is the amount of water that leaves the drainage basin through channel flow called
What is the fastest movement of water and why
Along the surface becsuse there are relatively few obstacles slowing it down
Why do urban surfaces have especially fast water movement
Because they are often designed to move the water quickly by having strategically placed slopes and very smooth surfaces
What are the differences of throughflow in woodlands compared to clay soil
Under woodlands there are many channels created by roots as well as burrowing animals and these allow relatively free movement. Whereas clay soils retain water, hindering ant movement, they can dry out from the surface down before they allow any horizontal movement.
How long can groundwater be held and why
A millennia because once the waters in the docks the rate of transfer slows considerably
What are the varying timescales of water movements
LOOK AT SFUDENT NOTES
What is the net transport from ocean to land with about the same amount returning by the rivers to the ocean
What indicated a considerable recirculating of water over land
The amount of precipitation over the continents is almost three times as high than that over oceans
What does the recirculation of water over land have
A marked annual cycle as well as having large variations between continents
When is the recirculation of water over land larger
During the summer and for tropical land areas
Where does most of the water from the Pacific Ocean recirculate between
Different parts of the Pacific itself with there being little net transport towards land
The pattern of water exchange between ocean and land is different in which oceans
The Atlantic and Indian Ocean
What fraction of the total net transport of water towards continents come from the Atlantic Ocean
Where does 2/3s of the total net transport of water towards continents come from
The Atlantic Ocean with the rest essentially from the Indian Ocean
Where does most of the continental water for North and South America, Europe and Africa emanates from and is returned to
From the Atlantic Ocean and returned to there by rivers
What is known as the water balance/budget
Within a drainage basin, the balance between inputs and outputs is known as this
When do rivers occur
Only if the stores are able to release water, there is a direct precipitation, or there is overland flow into the river
As a river moves downstream, what are they fed by
Their tributary streams
What is the rivers regime
Discharge levels rise and fall often showing an annual pattern - a rivers regime
What can the water balance be calculated by
Precipitation (P) = Discharge (Q) + Evapotranspiration (E)
+/- changes in storage (S)
What are the two most important parts of the water balance
Precipitation and 'potential' evapotranspiration
What is evapotranspiration closely related to
The prevailing temperature, the warmer it is the higher the evapotranspiration. It is often the case that the temperature, and so the atmospheres ability to hold water vapour, is greater rhan the amount of water available
What is potential evapotranspiration
The amount of water that could be evaporated or transpired (or both) from an area if there was sufficient water available
What is the relationship between precipitation and potential evapotranspiration for a place over a year illustrated by
A soil moisture graph
What does a soil moisture graph look like for eastern England
During Half of October, November, December, January and half of February: precipitation is higher than potential evapotranspiration and so the soil water store is fully recharged.
During other half of Febuary, March and April: precipitation is greater than PET so all space in the soil has been filled so it is in surplus, groundwater recharged and overland flow can occur leading to flooding.
During May, June, July: as it warms up PET exceeds precipitation so the water store is being used by plants (utilisation)
During August, September and the first half of October: there is a deficit of soil water. Plants either wilt or have adaptions fo survive dry conditions as the PET is falling rapidly.
PET rises to a peak in July and falls down again.
Precipitation gets only a little less during the peak of PET.
Why do soil moisture graphs vary significantly
It depends on the climate
What does a soil moisture graph look like for an equatorial area
The rainfall has two marked maxima. Because the temperatures vary very little throughout the year the PET stays relatively constant. High rain fall fills the soil stores rapidly. In short time between the rainfall maxima, soil water does not go into deficit and so rivers and plants have a source of water all year round. High potential of flooding between Februrary and June and again in August to November.
Example of Equatorial area
Soil moisture graph for a tropical wet/dry climate
During the rainy season (July to October) the soils are recharged until there is a surplus. This does not last long when rain stops. There is a short period of utilisation but from December to July the soil is dry. River levels fall with many drying up all together.
Example of a tropical wet/dry climate
Navrongo, Northern Ghana
How have vegetation adapted to fit sigh the tropical climate soil moisture graphs
Vegetation has adapted to this seasonal water supply by evolving characteristics to enable it to survive drought.
How have humans adapted to fit with tropical climates soil moisture graphs
By following migrating herds of animals that have themselves migrated flowing the rains north and south
How is river flow studied
By measuring the discharge of a river
How do you calculate river discharge
Multiplying the cross-sectional area of the river by its velocity at the measuring point
What is river discharge measured by
M^3/secs or cumecs
What does bankfull mean
The maximum discharge that a river channel is capable of carrying without flooding
What is the base flow
This represents the normal day-to-day discharge of the river and is the consequence of slow moving soil throughflow and groundwater seeping into the river channel
What is the discharge of a river
The amount of water in a river flowing last at a particular point
What is the lag time
The time between the peak rainfall and peak discharge
What is the peak discharge
The point on a flood hydrograph when river discharge is at its greatest
What is a storm flow
Discharge resulting from storm precipitation involving both overland flow, throughflow and groundwater flow
What is a storm hydrograph
A graph of discharge of s river over the time period when the normal flow of a river is affected by a storm event
What is discharge the combined result of
The many climatological and geographical factors which interact within a drainage basin
What is the knowledge of discharge very important in
The assessment and management of water resources (including irrigation provision), the design of water related structures (reservoirs, bridges, flood banks, urban drainage schemes' sewage treatment works) and flood warning and alleviation schemes.
It can also help in developing hydroelectric power and protecting both the ecological health of watercourse and wetlands and their amenity and recreational value.
Why is keeping records of river flows important
Climate change is expected to impact very unevenly on river discharge patterns so keeping records is key go identify, quantify and interpret hydrological trends
What will identifying hydrological trends help in
The development of more effective ways of dealing with future flood and drought episode
How many measuring stations does the UKs dense gauging station network have
1,500 supported by secondary and temporary monitoring sites
Why is such a large number of measuring stations of discharge in the UK needed
Because the UK contains a multiplicity of most small river basins and is diverse in terms of its climate, topography, geology, land use and patterns of water usage
What is a way to measure the discharge of a river
A weir of known shape
How does a weir of known shape measure discharge in a river
The amount of water flowing over the weir is proportional to the depth of water at the weir. The depth of the water flowing over the weird can be converted into discharge using an equation
What is a river regime
The variability in its discharge throughout the course of a year in response to precipitation, temperature, evapotranspiration and drainage basin characteristics
How many river systems are within the UK
What are river systems extremely sensitive to
Climatic variation, Land use change and water abstraction. They are also greatly influenced by the landscapes through which they flow
What do Uk rivers range from
Mountain torrents draining areas receiving up to five metres of rains year, to much more placid groundwater-fed streams supported by much lower rainfall in parts of southeast England
How is UK rainfall distributed throughout the year
Fairly evenly distributed with a slight Autumn/ winter maximum, particularly in the west. Late summer/early autumn minimum becsuse of temperate variations
What does seasonal variations in temperature and sunshine amount mean
That evapotranspiration loses are heavily concentrated in the summer
Where does the Mohawk River flow and what is its river regime
Out of the mountains of upper New York State. Here the extremely snowy, cold and long winters and drier, hot summers lead to a different pattern of river discharge
What does the river regime of the river Avon, Bath look like
Highest discharge in winter, slightly higher rainfall, much less evapotranspiration.
Discharge falls through spring and early summer as plants take up more water and leaves grow; evapotranspiration increases.
Late summer minimum, highest temperature and plants in full leaf increase evapotranspiration.
Flow rises in the autumn as leaves are lost and temperature fall. Often an increase in wind as well.
What has a major influence on flow patterns of river
The geological characteristics
Why do neighbouring catchments in the Thames basin have different river regimes
Although they experience almost identical climatic conditions, the flow regime for the Lambourn (which is supplied by springs from the underlying chalk) is much less variable than that for the Ock which drains an impermeable clay catchment
What does the river regime for the Mohawk River (New York) look like
Very low temperatures and long winters lead to moderately low discharge becsuse much of the precipitation remains on the ground as snow. Sometimes the river freezes.
Spring maximum discharge caused by snow melting in the Adirondak and Catskill mountains.
Summer temperatures averaging 26.5*C lead to high evapotranspiration rates.
Increasing rainfall from extra-tropical cyclones moving up from Gulf of Mexico increase discharge.
What do rainfall events mean for the pattern of river flows
They are not smooth
Why do some hydrographs have a jagged appearance
Becsuse each time it rains then the river responds quickly
What can be studied using a hydrograph
Each sudden rise and then subsequent fall in discharge
What are storm hydrographs
Graphs of discharge over the time period when the normal flow of river is affected by a storm event
Why are storm hydrographs important
Because they can predict how a river might respond to a rainstorm which can help in managing the river
What does are the components of a storm hydrograph
The base flow which is the amount of water that would be in the river without the addition of the storm water.
Rainfall event and then the Peak rainfall.
The rising limb indicates how quickly a river responds to a storm.
the Peak discharge.
Bankfull discharge, above this line the river will begin to overflow and from this line to the peak discharge is the amount of flood water.
What does the slow movement of water mean for a river
The changes in its discharges are small
What does the fast movement of storm water mean for a river
The river begins to be fed by much more fast-moving water and the discharge rises
When all storm water has passed through a river what happens
The river returns to its base flow
What is a flashy hydrograph
Hydrographs that have a short lag time, high peak discharge, steep rising and falling limbs
What are the physical factors that determine if it's a flashy hydrograph
Drainage basins that are more circular in shape lead to more flashy hydrographs than those that are long and thin.
Drainage basins with steep sides tend to have flashier hydrographs than gently sloped river basins.
Basins with a high drainage density.
If drainage basin is already saturated by antecedent rainfall.
If soil or rock type within the river basin is impermeable.
Less vegetation cover.
Amount and intensity of precipitation.
Large drainage basins catch more precipitation so have a higher peak discharge compared to smaller basins.
Why are more circular drainage basins likely to have a more flashy hydrograph
Because each point in the drainage basin is roughly equidistant from the measuring point on a river
Why are more steep sided drainage basins likely to have flashier hydrographs
Water flows more quickly on the steep slopes, whether as throughflow or overland flow and so gets to the river more quickly
What does high drainage density mean
They have a lot of streams acting as tributaries to the main river
Why are high drainage density drainage basins likely to have flashier hydrographs
All the water arrives at the measuring station at the same time becsuse of the surface streams acting as tributaries
Why are already saturated drainage basins likely to have flashier hydrographs
Overland flow increases because infiltration capacity has been reached. Since overland flow is the fastest of transfers the lag time is reduced meaning peak discharge is higher
Why are impermeable drainage basins likely to have flashier hydrographs
Overland flow will be higher. Throughflow and infiltration will be reduced meaning a flashy hydrograph, or if the surfaces are baked hard by the sun during a long period of dry weather or frozen surfaces from cold weather.
Example of impermeable surfaces
Clay soils or shale rocks
Why do drainage basins underlaid by sandstone have a subdued hydrograph
Because it is permeable so the water soaks into the porous rock
What are the two types of hydrograph
How does vegetation have an affect on the shape of a hydrograph
Thick vegetation will have a significant effect. This would intercept precipitation, holding the water on its leaves slowing the movement of rainwater to the ground and so to river channels. Water is also lost due to evaporation and transpiration from vegetation surfaces reduces how much water gets to the river. This subdues the storm hydrograph, increasing lag time and reducing peak discharge.
How does the amount of precipitation affect storm hydrographs
Heavy storms with a lot of water entering the drainage basin over a short time result in higher discharge.
How does the type of precipitation affect storm hydrographs
Lag time is likely to be greater if the precipitation is snow rather than rain this is because snow takes time to melt before the water enters the river channel. When there is rapid melting of snow the peak discharge could be higher
What are the human factors that affect the shape of a hydrograph
Agriculture: ploughing, terracing on hillsides, grass crops, large numbers of animals.
Growth of urban areas and other large impermeable surfaces.
Some soft engineering flood managment schemes.
How does deforestation determine the shape of the hydrograph
It reduces interception rates allowing rainwater to hit the surface directly and the lack of vegetation roots reduce infiltration rates. These lead to rapid overland flow and flashy hydrographs.
Also exposes the soil to erosion which leads to sedimentation of the channel which reduces the bankfull capacity of a river and leads to a greater chance of flooding.
How does afforestation determine the shape of a hydrograph
It has the opposite effect of deforestation making it a useful flood prevention measure. It increases interception and infiltration which slows the process of water to the river channel and subdues any changes in discharge
How does ploughing affect the shape of a hydrograph
It breaks up the top soil and allows greater infiltration, subduing hydrographs. This can be enhanced by contour ploughing as the furrows can act as small stream channels and lead to flashier hydrographs. Ploughing set soils can cause impermeable smears in the subsoil called plough pans which inhibit percolation leading to greater surface flows.
What is contour ploughing
Furrows are created that run directly down slope
How does terracing on hillsides change the shape of a hydrograph
They stop the movement of water downhill and subdues hydrographs
How do grass crops change the shape of a hydrograph
They increase infiltration and lead to subdued hydrographs
How do large numbers of animals affect the shape of a hydrograph
They impact soils leading to overland flows
What are some settlements built on that exacerbates the chance flashy hydrograph
What does urban growth lead to
The expansion of built-up, impermeable surfaces such as roads, car parks, shopping centres.
How does growth of urban areas and impermeable surfaces affect the shape of a hydrograph
Most settlements are designed to transfer water as quickly as possible away from human activity to the nearest river.
Impermeable surfaces due to the increase in the built environment.
Some settlements are built on flood plains.
How is the transfer of water away from urban environments to rivers done
Through road camber, building design and drainage systems.
In many cities in the UK what has there been a continued loss of
Front gardens in favour of paved drives
Why was a vegetated garden equivalent to 300ha/year lost in London between 1998-2006
Due to the growing number of two-three car families
Why are rivers altered in urban areas
To move the water rapidly away from the urban area
What do some soft engineering flood managment schemes attempt to reduce
Flashiness in a rivers hydrograph
How does water abstraction alter the shape of a hydrograph
It reduces base flow so more water must reach the channel before it reaches bankfull capacity
Where contains the worlds largest continuous tropical forest and Savannah ecosystems
Tropical South America
What do deforestation and forest degradation result in
A complex set of changes to streams of all sizes
When forests are removed what are the knock on effects
The new vegetation has fewer leaves and shallow roots.
Means it uses less water than the forest it replaces.
Results in less water evaporating from the land surface to be returned to the atmosphere; more water runs off the land and stream flow is increased.
What does the amount of change that occurs because of deforestation depend on
Local conditions including the amount of rainfall, how much of a watershed is deforested, topography, soils and the land use after deforestation
What have studies shown about the effect of a deforested basin
Little effect with less than 20% of a basin deforested but a large increase with 50-100% of a basin deforested. These changes occur at the local scale, but rivers of all sizes are affected when deforestation is extensive.
What does the effect of localised deforestation suggest about the climate, land surface and water cycle
If deforestation does not decrease rainfall via atmosphere feedbacks, discharge with likely be significantly increased through other parts of the rainforest.
If rainfall does decrease via atmospheric feedbacks the resulting decrease in river discharge may be greater than the chanted without feedbacks.
Changes in water resources caused by atmospheric feedbacks will not be limited to those catchment areas where deforestation has occurred but will be spread unevenly throughout the whole Amazon basin by atmospheric circulation.
What does subsurface drainage remove
Excess water from the soil profile
How is subsurface drainage usually carried
Through a network of perforated tubes installed 60-120cm below the soil surface. These tubes are commonly called 'tiles' because they were originally made from short lengths of clay pipes known as tiles
How do tiles work as subsurface drainage
Water would seep into the small spaces between the tiles and drain away.
When water table in the soil is higher than the tile, water flows into the tubing, either through holes in the plastic tubes or through the small cracks between adjacent tiles. This lowers the water table to the depth of the tiles over the course of several days.
Why is the most common type of 'tile' used in surface drainage
Corrugated plastic tubing with small perforations to allow water entry
What do drain tiles allow excess water to do
Leave the field
WhT happens when the water table has been lowered to the elevation of the tiles
No more water flows through the tiles
In most years in the UK, what months have drain tiles not flowed between
June and October
What is the effects of extensive deforestation on the water cycle
Positive feedback can occur. During localised deforestation much of the water leaves the area in the river channel rather than being recycled continuously between the forest and the atmosphere. Once the water has left the area there is less water valour available in the atmosphere for precipitation and so precipitation levels fall. Less water gets to the river channel and the flow is reduced.
When is agricultural drainage very good
For moderately to poorly drained soils
What does soil drainage help increase
The productivity of the field and improves the efficiency of growers
What did a study by Ohio State university demonstrate
That for every dollar spent on drainage the growers got back between $1.20 and $1.90 when growing corn and soybeans
What are 5 advantages of draining marginal farmland
The build up of an improved soil structure.
Increased aeration increase the ease with which the soil can be warmed.
Heavy machinery can work on the land.
Large numbers of animals can graze on the land.
How is the build up of an improved soil structure an advantage to draining marginal farm land
It makes it more friable and easier to work. It
makes it easier to achieve greater root penetration, enabling roots to travel faster and further.
How is the improved aeration an advantage to draining marginal farm land
It makes the conditions more favourable for microorganisms to thrive. This increase the rate at which organic matter is broken down into humus and plant nutrients are mineralised into an available form. Also provides the necessary supply of air for root cell respiration.
How is the ease of which the soil can be warmed an advantage to draining marginal farm land
This can make possible earlier sowing of seeds, with greater likelihood of improved germination
How is the ability of heavy machinery working on the land and large number of animals allowed to graze an advantage to draining marginal farm land
There's no danger of compaction (which would lead to increased overland flow)
What are the 3 disadvantages of draining marginal farmland
The insertion of drains artificially increase the speed of throughflow in the soil.
The dry topsoil can be subject to wind erosion if not properly protected.
How is the increased speed of throughflow in the soil a disadvantage of draining marginal farmland
Much more water reaches watercourses more quickly than before drainage. This can increase the likelihood of flooding and increase the range of flows in the river.m
Before the drainage of many flood plains in the UK from the eighteenth century onwards, what was the annual flow regime of rivers
More even due to rivers being more navigable then
How is the dry top soil being subject to wind erosion a disadvantage of draining marginal farmland
Top soil can dry out in periods of low rainfall. Dry soil can be blown away. Nitrates from fertilised are easily carried and can get into water courses and wetlands
What has soil loss by wind erosion been mainly documented for
Sandy and peaty soils
Where has soil loss by wind erosion been mainly documented
In the eastern and middle counties of England, especially arable fields in the East Midlands and East Anglia
What is the area of England and Wales subject to
Small wind erosion in some areas which get more severely eroded than by water erosion
What is the estimate for wind erosion rate in England and Wales
0.1 to 2tonnes/ha/year, although maximum values for fields can be one or two orders of magnitude higher
How is nitrate loss a disadvantage of draining marginal farmland
It can lead to eutrophication. Water draining from fields finds its way into local water courses. There is enriched ponds with nitrogen of phosphorus. It causes algae and higher forms of plant life to grow too fast. This disturbs the balance of organisms present in the water and the quality of the water concerned
What is a way to overcome the problems associated with draining marginal farm land
To use controlled drainage as this keeps the water table high during the off-season when crops are not growing.
What does a high water table increase
The rate of denitrification and reduces nitrate loss to the environment
What is denitrification
A process that converts nitrate to harmless nitrogen gas as soon as the saturated soil warms up in the spring
When can problems with the demand for water occur
When the demand exceeds the amount available during a certain period
Where does water deficit usually occur
In areas with low rainfall and high population density, and/ or in areas with intensive agricultural of industrial activity
In Europe what is the dominant source of fresh water
What are the consequences of water being pumped from beneath the ground faster than it is being replenished
Sinking water tables, empty Well's, higher pumping costs and in coastal areas the intrusion of salt water from the sea which degrades the groundwater
Where is saline intrusion into groundwater widespread along
The Mediterranean coastlines of Italy, Spain and Turkey because the demands of tourist resorts are the major cause of over-abstraction
In Malta, why has the country has to resort to expensive desalination plants
Because most groundwater can no longer be used for domestic consumption or irrigation because of saline intrusion
Why can sinking water tables make rivers less reliable
Many river flows are maintained in the dry seasons by springs that dry up when water tables fall
What does groundwater help to sustain
Surface reservoirs of water such as lakes and wetlands that are often highly productive ecosystems and resources for tourism as well as leisure activites
What is the main cause of groundwater over-exploitation in agricultural areas
How is the water within the chalk aquifer of southern England replenished
By rainfall that lands on the exposed chalk hills of the North and South Downs and Chilterns
When does recharge of the chalk aquifer talk place in southern England
During the winter months when potential evapotranspiration is low and soil moisture deficits are negligible
How do groundwater amounts vary seasonally in southern England
Levels rising from Autumn through winter into spring. During the summer months PET generally exceeds rainfall, soil moisture deficits build up and little percolation takes place
In the summer how does water still leave the chalk in southern England
From springs as well as by abstraction from bore holes
Why is the pattern of water abstraction from the chalk of southern England not constant
Since rainfall varies both over time and locations
What can rivers that are fed by groundwater from chalk aquifers in southern England have
Intermittent sections. These streams, often referred to as 'bournes', are a natural characteristic of chalk downlands
How do the position of springs feeding rivers fed by groundwater from chalk aquifers in southern England differ throughout the year
They are at greater altitude in winter and spring
What could happen in southern England if there are one or more dry winters when the effective rainfall available for recharge is low
These rivers can dry up all together
Where have some of the most actuate problems with over-abstraction been found
In chalk stream systems, where up to 95% of the flow is derived from aquifers
What do the catchments of chalk streams provide
Underground reservoirs of generally high quality groundwater which can be abstracted for public supply
What has abstraction for public water supply and industry dramatically reduced
The flow in many chalk streams, and in some cases, completely dried up sections of these important rivers, particularly during dry summers when public demand is at its highest.
What does water abstraction have an economic impact on
Local communities, resulting from the inability to fish, enjoy river views due to encroaching vegetation or undergo other recreational activities
How does the subsurface geology of the London basin store water
Chalk layers form a syncline beneath the London area.
Precipitation on these exposed chalk hills soak into the porous chalk where it is stored and released naturally at springs where it is in contact with either Greensand or Palaeogene rocks.
Throughout history in London how has water been abstracted
From wells and boreholes that penetrate down into the chalk
In the London basin, during the ninteeth century and first part of the twentieth century, what has been increasingly exploited
The chalk-basal sands aquifer
Why has the chalk-basil sand aquifer in the London basin been increasingly exploited
As a result of increased industrialisation and the associated development of groundwater sources
When was the peak of water abstraction in the London basin
During the peak of water abstraction of the London basin in the 1960s how much did the groundwater levels beneath central London dropped to
88m below sea level, creating a large depression in the water table
Where did a smaller cons of depression develop becsuse of the exploitation of the London basin in 1960
The river Roding In Essex
Since the mid-1960s what happened to industries such as brewing in central London
They were relocated or closed down
In the 1960s what did economic activity turn more to
Service industries and commerce than heavy industry
What did the subsequent reduction in abstraction because of industries being closed in London in 1960s result in
Groundwater levels recovering by as much as 3m/year in places by the early 1990s, leading to a gradual rebound of the water table
What was the threat posed becsuse of the recovering groundwater levels in the London basin in 1990
Rising groundwater to structures in the London basin such as the London Underground and building foundations
What did the threat of rising groundwater to structures in the London basin lead to
The implementation of the General Aquifer Research, Development and Investigstion Team (GARDIT) strategy to control levels
Why does 2000 provide a useful baseline year for comparisons for the London Basin
Because as a result of careful management of both abstraction and artificial recharge the rise in groundwater that the GARDIT strategy was designed to arrest had largely been achieved by 2000
What were the four differences in groundwater levels for January 2000 and January 2014 for the London Basin
Levels in west London have risen due to limited abstraction, 4 to 8 metres since 2000 which has levelled off in recent years.
Central and easy London levels have fallen in the order of 5-7m since 2000 as a result of increased abstraction.
Levels have fallen more than 2m across much of south London, with falls of up to 12m concentrated around the many large public water supply abstractions.
East London, there are chalk outcrops around the River Thames from Greenwich to Woolwich, there's a risk of saline intrusion. When groundwater levels near the river are lower than the water levels in the Thames, saline river water can enter the chalk aquifer.
Where is carbon found
In all life forms in addition to sedimentary rocks,diamonds, graphite, coal and petroleum
What is the carbon cycle
Complex process carbon undergoes as it is transformed from organic carbon like plants and trees to inorganic carbon and back again
Why is it that the carbon cycle means we can study energy flows on earth
Most of the chemical energy needed for life is stored in organic compounds as bonds between carbon atoms and other atoms
What are 5 important examples of carbon compounds
What is carbon dioxide (CO2)
Gas found in the atmosphere, soils and oceans
What is methane (CH4)
Gas found in the atmosphere, soils and oceans and sedimentary rocks
What is calcium carbonate (CaCO3)
Solid compound found in calcareous rocks, oceans and in the skeletons and shells of ocean creatures
What are hydrocarbons
Solids, liquids or gases usually found in sedimentary rocks
What are bio-molecules
Complex carbon compounds produced in living things. Proteins, carbohydrates, fats and oils, and DNA are examples
Why do we study carbon dioxide
It is thought to have a profound effect on climate
Why is it difficult to separate a natural carbon cycle from one that is affected by human acirivrtn
Human activity and associated emissions of carbon dioxide (anthropogenic CO2) fundamentally affect the carbon cycle and so affect climate
What is the primary source of carbon
The earths interior as it was stored in the mantle when the earth was formed
Where does carbon dioxide in the earths interior escape from
Constructive and destructive plate boundaries and hot-spot volcanoes
Where is much of the CO2 released at destructive plate margins derived from
The metamorphism of carbonate rocks sub-ducting with the ocean crust
What happens to carbon in the atmosphere when it’s released from earths mantle
Some remains in the atmosphere as CO2.
Some dissolves in the ocean.
Some is held as biomass in living or dead and decaying organisms.
Some bound in carbonate rocks.
How is carbon removed into long-term storage
By burial of sedimentary rock layers, especially coal and black shales and carbonate rocks like limestone (calcium carbonate)
What carbon does black shale store
Store organic carbon from undecaying biomass
What is the unit to measure the amount of carbon in a store
(1 Gt amounts to 1 billion tonnes)
Who measures carbon using a gigatonne
The United Nations climate change panel and the Intergovernmental Panel on Climate Change (IPCC)
How is flux of carbon within the cycle measured
Gigatonnes of carbon per year (GtC/year)
What is anthropogenic Co2
Carbon dioxide generated by human activity
What is the biosphere
Total sum of all living Matter
What is carbon sequestration
Capture of carbon dioxide from the atmosphere or capturing anthropogenic carbon dioxide from large-scale stationary sources like power plants before it is released from the atmosphere. Once captured, the carbon is put into long term storage
What is a carbon sink
A store of carbon that absorbs more carbon than it releases
What is a greenhouse gas
Any gaseous compound in the atmosphere that is capable of absorbing infrared radiation, thereby trapping and holding heat in the atmosphere
What’s the lithosphere
The crust and the uppermost mantle; this constitutes the hard and rigid outer layer of the earth
What is weathering
The breakdown of rocks in situ by a combination of weather, plants and animals
What does the lithosphere include
The crust and the uppermost mantle; this constitutes the hard and rigid outer layer of the earth
What is the pedosphere
The uppermost part of the lithosphere, the layer that chemically reacts to the atmosphere, hydrosphere and biosphere through the soil
Examples of inorganic deposits in the lithosphere
Fossil fuels like coal, oil and natural gas, shale (kerogens) and carbonate-based sedimentary deposits like limestone
Examples of organic forms of carbon in the lithosphere
Litter, organic matter and humic substances found in soils
What 4 stores is carbon in the lithosphere distributed between
Marine sediment and sedimentary rock.
Soil organic matter.
Fossil fuel deposits.
How much carbon is stored in marine sediments and sedimentary rock
Up to 100 million GtC
How much carbon is stored in soil organic matter
Between 1,500 and 1,600 GtC
How much carbon is stored in fossil fuel deposits
Approximately 4,100 GtC
What is peat
Accumulation of Dead but undecayed organic matter found in boggy areas called peatlands or mired
How much carbon is stored in peat
Approximately 250 GtC
Who has attempted to collate measurements of the amount of carbon in the oceans
The Global Ocean Data Analysis project (GLODAP)
How do GLODAP try to measure the amount of carbon in the ocean
Using data from respect ships, commercial ships and buoys. The measurements come from deep and shallow waters from all the ocean - some variations in the results and figures can into be an approximation
What can the oceanic store be divided into
The surface layer
Living organic matter
What is the surface layer oceanic stores
Sunlight penetrates so that photosynthesis can take place
How much carbon is stored in the euphoric zone of oceanic stores
Approx 900 GtC
What is the intermediate zone of oceanic stores
The twilight zone.
The deep layer of water
How much carbon is stored in the twilight zone
Approx 37,100 GtC
What is the living organic matter in an oceanic store
Fish, plankton, bacteria etc
How much carbon is stored in organic matter in oceanic stores
Approx 30 GtC in living organic matter and 700 GtC in dissolved organic matter
What is the total amount of stored oceanic carbon
Between 37,000 and 40,000 GtC
How does carbon get locked up for millions of years in the hydrosphere
When organisms die, their dead cells, shells and other parts sink into deep water. Some material sinks right to the bottom and where it forms layers of carbon rich sediment. Over millions of years chemical and physical processes may turn these sediments into rocks because of burial by overlying layers of sediment. It can eventually turn these sediments into sedimentary limestone
What is the total amount of carbon stored in the terrestrial biosphere
What does the distribution of carbon in the terrestrial biosphere depend upon
Examples of how much of the total terrestrial carbon is stored in different ecosystems
Temperature grassland: 10%
Tropical savanna: 8%
Tropical rainforest: 20%
Temperate forests: 7%
Boreal forests: 26%
What are the 5 stores of carbon in the terrestrial biosphere
What percentage of the carbon in the earths biosphere is stored in plants
Where is much of the carbon in plants stored
Directly in the tissues of the plants. However, although the exposed part of the plant is the most visible, the below ground biomass (root system) must also be considered
What does the amount of carbon in the biomass of plants vary between
35 and 65% of the dry weight
What does the amount of carbon in plants vary depending on
Location and vegetation type
Where does an estimated half of all carbon in forests occur in
Where does an estimated 1/3 of carbon in forests occur
What are the two largest forest reservoirs of carbon and what percentage of the worlds forest carbon do they contain
Vast expanses in Russia which hold roughly 25% of the worlds forests carbon and the Amazon basin which contains about 20%
What is plant litter
Fresh, undecomposed and easily recognisable (by species and type) plant debris which can be anything from leaves, cones, needles, twigs, barks, seeds/nuts etc
What is plant litter directly affect by
The type of ecosystem
What percentage of litter in forests does leaf tissue account for
What does woody litter tend to increase with
The forests age
Why is the annual fall of litter low in grass land
There is very little above ground perennial tissue
What does soil humus originate from
What is humus
A thick brown or black substance that remains after most of the organic litter has decomposed
How does humus get dispersed throughout the soil
By soil organisms such as earthworks
Approximately what percentage of carbon in all types of forests is stored in biomass
Approximately what percentage of carbon in all types of forests is stored in soil
What are the different types of forest
In tropical forests what approximately what percentage of carbon is stored in biomass and in the trees
50% in biomass and 50% in soil
Altogether what does the worlds soil hold more of than vegetation
Carbon (2,500 GtC)
How much carbon is stored in organic soil
How much carbon is stored in inorganic soil
What does inorganic carbon component consist of
Carbon itself as well as carbonate materials such as calcite, Dolomites and gypsum
What is the amount of carbon found in living plants relatively small in comparisons to
That found in soil (560 GtC)
Approximately, how much larger is the soil carbon pool compared to the atmospheric pool
3.1 times larger
What is a larger carbon store than soil
How does peat form
In wetland conditions, where almost permanent water saturation obstruct flows of oxygen from the atmosphere into the ground. This created low oxygen anaerobic conditions that slow down rates of plant litter decomposition
How much of the land and freshwater surface of the planet does peatland cover
Over 4 million km^2 or 3%
Where does peatland occur
All continents, from the tropical to boreal and arctic zones and from sea level to high alpine conditions
How much carbon does peat store
What are animals important for in the carbon cycle
The movement of carbon throughout the cycle
When was the Cambrian period
Around 500 million years ago
When was the quaternary glaciation
Last 2 million years
What were atmospheric carbon dioxide levels in the Cambrian period
7,000 ppm (parts per million), very high values
What did the atmospheric carbon dioxide levels drop to during the quaternary period
It sank to about 180 ppm
Today, what are the estimated atmospheric carbon dioxide levels
They vary from 720GtC to 800GtC (400ppm)
What percentage of the earths atmosphere does carbon make up
Why is the present concentration of CO2 the higher than it has been for at least 800,000 years and in all likelihood the last 20 million years
Due to human activities particularly deforestation and the burning of fossil fuels
What does Co2 play a vital role in doing
Regulating the earths surface temperature
What has the recent phenomenon of global warming been attributed to
Increasing industrial CO2 emissions into earths atmosphere
Where has atmospheric carbon in measured at since 1958
Mauna Loa Observatory (MLO) in Hawaii
Why is monitoring atmospheric carbon at MLO ideal
It has undisturbed air, it’s a remote location and there’s minimal influences of vegetation and human activity
What is the Mauna Loa Observatory part of
The American National Oceanic and Atmospheric Administrations (NOAA)
What do the measurements made by the MLO sho
The global annual mean concentration of Co2 in the atmosphere has increased markedly since the industrial revolution, from 280ppm to 317.7ppm in 1958 to 400.3 in 2015
What is the graph depicting changing carbon levels in the atmosphere called
The Keeling Curve
Who was one of the first scientists to gather evidence that linked fossil fuel emissions to rising levels of carbon dioxide
What can be used to gather data for what the concentration of carbon was in the past
Co2 trapped in ice cores from Antarctica and Greenland can be used to give a ‘proxy’ measure of the concentration in the atmosphere at the time the snow was laid down
When did the daily average measurement at MLO first exceed 400ppm
What is the rate carbon is increasing in the atmosphere as measured at MLO
When is a carbon store considered a net carbon sink
If more carbon enters a store than leaves it
When is a carbon store considered a net carbon source
If more carbon leaves a store than enters it
What is the geological component of the carbon cycle
Where it interacts with the rock cycle in the processes of weathering, burial, subduction and volcanic eruptions
In the atmosphere, how is carbon dioxide removed
By being dissolved in water and forming carbonic acid (H2CO3)
How does chemical weathering occur
Carbon dioxide in the atmosphere is dissolved in water forming carbonic acid. As the weak acid water reaches the surface as rain, it reacts with minerals at the earths surface, slowly dissolving them into their component irons
What are component ions broken down by chemical weathering carried in
Surface waters like streams and rivers and eventually they are carried to the ocean
When component ions are transported to the ocean what can happen
They settle as minerals like calcite, a form of calcium carbonate
What is calcium carbonate precipitated from
Calcium and bicarbonate ions in sea water by marine organisms like foraminifera, coccoliths or molluscs
How does coral extract calcium carbonate from sea water
They live and eventually die in the same location. Dead coral is built upon by later generations of live coral and so it too becomes buried. The carbon is now stored below the sea floor in layers of limestone
What can expose buried limestone on the sea floor
Example of tectonic uplift exposing limestone
In the Himalayas where some of the worlds highest peaks are formed of material that was once at the bottom of the sea
What do tectonic forces cause
Plate movement to push the sea floor under continental margins in the process of subduction
What would carbon rich material on the sea floor be classed as
The carbonaceous sea-floor depositors
How can carbon dioxide that was once trapped on the sea floor return to the atmosphere
The carbonaceous sea-floor deposits are pushed deep into the earth where they heat up, eventually melt, and fan rise back up to the surface through volcanic eruptions or in seeps, vents and Co2 rich hot springs
What do weathering, burial, subduction and volcanism control
Atmospheric carbon dioxide concentrations over time periods of hundreds of millions of years
What is photosynthesis
Using energy from sunlight to combine carbon dioxide from the atmosphere with water to form carbohydrates to store energy.
What’s a by-product of photosynthesis
What turns carbon into organic matter by the process of photosynthesis
Tiny marine plants (phytoplankton) in the sunlit surface waters (the euphotic zone) of the oceans as well as all terrestrial plants, photosynthetic algae and bacteria
What is the equation for photosynthesis
Co2 + H2O + sunlight -> carbohydrate + oxygen
How does respiration occur
Plants (and photosynthetic algae and bacteria) use the stored carbohydrates as an energy source to carry out their functions
What do consumers like animals and bacteria get their energy from
Excess biomass as some of the carbohydrates remain as biomass (the bulk of the plant etc)
When oxygen from the atmosphere is combined with carbohydrates what happens
It liberated the stored energy
What is the equation for respiration
Oxygen + carbohydrate -> energy + water + carbohydrate
What is photosynthesis the opposite of
Respiration - photosynthesis removed Co2 from the atmosphere and replaces it with O2.
Respiration takes O2 from the atmosphere to be replaced with Co2.
Why do the processes of respiration and photosynthesis not balance the atmosphere
Not all organic matter is oxidised.
Some is buried in sedimentary rocks.
What is the result because of the imbalance between photosynthesis and respiration
Over geological time, there has been more oxygen put into the atmosphere and carbon dioxide removed by photosynthesis than the reverse
What does decomposition include
Physical, chemical and biological mechanisms that transform organic matter into increasingly stable forms. The broad definition includes physical break up of organic material by wet-dry, shrink-well, hot-cold and other cycles
What biological mechanisms are included in decomposition
Animals and plants. Feeding and digestion aided by the catalytic effect of enzymes
What are some important physical mechanisms that cause decomposition
Leaching and transport in water
What does chemical transformations in decomposition include
Oxidation and condensation
What carries out the decomposition process
What is the role of decomposers
To break down the cells and tissues in dead organisms into large bio molecules and then break those bio molecules down into smaller molecules and individual atoms
What does decomposition ensure
That the important elements of life - carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, magnesium can all be continually recycled into the soil and made available for life
What does a plant need to make its DNA molecules
A supply of nitrogen, phosphorus and sulphur atoms from the soil in addition to the carbon, hydrogen and oxygen atoms it obtains through photosynthesis
What is plant growth limited by
The availability of nitrogen, phosphorus, magnesium and sulphur atoms in addition to the availability of carbon dioxide, water and light energy
What is vertical deep mixing
Important movement of CO2 in the ocean.
It occurs when warm water in oceanic surface currents is carried from the warm tropics to the cold polar regions.
Here the water is cooled, making it dense enough to sink below the surface layer, sometimes all the way to the ocean bed.
When cold water returns to the surface and warms up again, it loses carbon dioxide to the atmosphere.
What does vertical circulation in the ocean (vertical deep mixing) ensure
That carbon dioxide is constantly being exchanged between the ocean and the atmosphere
What leads to vertical deep mixing
Water is able to dissolve CO2. There is a negative correlation between temperature of the water and the amount of CO2 that can be dissolved. This leads to vertical deep mixing.
What does the virtual circulation of carbon in the ocean act an
An enormous carbon pump
What does the carbon pump in the ocean do
Gives the ocean a lot more carbon than it would have if the surface water was not being constantly replenished
What is the oceanic carbon pump
The concept of vertical deep mixing, where carbon dioxide is transported from the ocean surface to the ocean depths by sinking cold water in the high latitudes. If brought to the surface (for instance by upwelling) the cold water will warm up and release some of its carbon dioxide to the atmosphere
What is the biological pump
Living things in the ocean move carbon from the atmosphere into surface waters into rocks. This action of organisms moving carbon in one direction is called the biological pump
How does carbon get incorporated into marine organisms
As organic matter or structural calcium carbonate
What are animals that live in deep oceans called
When does combustion occur
When any organic material is reacted (burned) in the presence of oxygen to give off the products of carbon dioxide, water and energy
What can the organic material in combustion be
Any vegetation or fossil fuel such as natural gas (methane), oil or coal
What do organic materials contain
At least carbon and hydrogen and may include oxygen
How do pollutant molecules get created
Organic materials with oxygen combine with other elements to form a variety of pollutant molecules
Examples of pollutant molecules
Sulphur oxides and nitrogen oxides
What is biomass combustion
The burning of living and dead vegetation. It includes human-induced burning as well as naturally occurring fires
What 5 places does biomass combustion take place in
The boreal (northern) forests.
Agricultural waste after harvests
Where are boreal forests found
Alaska, Canada, Russia, China and Scandinavia
Where are savannah grasslands found
Where are tropical forests found
In Brazil, Indonesia, Colombia, Ivory Coast, Thailand, Laos, Nigeria, Philippines, Burma and Peru
Where are temperature forests found
US and Western Europe
Where is agricultural waste harvested
In the US and Western Europe
What is the life cycle of forests
Trees die after severe fire, setting the stage for new growth to begin.
If a forest fully replaces itself, what will be the net carbon change
There won’t be a change over the life cucleand
What percentage of the carbon in the atmosphere does biomass consumption consume
About 10-20% but immediately emits it back to the atmosphere
What is the balance between simultaneous production and decomposition in biomass consumption
New trees grow (storing carbon), old trees decompose (emitting carbon) and the organic layer of the soil accumulated (storing carbon)
What does the balance between simultaneous production and decomposition in biomass consumption determine
Whether the forest is a net source or sink
Left alone, what does terrestrial and atmospheric carbon do
They stay more or less in balance
What can change a carbon balance in a forest
Increasingly large/or more frequent fires, possibly made worse by warming temperatures and preoccupation levels
Every year, how much of earths land surface does fire burn
3-4 million km^2
How much carbon dioxide does fire release into the atmosphere annually
More than a billion tonnes of carbon
What are massive old-growth northern latitudes forests considered a carbon sink
Because older trees are repositories of decades or centuries of carbon; their heavy canopy blocks sunlight from reaching the forest floor, slowly decomposing the forest litter
What type of forest is also considered a carbon sink
Massive old-growth northern latitude forest
What has the United States Geological Survey (USGS) state
The carbon dioxide released in recent volcanic eruptions has never caused detectable global warming of the atmosphere
What are the two reasons that recent volcanic eruptions have not caused detectable global warming of the atmosphere
The warming effect of emitted CO2 is counterbalanced by the large amount of sulphur dioxide that is given out.
The amounts of carbon dioxide released have not been enough to produce detectable global warming.
How is the warming effect of emitted CO2 is counterbalanced by the large amount of sulphur dioxide that is given out in a volcanic eruption
Conversion of this sulphur dioxide to sulphuric acid, which forms fine droplets, increases the reflection of radiation from the sun back into space, cooling the earths lower atmosphere
Example of how The amounts of carbon dioxide released in volcanic eruptions have not been enough to produce detectable global warming
All studies to date of global volcanic Co2 emissions indicate that present-day sub-aerial and submarine volcanoes have released less than 1% of the Co2 released by human activities
What has been proposed about volcanic activity in the past
Intense volcanic release of carbon dioxide in the deep geological past did cause a large enough increase in atmospheric Co2 to cause a rise in atmospheric temperatures and possibly some mass extinctions, thigh this is a topic for scientific debate
What do dead plants and animals turn into following burial
How do dead plants or animals turn into fossil fuels
Pressure from multiple layers of sediment leads to an anoxic environment that allows for decomposition to take place without oxygen.
When this is combined with heat from the earth, the carbon in sugar molecules is rearranged to form other compounds.
What is an oxygen free environment called
What are animal remains likely to form following burial
Petroleum (crude oil)
What is plant matter likely to form following burial
Coal and natural gas
How do fossil fuels release carbon into the atmosphere
When they are extracted and burnt, carbon dioxide and water are released into the atmosphere
How does cement manufacture contributes CO2 to the atmosphere
When calcium carbonate is heated, producing lime and carbon dioxide.
CO2 is also produced by burning the fossil fuels that provide the heat for the cement manufacture process.
What is the estimation for what percentage of global anthropogenic Co2 the cement industry produces
Of which 50% is produced from the chemical process itself and 40% from burning fuel to power the process.
What is the amount of CO2 emitted by the cement industry in kg
More than 900kg of Co2 for every 1000kg of cement produced
In 2013, what were global emissions due to fossil fuel use and cement production
When is the Kyoto Protocol reference year
In 2013, how much higher was global Co2 emission due to fossil fuel use and cement productions in 1990
In 2013, how much higher was global Co2 emission due to fossil fuel use and cement productions in 2012
Which counties dominated the Co2 emissions because of fossil fuel use and cement production
European Union (10% but their states were in an overall 1.8% decline)
How many states in the EU
What is the 2013 Co2 emissions breakdown (fossil fuel and cement production only)
Coal - 43%
Oil - 33%
Gas - 18%
Cement - 5.5%
Gas flaring from oil wells - 0.6%
How is carbon lost to the atmosphere because of farming practices
When soil is ploughed, the soil layers invert, air mixed in, and soil microbial activity dramatically increases. It results in soil organic matter being broken down much more rapidly, and carbon is lost from the soil into the atmosphere
In addition to the effect on soil from ploughing, what else increases carbon dioxide levels in the atmosphere in farm practices
Emissions from the farm tractors
What is the largest source of carbon emissions within agriculture
What is enteric fermentation
When methane (CH4) is produced by livestock during digestion and released via belches
In 2011 what did enteric fermentation account for of the sectors total greenhouse gas outputs
What did carbon emissions from animals increase by between 2001 and 2011
What do greenhouse gases resulting from biological processes in rice paddies make up to of total agricultural emissions
10% (because of the generated methane)
What does the burning of tropical grasslands make up to of total agricultural emissions
What is FAO
United Nations Food And Agriculture Organisation
In 2011 what did FAO say if agriculture related greenhouse gas outputs
44% of them occurred in Asia, 25% by the Americas, 15% in Africa, 12% in Europe, 4% in Australasia
What has the regional distraction of agriculture-related greenhouse gas outputs been over the last decade
What does Co2 emissions from land use change (deforestation) account for of anthropogenic Co2 emissions
What is most deforestation driven by
The need for extra agricultural land
What is ‘slash and burn’ agriculture
Often subsistence farmers will clear a few hectares to feed their families by cutting down trees and burning them in this process
How does logging remove forest
Loggers, some of them acting illegally, built roads to access more and more remote forests which in turn leads to more deforestation.
What are the three main reasons deforestation occurs
Need for extra agriculture land.
Growing urban sprawl.
How is not all deformation intentional
Some is caused by a combination of human and natural factors like wildfires and subsequent overgrazing , which may prevent the re-establishment of young trees
How much of the worlds forests does the FAO estimate is cut down and conveyed to other land uses every year
13 million ha, an area roughly equivalent to the size of Greece
What has planting of trees resulted in
Forests being established or expanded on to abandoned agricultural land, this has reduced the net loss of total forest area
In the period 1990-2000 what was the world estimated to have suffered a net loss of forest in each year
8.9 million ha/year
In the period 2000-2005 what was the world estimated to have suffered a net loss of forest in each year
7.3 million ha/year
In the period 1990-2000 what percentage of the worlds forests did we lose
Presently, how much forest are we losing daily
What could happen at the current rate of deforestation
The worlds rainforests could completely vanish in a hundred years
When forests are cleared for conversion to agriculture or pasture what may release carbon into the atmosphere
If a large proportion of the above-ground biomass is burned it would rapidly release most of its carbon into the atmosphere
Why may deforested wood sometimes preserve carbon
If the wood is used as a wood product and not burned
What does forest clearing accelerate
The decay of dead wood, litter and below-ground organic carbon
How can forestlands quickly become barren deserts
Forest soils are moist, but without the shade from tree cover they dry out quickly. Trees also help maintain the water cycle by returning water vapour back into the atmosphere through transpiration but without the trees to full these roles, they can become deserts
How much of the worlds population lives in urban areas
Over half of the population
By 2030, what is the urban population expected to reach as a proportion of global population
60% with urban areas growing at a rate of 1.3 million people every week
As cities grow, what happens to land use
It changes from either natural vegetation or agriculture to one which is built up
How does urban growth increase CO2 emissions
They result from energy consumption for transport, industry and domestic use, added to the CO2 emitted in the cement manufacture required for all the buildings and infrastructure
What is a city
A metropolitan area above 0.5 million
In 2012 what percentage of global carbon emissions were cities responsible for
Under a business-as-usual scenario, what is the percentage of global carbon emissions that cities are responsible for predicted to increase to in 2030
What is the distribution of emissions in cities similar to
Population and economic output
Examples of the distribution of emissions in cities
21 highest emitting cities contribute 10% of global energy-related Caron emissions, 64 cities contributing 20% and 139 cities contributing 30%
In total, what are cities projected to be responsible for of the global increase in carbon emissions during the period 2012-2030
56%, with 10 cities contributing 10% of global emissions growth, 28 cities contributing 20% and 198 contributing 50%
What is the process of carbon sequestration
Involves capturing Co2 from the atmosphere and putting it into long-term storage
What are the two primary types of carbon sequestration
Terrestrial or biological sequestration
What is the process of geologic sequestration
Co2 is captured at urs source (for example a power plant) and then objected in liquid form into stored underground. These could be deleted oil and gas reservoirs, thin, uneconomic coal seams, deep salt formations and the deep experimental
What is the stage that geologic sequestration is at
The experimental stage
Why is the ocean capable of absorbing more additional carbon than terrestrial systems
Simply because of its sheer size
What is an advantage of ocean carbon sequestration
The carbon sequestered is quite literally ‘sunk’ within weeks or months of being captured from the air/water. Once it’s in the deep ocean it is in a circulation system commonly measured in thousands of years.
By the time carbon reaches the sea bed what has it entered
The earths geologic cycle
What does terrestrial/biological sequestration involve
The use of plants to capture Co2 from the atmosphere and then to store it as carbon in the stems and roots of the plants as well as in the soil
What is the aim of terrestrial sequestration
To develop a set of land management practices that maximises the amount of carbon that remains stored in the soil and in plant material for the long term
What do most authorities believe about the enrichment of plant ecosystems
It’s a positive environmental action with many associated benefits, including the enrichment of wildlife
What are the disadvantages to terrestrial sequestration
A forest planted to capture carbon might lose that carbon back to the air in a catastrophic forest fire or if the forest suffers disease or infestation.
Also land-based sequestration plantations are slow growing and require active monitoring and management for the lifetime of the plantation, usually many decades. The carbon within those systems is never removed permanently from the atmospheric system.
100 million years ago what was the carbon dioxide value in the atmosphere
The exact value is in doubt. But it was many times higher than it is now
500 million years ago what was the values of carbon dioxide in the atmosphere
20 times higher than present values
Timeline of carbon levels in the atmosphere
500 million years ago: 20 times higher than present levels
200 million years ago: 4-5 times present levels
100 million years ago: exact value is in doubt but it was many times higher than today
Pre-industrial time: levels have been following a slow decline until now
What is the only way to calculate the effects of the changing levels of carbon
Is to build a computer model
Why is a computer model the only way to calculate the effects of changing levels of carbon
They can have between 50 and 100 interacting equations describing all the different processes of the carbon cycle. The result of this is that models only predict possibilities not probabilities
What has the impact of increasing atmospheric CO2 on the land been subject to
Why has research on the impact of increasing atmospheric Co2 been unclear so far
They’ve only been over a relatively short time period, this is coupled to the fact that there are so many other variables that could have an impact on the land and the atmosphere
What has current research estimated about how much permafrost is in the Northern Hemisphere
How much could temperature increase by if 10% of the permafrost in the Northern Hemisphere were to melt
0.7*C by 2100
What are many of the observed physical and chemical changes in the ocean consistent with
Increasing atmospheric CO2 and a warming climate
Why are many of the causative links to climate change not very well understood
Because of the complex nature of the chemistry and biochemistry and the oceans and its inhabitants
What parts of the impact of Co2 on oceans is difficult to predict
The precise rate, magnitude and direction of change of Co2 uptake and how that affects acidity, salinity, storminess and nutrient enrichment. It is even more difficult to map these effects at a local scale
Once 1960s, what has happened to CO2 being taken up by plants
It has increased.
25% of emissions removed by plants
What has increased temperatures led to
An increase in the length of the growing season. More plant growth and higher evapotranspiration rates require more water. So growth is limited by water availability
What have increased temperatures warmed up
The land. In the Tundra areas warming of the land increased the rate of decay of accumulated dead organic matter leading to the release of CO2, methane etc
What has agriculture become because of land use decisions
More intensive. More crops from less land increases CO2 take up
What does more Co2 available in the atmosphere result in
More photosynthesis and plant growth. This is called ‘carbon fertilisation’. Growth limits reached when available water and nutrient limits are reached
What happened to farmland in mid-latitudes abandoned in the early twentieth century
Farmland was replaced by trees which store much more carbon than crops
What happens because of wildfires being extinguished
Leads to a build up of woody material that stores carbon. Fires and deforestation elsewhere has led to increased atmospheric CO2
About what percent of the Co2 that has been related into the atmosphere has been diffused unto the ocean
Through what process does CO2 get dissolved into the ocean
Direct chemical exchange
What does dissolved carbon dioxide in the ocean create
What does carbonic acid in the ocean cause
The slightly alkaline ocean to become a little less alkaline
Since 1750s how much has the PH of the oceans surfaces dropped by
0.1, a 30% change in acidity
While the impact of ocean acidification is largely unknown, what is the exception
What two ways does ocean acidification affect marine organisms
The shells of animals end up being thinner and more fragile.
Fall in marine biodiversity.
How does ocean acidification result in shells of marine animals being thinner and more fragile
Carbonic acid reacts with carbonate ions in the water to form bicarbonate.
However, those same carbonate ions are what animals like coral and many plankton speeches need to create their calcium carbonate shells.
With less carbonate available, the animals need to expend more energy to build these shells resulting in thinner and fragile ones.
How many people worldwide do coral reefs provide food and livelihood security to
How does significant reef loss and subsequent fall in biodiversity threaten the survival of coastal communities
Through reduced food availability and a reduced capacity of coastlines to buffer the impact of sea level rise, including increased storm surges
What are polar and sub-polar marine ecosystems projected to be low in, within this century
What may happen because of the polar and sub-polar marine ecosystems becoming low in carbonate ions
The waters may actually become corrosive to unprotected shells and skeletons of organisms currently living there
In 2007 what happened to farmed oyster larvae off the coast of Oregon and Washington
They began dying by the millions. It was found that these losses were directly linked to ocean acidificstiin
Example of the rise in acidity and subsequent oyster crash taking a significant toll on coastal communities
From 2005 to 2009 lost production cost millions of dollars in lost sales
What did further research into ocean acidification show
Evidence of acidic sea water rising up from the ocean depths and that the water rising up from the ocean depths and that the water rising from the deep ocean today holds Co2 absorbed approximately 30-50 years ago
Who is the chief hatchery scientist for Taylor Shellfish Farms
What did Benoit Eudeline liken the current ocean acidification problem to
Sitting on a ticking time bomb
What is a more optimistic view point on the effects of ocean acidification
The more acidic sea water is, the better is dissolved calcium carbonate rocks (chalk and limestone). Over time this reaction will allow the ocean to soak up excess Co2 because the more acidic water will dissolve more rocks, release more carbonate ions and increase the oceans capacity to absorb Co2
What could warmer oceans (a product of climate change) affect
The abundance of phytoplankton which grows better in cool, nutrient rich waters.
What could be the effect of a decreased amount of phytoplankton
It could limit the oceans ability to take carbon from the atmosphere through the biological carbon pump and lessen the effectiveness of the oceans as a carbon sink
What is essential for plant and phytoplankton growth
How may an increase in Co2 in the oceans help phytoplankton
It could increase their growth by fertilising those few species of phytoplankton and ocean plants like sea grasses that take carbon dioxide directly from the water
What does ocean warming kill off
The symbiotic algae which coral needs in order to grow, leading to bleaching and eventual death of reefs
In the last 35 years what have satellites monitoring sea ice in the Arctic measured
It’s retreat at 40%
How is sea ice melting part of a feedback mechanism
Because the highly reflective ice is replaced by more heat absorbent water. When it starts to melt the ocean is able to absorb more sunlight, which in turn amplifies the warming that caused it to melt in the first place
What does sea ice provide
A unique habitat for algae that appear in more concentrated forms and with more fat content in the ice
What does the loss of ice-bound algae affect
Marine predators all the way up the food chain, from krill and fish to seals, walruses and polar bears
How does melting sea ice affect polar bears
The loss of ice bound algae affects all the way up the food chain and they rely on sea ice to get to their main food source of seals and can no longer travel upon it
Where has there been an observed decrease in ocean salinity
In the deep North Atlantic
What is the decrease in ocean salinity in the deep North Atlantic probably caused by
Higher levels of precipitation and higher temperatures
How does ocean salinity affect the environment
The high levels of precipitation leads to higher river run-offs that eventually reach the sea. The higher temperatures are causing melting of the Greenland ice sheet and many alpine glaciers. This too will lead to an increase in fresh water reaching the ocean.
What have the changes in ocean salinity been linked to
A possible slowing down of the large scale oceanic circulation in the North-East Atlantic. This is turn will have an effect on climate of North West Europe
In summer and spring, the initial warming will cause ocean to absorb more heat. What will this lead to in autumn and winter
Warmer oceans -> larger ocean/atmosphere heat transfer in autumn -> warmer atmosphere in autumn -> formation of thinner ice in winter and slower formation and less ice in winter -> more open water and ice melt in summer
In winter, what does more open water lead to in spring and summer
Reduced albedo because ice is replaced by water -> more solar radiation absorbed by whole system -> ocean absorbs more heat
How long have global sea levels been more or less constant for
The last 5,000 years
What have studies of costal landforms show
They have been much lower in the past than they are today
What did the last glacial retreat lead to
A worldwide rise in sea levels about 10,000 years ago
What was the increase in sea levels rise in the last glacial retreat caused by
The melting of land-locked freshwater ice
What are the affects of ocean salinity on the Atlantic Ocean currents
Disruptions of Arctic conveyors means less warm water is drawn north and more flows south in the subtropical gyre
Since the 1990s, what has research indicated sea levels worldwide has been rising at a rate of
What are the two causes of sea level rise
Melting of terrestrial ice.
Why is the melting of terrestrial ice increasing
Persistently higher temperatures have led to an increased rate of summer melting as well as a drop in snowfall in the shorter winters.
What does the imbalance between increased summer melting and a drop in snowfall in the shorter winters results in
A significant net gain in water entering the oceans from rivers against evaporation from the ocean
Why are the massive ice sheets of Antarctica and Greenland moving quickly towards the oceans
Due to the increased amount of meltwater lubricating their bases
What is thermal expansion
When water heats up, it expands
About how much of the last century’s rise in sea level is thought to be attributable to warmer oceans having greater volume and so occupying more space
Have accurate measurements of thermal expansion been possible yet
If the earth continues to warm, how much can we expect the oceans to rise by 2100
Between 0.8 and 2m but this is not an exact science and there’s a range of predictions for rising sea levels
What is the enhanced greenhouse effect
The impact on the climate from the additional heat retained due to the increased amounts of carbon dioxide and other greenhouse gases that humans have released into the earths atmosphere since the industrial revolution
What is geo-sequestration
The technology of capturing greenhouse gas emissions from power stations and pumping them into underground reservoirs
What is radiative forcing
The difference between the incoming solar energy absorbed by the earth and energy radiated back to space
What is soil organic carbon
The organic constituents in the soil: tissues from dead plants and animals, products produced as these decompose and the soil microbial biomass
What percentage of the extra Co2 will remain in the atmosphere for thousands of years
What is Co2 important for
Controlling the earths temperature
Examples of greenhouse gases
How do greenhouse gases cause the greenhouse effect
They absorb a wide range of energy - including infrared energy emitted by the earth - and then re-emit it. The re-emitted energy travels out in all directions but some returns to Earth where it heats the surface
Without greenhouse gases, what would happen to the earth
It would be frozen at -180*C
With too many greenhouse gases, what would happen to the earth
It would be like Venus, where the greenhouse atmosphere keeps temperatures around 400*C
The greenhouse effect is good however what is the problem facing the earth
The enhanced greenhouse effect
What is radiative forcing
The concept is that energy is constantly flowing into the atmosphere in the form of sunlight that always shines on half of the earths surface. Some of this sunlight is reflected back to space and the rest is absorbed by the planet. Some of this absorbed energy is radiated back into the much colder surrounding space as infra red energy. If The balance between the incoming and the outgoing energy is anything other than zero there has to be some warming or cooling going on. The amount the earths energy budget is out of balance is called the radiative forcing.
What percentage of sunlight is reflected back to space in the enhanced greenhouse effect
If the radiative forcing is negative what effect would this have on the earth
THe earth would cool
What is radiative forcing used as a measure of
Recent human activity
What is radiative forcing measured in
What have studies shown about radiative forcing
That prior to 1750s, radiative forcing was negligible.
Since the 1750s why has radiative forcing increased
Because of increased greenhouse gas emissions and changing albedos because of land use change
Why is measuring the amount of actual radiative forcing difficult
Because of many complicating factors including natural changes in solar radiation and the effects of aerosols such as carbon particles from diesel exhausts
What is the current level of radiative forcing according to the IPCC
1.6 Watts/m^2 (with a range of uncertainty from 0.6 to 2.4)
What does 1.6 watts/m^2 amount to
A total of about 800 terawatts - more than 50 tines the worlds average rate of energy consumption
What is the worlds average rate of energy consumption
If Co2 levels continue to rise at projected rates what will happen to the earth
It will become hotter, possibly hot enough to melt much of the existing ice cover
What are the projected surface temperatures changes from 1960 to 2060 as estimated by NASAs Global Climate Model
+10 in Antarctica
+ 6 in Oceania
+4/5 in Asia
+4 in Europe
+5/6 in Africa
+4/5 In South America
+4/7 in North America
Describe the greenhouse effect
Solar radiation passes through the clear atmosphere.
Some solar radiation is reflected by the atmosphere and earths surface.
Solar energy is absorbed by the earths surface and warms it and is converted into heat causing the emissions of long wave (infrared) radiation back into the atmosphere.
Surface also gains more heat and infrared radiation is emitted again.
Some of the infrared radiation is absorbed and re-emitted by the greenhouse gas molecules. The direct effect is the warming of the earths surface.
Some of the infrared radiation passed through the atmosphere and is lost in space.
Examples of elements that carbon bonds with to form complex molecules
Although there’s a lot of water on Earth, how much supports all life on land
A fraction of one percent
What is increasing pressure on our water
Climate change and growing populations
How does the increased emissions of Co2 lead to a positive feedback system
Increases the temperature resulting in higher evaporation rates and a wetter atmosphere, which leads to more warming
What percentage of the earths greenhouse effect is caused by carbon dioxide
What percentage of the earths greenhouse effect is caused by water vapour
What percentage of the earths greenhouse effect is caused by clouds
What causes the extra 5% of the greenhouse effect
Small particles (arosols) and minor greenhouse gases like methane
What happens when carbon dioxide concentrations rise
Air temperatures go up.
Oceans warm up and more water vapour evaporated into the atmosphere.
This amplifies greenhouse heating.
Why does Co2 set the temperature of the earth even though it contributes less to the overall greenhouse effect than water vapour
CO2 controls the amount of water vapour in the atmosphere and therefore the size of the enhanced greenhouse effect
Describe the impact of water and carbon on climate change showing a positive feedback
More Co2 from human activity acts as a greenhouse gas. -> global temperatures rise -> increased oceanic temperatures -> dissolved Co2 released by warmer oceans -> more Co2, water vapour, clouds and methane in atmosphere -> global temperatures rise -> warming tundra emits Co2 and methane -> more greenhouse gases -> global temperature rise -> increased oceanic temperatures -> more energy for evaporation for water evaporates from the oceans surface -> water goes back into atmosphere -> more greenhouse gases
Why will the earths temperature increase because of carbon dioxide already in the atmosphere
There is a time lag between the increase in Co2 and increased warming because the ocean soaks up heat
What will the earths temperature increase by because of carbon dioxide already in the atmosphere
What does climate change mitigation refer to
Rescue or prevent emissions of greenhouse gases
What are the 7 processes to mitigate climate change
Carbon capture and sequestration technologies (CCS).
Increased use of renewable energy.
Improving the aviation industry.
Changing rural land use.
Increase use of nuclear fuel.
Improved vehicle fuel efficiency.
Example of renewable energy
Wave and tidal power.
Examples of how urban design can help mitigation
Sustainable urban transport system.
Waste management practices: capture landfill gas and recycling.
Building design: improved ventilation, green roofs, improved insulation.
Examples of changing rural land use to negate climate change
Afforestation and reformation Silviculture.
Changing agricultural methods e.g non-ploughing.
Examples of improving the aviation industry to mitigate climate change
Shorten flight time by efficient air traffic control.
Change of routes to reduce contrail formation.
Improved fuel efficiency.
How much CO2 emissions caused by the use of fossil fuels can CCS capture
Up to 90%
What does carbon capture and sequestration prevent
The carbon dioxide from entering the atmosphere
What are the three parts of the CCS chain
Capturing the Co2
Transporting the Co2
And securely storing the Co2
How does the capturing of the Co2 in CCS work
Capture technologies allow the separation of Co2 from gases produced in electricity generations and industrial processes by one of three methods
What are the three methods capturing technologies use to capture CO2
Pre-combustion capture, post-combustion capture and oxy-fuel combustion
How does the transporting part of CCS work
Transporting the Co2 by pipeline or by ship to the storage location: millions of tonnes of Co2 are already transported annually for commercial purposes by road tanker, ship and pipelines
How does the storing of the Co2 in CCS work
Co2 is converted into a high pressure liquid-like form known as ‘supercritical Co2’ which behaves like a runny liquid.
This supercritical Co2 is injected directly into sedimentary rocks.
Geochemical trapping mechanisms prevent the Co2 from escaping to the surface.
What an CCS systems be used to do
Extract a greater percentage of oil and gas out of existing reservoirs by the Co2 being objected under such pressure as to force the oil or gas out
What are the positives and negatives of trying to extract greater percentages of fossil fuels using CCS
It would partly pay for the CCS technology however it would also enhance the original problem by producing more fossil fuel for burning.
When Co2 is stored in deep geological formations what is it known as
During CCS where can the carbon dioxide be stored
underground in depleted oil and gas fields, deep saline aquifer formations or thin coal seams several kilometres below the surface or the deep ocean
What prevents the Co2 from escaping during CCS
Various physical (for example, impermeable ‘cap rock’) and geochemical trapping mechanisms
What is the disadvantage of storing captured Co2 in the ocean
The Co2 causes acidification of the oceans
What are the methods of ocean storage according to the IPCC
Co2 lakes offshore.
Sinking Co2 plumes.
Dispersal of Co2 by ship.
What is it called when liquified Co2 is injected into the ground to push more oil out of the ground
Enhanced oil recovery (EOR)
How can carbon stores be improved
By ensuring that carbon inputs to the soil are greater than carbon losses from it
What do strategies to improve carbon stores depend upon
Land use, soil properties, climate and land area
What are the three main rural land uses that can help improve carbon stores
Forested lands and tree crops.
What do grasslands offer a global greenhouse gas mitigation potential of
810 million tonnes of Co2
Where do grasslands store the carbon
Sequestered in the soil
What 4 ways can soil carbon storage in grasslands be improved
Avoidance of overstocking of grazing animals.
Adding manures and fertilisers.
Irritation and water management.
How does adding manures and fertilisers improve soil carbon storage in grasslands
They have a direct impact on soil organic carbon (SOC) levels through the added organic material.
What are the indirect benefits of using manures and fertilisers in grasslands
Increasingly plant productivity and stimulating soil biodiversity (for example earthworms that help degrade and mix the organic material)
How does revegetation improve soil carbon storage in grasslands
Especially using improved pasture species and legumes, can increase productivity, resulting in more plant litter and underground biomass, which can add to the SOC stock
How does irrigation and water management improve soil carbon storage in grasslands
Can improve plant productivity and the production of SOM
What are the 5 croplands techniques for increasing SOC
Reduced or no tillage.
Some use of animal manure.
Rotation of cash crops.
Using improved crop varieties.
How does mulching improve soil carbon storage in croplands
It adds organic matter. If crop residues are used, mulching also prevents carbon losses from the system
How does reduced no tillage improve soil carbon storage in croplands
(No ploughing or harrowing). It avoids the accelerated decomposition of organic matter and depletion of soil carbon that can other wise occur. It also prevents the break-up of soil aggregates that protect carbon
How does usage of animal manure or chemical fertilisers improve soil carbon storage in croplands
It can increase plant productivity and thus SOC
How does rotation of cash crops improve soil carbon storage in croplands
With pasture or the use of cover crops and green manures have the potential to increase biomass returner to the soil
How does using crop varieties improve soil carbon storage in croplands
Can increase productivity above and below ground, as well as increasing crop residues, thereby enhancing SOC
What are the 3 forested lands and tree crops techniques for increasing soil carbon storage
Protection of existing forests.
Reforesting degraded lands.
Trees in croplands.
How do forests store large stocks of carbon
Both above and below ground
How does protecting existing forests improve soil carbon storage in forested lands and tree crops
They preserve current soil carbon stocks
How does reforesting degraded land improve soil carbon storage in forested lands and tree crops
It increases tree density in degraded forests increasing biomass density and therefore carbon density, above and below ground
How does trees and orchards in croplands improve soil carbon storage in forested lands and tree crops
They can store carbon above and below ground. Co2 emissions can be reduced if they are grown as a renewable source of fuel
What is silviculture
Trees in croplands
According to the IPCC what are the percentages of the potential contribution of afforestation/ reforestation and agroforestry activities
Temperature afforestation/ reforestation: 31%
Temperature agroforestry: 2%
Boreal afforestation/ reforestation: 6%
Tropical agroforestry: 17%
Tropical afforestation/ reforestation: 44%
What is it important to note of mitigation schemes
That they have different and unwanted side effects
In 2013 how many passengers did the global aviation industry carry
In 2013 how many tonnes of Co2 did the global aviation industry product
705 million tonnes
Example of the aviation industry making a major stride to reduce its production of Co2
The Airbus A380 and the Boeing 787 both use less than 3 litres of fuel per 100 passenger km
What does the EU Directorate General for Climate Action predicts
That by 2020 the global emissions of CO2 will be 70% more than in 2005 and could be 300 to 700% more by 2050
Why are the ways in which aviation practices can be improved have to be treated with caution
Because many of them are still at the aspirational or theoretical stage
What are the 3 ways to mitigate carbon dioxide within the aviation industry
Design and technology.
What are the 6 ways design and technology can be utilised to mitigate Co2 emissions in the aviation industry
Increased engine efficiency.
Increased use of biofuels.
Reduced weight of aircrafts and engines.
Carbon capture within the engines.
Maximising the number of seats per aircraft.
What are the 3 ways movement management can be utilised to reduce carbon dioxide emissions in aviation practices
Towing aircraft while on the ground.
Avoiding circling, stacking, queuing etc.
Adopting fuel efficient routes.