ELSS Flashcards
(280 cards)
1
Q
why do people need water?
A
essential resource for economic activity: used to generate electricity, irrigate crops (p/s), provide recreational facilities and satisfy public demand (drinking water, sewage disposal). in huge range of industries including food manufacturing, brewing, paper making and steel making, power generation
animals are mostly made up of water
sweat (evaporation of water from skin) regulates body tempo by cooling. this is an example of negative feedback to restore equilibrium
respiration in animals converts glucose to energy through reaction w/ oxygen to produce carbon dioxide and water
consume animals & plants
water is the medium used for chemical reactions in the body including circulation of O2 and nutrients
2
Q
importance of water for plants?
A
require water to maintain rigidity (plants wilt when they run out of water)
needed to transport mineral nutrients from soil
transpiration of water from leaves’ surface cools plants by evaporation
respiration in plants converts glucose to energy through reactions with oxygen to produce carbon dioxide and water
water is the medium used for chemical reactions in the body including circulation of O2 and nutrients
plants manufacture own food through photosynthesis: in leaves, plants convert sunlight, water and CO2 to glucose, oxygen
3
Q
importance of water for animals?
A
in fur-covered mammals, reptiles and birds, evaporative cooling is achieved by panting
consumers require plants as producers
respiration in animals converts glucose to energy through reactions with oxygen to produce carbon dioxide and water
water is the medium used for chemical reactions in the body including circulation of O2 and nutrients
sweat (evaporation of water from skin) regulates body tempo by cooling. this is an example of negative feedback to restore equilibrium
4
Q
importance of water for climate?
A
water moderates environment: water vapour is an essential greenhouse gas which absorbs long-wave radiation from the Earth by helping to maintain average global temps about 15C higher than they would be otherwise AND clouds are made up of tiny water droplets and ice crystals, so reflect 1/5 of incoming solar radiation and decrease surface temperature= weather affected (distribute heat)
water helps create benign thermal conditions on earth e.g. oceans (71% of surface of Earth (and big carbon store)) moderate temps by absorbing heat, storing it and releasing it slowly. currents also created
5
Q
water makes up what % of all living organisms?
A
65-95%
is crucial for growth, reproduction and metabolic functions
6
Q
where is carbon stores on Earth?
A
in carbonated rocks e.g. limestone
sea floor sediments
ocean water (as dissolved CO2)
the atmosphere (as CO2 gas)
in the biosphere
7
Q
importance of carbon
A
life is built on large molecules of carbon atoms e.g. proteins, carbohydrates, nucleic acids
used as an economic resource: fossil fuels (e..g coal, oil, natural gas) power the global economy
most manufactured goods are carbon-based.
oil is used as a raw material in manufacture of products e.g. plastics, paint, synthetic fabrics
agricultural crops and forest trees store large amounts of carbon available for human use as food, timber, paper, textiles e.t.c.
CO2 needed for p/s in plants to produce O2 and glucose
CO2 and CH4 are GHGs, so help to maintain suitable temperature for life (Goldilocks zone)
can determine acidity of rain/rivers/oceans (CO2=acidic) so can affect wetahering
CO2 is a pollutant so can affect human and ecosystem health
8
Q
system definiton
A
a group of objects and the relationships that bind the objects together
9
Q
open vs closed system in terms of carbon and water cycles?
A
on GLOBAL scale, cycles are CLOSED systems driven by Sun’s energy (external to Earth). only energy, not matter, crosses the boundaries
on SMALLER scales, materials as well as Sun’s energy cross system boundaries therefore they are OPEN systems. e.g. tree, drainage basin, forest ecosystem
10
Q
equilibrium definition
A
long-term balance between inputs and outputs in a system
11
Q
negative feedback definition
A
an automatic response to a change in a system that restores equilibrium
usually good
e.g. sweating
12
Q
positive feedback definition
A
an automatic response to a change in a system that generates further change
usually bad
13
Q
difference between stores and flows?
A
stores keep carbon/water e.g. ocean, tree
flows are wen water/carbon moves between stores e.g. precipitation, combustion
14
Q
percentage of earth’s carbon stored in:
atmosphere
biosphere
ocean
lithosphere
A
0.5%
1.5%
27%
70%
15
Q
how is carbon stored in the atmosphere?
A
as CO2 gas
also stored as methane (to a lesser extent)
16
Q
what is the biosphere?
A
plants, animals and soil
17
Q
how is carbon stored in the biosphere?
A
stored as organic molecules in living & dead plants & animals
in the soil it is stored as organic matter from dead plant material and the activity of microorganisms ( the decay process releases CO2 back to the atmosphere)
18
Q
how is carbon stored in the ocean?
A
stored as dissolved CO2, but also as calcium carbonate in the shells of marine life which can fall to the sea floor and become marine sediment
much of the ocean carbon store is located at greta depths (only 4% found near the upper ocean surface)
19
Q
what is the lithosphere?
A
rocks
SLOW CARBON CYCLE ( takes millions of year to be formed and be released & is irreversible)
20
Q
how is carbon stored in the lithosphere?
A
stored as fossil fuels (coal, oil, gas)
stored in sedimentary rocks e.g. limestone and chalk
lithosphere=largest store of carbon
21
Q
what are phytoplankton?
A
very small ‘plants’ in ocean which photosynthesise
22
Q
how do phytoplankton play a crucial role in the carbon cycle?
A
‘producers’ so allow food chains to develop
photosynthesis removes carbon from atmosphere or carbon dissolved in the ocean
fall to the bottom of the ocean, undergo sedimentation and become lithified (become a rock) so enters slow carbon cycle
23
Q
how are carbon-containing rocks produced?
A
- the hardening of mud (containing organic matter) into shale over geological time
- the collection of calcium carbonate particles from the shells and skeletons of marine organisms ends up in ocean sediments and is ultimately lithified to form chalk and limestone
24
Q
how is carbon stored in the earth’s crust?
A
as hydrocarbons formed over millions of years from ancient living organisms under intense temperatures and pressure (fossil fuels e.g. coal, oil, gas)
25
3 ways that carbon can return to the atmosphere from the lithosphere
combustion of fossil fuels releases CO2 back to the atmosphere (anthropogenic)
volcanoes release huge volumes of carbon as CO2 and CH4 v quickly from magma in an eruption
exposed carbon-based rocks get weathered by atmosphere/water
26
processes in carbon cycle?
precipitation
photosynthesis
weathering
respiration
decomposition
combustion
sequestration
27
precipitation definition carbon cycle
this can dissolve atmospheric CO2 & this can form a weak carbonic acid. anthropogenic emissions of CO2 can increase the acidity of rainfall. this can have devastating effects on vegetation, human structures& fish stocks in lakes and rivers
28
photosynthesis definition carbon cycle
the process by which green plants & certain other organisms transform light energy into chemical energy. light energy is captured & used to convert water, CO2 & minerals into O2 & energy-rich organic compounds (incl. glucose)
29
respiration definition carbon cycle
the movement of oxygen from the outside air to the cells within tissues & the transport of CO2 in the opposite direction
30
weathering definition carbon cycle
the 'in situ' breakdown of rocks. when it involves the chemical action of rainwater, occurs bc the water is a weak carbonic acid, which is able to dissolve limestone and chalk by carbonation
31
decomposition definition carbon cycle
micro-organisms eg. bacteria and fungi break down dead organic matter, extracting energy & releasing CO2 into the atmosphere
32
combustion definition carbon cycle
occurs when organic material (containing carbon) reacts or burns in the presence of oxygen. the process will release CO2 into the atmosphere.
33
what are the 2 types of ocean sequestration?
physical (inorganic) pump
biological (organic) pump
34
does cold or hot water store more carbon?
cold water
35
describe the physical (inorganic) pump
involves the mixing of surface & deep ocean waters by vertical currents (creates more even distribution of carbon geographically and vertically) in the ocean.
initially CO2 enters the oceans from the atmosphere by diffusion. surface ocean currents then transport the water & its dissolved CO2 polewards where it cools, becomes more dense & sinks.
downwelling carries dissolved carbon to ocean depths where individual molecules may remain for centuries. eventually deep ocean currents transport the carbon to areas of upwelling. there, cold, carbon-rich water rises to the surface & CO2 diffuses back into the atmosphere
36
where does downwelling occur?
only a handful of places in the oceans e.g. North Atlantic between Greenland and Iceland
37
describe the biological (organic) pump
carbon is exchanged between the oceans & atmosphere through the actions of marine organisms
phytoplankton nr. ocean surface produce organic material when photosynthesising. whether they are consumed by animals in the marine food chain, or through natural death, carbon locked in phytoplankton either accumulates in sediment on ocean floor or is decomposed & released into ocean as CO2
other marine organisms e.g. molluscs, crustaceans extract carbonate & calcium ions from seawater to manufacture plates, shells, skeletons of CaCO3. most of this carbon-rich material ends up in ocean sediments and is ultimately lithified to form chalk and limestone
38
what % of all carbon fixation by photosynthesis takes place in the oceans?
50%
39
how much carbon is drawn from atmosphere by biological pump every year
about 50GT
40
largest store in carbon cycle?
sedimentary rocks
41
largest flow in carbon cycle? by how much?
oxidation of soil by 28Gt
42
what is meant by natural sequestration?
carbon being captured by and stored in natural environments e.g. oceans, trees, soil
43
residence times for carbon in slow carbon store?
150 million years
44
rate of transfer of carbon in fast carbon store
10-1000 times faster than those in slow carbon cycle
45
evapotranspiration definition
combined loss of water at the surface through evaporation and transpiration by plants
46
precipitation definition
moisture (rain, snow,hail) falling from clouds towards the ground
47
ablation definition
the loss of ice & snow, especially from a glacier, through melting, evaporation & sublimation
48
infiltration definition
the vertical movement of rainwater through the soil
49
run-off definition
the movement of water across the land surface
50
groundwater flow definition
the horizontal movement of water within aquifers
51
cryosphere definition
the frozen water part of the Earth system including frozen parts of the ocean e.g. waters surrounding Antarctica and Arctic
52
how does rain falling to the ground reach streams/rivers?
which is quicker?
infiltration (by gravity into soil and lateral movement or throughflow to stream & river channels)
overland flow (across ground surface either as a sheet or as trickles & rivulets to stream & river channels)
overland flow is faster
53
what is infiltration capacity?
how does this impact overland flow?
the maximum rate at which water, under the pull of gravity, soaks into the soil
when rainfall intensity exceeds infiltration capacity, overland flow occurs
54
where does groundwater flow move water to?
where soils are underlain by permeable rocks, water percolates deep underground. this water then migrates slowly through rock & joints as groundwater flow, eventually emerging at surface as springs/seepages
55
temperature in Amazon and why
constantly around 27C all year round bc on equator where suns rays are concentrated so constant growing season
v little seasonal variation bc on equator
56
how does precipitation vary annually in the Amazon?
convectional rain falls all year round, though most areas experience at least 1 drier period
highest precipitation in march 315mm
lowest in august 60mm
high average rainfall >2000mm w/ no proper dry season
on ITCZ (equator)= low pressure so air rises, cools, condenses so lots of convectional rainfall
57
what % of precipitation in the amazon is recycled?
what does this mean?
50-60% is recycled by evapotranspiraton
water losses form the amazonian basin result from river flow & export of atmospheric vapour to other regions. this loss is made good by an inward flux of moisture from the Atlantic Ocean
58
what is precipitation like in the amazon rainforest and why?
high average annual rainfall >2000mm
rainfall fairly evenly distributed throughout the year though short drier season occurs in some places
high-intensity, convectional rainfall
interception by forest trees is high (around 10% of precipitation)
intercepted rainfall accounts for 20-25% of all evaporation
low-pressure around equator->air rises-> cools and condenses->rain and clouds
59
what are rates of evapotranspiration like in the Amazon and why?
high rates of evaporation and transpiration due to high temps, abundant moisture and dense vegetation.
strong evapotranspiration-precipitation positive feedback loop sustains high rainfall totals
about 1/2 of incoming rainfall is returned to the atmosphere by evapotranspiration
most evaporation is from intercepted moisture from leaf surfaces
moisture lost in transpiration is derived from the soil via tree roots
60
what role does vegetation play in the water cycle in the amazon?
absorb and store water from the soil and release it through transpiration
61
3 physical factors affecting the amazon water cycle?
geology
relief
temperature
62
what is the geology in the Amazon and does this affects the water cycle?
how will this affect flood risk?
impermeable catchments (e.g. large parts of the Amazon Basin are an ancient shield area comprising impermeable, crystalline rock) have minimal water storage capacity, so there is rapid surface run-off and increased flood risk
permeable and porous rocks e.g. limestone and sandstone store rainwater, slowing run-off and reducing flood risk
63
what is the relief in the Amazon and how does this affect the water cycle?
how will this affect flows of water?
most of the Amazon Basin comprises extensive lowlands. in areas of gentle relief water moves across the surface (overland flow) or horizontally through the soil (throughflow) to streams and rivers
in the west the Andes create steep catchments w/ rapid run-off
widespread inundation across extensive floodplains e.g. the pantanal occurs annually, storing water for several months and slowing its movement into rivers
64
which of the 3 physical factors affecting amazon water cycle is most important? why?
temp will increase further in future due to CC so will have more significance (and changes daily and seasonally)
climate= most sig. bc it determines vegetation (by controlling water cycle e.g. trasnpiration), drives processes e.g. evaporation and precipitation
geology and relief are constant LT factors so are permanent but less sig.
but low-lying so may be flooded future bc of sea level rise cause by CC at mouth
65
how does deforestation affect flood risk?
topsoil not held together so increased soil erosion-> silts up rivers & decreases bankful capacity, increasing flood risk bc increased chance of peak discharge exceeding bankful capacity
minerals leached out of soil so it is infertile and trees cannot grow in the future
reduced interception so increased surface runoff and less infiltration into the soil-> quicker lag time, bigger peak discharge and more water to river more quickly, increasing flood risk
66
local vs downstream impacts of deforestation?
DOWNSTREAM: reduce interception increases surface runoff so increases risk of flooding
LOCAL: reduced evapotranspiration so reduced precipitation so drought
67
what happened in April 2014 in amazon?
Madeira river flooded w/ devastating impacts for Porto Velho community incl. 6o deaths, evacuations, cholera outbreaks, vast expanses of floodplains inundated
river reached record levels of 19.68m above normal
68
causes of April 2014 flooding in Amazon?
heavy rainfall
Santo Antonio and Jirau dams holding water for longer than natural flow
deforestation (less water storage in trees, soil, permeable rocks and atmosphere increase surface runoff)
69
how do runoff rates change due to deforestation?
converting rainforest to grassland increases runoff by a factor of 27
70
what percentage of rain falling on grassland goes directly into rivers?
50%
71
how can deforestation affect local climate?
rainforest trees= crucial part of water cycle (extract moisture from soil, intercept rainfall; releases to atmosphere by evapotranspiration) to stabilise forest albedo and ground temps
cycle maintains high atmospheric humidity, responsible for cloud formation and heavy conventional rainfall
deforestation breaks this cycle and can lead to permanent CC
72
how can deforestation affect regional climate?
projections of future deforestation in Amazonia predict a 20% decline in regional rainfall as the rainforest dries out and forest trees are gradually replaced by grassland
disruption of regional water cycle means forests 100s of kms downstream of degraded sites are affected too e.g. Manaus
73
are impacts of deforestation reversible?
yes
74
how much carbon can primary forest store per hectare
400 tonnes
75
selective logging can reduce the amount of carbon stored by....
50%
76
carbon stored in grassland and soya plantation (in comparison w primary forest)
16.2 tonnes/ha (25x less)
2.7 tonnes/ha (150x less)
77
how much carbon does the Amazon absorb each year?
2.4 billion tonnes
therefore is a major global reservoir of stored carbon
78
amount of carbon stored per hectare in trees, roots, and soil of amazon primary forest
large forest trees store about 400 tonnes C/ha above ground
further 40 tonnes C/ha in their roots
soil carbon stores average between 90 and 200 tonnes/ha
79
speed of exchange of carbon between atmosphere , biosphere and soil in amazon? why?
compared to other forest ecosystems, it is rapid
warm humid conditions ensure speedy decomposition of dead organic matter and quick CO2 release
rates of carbon fixation through p/s are high
80
physical factors affecting carbon cycle in amazon
vegetation
geology
temperature
organic matter in soil
81
how does vegetation affect the carbon cycle in the amazon?
carries out photosynthesis and respiration ( at accelerated rates due to high temps)
connects rainforest to atmosphere carbon stores
biggest store of carbonic TRF (60%)
400 tonnes of carbon per hectare
carbon sink of global importance
82
how does geology affect carbon cycle in amazon?
geology=carboniferous rocks (lots of carbon stored regionally in slow cycle)
rock si not exposed to weathering so this carbon doesn't influence fast carbon cycle
no volcanic eruptions
in west nr andes, outcrops of limestone do occur
83
how does temperature affect carbon cycle in amazon?
consistent 27C
fast flows bc optimum growing conditions
fast decomposition and p/s
results in lots of vegetation
84
how does organic matter in soil impact the carbon cycle in the amazon?
leaf litter and dead organic matter accumulates temporarily at soil surface/ within rainforest soils. high temps/ humid conditions promote rapid decomposition by bacteria/fungi, emitting CO2 which is returned to the atmosphere and releasing nutrients to soil for uptake by tree-root systems
90-200 tonnes C/ha
85
significance of different physical factors in amazon carbon cycle?
temperature is the most significant factor bc it determines the rates of flows e.g. p/s, decomposition (so determines organic matter in soil)
determines abundance/ photosynthesis of vegetation
INTERDEPENDENCE OF FACTORS
geology=less important: not involved in fast carbon cycle
86
how does deforestation on a regional scale in the Amazon have global impacts?
LOCALLY: releases 1b tonnes of CO2 annually. less stores of carbon in vegetation and soils (soil erosion). soil infertility in LT. less flows of p/s
GLOBALLY: increased stores of atmospheric CO2 enhances CC
THEREFORE HARDER TO REVERSE
87
how does the Amazon water cycles allow the carbon cycle to operate so fast?
increased precipitation makes for ideal growing conditions, increasing rates of photosynthesis so increasing carbon storage in vegetation
88
how does the vegetation (i.e. photosynthesis) link the 2 cycles in the Amazon and how does this change diurnally?
more vegetation increases rate of p/s (ONLY DURING DAY), increasing vol. of carbon stored. this also helps recycle water via transpiration
vegetation is a store of water
vegetation intercepts water, decreasing surface runoff
89
how does deforestation (change in carbon stored) link the water and carbon cycles?
decreased carbon stores decrease water stores too
less evapotranspiration means less precipitation, decreasing runoff and the erosion of soil by water
if less precipitation, less p/s so less carbon stores
90
list the strategies to manage the water and carbon cycles in the Amazon
shifting cultivation
afforestation by the government
international agreements: UN REDD scheme
improved agricultural techniques ( agroforestry ad rotational cropping
91
what is shifting cultivation?
a traditional method of cultivation in tropicals rainforests which involves the rotation of land rather than juts the rotation of crops
it involves producing just enough food for survival and then moving on to new land
small areas of forest are cleared to provide land for farming: the soil here stays fertile for 10 years before farmers move on, clear new forest, move again and repeat this until first plot fertile again
92
how does shifting cultivation alter deforestation rates?
forest cleared for crops until soil exhausted of nutrients
therefore increases deforestation rates as new areas of land are cleared after several years while previous plot recovering
better than mass clearing of trees
93
positives of shifting cultivation
more sustainable for the environment than other forms of deforestation as area shave time to regrow
soil regains its fertility when farmers move onto new land
traditionally used by indigenous people
good for environment bc plants can regrow whilst farmers are elsewhere
94
limitations of shifting cultivation
trees are cut down to make space for farming
more efficient for farmers to clear larger areas at a time
not utilised as much bc people want economic growth and don't care much ab the environment
not great for econ. progress; takes more time and planning
95
impacts on carbon cycle of shifting cultivation
creates less drastic change than deforestation
amount of p/s occurring decreases less than usual deforestation (clear felling)
less carbon stores removed at one time
less carbon released into the atmosphere
96
impacts on water cycle shifting cultivation
less significant change than deforestation
amount of precipitation decreases and surface runoff increases, but this is less sig bc only a few acres are cut down at a time so area can remain sheltered
97
AO2 effectiveness of shifting cultivation
effective as a small scale management strategy, what Amazon inhabitants have always done so already have knowledge and is in harmony w nature
less suitable for commercial farmers bc only small areas cleared at a time
doesn't solve problem of deforestation, only mitigates
in EDCs such as Brazil, where eon dev. is prioritised, not best bc limits it
98
what is the REDD scheme?
provides payment to the Surui indigenous group for protecting the rainforest and abandoning logging
granting of carbon credits, which can be purchased bye international companies who have exceeded their annual carbon emission quotas
e.g. in 2013 Natura, a larte TNC, purchased 120000 tonnes of carbon credits from the Surui
99
how do REDD schemes alter deforestation schemes?
dramatically reduced deforestation rates in the territory during first 5 years of operation, but it was suspended in 2018 after discovery of large gold deposits, sparking a surge in deforestation (LT impermanence)
limitation= leakage (a reduction in carbon emissions in one area that results in increased emissions in another, such as curbing clear felling in one region drives farmers to clear fell in another)
100
impact of REDD schemes on water cycle?
REDD schemes prevent deforestation in the Amazon , so limit the impacts felt by the water cycle (unaffected)
BUT potential impermanence and difficulty of monitoring this strategy may mean that deforestation will occur in these areas in the future, so water cycle affected
101
impact of REDD schemes on carbon cycle?
before being suspended, project generated 300,000 carbon offsets certified under the Verified Carbon Standard (equal to removing 64000 cars from the road for a year), helping to meet the global imperative to sequester carbon
primary forest reminds: storing 400tonnes C per hectare (less combustion and felling of forest, so stored carbon not released)
102
limitations of REDD schemes as a management strategy
difficult to monitor accurately and reliably e.g. mining of gold too widespread to control
carbon calculations may be inaccurate
LEAKAGE: deforestation will increase elsewhere, affecting carbon and water cycles there
impermanence: LT viability of reduced emissions is heavily dependent on the forests vulnerability to deforestation
local scale projects
103
positives of REDD schemes as a management strategy?
created financial mechanism, so incentivises people in Brazil to reduce deforestation
relatively cost-effective: offsets cost less than $50 per tonne of CO2 (carbon capture offset costs $250-650 per tonne)
finances sustainable community development initiatives which generate income, support traditional practices (in harmony w nature) so enable LT dev, put value on land
104
what is afforestation?
planting trees in areas that haven't recently has any tree cover, in order to create a forest
(e.g. desertified areas or areas used for agriculture)
acts as a method to reduce atmospheric CO2
reverses deforestation rates
provides habitat to local wildlife, creates wind breaks, supports soil health
105
impacts of afforestation on the water cycle
more flows of p/s
improves topsoil: nitrogen is fixed at a higher rate, neutralising soil pH
improvement in soil fertility and promotes ecosystem productivity
allows for more recycling of water via transpiration and evaporation from leaves
redues runoff
106
impacts of afforestation on the carbon cycle
more carbon is able to be stored so mitigates climate change
can reverse biodiversity losses and provide carbon sinks (absorb CO2)
increases carbon storage in biomass
interception decreases levels of surface runoff
increases soil fertility and amount of p/s so less soil erosion and more nutrients for decomposition
107
limitations of afforestation as a management strategy
depends on the quality of the soil
must suit the local environment: risk= use of non-local tree species e,.g. may use more water than the area has available
consider prevailing winds and direction of sunlight
takes 120 years for topsoil biomass to recover
not as good for wildlife as primary forest
108
overall effectiveness of afforestation as a management strategy
good in short term for reducing GHE and CC
take time to grow and reach optimal p/s levels
heavily relies on funding (NGOs, Govs)
hard to implement on a large scale
reduces flooding, so pos. social impacts too e.g. income generation
109
2 main diversification of agriculture methods
1.dark soils
2.agroforestry
110
what are dark soils
made from inputs of charcoal, waste and human manure
allow intensive and permanent cultivation, which would drastically reduce deforestation and carbon emissions
111
how do dark soils slow rates of deforestation
charcoal in the soils attracts microorganisms and fungi, allowing the soil to retain its fertility in the long term
this means that one area can be used to grow crops for multiple seasons and therefore limits the amount of open land farmers need to grow crops and decreases deforestation
112
what is agroforestry
doing some crop growth and leaving some trees
has lower yield of crops
but decreases soil erosion and maintains habitats
needs incentive
113
how does agroforestry help reduce deforestation
mimics nature using a polyculture of trees to regenerate land and restore biodiversity whilst also producing crops
a sustainable method of farming which artificially replicates the rainforest, decreasing deforestation
114
how does diversification of agriculture affect the water cycle?
agroforestry instead of slash and burn means less areas of open forest so increased interception, increasing lag time so reducing flood risk in local area. means more rainfall is recycled and increases transpiration
dark soils may have larger moisture storing capacity so decrease surface runoff and flood risk
115
how does diversification of agriculture affect the carbon cycle
amount of deforestation that must occur for farmers to make a living decreases, so less CO2 released when rainforest areas are felled or burnt
volume of CO2 absorbed by CO2 will increase
116
how effective is diversification of agriculture as a management strategy?
successful in LT bc less trees need to be felled
many farmers may continue to farm using current methods due to difficulty implementing strategy and increased cost, which means less profits (less attractive, esp. in an EDC)
NEEDS INCENTIVE
117
what is permafrost?
frozen ground which reminds frozen all year round for at least 2 years
118
where is permafrost found?
areas of high altitude or latitude
119
what is the top layer of permafrost called and what are its characteristics
active layer
30-200cm: freezes and thaws seasonally
120
why is biodiversity and NPP low in the Arctic Tundra
v. little vegetation bc low light in winter and cold, so v. little p/s so less CO2 absorbed
huge seasonal variation: a lot more in summer
cannot store as much carbon in frozen ground
frozen for 8 months in winter so no p/s or decompositions, meaning v. little biomass so low NPP
121
what is water cycle like in arctic tundra in summer
3-4 months period= summer where temps are above 0C
vegetation can grow so there is more evapotranspiration, so more flows of water e.g. condemnation and precipitation
122
what is water cycle like in arctic tundra in winter
too cold to rain
not enough energy to drive evaporation
everything is frozen
123
comparison between amazon and Alaska temperature
consistently 27C in amazon bc on equator so suns rays are conc and it is hotter. between -28 and 4C in Alaska, and negative for 9 months bc polar latitude so low levels of insolation and suns rays are diffuse.
much more seasonal variation in barrow (32C range) vs amazon (2C range) bc amazon on equator so no seasons, whereas Alaska at high latitude so large difference between summer and winter due to tilt of earth (24h dark in winter, 24h light in summer)
124
comparison between amazon and Alaska: precipitation
higher in amazon all year round (lowest of 60mm) bc in ITCZ so low pressure, air rises, cools and condenses to form rain and there is a lot of vegetation so more evapotranspiration and precipitation, Alaska peak is 29mm bc too cold for evapotranspiration, high air pressure and less solar energy to drive water cycle; less vegetation too.
125
impacts of low temp and rainfall on arctic tundra
NPP is low due to cold and dark for most of the year
3 months of the year where temp is over 0C so temp and prep rates are higher, but still low compared to other biomes. flows slightly faster due to suns energy starting flows of p/s/ evapotranp/condensation.decompostions
126
how much carbon is the permafrost in the Arctic Tundra estimated to hold?
1600GT
127
annual precipitation in arctic tundra
50-350mm
most falls as snow
128
arctic tundra transpiration rates and why
limited transpiration bc of sparseness of vegetation cover and short growing seaosn
also less evaporation so reduced cycle
129
arctic tundra evaporation rates and why
low rates of evaporation bc music of the suns energy in summer is expended melting snow so that the ground temperatures remain low and inhibit convection
also surface and soil water are frozen for most of the year
130
how does active layer affect infiltration rates and water cycle?
melting of uppermost later of permafrost in spring and summer increases river flow
permafrost is a barrier to infiltration, percolation, recharge and groundwater flow
131
physical factors affecting arctic tundra water cycle
geology
relief
temperature
132
physical factors affecting arctic tundra water cycle: GEOLOGY
low permeability bc of permafrost and crystalline rocks Dom. geology, so v. little percolation and poor drainage bc water cannot infiltrate soil (bc of permafrost at depth)
geology has allowed permafrost to form bc the initial rain collected on surface, froze and formed initial permafrost (significance of this changes over time; less role now but historic importance)
geology is buried under the permafrost so less sig. now
133
physical factors affecting arctic tundra water cycle:RELIEF
ancient rock surface which underlies the tundra has been reduced to a gently undulating plain by 100s of millions of yeas of erosion and weathering
therefore water does not run off so forms surface stores: lakes/pools
minimal relief and chaotic glacial deposits impede drainage and contribute to water logging during the summer months
134
physical factors affecting arctic tundra water cycle: TEMPERATURE
in winter, sub-zero temps prevent evapotransp. in summer, some occurs from standing water, saturated soils and vegetation
humidity low all year round
frozen so no flows
precipitation is sparse (50-350mm annually)
average temps are v. below freezing for most of the year so water is stored as ground ice in permafrost layer. in short summer, active layer thaws so liquid water flows on surface (increased precipitation and runoff and all other flows). meltwater forms millions of pools and shallow lakes which stud the tundra landscape
135
NPP in arctic tundra
140 g/ m^2/ year
136
sink of carbon in tundra soil?
permafrost: globally contains 1600GT of carbon
amount of carbon in tundra soils= 5x greater than in above-ground biomass
137
why is accumulation of carbon so slow in tundra
due to low temperatures which slow decomposition of dead plant material
138
why does p/s only occur in summer in the tundra
active layer thaws so plants grow rapidly in short summer
long hours of daylight allow the to flower and fruit within j a few weeks
139
carbon per hectare in tundra
4 to 29 tonnes C/ha
v small
depends on density of vegetation
140
in summer in tundra what happens in the soil and with micro organisms
tundra plants input carbon-rich litter to the soil
activity of m/o increases, releasing CO2 to atmosphere through respiration BUT CO2/CH4 emission in winter too: pockets of unfrozen soil and water in permafrost= sources of these GHGs. snow cover may insulate microbial organisms and allow some decomposition despite low temps
141
is the tundra a carbon sink or a cabron source?
in PAST: permafrost functioned as a carbon sink
TODAY, global warming has raised concerns that is is becoming a carbon source (but limited evidence so may remain in balance). e.g. outputs of carbon form permafrost increasing in recent years BUT increasing temp leads to plant growth, increasing p/s and CO2 uptake, and also increases rate of decamp and plat litter entering store
142
how long has carbon been locked up in tundra soil
500,000 years
143
how much of worlds carbon in stored in tundra
1/2
144
describe arctic amplification
PFL
warmer temps
active layer becomes deeper
greater carbon fluxes
more GHGs released to atmosphere
greater rates of global warming
145
what physical factors influence the flows and stores of the carbon cycle in the tundra?
temperature
geology
soil
vegetation
146
physical factors influencing flows and stores of carbon cycle in the tundra:
TEMPERATURE
slow decomposition, respiration and flows of CO2 to atmosphere
seasonal difference
growing season lasts barely 3 months, so average NPP and p/s rates throughout year are low (but some compensation for short growing season in long hours of daylight in summer)
unavailability of liquid water for most of year so limited plant growth, so total carbon store of biomass is small
147
physical factors influencing flows and stores of carbon cycle in the tundra:
GEOLOGY
store in slow carbon cycle
allows permafrost to lock away soil carbon
148
physical factors influencing flows and stores of carbon cycle in the tundra:
SOIL
most C frozen and locked away
stores decomposed vegetation: 5/6 of all tundra carbon (1600GT)
owing to impermeability of permafrost, rock permeability, porosity and mineral composition of rocks, exerts little influence on fast carbon cycle
water logging slows decomposition, respiration, and flows of CO2 to atmosphere
149
physical factors influencing flows and stores of carbon cycle in the tundra:
VEGETATION
v little vegetation cover except in summer
only 1/6 of carbon in biomass bc of slow growth (frozen 8 months) and low rates of p/s
growing season barely 3 months, so NPP and p/s rates averaged through year are low (but some compensation in long hours of summer daylight)
less sig but needed for soil carbon
150
how is the amount of oil being produced in the tundra changing?
why?
less in North Shore
low quality oil, more environmental awareness e.g. oil spills so more restrictions, difficult to extract bc frozen so costly and harder than elsewhere
151
examples of human activity in the tundra
construction of oil and gas infrastructure e.g. settlements, oil drilling rigs, houses (diffuse heat directly to env)
dust deposition by the side of the road creating darkened surfaces changing the amount of absorption of light (albedo effect)
removal of vegetation (insulates permafrost)
strip mining of aggregates (sand and gravel) for construction
152
construction of oil and gas infrastructure e.g. settlements, oil drilling rigs, houses (diffuse heat directly to env)
impact on carbon cycle
PERMAFROST MELTING
releases CO2 and CH4 and decreases carbon stores
increases GHG, contributes to GW and CC global scale
more atmospheric CO2 on local scale
153
construction of oil and gas infrastructure e.g. settlements, oil drilling rigs, houses (diffuse heat directly to env)
impact on water cycle
water abstracted from creeks and rivers for industrial use and fro building of ice roads in winter decreases localised runoff
PERMAFROST MELTS, diffused heat in env increases melting and evaporation and flows of water. increased runoff and river discharge, so more flooding esp. in summer so extensive lakes and wetland , increasing evaporation
154
construction of oil and gas infrastructure e.g. settlements, oil drilling rigs, houses (diffuse heat directly to env)
significance
management strategy e.g. stilts can reduce impacts on melting the permafrost (EFFECTIVE)
v localised
rate of drilling is decreasing so LT impacts will decrease
PFL
ARCTIC AMPLIFICATION
155
dust deposition by the side of the road creating darkened surfaces changing the amount of absorption of light (albedo effect)
impact on carbon cycle
PERMAFROST MELTING
releases CO2 and CH4 and decreases carbon stores
increases GHG, contributes to GW and CC global scale
more atmospheric CO2 on local scale
global temps increase due to arctic amplification, so more vegetation bc hotter, longer growing season, more p/s, more CO2 absorbed (neg feedback)
156
dust deposition by the side of the road creating darkened surfaces changing the amount of absorption of light (albedo effect)
impact on water cycle
PERMAFROST MELTS bc dakr surfaces absorb heat (PFL bc as ice melts, more dark surfaces= arctic amplification so increased global temps bc GW and CC). increased runoff and river discharge, so more flooding esp. in summer so extensive lakes and wetland , increasing evaporation
157
dust deposition by the side of the road creating darkened surfaces changing the amount of absorption of light (albedo effect)
significance
PFL (ARCTIC AMPLIFICATION) so methane released
fairly local scale, only on roads
worse in winter
158
removal of vegetation (insulates permafrost)
impact on carbon cycle
permafrost melts more easily, releasing CO2 and CH4, e.g. on North Slope, est. losses of CO2 from permafrost= 7 to 40 million tonnes per year and 24000 to 114000 tonnes CH4
less p/s and uptake of CO2 from atmosphere
thawing of soil increases microbial activity, decomposition and emissions of CO2
159
removal of vegetation (insulates permafrost)
impact on water cycle
flooding in summer bc less interception
less transpiration and therefore less precipitation
less p/s so less water taken in
160
removal of vegetation (insulates permafrost)
significance
slow growing so recovery form damage and regeneration takes decades therefore LT significance
vegetation in tundra is fragile
161
strip mining of aggregates (sand and gravel) for construction
impact on carbon cycle
PERMAFROST MELTING
releases CO2 and CH4 and decreases carbon stores
increases GHG, contributes to GW and CC global scale
more atmospheric CO2 on local scale
more dark surfaces so albedo and arctic amplification
less vegetation so less CO2 absorbed
162
strip mining of aggregates (sand and gravel) for construction
impact on water cycle
creates artificial lakes which disrupt drainage and expose permafrost to further melting
artificial lakes increase evaporation in summer
less vegetation decreases interception and transpiration so less precipitation and runoff, causing floods
163
strip mining of aggregates (sand and gravel) for construction
significance
only in summer (when ground thaws)
fragile environment so LT damage
PFL
ARCTIC AMPLIFICATION
164
oil/gas industry in tundra
local scale
impacts are geographically focussed in a small area
165
what is the purpose of the strategies to reduce the impacts of oil and gas exploration in the tundra?
pragmatic
melting permafrost causes widespread damage to buildings and roads as well as increased maintenance costs for pipelines/other infrastructure
166
examples of strategies to reduce the impacts of oil and gas exploration in the tundra
insulated ice and gravel pads
buildings and pipelines elevated on stilts
drilling laterally beyond drilling platforms
more powerful computers
refrigerated supports
167
insulated ice and gravel pads
describe
roads and other infrastructural features can be constructed on insulating ice or gravel pads, thus protecting the permafrost from melting
168
buildings on pipelines and elevated on stilts
describe
EFFECTIVE?
constructing builds, oil/gas pipelines and other infrastructure on stilts allows cold air to circulate beneath these structures, providing insulation against heat-generating buildings, piecework e.t.c., which would otherwise melt the permafrost
WIDESPREAD USE, SIMPLE, EFFECTIVE, CHEAP
169
drilling laterally beyond drilling platforms
describe
new drilling techniques allow oil and gas to be accessed several kilometres form the drilling site
with fewer sites needed for drilling rigs, the impact on vegetation and the permafrost due to construction (access roads, pipelines, production facilities) is greatly reduced
170
more powerful computers for oil/gas exploration
describe
fewer exploration wells are needed, so less drilling, so reduced impact on the environment
171
refrigerated supports in tundra
describe
used on the Trans-Alaska Pipeline to stabilise the temperature of the permafrost
similar supports are widely used to conserve the permafrost beneath buildings and other infrastructure
172
how effective are strategies to reduce impacts of oil and gas exploration?
effective bc ACs so have more money so can afford these and have more env. restrictions so need to put these in place
fragile ecosystem so slow to recover if damaged, reducing effectiveness
if arctic amplification happens, triggers v. sig change, threshold breached so sig. risk
173
timeframe for permafrost to form
tens/hundreds of thousands of years
174
step by step how does permafrost form
small plants grow then die/decompose
it rains, and this forms surface storage. bog forms
winter arrives so the water freezes 6-8 months
summer so some small plants grow
CONSTANTLY REPEATING
175
examples of dynamic equilibrium in the water cycle
after heavy rain, plants will intercept the water, leading to evapotranspiration, returning it to the atmosphere
rain increases adding inputs to a system (potential flood), and transfer/outputs increase to remove it, restoring equilibrium
tundra active layer melts in the summer allowing flows of carbon and water but in the winter it freezes and these flows stop
176
examples of dynamic equilibrium in the carbon cycle
amount of CO2 in atmosphere increases, plants grow faster to sequester it ad take it out, lowering atmos. CO2
trees may grow taking carbon out of the soil, but eventually tree dies and decomposes, returning carbon to soil
deciduous forests are net sources of CO2 in winter (resp>p/s) but in summer there is net NPP gain (p/s>rest), balancing out the 2 flows over a year
as CC melts tundra, active layer thaws, resulting in faster p/s rates of plants in this layer, removing CO2 in atmos and returning equilibrium
as atmos. CO2 increases, diffusion grad. increases so physical pump in oceans is enhanced. so more CO2 dissolved in ocean to restore equilibrium
177
water cycle PFL example
increasing temp= increased evaporation rate and ability of atmosphere to hold more water.but as water vapour is a GHG, will absorb more radiation so temp increases further, so more water vapour absorbed
178
water cycle NFL examples
increased temp= more water vapour absorbed so more clouds formed, so more solar radiation reflected, so reduced temp
rainfall reduced, trees e.g. silver bird stressed and shed leaves so less water taken in by tree so water balance restored
rainfall increases so stores fill up and flows e.g. surface runoff increase. greater discharge in river channels and more water leaving area into sea.
179
carbon cycle NFL example
CO2 levels increase in atmosphere, p/s stimulated so plant growth so more carbon in biosphere rather than atmosphere
180
carbon cycle PFL examples
temps increase, so permafrost melts so CO2 and CH4 released= GHGs so more increase so more released
warmer climate= more decomposition of organic material so more CO2 in atmosphere so more warming
181
amazon vs tundra NPP
2500g/m^2/year
<200g/m^2/year
182
amazon vs tundra annual precip
2500mm
50-350mm (majority as snow)
183
amazon vs tundra carbon stored per hectare
400 tonnes primary forest
1600GT (5/6 in soil)
184
land use changes which affect carbon and water cycles
urbanisation (conversion of land use from rural to urban. farmland/woodland replaced by housing, offices, factories, roads. natural surfaces e.g. vegetation/soil give way to concrete, brick and tarmac)
farming
forestry
185
how does urbanisation impact carbon cycle
less carbon stores bc less vegetation and green space
release carbon emissions as CO2 and CH4 (combustion of fossil fuels) e.g. for concrete manufacture/cement production, or vehicles (leading to global CC/GW)
albedo effect (increased temp due to urban heating)
186
urbanisation impact on water cycle
artificial surfaces in urban areas are largely impermeable so they allow little/no infiltration and provide minimal water storage capacity to buffer runoff
urban areas have drainage systems designed to remove surface water rapidly (gutters, sewers, pitched roofs) so a high proportion of water from precipitation flows quickly into streams/rivers, leading to a rapid water level rise.
encroaches on floodplains (which are natural storage areas for water). urban dev on these reduces water storage capacity in drainage basins, increasing river flow and flood risk
187
farming impact on water cycle
interception of rainfall, evaporation and transpiration by annual crops is less than forest/grassland
ploughing increases evaporation/soil moisture loss and furrows ploughed downslope act as drainage channels, accelerating runoff and soil erosion
surface runoff increases where heavy machinery compacts soils so peak flows on streams draining farmland are higher than in natural ecosystems
188
farming impact on carbon cycle
clearance of forest for farming reduces carbon storage in above and below ground biomass, whilst soil carbon storage is also reduced by ploughing and the exposure of soil organic matter to oxidation
methane released e.g. cows, rice paddy fields (GHG)
carbon exchanges through p/s are lower, partly due to lack of biodiversity and the short growth cycle compressed into 4/5 months
189
forestry impacts on carbon cycle
change from farmland, moorland and heath to forestry increases carbon stores (trees contain 170-200 tonnes C/ha, 10x higher than grassland, 20x higher than heathland)
soil=large carbon pool. forest soil carbon is 500 tonnes C/ha
forest trees extract CO2 from atmosphere and sequester it for 100s of years (stored in wood of trees). but these trees only active carbon sinks for first 100 years so forestry plantations have a rotation period of 90-100 years (felled and reforested)
190
forestry impact on water cycle
increased rates of interception e.g. E England Sitka Spruce=60%. also due to mainly conifers so high density of trees
increased evaporation(of intercepted rain on leaf surfaces)
less runoff and stream discharge w/ high interception and evaporation and the absorption of water by tree roots alters hydrology e.g longer lag times, low peak flows and total discharges
high transpiration:sitka spruce in pennines=350mm/year
clear felling to harvest timber creates sudden but temp. changes to local water cycle e.g. increased runoff, less evaporation, increased stream discharge
191
what is an aquifer
permeable or porous water-bearing rocks e.g. chalk which can be used as a water source by manufacturing a borehole or well
192
what is an aquifers water table
the level of water within an aquifer
can vary throughout the year ad over longer periods of time
the point where the ground is saturated with water
193
what causes a water table to rise and fall
precipitation fills up/recharges an aquifer
rates of infiltration /percolation
high temps increase evaporation so lower water table
human uses e.g. abstraction lowers water table
194
problems w water in uk
water stress increasing, especially in south east of uk
aquifer levels falling
195
solutions to water stress in the uk
increase price of water, which puts a value on it so used more conservatively
water transfer schemes (from NW to SE in pipes) but this is expensive
better water recycling/reducing leaks so less wastage
reuse grey water
196
why has water level risen over the last 60 years
declining demand for water by industry in London and reduced rates of abstraction allowed water table to recover
by early 1990s it was rising at a rate pf 3m/year and began to threaten buildings and underground tunnels
since 1992 thames water has been granted abstraction licences to slow the rise go the water table which is now stable
rules and regulations lead to management of the resource
197
what is an artesian basin
formed in a syncline, when an aquifer is contained within impermeable layers of rock
aquifer will contain the groundwater which ca be tapped by a borehole and water will flow to surface under artesian pressure (if you drill down, it natural comes up)
198
fossil fuels consumption releases hwo much CO2
has resulted in what increase in atmospheric carbon
10 billion tonnes per year
form 280ppm to 400ppm
199
why is global energy consumption increasing?
increasing global population
increasing wealth so increasing demand for fossil fuels/development
industrialisation of developing countries
200
are alternative energy sources making a sig. contribution to global energy consumption?
hydropower and nuclear are most sig. but still v small compared to fossil fuels
201
how do carbon cycle flows ad stores change naturally (longer term)?
in a glacial period, less photosynthesis bc less vegetation so less stores of carbon in biosphere
more carbon in permafrost
slower rates of decomposition
202
how do carbon cycle flows ad stores change naturally (shorter term)?
p/s during day not night so more flows of carbon e.g. in TRF: changes carbon balance
in summer more p/s so more plant growth and in winter there's less. difference is greater at poles (seasonal change in permafrost)
203
how do water cycle flows ad stores change naturally (shorter term)?
summer= more water flows bc less water frozen
seasonal change in rainfall patterns (wet season e.g. in temperate/monsoonal place e.g. Indian monsoon or UK climate)
204
how do water cycle flows ad stores change naturally (longer term)?
glacial to interglacial period is more flows of water and more water in oceans
ice age=more water locked in cryosphere so less in ocean stores
fewer flows as it is colder
205
what are short term changes to the water and carbon cycle
occur diurnally or seasonally
changes in climate, temperature, sunlight, and foliage which bring about changes in the carbon and water cycle
206
how does solar angle/intensity diurnal change impact water and carbon cycle
tropical region is when sun energy is high, so increased p/s leads to more evapotranspiration so more flows of water so more precipitation; can cause thunderstorm in afternoon due to convectional heating= DAILY CYCLE IN TROPICAL PLACES
207
diurnal changes in CO2 in amazon?
daily change to atmospheric CO2 levels due to increased p/s during day time
mor epronounced difference in tropical places bc hotter so increased rates of p/s during day (larger range)
208
what controls the season and where will these changes be more pronounced?
ultimately controlled by variations in the intensity of solar radiation
more pronounced closer to the poles e.g. tundra
209
how and why does atmospheric CO2 change in the northern hemisphere summer?
trees are in full foliage so net global flow of CO2 from the atmosphere to the biosphere (atmospheric CO2 levels fall by 2ppm)
at end of summer as p/s ends, flow is reversed w. natural decomposition releasing CO2 back to the atmosphere
seasonal fluctuations explained by conc. of continental land masses in N. hemisphere
210
how does the ocean change seasonally?
phytoplankton are stimulated into photosynthetic activity by rising water temperatures. more intense sunlight and the lengthening photoperiod
every year in North Atlantic there is an explosion of microscopic oceanic plant life which starts in March and peaks in mid-summer. the resulting algal blooms are so extensive they r visible from space
211
describe trends in ocean chlorophyll and suggest why this is occurring
more chlorophyll in N hemisphere in summer months bc hotter (seasonal change affects p/s rates)
more chlorophyll gathering around coastlines increases rate of p/s (nutrient-rich water provides better conditions for plants to grow (where deep water upwells))
212
how do chlorophyll patterns affect the carbon cycle?
carbon sequestered and stored at Northerly latitudes in summer months
taken up by p/s of phytoplankton/plants/algae
213
describe and suggest reasons for the relationship between discharge and rainfall
in temperate climates there are roughly seasonal patterns of precipitation (wetter in winter and drier in summer) causing seasonal change to river discharge (seasonal recharge of aquifers )
214
describe the changes in the carbon cycle over the past 400,000 years
how does this link to the temperature over the same time period?
fluctuating: peaks about every 100,000 years then decreases gradually
same pattern but slight delay between peak of CO2 and peak temp (as co2 increases, temp increases bc more GHG in atmosphere, enhancing GHE so less solar radiation leaves atmosphere into space so increased temp, causing global warming)
increasing temp increases p/s so decreases CO2 levels (NEGATIVE FEEDBACK)
215
during a glacial period, explain how the water cycle will be affected
net transfer of water from oceans to storage in ice sheets, glaciers and permafrost (in glacials, worldwide sea level falls by 100-130m and ice sheets&glaciers expand to cover 1/3 of continental land mass)
as ice sheets advance equator wards, they destroy extensive tracts of forest and grassland: the area covered by vegetation and water stored in the biosphere shrinks
in tropics, climate becomes drier and deserts and grasslands displace large area of rainforest
lower rates of evapotransp during glacial phases decreases exchanges of water between atmosphere and oceans, biosphere and soils. this, tgt w/ so much fresh water stored as snow and ice, slows water cycle significantly
more ice increases reflection of suns energy so less absorbed so colder so PFL
216
how could a cooler climate affect the carbon cycle in the tropics?
tundra biome will spread into warmer areas e.g. nearer tropics so less NPP so more carbon stored in soil (BIOME SHIFT)
less CO2 returned to atmosphere through decomp
less vegetation cover, forests, lower temps, NPP and precipitation means total volume of carbon fixed in p/s declines
217
how might rates of evapotranspiration be affected by cooler climates?
lower rates bc colder so decreased evap and flows of water bc less energy
lower ocean temps so CO2 is more soluble in water
218
explain how CO2 levels could eb caused to fall naturally in a glacial
expanses of tundra beyond the ice limit sequester huge amounts of carbon in permafrost
increased p/s decreases CO2
biological pump in oceans or physical pump (CO2 dissolves in oceans)
219
during glacial periods, the terrestrial carbon sink decreases
explain why
land surface is buried by ice so carbon stores in soils will no longer be exchanged with the atmosphere
less vegetation cover, forests, lower temps, NPP and precipitation means total volume of carbon fixed in p/s declines
biome shift: biomes move as climate changes e.g. deciduous forests to tundra
220
explain how a glacial period impacts biological pump (and physical)
excess CO2 may go from atmosphere to deep ocean
one mechanism= changes in ocean circulation during glacials: bring nutrients to surface and stimulate phytoplankton growth
fix large amounts of CO2 before dying and sinking to deep ocean where C is stores
CO2 is more soluble in cold water and ocean temps will drop so more C taken up by oceans
221
benefits of recording changes in water/carbon cycleusig satellite imagery
larger scale: much bigger area can be recorded/measured
see change over time instantly
cheaper and easier (most data produced by NASA and distributed for free)
see negative human actions e.g. deforestations OR ow management strategies are working (or not)
can be used to make future plans (e.g. where is vulnerable to s.l. rise.neat area to be deforested e.t.c.) so inform decisions
222
how does vegetation link the water and carbon cycles?
p/s required carbon and water. as plants sequester carbon through process, water is cycled (transp) and recycled. however, after deforestation, water cycle cont. but carbon cycle virtually stops
places w/ higher rainfall e.g. TRF= optimised p/s rates so more carbon sequestered
greater CO2 causing warming leads to greater rates of p/s in vegetation so water is cycled more quickly here
more surface runoff (esp. in deforested areas) means soil carbon is washed off land into rivers, silting them up and causing eutrophication, can also decrease fertility of land
223
significance of vegetation linking water and carbon cycles?
fats carbon cycle so ST/less permanent impacts, so easier to reverse effects
affects diff. biomes differently : relative sig. in a TRF is much larger bc lots of vegetation compared to tundra/desert
sig. changes seasonally (in higher latitudes, little p/s in winter)
224
how does the cryosphere link the water and carbon cycles?
more atmospheric CO2 increases temps, melting ice in tundra and exposing darker surfaces (altering albedo and increasing melting) so more methane released (PFL bc this increases warming) but also causes more flows of p/s bc plants are able tog row (more C stores) and decomposition increases so more cycling of carbon so greater flows of water via transp, convection and precipitation. greater water vapour could cause greater warming (bc GHG) is a PFL
seasonal change in tundra results in freezing of water stores, stopping flows of carbon (e.g. p/s, decomposition). in the summer, warming temps result in melting water allowing greater flows of water (so lakes, rivers, flooding) increasing flows e.g. transp so more convection and precipitation
225
significance of cryosphere linking water and carbon cycle
spatial variation: mainly in tundra; v little seasonal change in TRF
concerns ab C being released by arctic amplification (will decrease sig. of link)
PFL created (LT irreversible impacts w global sig. bc contributes to GHE/CC)
in winter in tundra, low temps stop all flows of carbon (HIGHLY SIG, SEASONAL DIFF)
226
how does the atmosphere link the water and carbon cycles?
carbon can dissolve into water vapour (causing acidic water vapour which creates acid rain)
as increased CO2 in atmosphere warms climate, more energy and heat to cause greater evapotransp so more water vapour in atmosphere (PFL)
increased CO2 causes warming so increased rates of p/s in vegetation so water cycled more quickly by vegetation
227
significance of atmosphere in linking water and carbon cycles
relatively small store of C and H2O BUT fragile so small change makes a big diff.
PFL created, so LT irreversible impacts w/ global sig. bc continue to GHE/CC
impacts of p/s only sig. in areas w/ lots of vegetation so not sig. for tundra for much of year
changes seasonally too (more in summer)
228
how do oceans link the water and carbon cycles?
in oceans, carbon can be sequestered via biological pump as phytoplankton p/s and can remove C from atmos, initiating food chain. these C-based landforms die and are sedimented on sea floor, lithified and form sedimentary rocks (fast to slow cycle)
carbon can be dissolved in the oceans via physical pump) down welled into deep water, and stored for 1000s of years. as atmospheric CO2 increases, warming climate, sea temps rise and rate of diffusion slows
higher rates of atmospheric CP2 occurring result in GW, melting ice sheets so s.l. rise (eustatic), increasing amount of water in oceans
229
sig. of oceans in linking water and carbon cycles
long-lasting impacts bc =moves C to slow cycle
biological and physical pump sig. varies seasonally and spatially
LT impacts: locked away for 1000s of years
warming= PFL so long lasting impacts
GW= global sig
230
impact of LT CC on water cycle
GW increases evap, so WV in atmosphere increases (GHG so PFL bc increases global temps, increasing evap and precipitation) so increases surface runs in water cycles, increasing flood risk
WV= source of energy in atmosphere, releasing latent heat on condensation, increasing power and frequency of extreme weather events e.g. hurricanes
GW accelerates melting of glaciers, ice sheets e.g. Greenland and permafrost in Arctic Tundra so water storage in cryosphere decreases as water transferred to oceans and atmosphere
231
impact of human activities e.g. rapid pop and econ growth, deforestation, urbanisation on water cycles (mainly local/regional scale)
compared to natural ecosystems, human activities (e.g. deforestation and urbanisation) decrease evapotransp and therefore precipitation, increase surface runoff, lower water tables. e.g. in Amazonia, forest trees are key component of water cycle. extensive deforestation breaks this cycle, so climates dry out and prevent regeneration
rising water demand for agriculture and public supply (esp. in (semi) arid env) leads to shortages in rivers and aquifers e.g. Colorado basin in USA. elsewhere, quality of freshwater decreasing (over pumping of aquifers in coastal regions of Bangladesh leads to incursions of saltwater so water unfit for irrigation or drinking)
232
impact of long term CC on carbon cycle
increasing global temps will increase rates of decomposition and accelerate transfers of carbon from biosphere and soil to atmosphere
carbon frozen in permafrost of tundra released as temps rise above 0C so oxidation and decomposition of peat stores
acidification of oceans through absorption of excess CO2 from atmosphere decreased p/s by phytoplankton, limiting capacity of ocean to store carbon (LT= less CO2 in biosphere and oceans, but will vary seasonally and spatially)
impact of global CC on cycle depends on rising temps and geographical differences in rainfall amounts (at high lats, boreal forests of Siberia, Canada and Alaska can expand polewards)(in humid tropics, increasing aridity threatens extent of forests, are replaced by grasslands so less C stored in biome)
233
impact of human activities e.g. rapid pop and econ growth, deforestation, urbanisation on carbon cycles (mainly local/regional scale)
soil= important carbon store being degraded by erosion caused by deforestation and agricultural management
land use change (mainly DF) trasnfers 1b tonnes of CO2 to atmos each year
stores in wetlands, drained for cultivation and urban dev are depleted as dry out/oxidised
phytoplankton absorb >1/2 CO2 from burning fossil fuels (more than TRF). acidification of oceans threatens this store
DF decreases forest cover by 50% so less C in biosphere and fixed by p/s
fossil fuels=87% of primary energy consumption, removes billions of tonnes of C from geological store. 8b tonnes transferred to atmosphere per year.
234
global management strategies to protect the carbon cycle
wetland restoration
reducing emissions
improving agricultural practices
afforestation
235
unsustainable practises taking place in agriculture
overcultivation
overgrazing
excessive intensification
(leads to soil erosion and release of CO2)
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how much carbon does livestock farming produce each year
100 million tonnes
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methods of reducing GHG emissions from agriculture
land/crop management
livestock management
manure management
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methods of reducing GHG emissions from agriculture: land/crop management
zero tillage: not ploughing the soil when growing crops conserving its carbon content and risk of erosion
polyculture (growing crops among trees) to provide cover and protection
crop residues: leaving roots/stems/leaves of previous plants to prevent soil erosion and drying out
avoiding heavy machinery (leads to compaction)
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methods of reducing GHG emissions from agriculture: livestock management
improving quality of animal feed
reduces enteric fermentation producing CH4
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methods of reducing GHG emissions from agriculture: manure management
controlling how it decomposes
storing manure in anaerobic containers and capturing CH4; renewable energy
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evaluation of improving agricultural practises to protect the cabron cycle
most practises are cheap so accessible for most levels of wealth
LIDCs often rely more on agriculture in their economies so may be less inclined to adopt practises that could reduce overall yield and cost more
ultimately doesn't reverse CC
could make small difference but won't be too significant
easier to implement on a local scale as easier to monitor and cheaper
no real way of enfocring and monitoring these practcies
pop rise leads to an increase in demand of produce so decreasing yield could lead to problems of not enough food being distributed
lack of yield so less produce and profit
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what is afforestation
planting trees in deforested areas that are not currently forested
trees are carbon sinks so afforesattion can help reduce atmospheric CO2 levels in the medium to long term to combat CC
reduces flood risk and soil erosion and increases biodiversity
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example of country that implemented large scale afforestation
china 1978
aims to afforest 400,000km^2 by 2050
(however a lot of countries/businesses make a big deal of planting trees, when the preservation of them after id just as/more important e..g Ethiopia planted 100m trees but not protected in LT)
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evaluation of afforestation to protect carbon cycle
works in Acs and LIDCs
additional ecological and socioeconomic benefits e.g. habitats, biodiversity conservation, soil protection water regulation, sustainable livelihoods
requires funding, technical expertise and LT commitment (LIDCs may face challenges in implementing large scale afforestation w/o financial assistance)
local communities' involvement is vital (their knowledge and participation ensures forest's sustainability) to promote social equity and respect land rights
competing land uses (less incentive for afforestation bc no econ benefit and no food/infrastructural development)
what tree do you plant? based on location
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what is wetland restoration?
wetland= freshwater marshes, floodplains, mangroves. have water table at or near surface so ground is permanently saturated
manipulation of former/degraded wetland's physical, chemical and biological characteristics to return to its natural functions
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how much of lands surface do wetlands occupy
how much of earths terrestrial carbon do wetlands contain
6-9%
35%
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why do wetlands need to be restored?
urbanisation, pop growth and econ dev have placed huge pressure on wetland environments
in lower 48 US states, wetland areas halved since 1600
negatively affecting biodiveristy, habitats, and releasing stored CO2/CH4
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how to restore wetlands?
reconnect rivers (remove flood embankments, controlled flood)
breach sea defences
divert/block drainage ditches w/ slucie gates
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Canada wetland restoration
canadas prairie provinces lost 70% of wetlands
restoration showed wetlands can store 3.5 tonnes C/ hectare/year
112,000ha planned to be restored
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evaluation of using wetland restoration to protect carbon cycle
only appropriate in coutnries which have wetlands (6-9% of land surface)
acquiring the land is expensive so little incentive to do so (e.g. Somerset levels, land used for farming so farmers need alternative income and expensive to buy land off them)
effective carbon store so have potential to be v. sig., but tensions regarding land use mean thye don't maximise potential
sig. varies between places
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example of reducing emissions scheme
EU emissions trading scheme
'cap and trade'= limit placed on the right to emit specified pollutants over an area
richer countries can transfer fund and tech to help them meet targets
companies can trade emission rights within area
NOT GLOBAL so causes leakage
gives incentive to reduce carbon
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is Paris agreement effective at reducing emissions
under countries' control so no obligation to abide
v. little progress made at each COP conference
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evaluation of reducing emissions as strategy to protect carbon cycle
large scale: global
can reverse CC impacts if all countries involved (should be bets strategy but countries have ultimate power)
keep below quota= benefit from profits from other countries who have gone over
co-operation difficult bc econ and political barriers
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strategies to sequester carbon
land use change
CCS
afforestation
encouraging and fertilising phytoplankton
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land use change to sequester carbon
stopping ploughing
encouraging wetland development
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land use change to sequester carbon : stopping ploughing
ploughing releases C into atmosphere and depleted m/o's which enrich the soil, so reducing ploughing means less CO2 released and less soil erosion
instead of ploughing, use variety of plant types (symbiotically protect each other and decompose to provide soil w/ nutrients)
min-till/no-till farming= less disturbance to soil
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effectiveness of land use change to sequester carbon
limitations: hard to enforce, prone to CC impacts, weakening carbon sink capacity, farmers in LIDCs depend on land for livelihood, so less ploughing limits income
more effective machinery to limit soil damage is more expensive so less accessible
needs incentive
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what is CCS?
technology that aims to reduce amount of CO2 emissions released into atmosphere form industrial processes, power generation e.t.c.
involves capturing CO2, compressing it, transporting it to a storage site where is it stored underground or in ocean , so its not released into atmosphere to contribute to GHE
put on power plants/ industry e.g. Teesside
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how effective is CCS?
has potential to be highly effective esp. in industries which are difficult to decarbonise through other means e.g. heavy industry, power gen.
slows rate of CC
cost of implementing the technology- limitation so less accessible to LIDCs (but this will decrease over time)
concerns over safety and long term viability of CCS
good in ST but less in LT bc should invest in renewables
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how do phytoplankton sequester CO2
CO2 taken in during p/s, ad carbon is incorporated into phytoplankton.
most of C is returned to near-surface waters when they are eaten or decompose, but some falls to ocean depths
'biological ocean pump'
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carbon transfers per year in biological ocean pump
10 gigatons form atmosphere to deep ocean per year
small changes in growth of phytoplankton affect atmospheric CO2 concs so feedback loop w global temps
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evaluation of fertilising and encouraging phytoplankton to sequester carbon
cost is variable and fairly unknown
carried out along coastlines and continental shelves, along equator and in high-latitude areas. winds play role in distribution of phytoplankton by driving currents
large potential due to scale of ocean so no competition over use of area
no ownership of oceans, so who should do it
iron conc is already good
only a ST solution
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how to fertilise phytoplankton
iron fertilisation in iron-poor areas
enhances biological productivity/ accelerare CO2 sequestration
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strategies to manage the water cycle
improving forestry techniques
drainage basin planning
water allocations
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strategies to manage the water cycle:what is improving forestry techniques
adapting techniques that promote LT health and productivity of forests while minimising negative impacts on water resources
e.g. selective logging, reforestation, maintaining forest buffer zones along water bodies
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how does improving forestry techniques manage the water cycle
increased ground coverage so increased interception, so increased evapotranspiration
decreased surface runoff so decreased flood risk
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what does watershed management involve?
considers entire hydrological cycle within a specific geographical area.
mapping and monitoring water resources, identifying critical areas for protection and implementing appropriate forest management practices to maintain water quality and quantity
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how does improving forestry techniques reduce LT negatuve human actions?
in Amazon, surface runoff has increased by 2700% and improving forestry techniques will help combat this by increasing interception and transpiration/precipitation so changing the climate
reduced levels of atmospheric carbon so combats CC
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evaluation of improving forestry techniques as a strategy to manage water cycle
scale= large. but due to rapid urbanisation of most countries, may be limited
cheap to implement so accessible for LIDCs
take a long time to grow so not a ST solution
lack of economic benefit so lack of incentive
volume fo CO2 produced by humans >>>>>> vol absorbed by trees
effectiveness depends on place(less growth in higher latitudes, best in tropics)
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strategies to manage the water cycle:what is water allocations
the process of distributing water supplies to meet the various requirements of a community
change depending on how wet/dry the year is
v effective as long as inputs are constantly added to the system
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example of water allocation scheme
in semi-arid conditions of water scarcity e.g. lower Indus Valley in pakistan and US colorado basin, water agreements divide up resources between downstream states
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what issue in water cycle does water allocation tackle?
tackles wastage of water through inefficient water management e.g. over-irrigating crops
encourages people to use strategies to minimise water loss, e.g. recycling of waste water from agriculture and industry -> efficient water use
sharing of limited water during droughts when supplies are inadequate to meet all needs
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how does water allocation reduce LT negative human actions?
resulting amount of water taken from a source sp don't run out
ensures no waste water as uses are monitored
maintains level of water stores
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effectiveness of water allocation as a strategy to manage water cycle
in ACs bc well-managed and within borders e.g. Thames (easier to allocate w/o conflict)
difficult to enforce in trans-boundary rivers e.g. Indus or when a country wants to sue to develop e.g. Ethiopia w/ Nile
issues when drought bc no inputs so need to decide how to split minimal water
international agrteement make this strategy more effective
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strategies to manage the water cycle:what is drainage basin planning?
holistic management approach to accommodate the conflicting demands of different water users (e.g. agriculture, industry, domestic use, biodiversity and so on)
encompasses everything; is the overall planning strategy (.e.g reducing flood risk through afforestation/flood defences, wetland restoration, water allocation, monitoring pollution levels)
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2 examples of drainage basin planning
river thames
Indus River
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river thames drainage basin planning example
river thames (on a chalk aquifer)
in 1960s, poor water management meant aquifer was being overused so water table fell drastically therefore management is v important
rules and regulations put in place by council e.g. water allocations. dynamic equilibrium reached
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indus river drainage basin planning example
trans-boundary
runs through pakistan and India
any water management e.g. dams put in place have substantial impact on water downstream
causes conflict and tensions
both EDCs with large/growing popultiaons and demand so more difficult management
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evaluation of drainage basin planning
most effective on local scale when in one country
better in ACs bc have money and resources to tackle issue
difficult bc many components and different players
relies on steady input of precipitation (hard to manage when floods or droughts)
more effective in countries w steady population and water demand
significant factor bc encompasses everything including other management strategies
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is water cycle easier or harder to manage than carbon
changes are easier to totally reverse bc slow to fast carbon cycle is harder to reverse
water cycle easier on local scale: don't need international agreements
