OCR A Level ELSS - Entire Course 3 Flashcards
Cryospheric processes
-ablation is loss of ice from snow, ice sheets and glaciers due to a combination of melting, evaporation and sublimation
-meltwater is an important component of river flow in high latitudes and mountain catchments in spring and summer
-rapid thawing of snow in winter is a common cause of flooding in adjacent lowlands
physical (inorganic) pump?
-involves mixing of surface and deep ocean waters by vertical currents
-creates a more even distribution of carbon in oceans
-CO2 diffuses into the oceans from atmosphere
-surface currents transport dissolved CO2 polewards where it becomes dense and sinks (downwelling)
-individual carbon particles may remain deep in the ocean for many centuries
-eventually deep ocean currents transport carbon back up to the surface (upwelling)
-cold, carbon rich waters rise to the surface where CO2 diffuses back into the atmosphere
biological (organic) pump?
-50% of carbon fixation happens by photosynthesis in oceans
-50GT of carbon is drawn from atmosphere by biological pump each year
-marine organisms (phytoplankton) drive the pump
-phytoplankton floating near surface combine sunlight, water and CO2 into organic material
-whether consumed in the food chain or through natural death, carbon locked in phytoplankton accumulates on the ocean floor or is decomposed and released as CO2. or is used by organisms for shells and skeletons
-most CO2 ends up in sediments such as chalk and limestone
What is permafrost?
a thick subsurface layer of soil that remains frozen throughout the year, occurring chiefly in polar regions.
what is the active layer?
-The top layer of permafrost.
-melts
water cycle negative feedback loop
heavy rainfall = increased water infiltration = more water stored in aquifers = water table is raised = more water is returned to the surface as springs = water table returns to normal levels
carbon cycle negative feedback loop
burning of fossil fuels = increased atmospheric CO2 = photosynthesis stimulated = more CO2 removed form the atmosphere = CO2 levels restored
3 land use changes?
- urbanisation
- farming
- forestry
land use changes - urbanisation?
-farmland and woodland areas replaced by tarmac and brick
-artifical surfaces are impermeable and allow little water infiltration and provide minimal water storage capacity, giving rise to run off
-urban areas have drainage systems designed to remove water rapidly (gutters, pitched roofs) therefore water form precipitation flows quickly into streams and rivers, leading to a rapid rise in the water tables
-urbanisation also encroaches floodplains which are natural water stores
-overall, urbanisation reduces water storage capacity in drainage basins, increasing river flow and flood risks
land use changes - farming and the carbon cycle?
-clearance of forest for farming reduces carbon storage in above and below ground biomass
-soil carbon storage is reduced by ploughing and exposure of organic material to oxidation
-harvesting of crops returns only a small amount of organic matter to the soil
-soil erosion by wind and soil is most severe when crops have been lifted and have little protective cover
-carbon exchanges through photosynthesis are lower due to a lack of biodiversity and a short growth cycle
land use changes - farming and the water cycle?
-crop irrigation diverts surface water from rivers and groundwater to cultivated land
-interception of crops is less than of grasslands,
-evapotranspiration is reduced by crops
-ploughing increases evaporation and soil moisture loss
-heavy machinery compacts the soil which leads to more surface run off leading to peak flows higher in farmland ecosystems
-ploughing causes infiltration which means even more water is transferred to streams and rivers
land use changes - forestry plantations and the water cycle?
-there is a higher rate of rainfall interception in natural plantations
-preferred plantation species in the uk are conifers with needle like structures, evergreen habit and high density
-increased evaporation form water stored on leaf surfaces
-reduced run off and stream discharge due to high interception and transpiration rates
-clear felling of harvest timber creates a sudden change in the water cycle, increasing run off, reducing evapotranspiration and increasing stream discharge
land use changes - forestry plantations and the carbon cycle?
-in the uk a typical plantation contains 10x more carbon than grassland and 20x higher than heathland
-soil represents a large carbon pool - 500 tonnes/ha
-forest trees extract carbon for hundreds or years only after 100 years since planting
-balanced by litter inputs into the soil
what were the CO2 levels in the atmosphere 800,000 years ago compared to today (2016)?
-260 ppm 800,000 years ago
-400.5 ppm 2016
-small changes over 800,000 years due to glacials and interglacials
what were the CO2 levels in the atmosphere in 1700 compared to 2016?
-most people lived in rural areas in 1700
-1800 - the industrial revolution and CO2 levels rapidly increased due to coal use
-1910 - the first production line car
-1913 - coal extraction
-1960 - increase in car use and central heating fitted in homes
-1700 - 310 ppm
-2016 - 400.5 ppm
changes in the CO2 levels in the past two years?
-400.5 ppm
-in spring and summer there is less CO2 in the atmosphere due to more vegetation therefore increased photosynthesis
-in winter there is increases in CO2 due to more use of heating inn homes
-increased in 5 ppm in two years
energy consumption overtime?
-oil (496 GT) and coal (673 GT) are the largest carbon emission sources
-coal has been used since the industrial revolution and oil has been used since 1920s
-since 1970s there has been an increase in use of nuclear and hydroelectric sources
-overall global energy consumption has increased rapidly since the 1960s with coal and oil being the main sources
3 stages involved in CCS?
- separate CO2 from power station emissions
- CO2 is compressed and transported to storage areas
3.injected into porous rock underground and stored permanently
what is the impact and plans of CCS?
-plays an important role in reducing CO2 and other emissions
-in USA, 40% of all carbon emissions could be reduced by 80-90%
-in the UK a CCS project is underway in peterhead, north east Scotland which is going to capture 2 million tonnes of CO2
-plan for carbon to be transported by pipeline to the North Sea and stored in depleted gas resevoirs
Why is the CCS limited?
-involves big capital costs
-uses large amounts of energy (compress and transport CO2)
-requires storage in specific geological locations
in 2013 what percentage did fossil fuels account for the overall energy consumption?
87% fossil fuels
what sources were used the most in 2013 for global energy consumption?
-oil (37%)
-natural gas (27%)
-coal (23%)
where have most of our carbon emissions come from (1750 - 2012)?
-coal - 673GT
-land use - 590GT
where have our carbon emissions gone (1750 - 2012)?
-atmosphere (879GT)
-ocean (590GT)
-land (528GT)
how many tonnes of CO2 is released into the atmosphere annually?
-10 billion tonnes
-increases the CO2 concentration over 1 ppm
impact of anthropogenic carbon emissions in the atmosphere?
-since 1750, 879GT of anthropogenic co2 emissions have remained in the atmosphere, tasing co2 concentrations from 280 ppm - 400 ppm
-co2 levels today have been the highest for 800,000 years
what is the impact of anthropogenic carbon emissions?
-compromise only 10% of the natural influx of from the biosphere, oceans and atmosphere
-however they impact significantly on carbon stores
-despite international efforts used to reduce carbon emissions, between 2000 and 2009 they grew faster than in any other decade
-without increased absorbtion of CO2 from oceans and biosphere, atmospheric concentrations would exceed 500 ppm
groundwater
water stored underground in permeable and porous rocks know as aquifers
aquifer
a water bearing band of porous or permeable rock
artesian aquifer
a confined aquifer containing groundwater under pressure, which will rise to the surface under its own pressure
artesian pressure
The hydrostatic pressure exerted on groundwater in a confined aquifer occupying a synclinal structure.
abstraction
the extraction of water from rivers and boreholes for public demand
impact of water extraction?
-rates of extraction have exceeded rates of discharge
-lower flows have reduced flood risk and temporary areas of standing water on floodplains
-lower groundwater levels ave caused springs to dry up and reduce the instance of saturated overground flow on chalk
the water table?
-the level below which the ground is saturated with water.
changes that occur in the water table levels?
-water table heights fluctuate seasonally by periods of lots of rainfall, drought and abstraction
-in normal years in southern England, the water table falls between march and September due to rising temperatures and increased evapotranspiration
-recharge resumes in late autumn
artesian basins
-when sedimentary rock forms a syncline, a downloaded basin like geological structure
-confined between layers of impermeable rock (clay)
-may contain groundwater under artesian pressure
-when groundwater is tapped by a well or borehole water will flow to its surface under its own pressure
what is remote sensing?
the scanning of the earth by satellite or high-flying aircraft in order to obtain information about it.
what is GIS?
-Geographic Information System.
-A computer that can capture, store, query, analyze, and display geographic data.
-analyses layers, spacial location and identifies any anomalies and trends
what are diurnal changes?
-significant changes that occur within a 24 hour period
-lower temperatures at night reduce evaporation and transpiration
-during the day convectional precipitation is dependent on direct heating of ground surface by the sun
-flows of carbon are reversed at night compared to day
what are seasonal changes?
-seasons are controlled by the variations in solar radiation
-in uk, solar radiation peaks in mid June (800 w/m2) in southern england
-compared to input of (150 w/m2) in December
-80% of precipitation is lost to evaporation in driest parts of lowland England, which exhausts soil moisture and river flows are lowest in late summer
how are seasonal changes reflected in the carbon cycle?
-month-month changes in the net primary productivity (NPP)
-in middle and high latitudes day length of photoperiod drive seasonal changes in NPP
-similar variations occur in tropics, but there main cause is water availability
carbon dioxide flows in the summer?
-net flow of CO2 from atmosphere to biosphere
-causes CO2 levels to fall by 2ppm
-at end of summer flow is reversed by natural decomposition releasing CO2 back to atmosphere
what are seasonal fluctuations in global CO2 flux explained by?
-concentration of continental land masses in the northern hemisphere
-during growing season, ecosystems such as boreal and forests extract huge amounts of CO2
from atmosphere which has a huge global impact
what happens during seasonal changes to phytoplankton in the oceans?
-in oceans phytoplankton are stimulated to photosynthesise by rising water temperatures, more intense sunlight and the lengthening photoperiod
-in northern Atlantic, ever year there is an explosion of microscopic ocean activity, resulting in algal blooms which peak in mid summer
impact of long term changes - how many major glacial cycles in the last 400,000 years?
-4 major glacial cycles in the last 400,000 years
-each last around 100,000 Years
-followed by warmer interglacials
temperatures at the height of the last glacial?
-20,000 years ago
-temperatures on average 5 degrees lower than they are today at the peak of the last glacial
what happened during the last glacial to most of the UK?
-scotland, Wales and Northern Ireland were submerged in ice up to 1km thick
impact on water cycle during glacial periods (sea level and sea ice)?
-in glacials sea level falls by 100-130m
-ice sheets expand over one third of the continental land mass
-ice sheets destroy forests and grasslands as they expand towards the equator
-lower rates of evapotranspiration reduces flows of water in the cycle
-overall water cycle decreases
impact on carbon cycle during glacial periods (temperature and CO2 concentration, oceans and phytoplankton ) ?
-dramatic reduction in CO2 in atmposphere
-glacial maxima concentrations fall to 180 ppm
-warmer interglacials they were 100 ppm higher
-close correlation between temperature and CO2 concentration
-more CO2 dissolves in oceans at lower SST as lower temperatures make the sea more soluble
-ocean circulation brings nutrients to the surface and stimulates phytoplankton growth
-overall a slowing carbon flux and smaller amounts of CO2 returned to atmosphere by decomposition
how are carbon and water cycles linked by the atmosphere?
-atmospheric CO2 has a greenhouse effect
-CO2 plays role in photosynthesis for plants and phytoplankton
-plants extract water from soil and transpire it to the atmosphere
-water is evaporated from the oceans to the atmosphere which causes CO2 to be transferred between both stores
how are carbon and water cycles linked by the ocean?
-ocean acidity increases when CO2 stores are unbalanced
-solubility of CO2 increases with lower SST
-CO2 levels influence SST, thermal expansion, air temperatures, melting of ice and sea level
how are carbon and water cycles linked by vegetation and soils?
-water availability influences photosynthesis, NPP, inputs of organic material and transpiration
-increased inputs of organic material to the soil increases the soils water storing capacity
-temperatures and rainfall affects decomposition and release of CO2
how are carbon and water cycles linked by cryosphere?
-CO2 levels determine the intensity of the greenhouse effect and melting of ice sheets, glacials and sea ice
-melting of ice exposes land which increases the absorption of solar radiation which increases temperatures
-melting of permafrost exposes dead organic material to decomposition and oxidation
-run off, river flow and evaporation respond to temperature change
what 4 anthropogenic factors have impacted the water and carbon cycles?
-urbanisation
-rapid population change
-deforestation
-economic change
=they have changed the size of stores and impacted most at local and regional scales
what has created shortages in the water cycle?
-rising demand for water for agriculture, irrigation and public supply
-human impact most evident on rivers and aquifers
what effect do anthropogenic factors have on the water cycle?
-decrease through flow
-lower water tables
-increase run off
-reduce evaporation and precipitation
where have human activities had a detrimental impact on the water cycle - examples?
-colorado basin, southwest USA
-surface supplies diminished as more water extracted from rivers
-huge amount evaporated from reservoirs in Lake mead and Powell
-bangladesh
-excessive water pumping of aquifers led to inclursions of salt water which makes the water unfit for drinking and irrigation
what are the impacts of deforestation?
-impact areas like Amazonia as forest trees play a huge role in the water cycle
-deforestation has decreased evapotranspiration therefore precipitation, breaking the cycle in some places which stops forest regeneration
how is human actives impacting the carbon cycle? (3)
-extracted billions of tonnes of carbon from the geological store
-the world relies on fossil fuels for 87% of the worlds total energy consumption
-land use changes, deforestation transfers 1 billion tonnes of carbon to atmosphere annually
-more CO2 absorbed by oceans due to more CO2 in atmosphere
-increases ocean acidity which kills phytoplankton
-soil degraded by erosion caused by deforestation and agricultural mismanagement
why has exploitations of coal, oil and gas stores increased rapidly recently?
exploitations of coal, oil and gas has increased rapidly due to the increasing industrialisation in India and china
Carbon cycle: burning fossil fuels transfers ____________________ of carbon to the atmosphere
8 billion tonnes
Carbon cycle: land use changes (deforestation) transfers ____________________ carbon to the atmosphere
1 billion tonnes
Carbon cycle: ocean acidification
-Ocean acidity increases when exchanges of CO2 aren’t in balance
-more CO2 dissolves into oceans when more co2 is in the atmosphere
-acidification kills phytoplankton
Carbon cycle: soil is degraded by erosion caused by what? (2)
deforestation and agricultural mismanagement
Carbon cycle: why are carbon stores in wetlands depleted?
When the wetlands are drained for cultivation and urban development they dry out and are oxidised
global warming leads to increased —– in the atmosphere?
leads to increased water vapour in the atmosphere
impact of long term changes on the water cycle?
-more water vapour in the atmosphere is a natural GHG
-vapour releases heat when it evaporates, cools and condenses which increases frequency of tropical storms
-global warming also accelerates melting of glaciers which transfers water from cryosphere to oceans + atmosphere
What does water release as it evaporates, cools and condenses?
heat
What could global warming increase the prevalence of and why?
hurricanes as they rely on warmer water
