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4a. To what extent are the water and carbon cycles linked ? - Coggle…
4a. To what extent are the water and carbon cycles linked ?
Interdependent
Oceans
Ocean acidity increases when exchanges of co2 are not in balance (inputs exceed outputs)
Solubility of co2 in the oceans increases with lower SSTs
Atmospheric CO2 levels influence SSTs and thermal expansion of the oceans ; air temp; the melting of ice sheets and glaciers and sea level
Atmosphere
Atmospheric CO2 has a greenhouse effect. CO2 plays a vital role in photosynthesis
Plants extract water from the soil and transpire it as part of the water cycle
Water is evaporated from the oceans to the atmosphere and co2 is exchanges between the two stores
Cryosphere
CO2 levels in the atmosphere determine the intensity of the greenhouse effect and melting of ice sheets, glaciers, sea ice and permafrost
Melting exposes land and sea surfaces which absorb more solar radiation and raise temperatures further
Permafrost melting exposes organic material to oxidation and decomposition which releases co2 and ch4
Run off, river flow and evaporation respond to temperature change
Vegetation
Water availability influences rates of photosynthesis, NPP, inputs of organic litter to soils and transpiration
The water storage capacity of soils increases with organic content
Temperatures and rainfall affect decomposition rates and the release of co2 to the atmosphere
Human activities cause change on the carbon stores
World relies on fossil fuels for 84% of its primary energy consumption
exploitation of coal, oil and natural gas
8 billion tonnes of carbon a year a are transferred to the atmosphere by burning fossil fuels
Land use change releases 1 billion tonnes of carbon to the atmosphere annually
Soil degraded by erosion
Carbon stores in wetlands drained for cultivation and urban development, have also been depleted as they dry out and are oxidised
Impact of long-term climate change
Water cycle
Global warming = Increased evaporation and therefore the amount of water vapour in the atmosphere
More vapour has a feedback effect, helping to raise global temperatures, increase evaporation and precipitation
Increased precipitation will result in higher run-off in the water cycle and greater flood risks
Water vapour is a source of energy in the atmosphere releasing latent heat on condensation. With more energy in the atmosphere extreme weather events become more powerful and more frequent
Accelerated melting of glaciers, ice sheets like Greenland and the permafrost in the Artic Tundra
Water storage in cryosphere shrinks as water is transferred to the oceans and atmosphere
Carbon cycle
Higher temp will in general increase the rates of decomposition and accelerate transfers of carbon from the biosphere and soil to the atmosphere
In the humid and tropics climate change might increase aridity and threaten to extend forest
As forests are replaced by grasslands the amount of carbon stored in tropical biomes will decrease
Carbon frozen in the permafrost is released as temperatures rise above freezing and allow oxidation and decomposition of vast peat stores
Acidification of the oceans through the absorption of excess CO2 from the atmosphere reduces photosynthesis by phytoplankton limiting the capacity of oceans to store carbon
Will see an increase in carbon stored in the atmosphere and a decrease in carbon stored in the biosphere
Movement of water and carbon into and out of the atmosphere will vary regionally, depending on changes in rates of photosynthesis, decomposition and respiration
Impact on water stores due to human activity
Over-pumping of aquifers in the coastal region of Bangladesh has led to incursions of salt water, making the water unfit for irrigation and drinking
Deforestation reduce evapotranspiration and therefore; precipitation; increase surface run off; decrease through-flow ; and lower water tables. (MADEIRA BASIN )
Rising demand for water for irrigation, agriculture and public supply