climate changes effecting water and carbon cycles

  • Created by: beaw18
  • Created on: 06-05-19 11:12

human activities cause changes in water and carbon

  • population and economic growth, deforestation and urbanisation have modified size of water and carbon stores 
  • human impacts on water cycle:
    • rising demand for water has created shortages in aquifers, rivers, and surface supplies.
    • quality of fresh water supplies have also dropped - overpumping of aquifers in coastal regions leading to incursions of salt water
    • deforestation reduces evapotranspiration and therefore precipitation, increasing surafce runoff and decreasing throughflow, therefore lowering water tables 
  • human impacts on carbon cycle: 
    • world relies on fossil fuels for 87% of primary energy consumption: releases billions of tonnes of carbon 
    • 8 billion tonnes of carbon transfered into atmosphere by burning fossil fuels 
    • land use changes add a further billion tonnes to atmosphere 
    • decline in carbon stored in biosphere - planet's forest cover declined by 50% from historic times 
    • acidification of oceans threatens phytoplankton (which absorb more than half of CO2 released from burning fossil fuels
    • soil erosion also decreases carbon stored 
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interlinkages between water and carbon cycles

  • atmosphere: CO2 plays vital role in photosynthesis, stimulated growth. plants extract water from soil and transpire in the water cycle. water from oceans evaporated to enter atmosphere - CO2 also exchanged between these two stores 
  • oceans: ocean acidity increases with excess CO2. solubility of CO2 in oceans also increases 
  • vegetation and soil: water availability influences rates of photosynthesis, NPP and transpiration. water storage in soils increases with more organic matter. temperatures and rainfall effect decomposition rates and CO2 release in atmosphere 
  • cryosphere (frozen part of earth's systems): CO2 levels increase greenhouse effect, causing rise in global temperatures whic melts icesheets and glaciers. melting permafrost releases carbon and methane. runoff, river flow and evaporation increase in warmer climate 
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long term climate change: the water cycle

  • global warming increases evaporation rates, and therefore the amount of water vapour in the atmosphere 
  • more vapour has positive feedback which raises global temps further
  • flood risks increase with more precipitation 
  • more energy in atmosphere increases extreme weather events such as hurricanes
  • gloabl warming melts polar ice, ocean levels rise 
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long term climate change: the carbon cycle

  • higher global temperatures increase rates of decomposition in the biosphere, releasing even more carbon into atmosphere 
  • hotter weather may cause tropical forests to become arid, or at least turn forests into grasslands which decreases carbon stored, meaning more enters atmosphere 
  • carbon frozen as permafrost is released 
  • oceans become more acidic, reduces photosynthesis from phytoplankton, limits ocean's capacity to store carbon 
  • increase in carbon stored in atmosphere, decrease in biosphere and oceans 
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