monitoring changes to the global water and carbon cycles

  • Created by: beaw18
  • Created on: 05-05-19 18:46

diurnal changes

  • significant changes can happen in 24hr periods 
  • water: 
    • lower temps at night reduce evaporation and transpiration in water cycle, convectional rainfall a purely daytime phenomenon
  • carbon: 
    • during day CO2 flows from atomosphere to vegetation, opposite occurs at night
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seasonal changes

  • seasons controlled by variations of solar radiation 
  • evapotranspiration highest in summer, lowest in winter 
  • river levels drop in hotter months due to this 
  • in carbon cycle, NPP is highest in longer day lengths or photoperiods occuring in summer 
  • when there is the most vegetation, carbon flows from atmosphere into biosphere, in winter when vegetation decomposes, the opposite occurs
  • in oceans phytoplankton are stimulated into photosynthetic activity by rising water temperatures, more intense sunlight and longer photoperiod
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long term changes

  • earth's climate over the last million years has been massively unstable - ice age periods occur, lasting around 100,000 years each 
  • world has also had much hotter periods too
  • both these occurences have implications on the water and carbon cycles 
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long term changes: water cycle

  • glacial periods: water most commonly stored in ice sheets, glaciers and permafrost - cover a third of continetal land mass
  • global sea levels drop by 100-130 meters 
  • biosphere shrinks 
  • lowered rates of evapotranspiration - slows water cycle 
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long term changes: carbon cycle

  • reduction of in CO2 in atmosphere during glacial periods - no clear explanations for why this occurs 
  • vegetation reduced in colder climate, therefore as does the carbon stored
  • carbon stored in soils is trapped under the ice, meaning carbon exchanges between soil and atmosphere disappear
  • carbon mostly stored as permafrost 
  • NPP falls, as do decomposition rates 
  • carbon cycle overall slowed 
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