water, carbon and climate

• why is carbon a fundamental building block of life?

  all living things contain carbon
• why does photosynthesis require inputs of both water and carbon?

  plants use energy from sunlight to covert CO2 and water into biomass that gets passed up the food chain
• how is water present in the atmosphere?

  water vapour and water droplets
• how is carbon present in the atmosphere?

  carbon dioxide and methane - create natural greenhouse effect which prevents energy from escaping into space and reflects it back to Earth

  • without greenhouse effect - Earth would be frozen and uninhabitable
• positive feedback

  amplifies changes - move away from dynamic equilibruim , more unstable
• negative feedback

  dampens change - move towards dynamic equilibrium , more stable
• examples of positive feedback in the carbon cycle

  temperatures rise

  • plant respiration rate increases
  • amount of CO2 in atmosphere increases
  • greenhouses effect increases
• examples of negative feedback in carbon cycle

  CO2 in atmosphere increases

  • extra CO2 causes plants to increase growth
  • plants remove and store more CO2 in atmosphere
  • amount of co2 in atmosphere reduces
• examples of postitive feedback in the water cycle

  temperatures rise

  • evaporation increases
  • amount of water vapour in atmosphere increases
  • greenhouse effect increases
  • increases global warming - amplifiying temperature rise
• examples of negative feedback in the water cycle

  temperatures rise

  • evaportranspiration increases
  • amount of water vapour in atmosphere increase , causes more clouds to form
  • increased cloud cover reflects more of Sun's energy back into space
  • temperatures fall

  cancels out temperature increase , global warming won't increase
• sea ice melting feedback loops

  • ice reflects radiation from sun , less heat absorbed from the surface
  • as Artic sea ice is rapidly shrinking , there is consequently less reflection and more absorption from exposed water - warms water , further melts the ice
  • no Arctic sea ice will affect trading routes , development of settlements
  • will affect patterns of precipitation and availability of freshwater
• permafrost feedback loop

  • higher temperatures have started to melt permafrost , partcularly in parts of Siberia
  • organic matter trapped in the frozen ground act as important carbon store
  • on melting, organic matter starts to decompose as oxygen is introduced
  • bacteria involved produced CO2 and methane as a waste product and these gases bubble to the surface and escape to the atmosphere
• carbon combines with water to allow what?

  chemical weathering , removes carbon from the atmosphere
• water is needed for photosynthesis which removes carbon from the atmosphere
• amount of CO2 in the atmosphere affects global temperatures , affects amount of evaporation that can take place , affects amount of precipitation
• climate change effects on Earth

  • pattern of precipitation changes
  • extreme weather events
  • sea levels rise = flooding
  • plankton numbers decline if temperatures increase = knock on effect on marine food chains