The water and carbon cycles are linked and interdependent (7)

How the water and carbon cycles are linked via the atmosphere (4 points)

- CO2 exchanged between atmosphere and oceans.

- CO2 contributes to greenhouse effect.

- CO2 is exchanged between soils, vegetation and atmosphere in processes such as photosynthesis, combustion, respiration and decomposition.

- Water evaporates from oceans and returns via various flows

How the water and carbon cycles are linked via the oceans (4 points)

- Atmospheric CO2 levels rise - global temps. rise and ability of oceans to absorb CO2 decreases, resulting in more CO2 in the atmosphere.

- As SSTs rise, evaporation rates increase and more latent energy transfers to atmosphere.

- Thermal expansion of sea water contributes to rising sea level.

- Increased global temps. result in increased melting of ice sheets and glaciers and this water flows back into oceans, raising sea levels

How the water and carbon cycles are linked via vegetation and soils (2 points)

- Rates of photosynthesis, NPP, transpiration and decomposition increase when there is no shortage of water.

- Exchange of CO2 with the atmosphere is therefore affected

How the water and carbon cycles are linked via the cryosphere (4 points)

- Increased CO2 levels in atmosphere - global temperatures rise, causing increased melting of ice.

- Loss of ice (land + sea) decreases albedo and increases absorption of solar radiation, increasing temps. further.

- Flows of water from land to oceans increase.

- Thawing of permafrost increases rates of oxidation and decomposition of organic matter, increasing release of CO2 and CH4 to atmosphere where they trap yet more solar radiation

Impact of long-term climate change on the water cycle - water vapour

- Global warming has increased evaporation - more water vapour enters atmosphere. Water vapour is a natural greenhouse gas so more solar radiation is trapped, raising temps. which increases evaporation.

- More water vapour in atmosphere - precipitation is more likely. This can mean higher run-off into streams and rivers, increasing flood risk.

Effects of water vapour and latent heat - long-term climate change

- Water vapour condenses - latent heat given off in atmosphere.

- With more energy in atmosphere, extreme weather events such as tropical storms (cyclones, typhoons) and mid-latitude storms increase in occurrence and intensity

Changes to the cryosphere - long-term climate change

Water stored in the cryosphere is coming out of these long-term stores as a result of global warming.

This water is then transferred into the oceans and eventually into the atmosphere

Long-term climate change - impacts on the carbon cycle: decomposition and photosynthesis

- Higher temps. increase rates of decomposition so more carbon is transferred from biosphere and soil to the atmosphere.

- However, higher temps. also increase rates of photosynthesis, so increasing carbon accumulation in plants

What global warming may allow to happen in high-latitudes

May allow the boreal forests of Canada and Siberia to expand, increasing carbon stores in these regions

Long-term climate change - rainfall patterns and the carbon cycle

- Rainfall patterns are disrupted by climate change - some regions may experience reduced water availability, this will cause carbon uptake by plants to diminish as vegetation patterns alter. E.g. forests might be replaced by grasslands in low latitudes

Long-term climate change - peat and permafrost as stores in the carbon cycle

Carbon locked in permafrost in high latitudes may be released as soils thaw with global warming. Vast quantities of peat in high latitudes could also be decomposed with higher temperatures, so releasing carbon into atmosphere

Long-term climate change - effects on the oceans

Absorption of vast quantities of CO2 by the oceans is leading to sea water becoming increasingly acidic - causes a reduction in the phytoplankton which are responsible for storing huge amounts of carbon

Long-term climate change and carbon stores generally

May bring about increase in carbon stored in atmosphere, decrease in carbon stored in the biosphere, and possibly a decrease in carbon stored in the oceans.

- Likely to be regional variations in carbon cycling depending on rates of photosynthesis, respiration and decomposition