NSP - Climate change
 

It has been projected that, due to the effects of climate change, by the end of the 21st century, global temperatures will rise by 1.4-5.8°C with an increase in global sea levels of from 0.09-0.88 m (IPCC Technical Paper V, 2002). The effects will be felt by many ecosystems and can be generalised:

  • Loss and redistribution of species
  •  Loss and change to habitat
  • Changes in behaviour such as reproduction, migration
  • Change in pH affecting solubility of minerals and nutrients
  • Distribution of disease organisms
  •  Reduction in levels of oxygen in lakes

·         Changes in productivity and food webs, for example through increased microbial respiration rates

The effects on biodiversity may be localised with each species giving its own response to the change or the effects could be felt more widely.  For example it is believed that in mountainous regions, tree lines are migrating north away from unfavourable climate conditions. This would suggest that the entire ecosystem associated with the trees would migrate as well.  However, the amount of available land may be reduced as well as the levels of nutrients and the amount of daylight in relation to the growing season (having a reduced growing season the further north). These would affect the food webs associated with the soil microorganisms and plants.

Measuring the response of the soil biota to climate change is problematic not least because of the complexity of the food webs and interactions which occur in soil. With increasing carbon dioxide levels it may be that microbial communities are not invulnerable to changes to the climate. It is thought that the main effect on the microbial community is due to changes in plant photosynthetic activity rather than direct effects on the microbes themselves (Drigo, et al., 2008). Increasing the throughput of carbon into the soil may alter the carbon:nitrogen ratio and hence on the activity of specific flora. Increasing the soil atmospheric carbon dioxide level may impact of soil pH and hence on nutrient solubility in some soils.

Some regions are more sensitive to change than others. A 2-3 °C warming may irreversibly damage the Amazon rainforest (Stern review). Countries which are heavily dependent upon agriculture may also suffer to a greater extent than others. Some food crops (e.g. maize) may be more vulnerable to drought with reduced yields and affecting local economies and migration.

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FAO climate change website