Climate Change Risks: Temperature Change

Global temperatures have already risen by 0.85 degrees, and are predicted to rise further. Below is a projection of four carbon dioxide emission scenarios and the temperature increases that will result: low, medium, medium-high and high emissions.

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The low emission scenario is extremely unlikely requiring co-operated global mitigation on a huge scale. Whichever of the other three emissions scenario occurs it will have profound impacts on much of Africa. This is because a temperature increase will increase evapotranspiration, obvious right? But in water scare regions, like large sections of Africa, the impact of this can be devastating.

For example, if rainfall is 1200mm and evapotranspiration equivalent to 1000mm in a given catchment, flow will be 200mm. A 10% rise in evapotranspiration to 1100mm will then reduce flow 50% to 100mm. This is a similar relationship to how I describe when considering changing rainfall patterns.

The above scenario that best represents future climatic conditions is up to humans and how we managed our emissions. The smaller the temperature change the easier job Africa will have, but the increase in evapotranspiration will have major impacts on future water supply.