This project has assessed the impacts of climate change avoided by a set of climate policies, focusing on water resources stress, crop production and undernourishment.
Climate change has the potential to increase water resources stresses for many millions of people. The climate policies evaluated here reduce the effects of climate change, with the earlier the peak the greater the reduction. There is, however, considerable uncertainty in the numbers of people adversely affected by climate change and “saved” by climate policy, largely due to differences in projected changes in rainfall between different climate models.
For example, by 2100 policies which peak emissions in 2016 avoid between 20 and 55% of the adverse effects of climate change, with the range largely due to differences in projected change in rainfall (and hence water resources) in southern Asia. The effect of uncertainty due to differences between climate models is larger than uncertainty due to either uncertainty in change in temperature for a given emissions scenario, or uncertainty in future socio-economic characteristics.
Global wheat production could decrease (in the absence of adaptation) by between 30 and 40% by 2050, with relatively little difference between climate models. Climate policies have little effect by 2050, but prevent production declining further through the 21st century. There are some regional differences between the climate models considered, although these differences are relatively small compared to differences in runoff and water resources. This is because runoff effects are largely driven by precipitation changes, but wheat productivity change is a function of both temperature and rainfall. Soybean production is also projected to decrease, by a similar magnitude to wheat production. Mitigation reduces the effect of climate change, and has an effect slightly earlier than for wheat: by 2050, mitigation offsets production loss by 10-30%. In some regions – such as Europe – the effect of mitigation is highly dependent on the climate model pattern.
Unmitigated climate change is projected to have very substantial effects on exposure to undernourishment during the 21st century in a sample of countries. Assuming some form of adaptation – reducing exports and reducing the diversion of crops to feedstock – reduces, but in most cases does not eliminate, the projected impacts of climate change. Absolute numbers of undernourished people are also affected significantly by assumed changes in population, and by the assumed non-climatic changes in crop production. Mitigation reduces the numbers of people exposed to undernourishment, but the differences between policies are not very clear. Policies typically reduce exposure to undernourishment by 30-50%. In practice, food trade is likely to be used to adapt to climate change and therefore reduce undernourishment, and the results can be interpreted as characterising the demand for adaptation.