What impacts are expected in the future?
What impacts are expected on natural systems, on human populations, in specific regions? What is their magnitude? What are the projected impacts of extreme climate events?
Impacts on natural systems
Over the course of the 21st century, many impacts are expected to occur in natural systems. For instance, changes in precipitation and the melting of ice and snow are expected to increase flood risks in some areas while causing droughts in others. If there is significant warming the capacity of ecosystems to adapt will be exceeded, with negative consequences such as an increased risk of extinction of species.
Impacts on human populations
The most vulnerable people are in general the poor, since they have less capacity to adapt, and their livelihoods are often dependent on resources that are linked to climate.
Impacts on specific regions
Africa is found to be particularly vulnerable to climate change, because of existing pressures on its ecosystems and its low capacity to adapt. On all continents, water supply and the threat to coastal areas will be an issue. Overall future impacts are expected to be negative, although some positive effects are also expected initially, such as an increase in agricultural productivity at high latitudes accompanying a moderate warming, or decreased heating needs in cold regions.
Magnitude of expected impacts
Impacts will depend on the magnitude of the temperature increase. For instance, some crops at mid- to high latitudes will have higher productivity if local temperature increases by 1-3 °C, but will be negatively affected beyond that. If higher temperatures persist after the 21st century it could result in very large impacts. For instance, the large sea-level rise that would result from the melting of the Greenland and Antarctic ice sheets would have major repercussions on coastal areas. The cost associated with the effects of climate change is projected to increase over time with rising temperatures.
Impacts of extreme climate events
A projected increase in the severity and frequency of droughts, heat waves, and other extreme weather events is expected to cause major impacts over the course of this century.