Experts have warned that in many cases, people are ill prepared to cope with the risks of a changing climate.
The Intergovernmental Panel on Climate Change report says the world has seen changes in recent decades to water resources as a result of melting glaciers and differences in rainfall, and reductions in wheat and maize yields.
There has been a decrease in the number of people dying from the cold but an increase in heat-related deaths in some areas, such as England and Wales, the report suggested.
Species including fish stocks are shifting their ranges, coral reefs are being damaged and wildfires are becoming more frequent.
The report on the impacts of climate change said rising temperatures are expected to lead to increased risk of flooding, more droughts and heatwaves, drive species extinct and cause forests to die in many regions of the world.