The summary report examines the current scientific understanding of impacts of climate change on the Earth's systems, their vulnerability and capacity to adapt. It outlines that all continents are being affected by climate change and that over the last three decades human activity has had a visible impact on many of the planet's systems.
The content of the report is wide-ranging, laying out predicted impacts for all continents and identifying six major systems with specific detail.
The summary report can be downloaded from the IPCC web site.
Some of the main findings are in the following areas
1. Fresh water resources and their management
- Impacts on water resources could be geographically extensive and in some locations dramatic. As the planet warms it is highly likely that, depending on location, there will be an increase in the frequency and severity of floods and droughts.
2. Food, fibre and forest products
- Crop yield is projected to increase in temperate regions for a local mean temperature rise of 1-3 °C, and then decrease beyond that in some regions.
- In tropical areas, crop yield is projected to decrease, even with relatively modest rises of 1-2 °C in local temperature, increasing the risk of hunger.
3. Ecosystems
- Increased risk of extinction among 20-30% of plant and animal species is likely if the global temperature increase exceeds 1.5–2.5 °C.
- In the second half of this century terrestrial ecosystems will see net carbon uptake weaken or reverse.
4. Coastal areas and low-lying areas
- There is high confidence that these areas will be under increased pressure from changes in climate and human activity.
- Increases in sea-surface temperatures of 1-3 °C are projected to result in a major decline of most corals.
- Many millions more people will become vulnerable to flooding due to sea-level rise by the 2080s.
5. Health
- Projected changes to the climate will affect the health of millions of people worldwide. The changes will be most felt by those least able to adapt, such as the poor, the very young and the elderly.
6. Industry, settlement and society
- Areas most likely to be affected are the poorer, often rapidly expanding communities near rivers and coasts which use climate-sensitive resources and are prone to extreme weather.
- Where extreme weather events become more intense and or more frequent, their economic and social costs are predicted to increase.
The report highlights current knowledge about responding to climate change, emphasising the point that future vulnerability not only depends on climate change, but also on development in key areas. It also identifies that more needs to be done to take research forward and give policymakers more detailed information in the future.
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The table below shows examples of impacts of temperature changes across a range of IPCC greenhouse gas emissions scenarios, when adaptation to climate change is not included. Entries are placed so that the left-hand side of text indicates approximate onset of given impact.
Source IPCC Working Group II Summary Report.