The report published by the IPCC’s working group on climate change impacts, adaptation and vulnerability charts global warming’s implications for different sectors and regions.
The policy-makers’ summary was approved by government representatives from around the world after fraught discussions ran late into the night. Several sections were watered down or dropped.
According to the IPPC, some parts of northern Europe may initially benefit from a reduction in demand for heating and increased crop yields. But if climate change continues unabated, negative impacts such as heatwaves, increasing water scarcity and species loss will outweigh these effects.
The panel puts the total cost of a 4°C temperature rise at 1-5% of global GDP, but says the figure is likely to be higher in developing countries which will be less able to adapt. Last year’s Stern Review put the cost of a 5°C increase at 5-20% of annual global GDP (ENDS Report 382, pp 34-36 ).
The report says changes to natural systems - including earlier leaf burst in spring, melting of permafrost and migration of species towards the poles or higher ground - have been recorded across the world. It also offers more certainty on future changes than previous assessments:
Low-lying islands and the highly-populated flood plains of Asia are expected to be badly hit, as are Africa and the Arctic, where warming will be greatest.
The IPCC notes that little is being done to mitigate the potential effects of these changes despite the time lag between greenhouse gas emissions and global warming, which means another 0.6°C or so of warming is inevitable. In the long run, both adaptation and mitigation measures - including technological, behavioural and policy changes - are required, the IPCC says.
The UK Climate Impacts Programme (UKCIP), established by the Environment Department (DEFRA) to aid adaptation in 1997, has contested what it saw as an unjustifiably gloomy view of current adaptation efforts. Its own assessment suggests "a much broader acceptance of the need for, and investment in, adaptation actions". The disparity has arisen from the IPCC’s narrower definition of adaptation, it argues.