IPCC paints bleak picture of a warmer world

26 Apr 2007

Climate change is already affecting all continents and will wreak havoc on the environment and human activities if it continues unabated, warns the latest report from the UN Intergovernmental Panel on Climate Change.1 It urges countries to focus more on adapting to changes, some of which are now unavoidable.

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:

  • Water: Continued climate change will boost water availability by 10-40% in polar regions and some tropical areas by the middle of the century. But mid-latitude and dry tropical areas face worsening droughts as water becomes 10-30% more scarce. Storms and flooding are expected to become more common.

  • Ecosystems: A temperature increase of 1.5-2.5°C would put 20-30% of plant and animal species at risk of extinction globally. Over the course of the century, many terrestrial ecosystems are expected to become net sources of carbon and add to the effects of climate change (ENDS Report 381, pp 34-36 ).

  • Food: Temperature rises of 1-3°C are expected to improve yields in most crops in middle and high latitudes. Beyond this point, productivity is expected to fall. Lower latitudes are likely to see reduced crop yields but technological improvements will mitigate some effects.

  • Coasts and low-lying land: Millions of people could face coastal flooding each year by 2080. Thirty per cent of coastal wetlands could disappear after being starved of sediment or squeezed against landward barriers.

  • Health: Deaths from cold exposure are expected to fall in higher-latitudes but a plethora of other problems will outweigh these effects at the global scale. Malnutrition is expected to become more common as are deaths from storms, heatwaves and drought. The distribution of vector-spread diseases like malaria will also change.

    • 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.