The world’s uphill struggle

The impacts of global warming could lead to irreversible changes. Jennifer Rankin reports.

Billions of people at risk from hunger, increases in disease, drastic loss of biodiversity, retreating glaciers, expanding deserts: these are just some of the conclusions from the latest report by the UN’s Intergovernmental Panel on Climate Change (IPCC). This bleak report is a synthesis compiled from a series of equally sobering reports published this year. The latest synthesis report is likely to become the holy writ of climate change. It will be pored over by policymakers ahead of the Bali conference. Governments, campaigners and business leaders will use it as the basis for taking decisions about how to respond to climate change.

Collectively this year’s IPCC reports, running to thousands of pages, make up the IPCC’s fourth assessment report (AR4) and together they helped the panel to win this year’s 2007 Nobel Peace Prize, shared with climate-change campaigner Al Gore. Earlier assessments on the state of the climate were published in 1990, 1995 and 2001.

The first report of this year was published in February and was devoted to the physical science base. It concluded that humans were "very likely" to have caused climate change. The second report, published in April, grabbed headlines with its alarming forecasts on the impact of climate change. May’s report on mitigating climate change concluded that it could be tackled at a reasonable cost. Lending his weight to the synthesis report that was concluded on 16 November, Ban Ki-moon, the UN secretary-general, insisted "only urgent global action will do".

The synthesis underscores that the evidence on global warming has become more solid since 2001. It refers to "new and stronger evidence" of the impact of climate change on ecosystems, such as mountains and the polar regions, and concludes that the earth is more vulnerable than the third assessment report assumed. The range of predicted temperatures is largely consistent with the earlier report, but upper ranges are higher because of the uncertainty over feedback mechanisms.

This latest report also concludes that "warming of the climate system is unequivocal" and increases in "hot extremes, heat waves and precipitation" are "very likely". Despite the subject matter, the reports are not a racy read. Phrases such as "very likely" and "high agreement" are not thrown around, but defined and used carefully.

Fractious arguments (between governments) lie behind this dry text. Governments had to agree on the final wording of the reports, which typically led to drawn-out negotiations. This year’s discussions over the latest synthesis report were no exception, with Russia, the US and Saudi Arabia leading efforts to water down the text. Nevertheless, environmental campaigners are happy that the final synthesis report - agreed close to midnight on 16 November - was a decent outcome. Stephan Singer, head of climate change at WWF in Brussels, says that "it was much better than we had originally feared it would be…of course it is not as strong as it could have been, but as a consensus-based document it is a very good guide for governments…the urgency is clearly expressed." Singer also considers that the synthesis gives a strong signal to "the vast majority of countries" who are neither the biggest sceptics (the US) nor the most worried about climate change (the island states). The report gives "ammunition to policymakers in the vast majority of countries in the middle", he says.

The IPCC reports represent a consensus view because they are written and peer-reviewed by hundreds of scientists who sift through the existing evidence on climate change rather than undertake new research. As such they represent a conservative view and tend to err on the side of caution. In a survey of 140 scientists cited on the BBC website, 18% thought the IPCC reports were too alarmist, while 82% thought they represented a reasonable consensus or were over-cautious.

James Lovelock, a British scientist, thinks the reports do not go far enough. In a speech to the UK’s Royal Society in October, he said: "I now take an apocalyptic view of the future because I see six to eight billions of humans faced with ever diminishing supplies of food and water in an increasingly intolerable climate." Some scientists have argued that climate change will be sudden, rather like the pressure on a light switch where a sudden tiny change has a dramatic effect. Yet even this IPCC synthesis concludes, in its typically reserved language, that "anthropogenic warming could lead to some impacts that are abrupt or irreversible, depending upon the rate and magnitude of the change". The report offers policymakers meeting in Bali their starkest warning yet.

What the scientists predict?*

By 2020 between 75-250 million will face "increased water stress".

Agricultural yields could fall to 50% in some countries so exacerbating malnutrition.

Cost of adaptation for the continent is between 5-10% of gross domestic product.

By 2080 arid and semi-arid land on the continent will have increased by 5-8%.

By 2050 freshwater will decrease and coastal areas will be at greater risk of flooding.

Death and illness from water-borne diseases associated with floods and droughts are expected to rise.

Australia and New Zealand

By 2020 significant loss of biodiversity in the Great Barrier Reef and Queensland Wet Tropics.

By 2030 water security problems are projected to intensify and production for agriculture expected to decline because of increased flood and fire. Parts of New Zealand will benefit.

Glacier retreat in mountains, reduced winter tourism and extensive loss of species that could be up to 60% in some regions.

More droughts, wildfires and health risks especially in southern Europe. Less rain in central and eastern Europe causing "water stress".

In northern Europe, higher agricultural yields and increased forest growth, however these potential benefits could be outweighed by more floods and endangered ecosystems.

Climate change will magnify the difference between Europe’s natural resources and assets.

Latin America

Gradual replacement of tropical forests by savannah in eastern Amazonia, with significant loss of biodiversity.

The risk of hunger will increase in some regions, as crop productivity falls.

North America

In the Western Mountains, winter time will bring more flooding, while drier summers will lead to more competition for water resources.

Stresses on big cities due to heat waves with "potential for adverse health impacts".

Polar regions

In the Arctic, loss of sea ice, permafrost and erosion will threaten indigenous ways of life as well as birds and mammals.

Warming will also bring more navigable northern sea routes and reduced heating costs.

At both poles ecosystems and habitats are vulnerable as barriers to species invasion are lowered.

Small islands

Erosion of beaches and coastal bleaching will damage local industries, such as tourism and fishing.

Rising seas will threaten homes, infrastructures and livelihoods.

By the mid-century some small islands, eg in the Caribbean and Pacific, will not have enough water to meet demand.

*Refers to projections where the IPCC have "high confidence" or "very high confidence".

The impacts of global warming could lead to irreversible changes. Jennifer Rankin reports.