Munich

As representatives from 188 countries gather in Milan, Italy, to work through the latest round of negotiations for the Kyoto Protocol on limiting greenhouse-gas emissions, German researchers have released a study showing that “intolerable” levels of climate change are more likely than decision-makers may realize.

In a report published on 25 November, the German Advisory Council on Global Change contends that the world can tolerate a rise of up to 2 °C over pre-industrial levels. Beyond this, the effects of climate change on society would become too severe, they say. This would be mainly due to sudden phenomena such as the possible irreversible disintegration of large ice sheets, or abrupt disturbances to the North Atlantic Ocean's currents and to monsoons in Asia.

Global mean temperatures have already increased by 0.6 °C since 1900. By the end of the twenty-first century, temperatures may increase by a further 1.4–5.8 °C, according to the latest projection of the Intergovernmental Panel on Climate Change.

Even the lower limit of this estimate will pose an intolerable threat to human health, food and water supplies, economic development and natural ecosystems in many parts of the world, says the German report.

But it seems unlikely that political action will be able to keep temperature increases down. The 1997 Kyoto Protocol has yet to be ratified, as Russia has not decided whether to sign it. But even if the protocol comes into effect, the cuts that it prescribes will be insufficient to hold climate change to a 'tolerable' level, the report says.

It concludes that global carbon dioxide emissions would need to be curbed by 45–60% by 2050 compared with 1990 levels to avoid dangerous climate change. The Kyoto Protocol calls for average cuts of 5% in industrialized countries by 2012, and even that may be unrealistic.

The report will be presented in Milan at the ninth Conference of the Parties to the United Nations Framework Convention on Climate Change on 10 December. But it is unlikely to have an immediate impact on Kyoto negotiations, say the report's authors.

“These findings reinforce our position,” says Karsten Sach, head of the German environment ministry's international climate-protection department, and leader of the German delegation in Milan. Germany is committed to a reduction of 40% in its emissions by 2020, he says, regardless of whether the Kyoto Protocol comes into effect. Other European countries, including Britain, France, Sweden and the Netherlands, have similarly set their own goals.

Plans for a climate-protection strategy beyond Kyoto are not yet on the table, but some analysts expect the Italian host delegation in Milan to outline possible next steps.