Storms will increase in frequency

More than 300 scientists were involved in the peer review process before the report's publication, co-ordinated by the US Global Change Research Programme.

Philip Clapp, president of the National Environmental Trust, said: "This report is yet another blow to the global warming naysayers.

"It confirms the validity of the science and the seriousness of the impacts on human health, our economy and our environment."

The report's findings include:

• assuming continued growth in world greenhouse gas emissions, average US temperatures will increase by three to six degrees C during this century
• there will be pronounced variations, with some regions getting more rain and others becoming drier
• some ecosystems are highly vulnerable to the probable rate and magnitude of change. Alpine meadows in the Rockies are likely to disappear entirely
• coastal infrastructure - buildings, roads and powerlines - will face increased threats, and storm surges and flooding will increase
• overall US crop productivity is likely to increase over the next few decades, but not uniformly, and pests, droughts and floods will become more of a problem.

Species distribution may alter

The international talks in Bonn, Germany, involve countries which have signed the Kyoto Protocol, the international agreement on tackling climate change. This commits developed countries to cut their emissions of six greenhouse gases by an average of 5.2% on their 1990 levels by between 2008 and 2012.

This month's talks are a preliminary to a much higher-profile meeting in November, when there will be pressure for leading polluters to ratify the Protocol, which none has yet done.

But environmentalists are accusing some members of the Organisation for Economic Co-operation and Development of trying to undermine the Protocol by exploiting loopholes in its provisions.

Emissions trading

They say some OECD members, including the US, are trying to avoid cutting their own emissions through greater reliance on nuclear power, and by buying the right to emit greenhouse gases from poor countries which cannot afford them.

Some researchers doubt that human activities are inducing rapid climate change. They highlight the inconsistencies between the temperature records taken at the Earth's surface, which show rapid warming over the last two decades, and the data produced by satellite and balloon studies.

These show little or no warming higher in the atmosphere over the same period, and some scientists say our understanding of climate processes is still too limited to support an acceptance of human-induced climate change.

All photographs courtesy of US National Oceanic and Atmospheric Administration