The risks of global warming are “more serious than previously thought”, concluded a major international climate conference on Thursday.

“Major investment is needed now in both mitigation and adaptation,” stresses the preliminary report, summarising results presented at the conference, called Avoiding Dangerous Climate Change, in Exeter, UK.

The impacts of global warming discussed at the meeting sounded like a roll call of disasters. Topics ranged from the collapse of ice sheets in Antarctica to the irreversible melting of the Greenland ice caps; from droughts in Africa to floods in Japan. And fears were also raised over the rapidly changing current-patterns in acidifying ocean .

But the scientists shied away from stating that such climate change was “dangerous”. “That’s a value judgement to be made by policy makers,” said Bert Metz, from the Netherlands Environmental Assessment Agency and one of the report’s authors.

To help policy makers decide where to draw the danger line, the report echoed some researchers’ calls to establish “critical thresholds that we should aim not to cross”.

For example, the report drew attention to the results of Jason Lowe, from the Hadley Centre in Exeter. He says that local warming of more than 2.7�C, associated with global warming of only 1.5�C, could trigger Greenland’s ice sheet to start contracting.
Dramatic cuts

Collating results from published studies indicated that damage increases as the world warms by between 1�C and 3�C, while serious risk of large scale damage becomes likely above 3�C, the report said. This lends some support to the European Union’s target of keeping global warming to under 2�C by 2050. Other presentations at the meeting suggested that only with dramatic emissions cuts can such a goal be achieved.

The report also warned that more research was needed into the effects climate change could have on the frequency of extreme natural events. It cited the European heat wave of 2003 - during which thousands of people died - as an example of an extreme event made more likely by global warming.

The last substantial review of climate change was conducted by the Intergovernmental Panel on Climate Change in 2001. But now “there is greater clarity and reduced uncertainty about the impacts of climate change”, says the new report.

The meeting was opened by Margaret Beckett, the UK’s Secretary of State for the Environment, who said on Thursday: “I think this conference will be seen as a turning point in the perception of climate change. It underlines the need for the international community to take urgent action to combat climate change.”

New Scientist Breaking News - Alarm bells ring louder over climate change