Munich

The politically sensitive issues of carbon sequestration and regional climate forecasts are to form part of the fourth assessment report by the Intergovernmental Panel on Climate Change (IPCC).

The assessment, due in 2007, was discussed by some 300 IPCC members in Paris on 19–21 February. Sequestration was chosen as the subject for a special report, separate from the main assessment. After the meeting, Rajendra Pachauri, director of the Tata Energy Research Institute in New Delhi and chair of the IPCC, confirmed that more detailed regional models of the impact of climate change would be considered by the assessment's authors.

Previous regional projections have generated controversy. A 2000 report from the US Global Change Research Program described the possible regional effects of climate change in the United States, but the results of this and other similar studies were deemed too unreliable by the Bush administration to be included in its strategy for climate-change research, released last November (see Nature 420, 110; 2002).

“I am aware that there is an opportunity for much political debate when you start to predict the impact of climate change on specific regions,” said Pachauri. “But if you want action you must provide this information.”

Carbon-sequestration schemes, such as using empty oilfields to store the carbon dioxide from power plants, also provoke strong reactions. Environmental groups accuse advocates of the idea of damaging attempts to reduce emissions of greenhouse gases.

But the panel's fourth assessment will come too late to provide scientific input into negotiations on greenhouse-gas emission targets for 2013 onwards, the second phase of the Kyoto Protocol. Talks on these targets begin in 2005. “We will have to come up with some means to update negotiators with the latest scientific information,” said Pachauri. One possibility, he said, would be for some panel members to hold workshops to provide tentative directions for the negotiating parties.

The run-up to the Paris meeting was overshadowed by criticism of a previous IPCC special report on emission scenarios, which explored how changes in global economic and social conditions could affect emissions. In several papers over the past year, economists Ian Castles of the Australian National University in Canberra and David Henderson of Westminster Business School in London argued that the scenarios were “technically unsound” because of false assumptions on likely economic growth in developing countries.

Pachauri and others at the meeting agreed that the projections may need minor changes, but denied that they are flawed. “The emissions scenarios covered a very broad range,” said Thomas Stocker, a climate modeller at the University of Bern in Switzerland, and a lead author on the third assessment report. “It is extremely unlikely that they do not include the actual development of emissions.”

Details of the next assessment will be approved at an IPCC meeting in October. The IPCC will then appoint about 2,000 authors and reviewers from around the world, who could then begin work next year. Pachauri says he is keen to involve more young authors.