A long-awaited report by an international scientific network will offer much stronger evidence of how humans are changing Earth's climate, and should prompt balky governments into action against global warming, the group's chief scientist said Monday.

The forthcoming multi-volume UN assessment — on melting ice caps and rising seas, with authoritative new data on how the world has warmed — "might provide just the right impetus to get the negotiations going in a more purposeful way," Rajendra Pachauri said in an interview during the annual two-week UN climate conference.

The Indian climatologist is chairman of the Intergovernmental Panel on Climate Change. The global network of some 2,000 scientists regularly assesses the state of research into how carbon dioxide and other heat-trapping gases produced by industry and other human activities are affecting the climate.

In its pivotal Third Assessment, in 2001, the panel concluded that most global warming — temperatures rose an average 0.6 C in the past century — was likely the result of such man-made greenhouse gases.

In its Fourth Assessment, to be issued in instalments beginning next February, "there's much stronger evidence now of human actions on the change in climate that's taken place," Pachauri told the Associated Press.

The 1997 Kyoto Protocol requires 35 industrialized countries to reduce their greenhouse emissions by five per cent below 1990 levels by 2012. The United States and Australia are the only major industrial nations to reject Kyoto. U.S. President George W. Bush contends the emissions cuts would harm the American economy.

At the Nairobi conference, Kyoto parties are discussing what kind of timetables and quotas should follow that pact's expiration in 2012.

Canada, as a signatory to the treaty, promised to reduce emissions to six per cent below 1990 levels between 2008 and 2012.

However, the new Conservative government has repeatedly said the country cannot meet Kyoto targets for pollution reduction, a position that critics see as a virtual abandonment of the treaty, even though the Tories aren't formally pulling out.

Pachauri said the document will offer significantly more evidence on sea-level rise, the melting of glaciers and the growing scarcity of water. He didn't discuss details, since the Fourth Assessment Report is still in the draft stage.

Pachauri said increasingly powerful super-computers allow scientists to run more accurate models of future climate.

The match between what the computer models have predicted and what is actually happening to the climate has become "much, much sharper," he said. This has allowed his panel to narrow its range of scenarios for 21st-century climate.