But the scale of change and its cause are hotly contested, as blocs of countries including Europe and the United States are split on how quickly the world should act.

The UN-founded group, the International Panel on Climate Change (IPCC), has prepared its fourth report, at draft stage and due for publication in 2007, on the case for climate change, and finds that evidence has hardened, Watson said.

The IPCC's research work is split into working groups, with scientific evidence delegated to Working Group 1.

"Everybody I've talked to in Working Group 1 says the evidence (for climate change) is getting stronger, that this is more and more solid ... and (evidence) that most observed warming is due to human activities," said Watson, who is former chairman of the IPCC.

The third report in 2001 spoke of "new and stronger evidence" that human activities were warming the globe, in turn stronger than the previous report in 1995, which described a balance of evidence suggesting discernible human influence.

Citing most recent, and not necessarily IPCC research, Watson also found a consensus emerging that an expected rise in world temperatures by 2100 compared to 1990 was at the upper end of previous estimates.

"The latest climate change models suggest changes on the upper end of the scale, a projected temperature increase of 3 to 5 degrees."

"The third IPCC report predicted a temperature rise of a 1.4 to 5.8 degrees centigrade increase. This is a global average, increases on land are higher than in oceans, and over polar regions highest of all."

The third IPCC report's estimate translated into a sea level rise of 9-88 cm by 2100, so any higher temperature rise would be bad news to anyone living by the sea.