But far from making any recommendations for action to their political masters, the scientists from 30 countries will review the state of knowledge and try to define just what constitutes "dangerous" levels of climate warming.
"We will not try to come up with a consensus number on what should be a target. That is a job for the politicians," conference chairman Dennis Tirpak said on Wednesday.
"The purpose is to have a debate of the scientific facts. We will collect the best information we have to give to the politicians … but don’t expect to make any recommendations," he told reporters.
It is a far cry from the fanfare with which British Prime Minister Tony Blair announced the conference last September, promising a cutting edge meeting that would set the political agenda for his presidency of the Group of Seven rich nations.
Scientists have said that two degrees centigrade of warming is already expected — with a major input from human activities like burning fossil fuels to generate electricity, which produces vast quantities of the greenhouse gas carbon dioxide.
They have also warned that warming of more than that will start to fuel itself, pushing the planet into the unknown as ice caps melt, sea levels rise and weather patterns change at accelerating rates, putting millions of people at risk.
An international report this week said the climate was a ticking time bomb and urgent action was needed now to curb greenhouse gas emissions. One computer model predicted climate warming of up to a catastrophic 11 degrees.
Environment campaigner Tony Juniper of Friends of the Earth was upbeat about the meeting.
"A clear demonstration of a scientific consensus will send an unmistakable message to the politicians that they have to take action on carbon dioxide emissions now," he said.
The scientists from countries as varied as Australia, India, Sri Lanka, China and Japan will meet in isolation for three days starting on Tuesday — ?ust two weeks before the Kyoto climate change treaty finally kicks in.
A tiny step to limit rising temperatures, Kyoto aims to cut CO2 emissions by developed states by 5.2 percent below 1990 levels by 2008-12.
The United States — the world’s biggest generator of greenhouse gases — has refused to sign up.