BERLIN: Ministers from countries accounting for more than two-thirds of the world's carbon pollution gather in Potsdam Thursday for the first test of Europe's proposal to slash greenhouse-gas emissions by 2020.

At the table will be environment ministers from the Group of Eight (G8) countries and their counterparts from five major developing nations: Brazil, China, India, Mexico and South Africa.

With Cecilienhof chateau, the venue of the 1945 Potsdam conference, providing the spice of history, the talks offer the best opportunity in years for advancing a global deal on climate change, German officials believe.

"The meeting won't be a breakthrough, but an important intermediate step," German junior environment minister Matthias Machnig, whose country is current president of the G8, said.

The only worldwide pact for reducing global-warming emissions is the UN's Kyoto Protocol.

That treaty runs out in 2012 but it has been virtually crippled by a walkout by the United States, which by itself accounts for nearly a quarter of world pollution.

Negotiations are underway for Kyoto's post-2012 format. Everyone agrees it must deliver enormous cuts to avoid what many experts fear could be deep, irreversible damage to the climate system.

But for this to happen, the post-2012 deal needs to rope in the United States and get a stronger commitment from big developing countries.

China, India and Brazil are becoming major polluters in their own right, but under the present Kyoto format do not have to make pledges of targeted curbs in their emissions.

That requirement only applies to industrialised countries.

Can the United States be coaxed back into the multilateral fold while President George W. Bush is still in power? What kind of concessions are the high-population developing countries willing to make? Will they agree to binding emissions cuts, despite the economic cost this may carry?

Last week, Germany, which is concurrently president of the European Union, corralled the EU countries into a deal by which the 27-nation bloc would cut its own greenhouse-gas emissions by 20 per cent by 2020.

The EU would deepen this to 30 per cent if, in the words of German Chancellor Angela Merkel, "international partners" follow suit.

The Potsdam meeting, after a roundtable on biodiversity on Friday, provides the first occasion to see if the EU's dramatic offer gains any traction.

Eliot Diringer, director of international strategies at the Pew Center on Global Climate Change, a Washington think tank, said Bush had been weakened by the Iraq War and the Democrats' control over Congress, which had already translated into proposals for climate laws.

That means the timing is right for Bush to show "stronger international leadership" on climate change, which could be presented as an initiative for energy efficiency, he suggested.

"President Bush has a reputation for being rather stubborn, but if you look at other issues, he has in some cases shifted," said Diringer. "Look at North Korea and engagement with Syria and Iran. They are examples of this administration's ability to shift when necessary."

Susanne Droege of the German think tank Stiftung fuer Wissenschaft und Politik (SWP) said there was "no chance" of getting the big developing countries to endorse targeted cuts.

The best that could be hoped was a tailored agreement that spurred energy efficiency and transfer of clean technology to these countries, she said.

In January, the UN's top climate scientists sounded their loudest warning yet about the impact of burning fossil fuels on Earth's delicate climate system.

The Intergovernmental Panel on Climate Change (IPCC) pointed to alarming changes that had already taken place in Earth's ice cover, rainfall patterns and permafrost.

By 2100 global average surface temperatures could rise by between 1.1 and 6.4 C (1.98 and 11.52 F) depending on how much carbon dioxide (CO2), the principal greenhouse gas, is in the air, the IPCC said.

After a gala dinner on Thursday, the ministers get down to work on Friday with a session on biodiversity, followed by talks on climate change on Friday afternoon and Saturday morning.

The talks will also be attended by the European Commission, the UN Environment Programme (UNEP), the UN Framework Convention on Climate Change (UNFCC) and the World Conservation Union (IUCN). - AFP/yy