"The interlocking challenges of climate change and clean energy are two of the most pressing, urgent and difficult global issues that we face together," she said in a speech to a meeting of Group of Eight (G8) ministers in Berlin.

"It seems that the weather has become destabilised already. And while we watch, the glaciers are retreating. The Arctic is melting ... The world only has a short window of opportunity."

The former Norwegian prime minister said all nations needed to be included in a new treaty under the United Nations Framework on Climate Change to replace the Kyoto Protocol on cutting greenhouse emissions, which expires in 2012.

But Brundtland said that a few months ahead of a crucial meeting on climate change to start the process of replacing Kyoto, there was deep distrust between nations and confusion about how to handle the crisis.

"We are hampered by a deep-rooted lack of trust -- between the industrialised and developed countries, and lack of trust within groups of countries," she added.

"No single country is in control or will be able to opt out," she said in a veiled reference to the United States, the world's number one greenhouse gas emitter, which walked away from Kyoto in 2001.

"There isn't any business as usual or an easy way out of the problem. But this has still not sufficiently influenced the major powers. Still we are struggling with the fact that those who are the least willing often have the strongest say," she said

Brundtland was addressing the third and penultimate meeting of the G8's so-called Gleneagles Process on climate change, clean energy and sustainable development in Berlin.

The environment and economy ministers of the 20 biggest energy users, including several big developing nations such as Brazil, China, India, Mexico, Nigeria and South Africa are attending.

Germany, which holds the presidency of the G8 this year, in June managed to persuade members of the wealthy club of nations to agree to a non-binding goal of halving greenhouse gas emissions by 2050.

However, the post-2012 global negotiations are badly bogged down.

One problem is how to configure a treaty so that it encourages cuts by the United States, which opposes the cap on emissions set down under Kyoto and is pushing a voluntary, technology-driven approach.

Another problem is what kind of commitments large developing countries should make under post-2012 Kyoto.

These countries, notably China and India, are now big emitters in their own right and their pollution is set to grow massively in the years ahead.

President George W. Bush says it is impossible to conceive of any global deal that does not include tough pledges from these economies.

Under the present format, they are exempt from making binding commitments on curbing emissions.

They insist on retaining this right beyond 2012, fearing that a change could imperil their rise out of poverty and arguing that, in any case, rich countries bear the historical responsibility for global warming.

Greenhouse-gas emissions are overwhelmingly caused by the burning of oil, gas and coal, the energies that drove the Industrial Revolution and remain the backbone of today's global economy.

German Environment Minister Sigmar Gabriel said the Berlin meeting sought to find common ground between the industrialised countries and the developing world ahead of the key UNFCCC negotiations in Bali, Indonesia, in December.

"We are here to talk about convincing the developing world. Up to now, China and India have said that they do not have to negotiate," Gabriel told reporters.

"By Bali we need to have changed this attitude. We need agreement between the developed and the developing world."

A further conference on emissions curbs takes place under the UN umbrella on September 24, following by a meeting on climate change in the UN General Assembly, and under US chairmanship in Washington on September 27-28.