GORDON Brown will today urge world leaders to heed the warnings of the Met Office that there is no greater threat than "dangerous climate change".

The Prime Minister will arrive in Copenhagen earlier than expected in a bid to get crunch talks back on track, after developing countries staged a half-day suspension yesterday afternoon. The G77 group, led by African countries, walked out over accusations that richer countries were seeking to use the UN-sponsored conference to dodge their obligations to cut carbon emissions.

Earlier this month, Met Office chief scientist Professor Julia Slingo said it is "not all lost" if world leaders act now.

The Prime Minister stressed the world is only "half way" to an agreement and said developed and developing countries must not "divide" in the talks. He remains "optimistic" that an agreement can be reached. Before leaving London, he warned last night: "We cannot wait until the last moment to do a deal."

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The WMN understands Mr Brown is prepared to take a "leadership role" similar to his involvement in the G20 finance conference in London this year. A source said: "He has been prepared to put himself on the line from the beginning. He has got a detailed understanding of the issues that allows him to play the role of broker."

The Prime Minister was not due to travel to Copenhagen until Thursday, but growing fears that a deal will not be reached forced his diary to be torn up.

In an interview with the WMN before the talks began in the Danish capital, Professor Slingo said global carbon emissions needed to peak by the end of the next decade if the planet was to avoid "dangerous climate change".

The professor, who is part of the delegation from the Exeter-based Met Office attending the Copenhagen conference, said: "It's going to be hard work to keep within the 2C temperature change that governments have agreed is where we need to be to avoid dangerous climate change."

This week, more than 70 world leaders and representatives from 192 countries will attempt to hammer out a deal on reducing carbon emissions in an effort to halt the increase in global temperatures that could have catastrophic effects.

Mr Brown last night took up the Met Office's stark message, saying: "We can't wait until the last moment to do a deal. That's why I will go to Copenhagen to work with other leaders who will also arrive to push negotiations forward.

"There is simply no bigger test of global co-operation than the threat of dangerous climate change."

Environment Secretary Hilary Benn has been in Copenhagen to urge negotiators to secure a deal that would protect the world's forests, in the wake of the Prime Minister's call for £15 billion in funding from rich countries up to 2015 to reduce deforestation, which accounts for almost a fifth of total global emissions.

And Climate Change Secretary Ed Miliband warned the world's ministers must "get their act together" to get the talks back on track.