The effects of climate change will be worse than previously predicted and, without immediate action, could have catastrophic consequences, according to a report published today by one of the most high-powered groups of scientists in the world.

The 2500-strong Intergovernmental Panel on Climate Change (IPCC), advisers to the UN, squarely held human activity responsible for the climate changes, which are likely to bring about more extremes of weather throughout the world.

The scientists, drawn from 130 countries, maintain that oceans will keep rising for more than 1000 years even if governments stabilise greenhouse gases emissions this century. They agreed that the changes would specifically bring about more heatwaves, droughts and rising seas.

The scientists, who will publish the report summing up the latest research about global warming in Paris, will intensify pressure on governments and companies to do more to curb a build-up of greenhouse gases mainly from burning fossil fuels in power plants, factories and cars.

The UK government appears ready to accept the thrust of the IPPC report. Speaking exclusively to The Herald, before making a speech at Edinburgh University today, David Miliband, the Secretary of State for Environment, Food and Rural Affairs, admitted that the government's policies had not kept up with the science of global warming.

He said: "What is true, and that applies as much in the UK as anywhere else, is that the science is faster than the policy or the politics, and the science has got more dangerous, more quickly than the policy has been reorientated to take account of this carbon challenge."

Mr Miliband, who as Secretary of State, negotiates on behalf of the Scots as well as the English, Welsh and Northern Irish at international talks, will take the chance to visit eco-friendly projects in Scotland, including Currie High School in Edinburgh.

He argued that because the UK government was a G8 player Scottish innovation, Scottish ideas, and Scottish practice can be reflected into the international arena in a way that it could not be if Scotland was not part of the UK.

Extolling the merits of devolution, he said: "I want to learn what Scotland is doing in respect of renewable energy and in respect of education and engagement of young people and in respect of housing where they're doing things that we're not yet doing in England.

"If we can create a system where there really are laboratories of democracy in the different bits of the UK that can only be a good thing. We can collaborate and have a bit of competition between us."

Anticipating the IPPC report, Chris Huhne, the LibDems' environment spokesman, urged the government to make a serious effort to reduce the fast-growing emissions from cars and planes.

"The big test will be whether the government reverses the cuts in green taxes that have taken place every year since 1999 and begins to use the tax system to encourage people to change their behaviour. But it is crucial in winning public support that every penny raised in green taxes is used to cut taxes on good things like work, risk and effort. We should tax pollution not people," he said.

The Scottish Green Party challenged the mainstream parties in Scotland to face up to the challenges of climate change.

Mark Ruskell, MSP for Mid-Scotland and Fife, said the IPCC report "must serve as the final alarm call for urgent action needed at a political level. The other parties in Scotland must abandon their climate-wrecking commitments, like air and road expansion, or hold their heads in shame".

Duncan McLaren, Friends of the Earth Scotland's chief executive, said: "This report should provoke the UK government and Scottish Executive to move its plans for action on climate change up a gear. In the run-up to May's elections, we will be watching carefully to see which of the political parties are prepared to commit to year-on-year pollution cuts now needed."