The prime minister will face a daunting dilemma next month when the world's most authoritative report on climate change is published, providing a clear warning from scientists about the scale of the risks posed by rising levels of carbon dioxide and other greenhouse gases in the atmosphere.

Mr Cameron will have to decide whether to keep pandering to the noisy band of unscientific sceptics in the Conservative party or instead listen to the experts.

The Fifth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC) is one of the most important scientific documents ever published.

The first volume of the report will be published next month, providing a comprehensive analysis of the latest research on the basic science of climate change.

It has been prepared by 255 scientific experts from universities and research institutes in 38 countries, who were commissioned by the world's governments to review all of the available evidence, including thousands of scientific papers.

The experts' assessment for the IPCC has been subjected to one of the most rigorous audit processes in the history of science, with more than 50,000 comments made on draft versions that were made available to hundreds of reviewers around the world, including climate change sceptics.

One draft was leaked by a sceptic earlier this year, revealing that the IPCC is, for the first time since it was created in 1988, intending to provide an estimate of the budget of greenhouse gas emissions that must not be exceeded if the world is to have a reasonable chance of avoiding global warming of more than 2°C above preindustrial temperatures.

The world's governments, at the United Nations climate change summit in Cancún, Mexico, in December 2010, agreed that greenhouse gas emissions should be reduced to avoid dangerous levels of climate change due to global warming of more than 2°C.

Numerous recent studies, which have been reviewed by the IPCC experts, show that current proved reserves of fossil fuels, if burned, would release enough carbon dioxide to create a very strong probability of global average temperature rising by much more than 2°C above its preindustrial level by the end of this century.

While more than 100 countries, including China, the United States and the other largest greenhouse gas producers, have now made commitments and pledges to take domestic action against climate change, their planned efforts are collectively inadequate and would still mean that the emissions budget for 2°C will be busted within the next few decades.

Countries are now negotiating a new international treaty, to be signed at the 2015 climate change summit in Paris, to try to ensure that sufficient global emissions reductions are made.

The new IPCC report makes clear that, unless the upward trend in annual emissions is reversed, the world will be all but condemned to global warming of more than 2°C, creating a prehistoric climate not seen since the Pliocene epoch 3 million years ago, when the polar icecaps were much smaller and global sea level was about 20 metres higher than today.

However, the IPCC report should also be used by the prime minister to end the damaging public battle between ministers within the "greenest government ever" about climate change.

The Department of Energy and Climate Change (DECC) has attempted to keep the UK on course to meet its target, set under the Climate Change Act 2008, to reduce annual emissions by 80% by 2050 compared with 1990 through a series of successive five-year carbon budgets.

The goal set by the act was recommended by the independent experts on the committee on climate change because it is consistent with the global aim of having a reasonable chance of avoiding global warming of 2°C.

But DECC is being hamstrung by some Conservative members of the government and backbenchers.

Owen Paterson, who, as environment secretary, is the cabinet minister responsible for making the UK resilient against the impacts of climate change, has publicly championed sceptic claims that greenhouse gas emissions are not responsible for global warming.

Even worse, Paterson's department is failing to increase spending on flood defences to take into account rising sea levels and heavier rainfall, which the UK is already experiencing.

Meanwhile, the chancellor has been making speeches that present a false choice between promoting growth and tackling climate change, hence undermining private investment in the UK's transition to a low-carbon economy.

And the Treasury was responsible for insisting that the gas generation strategy, published last December ahead of the public relations offensive to encourage fracking, should also initiate a review in 2014 of the UK's carbon budgets with a view to weakening them.

These cabinet members are being egged on by Lord Lawson, chairman of the Global Warming Policy Foundation, a lobby group for climate change sceptics, Lord Ridley, the former chairman of Northern Rock and hereditary Conservative peer, and Peter Lilley, who supplements his pay as an MP with a part-time job as vice chairman of Tethys Petroleum.

But, next month, the prime minister will be caught between the proverbial rock and a hard place, when he is confronted with the overwhelming weight of the scientific evidence presented in the IPCC report.

He should put the public interest first by ensuring the government's approach to energy and climate change is based firmly on the scientific evidence instead of the ideological hot air generated by unscientific sceptics within his own party.

Bob Ward is a reviewer of the IPCC report and policy and communications director at the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science