The United Nations IPCC report on climate change will present such compelling scientific evidence that humans are responsible for global warming that governments around the world will respond by introducing ambitious legally-binding targets to reduce their carbon emissions, Lord Stern predicts.

Lord Stern, the author of the hugely influential Stern Review into the financial implications of climate change, said he had been greatly encouraged by recent signs from key carbon emitters such as China and the US that they finally intend to take firm action to reduce their emissions of the greenhouse gases that are largely responsible for warming the climate.

Furthermore, he believes many countries will redouble their efforts following the release of the Intergovernmental Panel on Climate Change (IPCC) report on Friday, which will declare with 95 per cent certainty that human-related greenhouse gas emissions are the principal cause of global warming.

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The IPPC report will make clear that the risks from climate change are "immense", said Lord Stern, adding that it will nonetheless underestimate the true scale of the risks posed by global warming. This is because areas such as the methane emissions associated with melting permafrost, or ground ice, in the Antarctic, and the warming Arctic seabed are not sufficiently well-understood to yet be included in climate models, he said.

However, he is becoming increasingly confident that the world can mobilise itself to take dramatic, co-ordinated action.

Lord Stern, who has not worked on the forthcoming report but has been briefed on its contents by some of the key scientists involved, said: "Following the publication of the IPCC report… I would expect more countries to follow the example set by the UK and to introduce domestic legislation to create the necessary commitment to reduce emissions in line with the goal of avoiding global warming of more than 2C."

He was referring to the UK's Climate Change Act 2008, introduced by the previous Labour government, which set a legally-binding target for the country to reduce its greenhouse emissions by 80 per cent by 2050. This is the broadly in line with the cut that needs to be seen globally to give the world a reasonable chance of limiting global warming to 2C - the level beyond which the consequences become increasingly devastating.

"Many countries, including the biggest emitters, are increasing action against climate change and not waiting for an international agreement. Not only do they recognise the huge risks created by unmanaged climate change, but they see the big economic opportunities presented by the transition to low-carbon growth and development," Lord Stern said, adding that these actions would, in turn, "reinforce movement towards an international agreement".

Lord Stern is particularly excited by developments in China, the world's biggest carbon dioxide producer. This is because the country has given signals recently that it may look to start bringing down its carbon emissions from 2025 - rather than from 2030 as many had predicted - and that it could begin to reduce its coal use as soon as 2020. He is also hopeful that China could for the first time announce an emissions reduction target within the next few years. Ethiopia and Mexico are also making significant progress towards reducing their carbon footprint, Lord Stern said.

Lord Stern also criticised the coalition for putting off potential investors in Britain's energy sector by "undermining the credibility" of its targets in the Climate Change Act.

He cites the "lack of willingness" to have a target to green, or "decarbonise" Britain's electricity supply and well-documented battles between the Treasury, Department of Energy and Climate Change and the Department for Environment, Food and Rural Affairs as examples of government behaviour that is putting off investors.

Asked about the value of climate sceptics, he said: "It would be extraordinary and unscientific to argue that you are confident that the risks of climate change are small… That would be an astonishing statement to make given the science of the past 200 years."