Most of the world's fossil fuel reserves will need to stay in the ground if dangerous global warming is to be avoided, modelling work suggests.
Over 80% of coal, 50% of gas and 30% of oil reserves are "unburnable" under the goal to limit global warming to no more than 2C, say scientists.
University College London research, published in Nature journal, rules out drilling in the Arctic.
And it points to heavy restrictions on coal to limit temperature rises.
"We've now got tangible figures of the quantities and locations of fossil fuels that should remain unused in trying to keep within the 2C temperature limit," said lead researcher Dr Christophe McGlade, of the UCL Institute for Sustainable Resources.
"Policy makers must realise that their instincts to completely use the fossil fuels within their countries are wholly incompatible with their commitments to the 2C goal."
Past research has found that burning all of the world's fossil fuel resources would release three times more carbon than that required to keep warming to no more than 2C.
The new study uses models to estimate how much coal, oil and gas must go unburned up to 2050 and where it can be extracted to stay within the 2C target regarded as the threshold for dangerous climate change.
The uneven distribution of resources raises huge dilemmas for countries seeking to exploit their natural resources amid attempts to strike a global deal on climate change:
The Middle East would need to leave about 40% of its oil and 60% of its gas underground
The majority of the huge coal reserves in China, Russia and the United States would have to remain unused.
Undeveloped resources of unconventional gas, such as shale gas, would be off limits in Africa and the Middle East, and very little could be exploited in India and China.
Unconventional oil, such as Canada's tar sands, would be unviable.
The research also raises questions for fossil fuel companies about investment in future exploration, given there is more in the ground than "we can afford to burn", say the UCL scientists.
"We shouldn't waste a lot of money trying to find fossil fuels which we think are going to be more expensive," co-researcher Prof Paul Ekins told the BBC.
"That almost certainly includes Arctic resources. It will certainly include a lot of the shale gas resources in Europe, which have not really been explored or exploited at all."
Carbon capture and storage would have only "a relatively modest effect" on how much fossil fuels can be used because of its expense and late introduction, the scientists added.
Emma Pinchbeck, WWF-UK's head of energy and climate change policy, said the study showed "yet again that the majority of the world's fossil fuel reserves, and coal in particular, must stay in the ground to stay within two degrees of warming".
And Rob Bailey, research director for energy, environment and resources at Chatham House, said the finding that half of natural gas reserves must remain untapped will make uncomfortable reading for governments seeking to replicate the US shale revolution and displace dirtier coal.
"The recently heralded golden age of gas will be short lived if we are to avoid dangerous climate change," he said.