More than 80% of the world’s coal reserves, half of the gas, one-third of the oil, all Arctic oil and gas, and most Canadian tar sands/oil sands are declared unburnable in a study this week by the Institute for Sustainable Resources at University College London.

The study is the world’s first to identify the specific fossil fuel sources that are incompatible with a 2ºC limit on atmospheric warming.

“We’ve now got tangible figures of the quantities and locations of fossil fuels that should remain unused in trying to keep within the 2°C temperature limit,” said lead author Dr. Christophe McGlade, after the paper appeared Wednesday in the journal Nature.

“Policy-makers must realize that their instincts to completely use the fossil fuels within their countries are wholly incompatible with their commitments to the 2°C goal,” he added. “If they go ahead with developing their own resources, they must be asked which reserves elsewhere should remain unburnt in order for the carbon budget not to be exceeded.”

Fossil fuel companies spend more than $670 billion (£430 billion) per year on new exploration and development, noted co-author Prof. Paul Ekins. “They will need to rethink such substantial budgets if policies are implemented to support the 2°C limit, especially as new discoveries cannot lead to increased aggregate production,” he said. “Investors in these companies should also question spending such budgets.”