About two-thirds of all proven reserves of oil, gas and coal will have to be left undeveloped if the world is to achieve the goal of limiting global warming at two degrees Celsius, according to the chief economist at the International Energy Agency.

Addressing participants in the latest round of UN climate talks in Bonn, Fatih Birol said this should be an “eye-opener” for pension funds with significant investments in the energy sector — particularly in coal — as well as for ratings agencies.

He predicted coal would be hardest hit in the “unburnable carbon” scenario, followed by oil and gas. “We cannot afford to burn all the fossil fuels we have. If we did that, it [average global surface temperature] would go higher than four degrees.

“Globally, the direction we are on is not the right one. If it continues, the increase would be as high as 5.3 degrees — and that would have devastating effects on all of us.”