Sir, At next week's G20 summit in Antalya, Turkey, just ahead of the critical UN climate summit in Paris, world leaders must take urgent action to cut fossil fuel subsidies.

Despite pledging in 2009 to phase out these subsidies, new research by the Overseas Development Institute and Oil Change International, shows that G20 governments are pumping $452bn annually into the exploration for and production of fossil fuels.

As three-quarters of known reserves of oil, gas and coal have to stay in the ground if harmful climate change is to be avoided, this use of public funds is not only calamitous for the planet but poor economics too.

Governments can no longer afford to ignore the rising health costs of air pollution, the falling returns on fossil fuel exploration, and the rapid emergence of alternatives from low cost solar to electric vehicles, which make low-carbon energy systems the smart investment choice. Some governments have been acting to rein in highly subsidised fossil fuel production, but much more has to be done by leading economies.

Ahead of the Paris summit, a declaration of a robust timetable for action on subsidies would restore the credibility of the G20's pledge. It would also send a clear message that the largest economies in the world are willing to take the tough decisions necessary to meet the challenge of climate change.

Prof Jeffrey Sachs (US)

Director, Earth Institute, Columbia University; Director, UN Millennium Project

Prof Fan Gang (China)

Peking University and National Economic Research Institute, Beijing

Dr Shenggen Fan (China)

Director General, International Food Policy Research Institute

Prof Alejandro Nadal (Mexico)

Professor of Economics, Centre for Economic Studies, El Colegio de Mexico

Dr Richard Dennis (Australia)

Chief Economist, Australia Institute

Prof Simon Wren-Lewis (UK)

Professor of Economic Policy, Oxford University

Prof Simon Dietz (UK)

Director, ESRC Centre for Climate Change Economics and Policy

Dr Evsey Gurvich (Russia)

Economist

Dr Liberty Mncube (South Africa)

Chief Economist, South African Competition Commission

Dr Ha-Joon Chang (South Korea)

Faculty of Economics, University of Cambridge