WHILE the governments of the world continued negotiations toward a global climate deal in Bonn, faith leaders met in Paris - the city where, it is hoped, the deal will be signed next December, to launch the Fast for the Climate campaign.

Inspired by the two-week fast by the leader of the Philippines delegation, Yeb Sano, at last year's summit in Warsaw (News, 22 November), faith groups responded by agreeing to fast on the first of every month until the deal was struck at the Paris summit.

At the international campaign launch, Mr Sano, who was moved to tears in Warsaw by the devastation caused by Typhoon Haiyan, said people of faith had a vital role to play.

"It was Victor Hugo who once wrote that 'No force on earth can stop an idea whose time has come.' Fast for the Climate is an idea whose time has come. Nothing can stop the indignation and righteous anger of the world's peoples against climate injustice. Nothing can stop the fervent prayers of communities around the world. Nothing can stop this global solidarity. No force on earth can stop this planetary awakening.

"Next year, here in Paris, we decide the future of the world. We have two clear choices: to halt climate change in its tracks, or to let it spiral into an unmanageable menace. Climate change is the defining issue of our generation. Our generation will be judged by our response to this challenge."

Among the hundreds of people who have signed up are faith leaders, including the Archbishop of Cape Town, the Most Revd Thabo Makgoba, the General Secretary of the World Council of Churches, Olav Fykse Tveit, and the Bishop of Peru, the Rt Revd William Godfrey.

At the launch was the President of the French Protestant Federation, Francois Clavairoly, who co-chairs the Council of Christian Churches in France. He said: "The strength of the message from Christians will be even better understood if we stand united within our community and beyond Christianity with those who have joined us."

The talks in Bonn, which conclude on Sunday, have taken place amid renewed optimism after the announcement by President Obama that the United States' Environment Protection Agency would limit emissions from coal-fired power plants.

The legislation was welcomed by the Presiding Bishop of the Episcopal Church in the United States, Dr Katharine Jefferts Schori, and the Presiding Bishop of the Evangelical Lutheran Church in America, the Revd Elizabeth A. Eaton. In a joint statement they said: "Our faith traditions teach us that no single person can be whole unless all have the opportunity for full and abundant life. That wholeness and collective well-being is only possible as a global community.

"We recognise our connections to fellow citizens and neighbours around the world who are already suffering from the consequences of climate change, and acknowledge our responsibility to those yet unborn, who will either benefit from our efforts to curb carbon emissions or suffer from our failure to address this ethical imperative. We believe that addressing climate change is a moral obligation to our neighbours and to God's creation."

In Bonn, progress was made on ensuring that "equity" would be a part of any Paris agreement. Some rich developed countries have pushed back on the idea that they should do more to tackle climate change because of their historical responsibility in creating the problem.

The senior climate-change adviser at Christian Aid, Mohamed Adow, said: "The good news is that the issue of equity, or climate justice, is now on the table. We now need countries to agree how this will be included in the 2015 agreement with countries most responsible doing the heavy lifting. There was also good discussion about how to help poor countries adapt to the changes in climate they are already experiencing.

"But the world is not on track to keep global temperature-rise to below two degrees Celsius, the level deemed as dangerous climate change. . . Countries must ratchet up their energy-efficiency and renewable-energy commitments to close this ambition gap."