A Labour MP is to step down at the next general election to campaign full time for global action on climate change.
Colin Challen led the Parliamentary Climate Change Group
Colin Challen, 53, who represents Morley and Rothwell in West Yorkshire, is a founding chairman of the All Party Parliamentary Climate Change Group.
In a letter to party members, he said: "The world must grasp the nettle and take very serious and urgent action to address the climate change problem."
He expects to work in Africa and focus on the economics of global warming.
Mr Challen said he would be working with Sir Nicholas Stern, author of last year's Stern Review, which warned about the economic impact of climate change.
"I will be spending more time on this work than ever before, and eventually I want to devote 100% of my time to this campaign," he said.
In his letter, Mr Challen explained how his concern for the environment went back many years.
"The now very obvious warming of the Earth means political leaders around the world must grasp the nettle and take very serious urgent action to address the climate change problem, he said.
Mr Challen attended the UN climate change conference in Nairobi
"My experience at the Nairobi climate change talks last November made two things very clear.
"The first is that young Africans are already dying because of global warming.
"The second is that there is no agreement to change that situation at the pace the world needs to give their sisters and brothers a better hope of life.
"So we must quickly come to some agreement on how to do that and, specifically, how to find a new international framework by 2012 to replace the present international Kyoto Protocol."
He said he would continue to represent Morley and Rothwell until the next general election "to the best of my ability".
Mr Challen was first elected in 2001 and at secured a majority of 12,343 in 2005.
A Boundary Commission reorganisation means his constituency will form part of a new one to be called Morley and Outwood.