Ed Miliband: climate change deniers are 'profoundly irresponsible'

Ed Miliband, the climate change secretary, today said critics who argue that climate change is not the result of human actions are "profoundly irresponsible".

As negotiating teams from 192 countries gather in Copenhagen for the climate change summit, Miliband admitted there was "further to go" on persuading climate change sceptics here and abroad. But he defended Gordon Brown's criticism of them in the Guardian as "behind-the-times, anti-science, flat-earth climate sceptics" .

Miliband told BBC Radio 4's Today programme: "The overwhelming consensus of scientists across the world is that climate change is real and is man-made and is happening. The people who do somehow want to suggest that the science is in doubt are profoundly irresponsible."

He added: "We know that carbon dioxide concentrations are the highest level in the atmosphere in 600,000 years – nobody doubts that. We also know from the physicists that the CO2 effect when CO2 is emitted is it traps the heat in the earth's atmosphere and then warms the planet. That is very clear and not in dispute.

"This is not an observation or people just running models. This is a clear scientific effect people are talking about. In those circumstances I think it's right for us to say: 'Look, we are not scientists, but we should represent to you fairly the science, and it's because the scientific view is so clear and overwhelming on this we must fairly represent that.'"

In an article in today's Guardian, the prime minister underlines the historic nature of the summit, which has been described as the most important international gathering since the end of the second world war. "Sometimes history comes to turning points," he writes. "For all our sakes the turning point of 2009 must be real."

Brown calls on the 100 world leaders expected in Copenhagen on the final day of the talks to move quickly to reinforce an anticipated political deal with a fully-fledged treaty, which would be made legally binding in international law within six months.

Miliband said that the central objective of the summit was to secure a political agreement to cap global emissions by 2020. "We are going for something very big. I don't think it is guaranteed that we will succeed, but we will do everything we can in the next two weeks not just to get a deal but to get a deal that is consistent with the science," he said.

He denied that the government's backing for a third runway at Heathrow airport was at odds with government rhetoric on tackling climate change.

He framed the government's decision to allow expansion for extra flights backed by a freeze on aviation emissions as a "sensible approach".

"Increases in passenger numbers will have to be paid for by improvements in carbon efficiency."

He added: "The most important thing is to take people with you, and the way you take people with you is by saying this is a sensible approach."