The Foreign Secretary accused the public yesterday of lacking a sense of urgency in the face of the potentially devastating consequences of climate change.

David Miliband said that people had grown apathetic about the issue when they needed to be galvanised into action before the Copenhagen climate change summit in December.

“For a lot of people the penny hasn’t dropped that this climate change challenge is real and is happening now,” he said. “There isn’t yet that feeling of urgency and drive and animation about the Copenhagen conference.”

Mr Miliband and his brother, Ed Miliband, the Climate Change Secretary, were opening an exhibition at the Science Museum in South Kensington designed to illustrate the potential impact of world temperatures increasing by 4C. Current models predict that this could happen by 2060 if no action is taken.

Mr Miliband warned of water and food shortages, mass migration and conflict. A map unveiled at the exhibition showed temperatures increasing by up to 15C in the Arctic, storm surges hitting the East Coast of Britain and forest fires and droughts in Europe.

Ed Miliband said that only 18 per cent of people believed that climate change would affect their children.

He stood by the Government’s hard-hitting public information broadcast to promote the Government’s Act on CO2 initiative.

The Advertising Standards Agency is investigating complaints that the three minute advertisement, which shows a cartoon sequence of streets under water and animals and people drowning, is upsetting for children.

However, he said that it was also vital to give people a positive vision of a low-carbon future. “If Martin Luther King had come along and said ‘I have a nightmare’ people would not have followed him,” he said.

Chris Rapley, the director of the Science Museum, said that a last minute decision had been made to create the exhibition in August after a briefing at the Department of Energy and Climate Change.

“We realised that public interest had flattened out and yet here we were approaching the most historic negotiations in human history,” he said. The museum had not been planning to run a climate change exhibition until 2011.

The interactive exhibition allows participants to consider climate change from the perspective of the different players involved in the Copenhagen negotiations, including a climate scientist, a human rights experts and an economist.

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