Worldwide interest in the threat from greenhouse gases has undergone a "massive change", the government's chief scientific adviser has said.
Sir David King told the Commons Environmental Audit Committee he had noticed a "culture change" in attitudes to pollution in the last two years.
But this had to be translated into a greater international effort.
Sir David warned of rising sea levels and melting ice caps if global warming was allowed to worsen.
He told MPs no government in the world would switch off its power stations to maintain carbon dioxide levels below 400 parts per million, if this seemed to threaten the country's economy.
He said that globally, if carbon dioxide was to be kept below 550 parts per million, there would need to be a reduction of CO2 by 2050 of between 60% and 65%.
But this would mean getting a worldwide agreement to cutbacks in fossil fuel, which was "unrealistic".
Sir David said: "We are not anticipating that Africa and India will reduce their emissions, let alone reduce them by that amount over that period of time.
"If we could maintain China, India, and Brazil to a relatively low growth in emissions, we'd be doing rather well."
However, environmentalists had "managed to achieve something of a culture change. I'm not saying that we're all the way there.
"But certainly when I went out to Australia a few weeks ago, there was an enormous amount of interest in climate change. It got a lot of media attention.
"So climate change is very much up there and people are considering it."