Labour MP Michael Meacher set out a cataclysmic vision of the dangers posed by climate change at the Insurance Times Climate Change conference on Tuesday.
He said: "Scientists say that a 70% reduction is needed in carbon emissions by 2050, but no country anywhere in the world has developed a policy to deal with this level of reduction."
And he added that doing nothing is not an option. "If we do nothing, global warming will kill billions this century."
He also said that past performance on the issue has been poor.
"Emissions have increased in six out of the last nine years," he said.
Meacher criticised his own government's climate change bill. "This bill does not set out any targets. It only has five-year targets but what is needed is the commitment to reduce emissions by 70% by 2050, and annual targets to work towards this."
Though the UK has only 1% of the world's population and accounts for 2% of world emissions, the UK should take a lead on the issue, said Meacher. "We can and should show world leadership on the issue."
He warned: "Some says this is all in the future, but they are wrong. We have at most 10 years to drastically cut emissions. We need greater urgency."