There is growing evidence that climate change is causing more extreme weather disasters such as the Philippines typhoon, David Cameron said.
In remarks likely to infuriate the green sceptics in his party, the prime minister gave his first acknowledgement that global warming may be linked to increasingly intense storms across the world.
The remarks are Cameron's strongest defence of climate change science for a while, after repeated accusations that he has retreated from his pre-election pledge to run the greenest government ever.
Despite urging people to "vote blue, go green" in 2010, he has not given a full speech on the issue nor attended a UN environment summit since becoming prime minister.
Under pressure from many backbenchers, he has tightened planning controls on windfarms and pledged to "roll back" green subsidies on bills, leading to fears of dwindling support for the renewables industry.
However, Cameron spoke out on the need to tackle global warming at the Commonwealth summit in Colombo, Sri Lanka, after typhoon Haiyan killed at least 4,000 people and caused devastation across the Philippines.
Asked on Fridaywhether climate change was linked to the Philippines disaster, Cameron said: "I'll leave the scientists to speak for themselves about the link between severe weather events and climate change. But the evidence seems to me to be growing. As a practical politician, I think the sensible thing is to say let's take preventative and mitigating steps given the chances this might be the case."
He added: "Scientists are giving us a very certain message. Even if you're less certain than the scientists, it makes sense to act both in terms of trying to prevent and mitigate."
His comments also coincide with the United Nations talks on climate change in Warsaw, which has seen Japan slash its commitment to reducing CO2 emissions and Australia fail to send a minister to the conference for the first time in 16 years.
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