The UK government's chief scientist
has repeated his controversial remarks that climate change poses a bigger threat than terrorism.
Sir David stands by his comments on climate change
Sir David King's comments come despite recent ministerial pressure from Downing Street.
He courted controversy when he made remarks in an article for the American journal Science.
In the piece, Sir David criticised the US government for failing to take global warming more seriously.
"In my view, climate change is the most severe problem we are facing today, more serious even than the threat of terrorism," he wrote.
The government feared his comments could undermine relations with the US on terror and a Downing Street official wrote to Sir David asking him to tone down his remarks.
Now, he has told an environmental audit committee that he stands by his comments.
"Terrorism was a very serious threat," he said.
"But climate change could bring disaster to the world.
"Indeed it may take a disaster for the international community to treat climate change seriously enough."
Sir David believes that if carbon emmissions are cut radically enough, serious damage could be avoided.
"If we don't do enough there could be floods every few years causing tens of billions of pounds worth of damage in the south of England," he added.
Sir David believes that a second Thames barrier needs to be built within the next 20 years to protect the city from rising flood waters.