More people in Wales will face flooding, and more often, according to an investigation by BBC Wales Week In Week Out.
World-renowned climatologist Sir John Houghton warns that extreme weather patterns are here to stay, and the risk of flooding will rise.
One in five or 600,000 people live in flood risk areas in Wales.
"The rain will come down in bigger droplets with more intense weather," the expert warned.
"The likelihood is we are going to get, on average across the globe by the middle of the century, an increase in the risk of flooding and droughts in the order of five( fivefold increase of risk). That's a significant number.
"Some people in government seem unwilling to accept how bad it is likely to be."
While agencies have been praised for their response to the floods which affected Ceredigion, Week In Week Out raises questions about whether the government's strategy to keep people safe from flooding is working.
In 2004 a new regulation Technical Advice Note 15 (or TAN 15) to reduce the amount of development in flood risk areas was passed by the government.
But Week In Week Out discovered the percentage of schemes being passed now is the same as before the legislation - 745 schemes have been given the go-ahead in flood risk areas since 2004.
A report by Prof Mark Macklin of Aberystwyth University into the local floods highlighted the cost paid by building on flood plains.
He said the Aberystwyth floods were caused mainly by overdevelopment - not the extreme weather.
"People are exposed to a greater flood risk. And also a consequence of that development itself changes the flood risk up and down the stream so there is a two-fold risk."
However, Welsh Environment Minister John Griffiths defended the government's policy.
"We do have a very restrictive policy in place that does effectively stop building on flood plains."