Robert Redford is urging U.S. President Barack Obama to act swiftly in a bid to curb climate change.

The Oscar-winning actor has filmed a new advertisement for environmental group the Natural Resources Defence Council in which he encourages Obama to make good on his pre-election promises.

In the clip, which will air online and on U.S. Tv, The Sting star Redford says, "Climate change is happening fast. We've got to stop making the problem worse, and that means reducing carbon pollution from its biggest source, coal-fired power plants. The good news is that President Obama has pledged to act. I just hope the President has the courage of his convictions."

The advert, which also features footage of Obama agreeing to act to curb climate change in a speech after becoming President for the second time last year (12), ends with Redford encouraging his fans, "Please, urge the President to make dirty power plants clean up their carbon pollution."