Tired of waiting for President Obama to make good on his inaugural promise to tackle global warming, eco-activist Robert Redford has called on the public to press the president to act, questioning Obama's "courage of his convictions."

In a new TV ad and YouTube campaign for the Natural Resources Defense Council, the star of "Butch Cassidy and the Sundance Kid," "The Sting" and "All the President's Men" blames coal-fired energy plants for accelerated climate change and begs Obama for action.

As the ad shows the president promising in his inaugural address to "respond to the threat of climate change," Redford said. "The good news is that President Obama has pledged to act. I just hope the president has the courage of his convictions. Please urge the president to make dirty power plants clean up their carbon pollution."

The NRDC has written an email for climate-change activists to send to Obama. "It's been months since President Obama said we'd 'respond to the threat of climate change,' " said the group. "Since then, we pumped over one billion tons of carbon pollution into our atmosphere -- the climate-warming gas responsible for the extreme floods, storms, wildfires and droughts that threaten our families. We can't wait any longer. Email President Obama and ask -- what's your plan for climate action?"

Lately, Obama has become a punching bag for liberal groups including the ACLU, which has been hitting his expansion of Internet and cellphone snooping by the National Security Agency.