This post originally appeared February 20, 2013, on the Huffington Post and is reposted with the author's permission.
Forty thousand people marched around the White House Sunday. They want the president to reject the permit application for the Keystone pipeline.
They came from all 50 states. Some even drove from California.
I talked to many of them. Their passion and seriousness took my breath away.
Everyone said they had been deeply encouraged by the president's innaugural and State of the Union addresses. Thank god, most said, he has come around to taking action.
When the president asked Americans to be active on climate and other issues, these activists were energized and they gave up their long weekend to show their commitment.
It looks to me like people are fired up and prepared to go to bat for the president on climate.
It's his turn now to return the favor. I hate to think what would happen if the permit is now approved. I don't think the 40,000 people ringing the White House Sunday or the millions of others they represent will understand it if the president and the State Department don't support them.
If the president really wants support for his climate agenda, this political reality has to be front and center in the deliberation process. To take the air out of the balloon on this exciting, vibrant, growing climate movement would be supremely counter productive.
These folks are going to be essential to coming battles on standards for existing power plants and other necessary initiatives the president has signaled he wants to take using his executive authority.
There is an enormous opportunity to build cars that don't require gasoline, to expand clean energy generation and markets, and to bend the dangerous curve of both U.S. and global emissions downward these next four years. A no to Keystone would be a fantastic spark to national level public engagement and support for climate action.
Thank you, Mr. President, for lighting the fire with your words. It is very exciting to think you will be doing the same with your actions.
Michael Northrop directs the Sustainable Development grantmaking program at the Rockefeller Brothers Fund in New York City, where he focuses on climate change. He is also a lecturer at the Yale School of Forestry and Environmental Studies. The views in this article are those of the author and not necessarily his employers.