The more we raise our voices and shine a spotlight on acts of environmental injustice, the harder it is for the industry to maintain its protective shroud of silence. So let's join Rev. Yearwood and follow the example of Dr. King. Tackling climate change is the challenge of our time.

Despite what oil companies like Exxon want you to believe, oil pipelines leak. It's what they do. What's happening in Arkansas right now could be the future for communities from North Dakota to Texas if President Obama approves the Keystone XL pipeline.

Because the impact statement was written by a TransCanada contractor, not by State Department officials, it should come as no surprise that it presents a worldview of a global economy inevitably dependent on dirty fossil fuels.

It is time for our leaders here at home and around the world to grasp the urgency of dealing with climate change. We cannot continue down the path of business as usual. We cannot assume that we can go after every last drop of oil around the world and still have healthy communities and economies.

The fact that tar sands pipelines are not in our national interest becomes clearer by the day.

The national political fight over the Keystone XL pipeline is a long ways off for people of this central Michigan community. But in some ways, it's as close as the icy rapids of the Kalamazoo River, a natural treasure that 20 months later still remains off limits along a 40-mile stretch.

Now that Obama has at least temporarily blocked Keystone XL, now that his team has promised to consider climate change as a factor in any final decision on the pipeline's eventual fate, he can campaign on the issue. And in many ways, it may prove a surprise winner.

The tar sands are the dirtiest source of liquid fuel on the planet. President Obama should listen to the voices of those outside the White House and block this dirty energy pipeline.

President Obama's decisions on Keystone XL and standards for greenhouse gas emissions from power plants will shape this legacy.

I couldn't help but think of that great line from The Breakfast Club when I read that Big Oil has resorted to creating fake Twitter accounts in order to fabricate an illusion of 'grassroots' support for the controversial Keystone pipeline project.

The Obama Administration has a simple choice -- help stop global warming and reject the Keystone XL project or approve Keystone XL and help another country fail to meet its global warming commitments.

Today I was privileged to be an invited guest of the community of Fort Chipewyan, Canada. I can't blame you if you've never heard of "Ft. Chip" -...

It is refreshing and reassuring to see that "green" no longer just applies to the color of our warriors' uniforms.