The center of the earth is about a million degrees.

The United States is the only nation that can lead the world toward a solution on climate change.

The science linking the increased frequency and severity of extreme weather to the climate crisis has matured tremendously in the last couple of years.

Someone who expresses a view that is contrary to the view of the overwhelming majority should be allowed to stand undisturbed as a monument to our commitment to free speech.

There's no such thing as clean coal. It's non-existent. Theoretically, it might be possible, many years from now, to come up with a way to clean it as it's burnt. But there's not a single demonstration project in the United States. [...] Clean coal doesn't exist.

There's a law of physics: For every action there's an equal and opposite reaction. And sometimes that shows up in politics and society. And I think that the reaction to President Trump's decision on the Paris Agreement has been much stronger than I had even hoped for. And the determination being expressed by so many people in state governments, city governments, in the business community, the investor community, is really heartening to me.

CO2 is the exhaling breath of our civilization, literally... Changing that pattern requires a scope, a scale, a speed of change that is beyond what we have done in the past.