There are several types of greenhouse gasses, but carbon dioxide is the most important.

The Paris pact was correctly described by its opponents - greens and anti-greens alike - as toothless. But it was also the first time that nations around the world had officially agreed that climate change was a problem and that concrete steps should be taken to avoid its worst effects.

Canceling the climate pact will loudly demonstrate Trump's willingness to fight - an important step for the White House because, on a concrete level, few tools are available to revive the coal industry.

Charles C. Mann Quotes