Under the Paris agreement, every one of the 147 signatories issues what is called an 'intended nationally determined contribution' (INDC), which amounts to a promise that the nation will take certain actions to reduce greenhouse-gas emissions by a certain date.

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.

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

Charles C. Mann Quotes