The Paris Agreement on Climate Change comes into effect today, November 4. Auspiciously for climate warriors, that is just three days before the next United Nations climate change conference opens in Marrakech, Morocco. The Republican presidential nominee has declared that if elected he will cancel U.S. participation in the Paris Agreement. Earlier this week, Elliot Diringer, executive vice president of the Center for Climate and Energy Solutions, asserted in Reuters that "Entry into force only goes one way. It can't be reversed." Is that so?