Today, to celebrate Earth Day, 155 countries will sign the Paris Agreement on Climate Change at the United Nations headquarters in New York. This signing cements the agreement 196 countries made in December 2015 to work to limit the overall temperature rise to below 2 degrees Celsius.

The Paris Agreement becomes effective 30 days after at least 55 countries have reached the full requirements under the agreement. The deal, which is legally binding and was agreed upon by nearly every country in the world, requires that all participating counties take some form of action against climate change. Also noteworthy is that the pact applies the same requirements to all counties, including developing ones such as China and India, which have historically been exempt from such agreements.