Enough nations have committed to the Paris climate accord that it will go into effect this year, The New York Times reports. That means that Republican presidential candidate Donald Trump won’t be able to pull out if elected.

The Paris accords, approved by the United Nations last year, commit almost every country to lowering their greenhouse gas emissions. It’s not a miracle plan. Scientists have said that, if fully implemented, the plan would still only reduce emissions by half as much as necessary to prevent a global temperature increase of 3.6 degrees Fahrenheit. (It’s considered crucial to avoid the 3.6 degree temperature increase in order to protect the planet.) Still, the accord represented a major milestone because it required action from every country, including ones such as China and India that are major polluters but haven’t signed climate deals before.

These agreements often take a long time to go into action, but this particular one was pressing because of Trump’s plan to withdraw if elected president. His remarks were widely condemned by scientists. Now that the accord will be enforced before January’s presidential inauguration, it will take four years for the US to withdraw.

"We are absolutely certain that we will have the Paris agreement entering into force by the end of 2016," David Nabarro, a special adviser to UN Secretary General Ban Ki-Moon, told The New York Times.

Ban has been a strong supporter of the accords. He has personally pushed to win the necessary commitments from 55 countries. These countries represent 55 percent of global emissions.