For the Paris climate agreement to go into effect, 55 countries representing 55 percent of global emissions had to sign up. That’s finally happened.

While 195 nations endorsed the agreement at the COP 21 climate meeting in Paris last December, those countries then had to approve them domestically and submit their final approval to the United Nations. Earlier this week, the European Parliament voted to ratify the Paris agreement, which in turn allowed the European Union and seven of its member states to sign up to the pact. Canada, Nepal, and India have all also stepped up to the mark.

And with that, the limits are met—73 nations accounting for over 56 percent of the world’s emissions are now signed up to the accord. It’s hoped that the pact will be activated on November 4.

U.N. Secretary General Ban Ki-moon, Chinese President Xi Jinping, and U.S. President Barack Obama shake hands after China and the U.S. signed on to the Paris climate agreement in September 2016.

That’s commensurate with the hopes of U.N. Secretary General Ban Ki-moon. Two weeks ago at the U.N.’s General Assembly meeting, he said that he was “ever more confident” that the accord would be ratified this year. His hopes have been realized. Reacting to the the news, President Obama has said that enactment of the pact “gives us the best possible shot to save the one planet we got.” (Killer rhyme, Barack.)

Now comes the hard part. There’s still a long way to go if we’re to ensure that the planet doesn’t warm by more than the 2 °C described in the pact. The agreement is, after all, little more than a piece of paper. Now we need action by local and national governments to save us from ourselves.

(Read more: Science, The Guardian, “The Paris Climate Accord Just Passed a Crucial Threshold,” “Six Months after Paris Accord, We’re Losing the Climate-Change Battle”)