This year, Earth Day is being marked by a very special event: the signing ceremony of the Paris Agreement. It is expected that more than 170 countries will sign the agreement on this opening day, which will be a record. But wait, didn’t 196 parties already agree to this historic treaty at the COP21 climate conference in Paris last December? So, why aren’t they all signing? And now that the treaty is signed, will it go into effect immediately? Here are the answers to all (or at least most!) of your questions on what to expect from the Paris Agreement!