A historic agreement on climate was reached in December at a summit in Paris, with 175 countries signing on to a major effort to reduce carbon emisisons and slow the march of global warming. But is it too little, too late?

Leaders around the world say that more action is needed in order to stop global temperatures from rising to catastrophic levels, leading to worldwide flooding, severe droughts, violent storms, brutal famines, and a host of other problems.

The Paris Agreement aims to have every country make an effort to do their part in cutting back on emissions, but some wonder just how useful it is and whether it is enough to fight climate change, with U.N. Secretary-General Ban Ki-moon calling it a “race against time.”

China and the United States will make up a big part of the effort, as they account for 38 percent of global emissions. They have both pledged to put in place measures later this year.