Transcript for Major concession by Trump

Now, to another major breaking headline. The major concession by president trump on climate change. He called it on more than one occasion a hoax, but tonight, the administration saying the president does believe that the climate is changing. The dramatic switch coming on the heels of global criticism of the president's decision to pull out of the Paris climate accord. ABC's Gloria Riviera reports. Reporter: Tonight, after denying climate change on the campaign trail -- So, Obama is talking about all of this with the global warming and the -- a lot of it is a hoax. Reporter: President trump's administration making a stunning reversal. President trump believes the climate is changing and he believes pollutants are part of that E case so, that is the fact. Reporter: Just a day ago, the head of the EPA couldn't respond to a direct question. Yes or no. Does the president believe that climate change is real and a threat to the United States? You know, what's interesting about all the discussions we had through the last several weeks have been focused on one singular issue -- is Paris good or not for this country? Reporter: Since trump pulled out of the Paris accord, at least 80 mayors and 100 business leaders pledging to stay the course. And we will meet our targets. Reporter: Former New York City mayor Michael Bloomberg meeting with France's president macron, pledging $15 million of his own money. Trump is promising to create a better deal. We will see if we can make a deal that's fair. Reporter: Ambassador to the united nations Nikki Haley offering further reassurance. Just because we got out of a club doesn't mean that we don't care about the environment. Reporter: Trump supporters today rallying in front of the white house. So, for you, this exit, this was cause for, safe to say, celebration? Yes. Well, there's a lot to be done. What's going on is not good for us right now. And, you know, Obama had no right to just go ahead and sign it. Reporter: Getting out of the Paris agreement takes time. In fact, president trump is likely stuck with current obligations until the year 2020. Tom? Gloria Riviera for us tonight. Gloria, thank you. And of course, much more on all of this tomorrow on "This week." With EPA administrator skoet pew hit, former vice president Al gore and former national security adviser Susan rice.

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