In this Sunday, July 24, 2016 file photo, climate change activists carry signs as they march during a protest in downtown in Philadelphia a day before the start of the Democratic National Convention.
In this Sunday, July 24, 2016 file photo, climate change activists carry signs as they march during a protest in downtown in Philadelphia a day before the start of the Democratic National Convention. John Minchillo AP
In this Sunday, July 24, 2016 file photo, climate change activists carry signs as they march during a protest in downtown in Philadelphia a day before the start of the Democratic National Convention. John Minchillo AP