President Obama speaks at Yosemite National Park

Barack Obama warned on Saturday that climate change could ravage many of America’s vaunted national parks, criticizing political opponents who “pay lip service” to areas of natural beauty while opposing efforts to reduce greenhouse gas emissions.

President Barack Obama speaks by the Sentinel Bridge, in the Yosemite Valley, in front of the Yosemite Falls which is the highest waterfall in the Park at Yosemite National Park, Calif., on Saturday, June 18, 2016.

Obama said many natural wonders are at risk from climate change, echoing warnings he made on a visit to Alaska in September.

Malia Obama, left, first lady Michelle Obama, President Barack Obama, and Sasha Obama walk to board Air Force One in Roswell, N.M., after visiting Carlsbad Caverns National Park, on Friday, June 17, 2016.

The passes – available to any fourth-grade student – are part of the “Every kid in a park” promotion to get more families to visit national parks.

After exiting the helicopters and walking about 30 yards through the grass, the Obamas stopped to speak with park rangers and staff, then greeted the crowd briefly before entering the presidential motorcade for a short drive to their lodge for the night. Obama also spent time meeting vacationers, and plans a family hike later in the day.

He’s hoping to lead by example by taking his wife, Michelle, and daughters Malia and Sasha, along to help celebrate the park service’s centennial, which is in August. The Secretary of the Interior went on to discuss the economic benefits our the national parks system. Obama touted his administration’s record of preservation, saying he has protected 265 million acres of federal land and waters, more than any other president.

Some members of Congress accuse Obama of overreach every time he uses that authority to create a national monument without their input.

“Make no mistake. Climate change is no longer just a threat”.

Also hampering the park system is an estimated $12 billion in deferred maintenance.

“Rising temperatures could mean no more glaciers at Glacier National Park”. Yosemite advised people to enter the park either before 8am or after 6pm to avoid the worst of the disruption.

For Obama, the parks trip caps a hard week that opened with Sunday’s shooting deaths of 49 people at an Orlando, Florida, nightclub.