Yosemite National Park, June 19: President Barack Obama says climate change is the biggest threat to US national parks.
Obama says meadows are already drying out at Yosemite National Park in California, where he spoke today after spending the night in the park with his wife, Michelle, and daughters Malia and Sasha.
He adds that a rabbit-like animal known as a pika is being forced further upslope in Yosemite to escape warming temperatures.
Obama and his family are spending the weekend at Yosemite after touring an underground cave yesterday at Carlsbad Caverns National Park in New Mexico.
He wants more people to appreciate and visit America's national park as the system nears its 100th birthday in August.