"There is a void of federal action," Spencer said. "We need federal efforts to limit global warming pollution in the near term to slow, stop and reverse global warming pollution from power plants and vehicles. It's as simple as that."
The National Park Service told ABC News today it is reviewing the report, but a representative did not have any immediate comment.
The report lists the 12 national parks most as risk from climate change. The effects range from loss of beaches, wildlife extinction, overcrowding and, in the case of Death Valley, intolerable heat.
The parks include:
Yellowstone National Park in Wyoming, Montana and Idaho
Yosemite National Park in California
Glacier National Park in Montana
Rocky Mountain National Park in Colorado
Bandelier National Monument in New Mexico
Death Valley National Park in California
Glen Canyon National Recreation Area in Utah and Arizona
Golden Gate National Recreation Area in California
Grand Teton National Park in Wyoming
Mesa Verde National Park in Colorado
Mount Rainier National Park in Washington
North Cascades National Park in Washington