Tai Shan on his first birthday. The panda was conceived in 2005 through artificial insemination in a procedure performed by National Zoo scientists and veterinarians. Ann Batdorf/Smithsonian Institution via AP hide caption

itoggle caption Ann Batdorf/Smithsonian Institution via AP

Water in the atmosphere traps heat, like glass in a greenhouse. When there's less water vapor in the atmosphere, less heat is trapped. Space Frontiers/Getty Images hide caption

itoggle caption Space Frontiers/Getty Images

Goodell's most recent book, Big Coal: The Dirty Secret Behind America's Energy Future, considers the perils of coal dependency in America. Eric Etheridge hide caption

itoggle caption Eric Etheridge

Workers ride past cooling towers at a coal-fired power plant on the outskirts of Beijing. Such power plants are at the center of a debate about the future of energy production in China and the U.S. Frederic J. Brown/AFP/Getty Images hide caption

itoggle caption Frederic J. Brown/AFP/Getty Images

Smog shrouds the Los Angeles skyline. New ozone standards from the EPA aim to reduce smog, but may actually increase global warming. David McNew/Getty Images hide caption

itoggle caption David McNew/Getty Images

Haitians watch the L.A. County Search and Rescue working at a collapsed building in Port-au-Prince. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

White-rumped sandpiper chicks on northern Canada's Bylot Island. Laura McKinnon hide caption

itoggle caption Laura McKinnon

The prolonged Arctic blast is now the worst cold spell seen in Scotland for almost 50 years, according to the country's first minister. Andrew Milligan/Press Association via AP hide caption

itoggle caption Andrew Milligan/Press Association via AP