Glaciers are melting, sea levels are rising, cloud forests are drying, and wildlife is scrambling to keep pace. It's becoming clear that humans have caused most of the past century's warming by releasing heat-trapping gases as we power our modern lives. Called greenhouse gases, their levels are higher now than in the last 650,000 years.
We call the result global warming, but it is causing a set of changes to the Earth's climate, or long-term weather patterns, that varies from place to place. As the Earth spins each day, the new heat swirls with it, picking up moisture over the oceans, rising here, settling there. It's changing the rhythms of climate that all living things have come to rely upon.
What will we do to slow this warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the face of the Earth as we know it—coasts, forests, farms and snow-capped mountains—hangs in the balance.
Temperatures are rising worldwide. That's causing weather to change. It is also affecting wildlife.
The rising surface temperature is called global warming. Since 1850, Earth has warmed by about one degree F. Some places, such as Glacier National Park, have warmed up more. Some have warmed up less.
WORLDWIDE WARMING
One degree may seem small. But it is causing big changes worldwide. In the Antarctic and Arctic, sea ice is melting. The meltdown forms clouds that can make more snowfall than usual. More snow can harm wildlife.
Penguins in Antarctica are having a hard time finding a place to lay eggs. They normally lay eggs on dry ground in the spring. But more snow is falling today. The penguins have to lay their eggs in the snow. When the snow melts, the water rots many of the eggs. That's causing the number of penguins to drop.
TROUBLE IN THE TROPICS
Earth's warmer areas are also affected. Tiny animals called coral polyps build huge reefs in warm ocean water. Reefs come in