Calentamiento global

The planet is warming, from North Pole to South Pole, and everywhere in between. Globally, the mercury is already up more than 1 degree Fahrenheit (0.8 degree Celsius), and even more in sensitivepolar regions. And the effects of rising temperatures aren’t waiting for some far-flung future. They’re happening right now. Signs are appearing all over, and some of them are surprising. The heat is notonly melting glaciers and sea ice, it’s also shifting precipitation patterns and setting animals on the move.
Some impacts from increasing temperatures are already happening.
• Ice is meltingworldwide, especially at the Earth’s poles. This includes mountain glaciers, ice sheets covering West Antarctica and Greenland, and Arctic sea ice.
• Researcher Bill Fraser has tracked the decline of theAdélie penguins on Antarctica, where their numbers have fallen from 32,000 breeding pairs to 11,000 in 30 years.
• Sea level rise became faster over the last century.
• Some butterflies, foxes, andalpine plants have moved farther north or to higher, cooler areas.
• Precipitation (rain and snowfall) has increased across the globe, on average.
• Spruce bark beetles have boomed in Alaska thanksto 20 years of warm summers. The insects have chewed up 4 million acres of spruce trees.
Other effects could happen later this century, if warming continues.
• Sea levels are expected to risebetween 7 and 23 inches (18 and 59 centimeters) by the end of the century, and continued melting at the poles could add between 4 and 8 inches (10 to 20 centimeters).
• Hurricanes and other storms arelikely to become stronger.
• Species that depend on one another may become out of sync. For example, plants could bloom earlier than their pollinating insects become active.
• Floods and droughts willbecome more common. Rainfall in Ethiopia, where droughts are already common, could decline by 10 percent over the next 50 years.
• Less fresh water will be available. If the Quelccaya ice cap in...