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...