How have global air temperatures changed over the past century?

Recent evidence from multiple studies indicate that the Earth’s temperature is clearly rising. Since the start of the 20th century, the average temperature has increased about 1ºF. In addition, the 1990s were the warmest decade of the past 100 years, with 1998 being the warmest year since 1850. Studies have also documented:

• Increases in nighttime temperatures over many land areas are occurring at about twice the rate of daytime temperature increases.
• A decrease in Northern Hemisphere sea-ice amounts: substantial thinning (40% in recent decades) of Arctic sea-ice in late summer to early autumn.
• Plants are flowering earlier, birds are returning north sooner and there is an earlier emergence of insects in the Northern Hemisphere.

Learn more about the impacts of rising global air temperatures at:

Intergovernmental Panel on Climate Change (IPCC) (http://www.ipcc.ch/)
IPCC Working Group I (http://www.grida.no/climate/ipcc_tar/wg1/index.htm)