Earth has 3rd-warmest summer on record in 2012

While the USA sweated through one of its warmest summers on record, so, too, did the rest of the globe, federal scientists from the National Climatic Data Center announced Monday.

The average summer temperature over global land and ocean surfaces tied with 2005 as the third-highest on record at 61.25 degrees F, or 1.15 degree F above the 20th century average of 60.1 degrees F.

Only the summers of 1998 and 2010 were warmer. Records go back to 1880.

Climatologists define summer in the Northern Hemisphere as the months of June, July and August. The climate center is a branch of the National Oceanic and Atmospheric Administration (NOAA).

"Considering global land surfaces only, June - Aug. 2012 was record warm, at 1.85 degrees above average," the center's online report stated. The most unusual warmth occurred across parts of the Northern Hemisphere, including most of the United States and Canada, southern and eastern Europe, Kazakhstan and eastern Siberia.

Droughts in the USA, eastern Russia and India all contributed to the high heat, says Jessica Blunden, climate scientist with the data center. If you have drought, the atmosphere doesn't have the moisture available to lessen the heat, she says.

Also, Blunden says the change from La Nina, a cooling of Pacific Ocean water, to El Nino, a warming of that water, was another main factor in driving the global heat.

The unusual warmth also caused Arctic sea ice to shrink to its lowest level on record, the National Snow and Ice Data Center reported.

August itself was the fourth-warmest August on record worldwide. It marked the 330th consecutive above-average month. The last cooler-than-average month globally was February 1985, the climate center reports.

Federal scientists last week announced that the USA experienced its third-warmest summer on record, trailing only 1936 and 2011.