2005 was warmest year on record

Last year’s global average temperature of 14.6°C (58.3°F) was the warmest recorded since scientists began compiling records in the late 1800s.

HOT, HOT, HOT. Last year’s average temperature in large portions of the Northern Hemisphere was more than 1.5°C above normal (red and dark red areas). GISS/NASA

The previous record for global warmth was set in the El Niño year of 1998, when high sea-surface temperatures in the equatorial Pacific pushed up the global average, says James Hansen, director of NASA’s Goddard Institute for Space Studies in New York. This year’s record warmth is notable because temperatures didn’t get a boost from El Niño, he notes. Hansen and his colleagues announced results of their analyses on Jan. 24.

Global average temperatures have risen 0.6°C in the past 30 years and 0.8°C in the past century. Recent warming coincides with rapid growth in the atmospheric concentrations of greenhouse gases such as carbon dioxide and is consistent with predictions from climate models based on industrial emissions of those gases, says Hansen.

During the past half-century, the largest increases in temperature have occurred in high-latitude regions such as Alaska, Siberia, and the Antarctic Peninsula. Last year, the average temperature across large swaths of Alaska, Canada, Scandinavia, and Russia was more than 1.5°C higher than the average recorded for those areas between 1951 and 1980.

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