2005 was century's warmest: NASA

Scientists say the highest global annual average surface temperature in over 100 years has been recorded for 2005.

The year 2005 may have been the warmest year in a century, according to NASA scientists studying temperature data from around the world.

Climatologists at NASA's Goddard Institute for Space Studies (GISS) in New York City said the highest global annual average surface temperature in more than a century was recorded in their analysis for 2005.

Previously, the warmest year of the century was 1998, when a strong El Nino, a warm water event in the eastern Pacific Ocean, added warmth to global temperatures.

"However, what's significant, regardless of whether 2005 is first or second warmest, is that global warmth has returned to about the level of 1998 without the help of an El Nino," the report said.

"The five warmest years over the last century occurred in the last eight years," said James Hansen, director of the Goddard Institute.

"The result indicates that a strong underlying warming trend is continuing rapidly at almost 0.2 degree per decade, while before 1975 the global warming was slow and with large fluctuations."

The scientists found that current warmth seems to be occurring nearly everywhere at the same time and is largest at high latitudes in the Northern Hemisphere.

In order to figure out whether the Earth is cooling or warming, the scientists use temperature data from weather stations on land, satellite measurements of sea surface temperature since 1982, and data from ships for earlier years.

Over the last 50 years, the largest annual and seasonal warmings have occurred in Alaska, Siberia and the Antarctic Peninsula. Most ocean areas have warmed. Because these areas are remote and far away from major cities, it is clear to climatologists that the warming is not due to the influence of pollution from urban areas.