Researchers have found that 2007 was the second warmest year in a century, with greatest warming occurring in the Arctic and the neighboring high latitude regions.
Climatologists at the NASA Goddard Institute for Space Studies in New York City found that 2007 tied with 1998 as Earth's second warmest year in a century.
The eight warmest years in the GISS record have all occurred since 1998, and the 14 warmest years record have all occurred since 1990.
"As we predicted, 2007 was warmer than 2006, continuing the strong warming trend of the past 30 years that has been confidently attributed to the effect of increasing human-made greenhouse gases," said James Hansen, director of GISS. "It is unlikely that 2008 will be a year with truly exceptional global mean temperature," he said.
"Barring a large volcanic eruption, a record global temperature clearly exceeding that of 2005 can be expected within the next few years, at the time of the next El Nino, because of the background warming trend attributable to continuing increases of greenhouse gases," he was quoted as saying by the ScienceDaily online.
The researchers used temperature data from weather stations on land, satellite measurements of sea ice temperature since 1982 and data from ships for earlier years. The greatest warming in 2007 occurred in the Arctic, and neighboring high latitude regions.
Global warming has a larger affect in polar areas, as the loss of snow and ice leads to more open water, which absorbs more sunlight and warmth. Snow and ice reflect sunlight; when they disappear, so too does their ability to deflect warming rays.
The large Arctic warm anomaly of 2007 is consistent with observations of record low geographic extent of Arctic sea ice in September 2007.