Feature

Text Size

2007 Was Tied as Earth's Second-Warmest Year
01.16.08
 
Climatologists at the NASA Goddard Institute for Space Studies (GISS) in New York City have found that 2007 tied with 1998 for Earth’s second warmest year in a century.

Screen capture from the Earth Temperature web short Image right: Click this image for the "Earth's Temperature" Web video. Credit: NASA / Goddard Space Flight Center

"It is unlikely that 2008 will be a year with truly exceptional global mean temperature," said Hansen. "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."

The eight warmest years in the GISS record have all occurred since 1998, and the 14 warmest years in the record have all occurred since 1990.

Goddard Institute researchers used temperature data from weather stations on land, satellite measurements of sea ice temperature since 1982 and data from ships for earlier years.

Still from animation showing the temperature anomaly for 2007. Image right: This still from the animation presented shows the temperature anomalies that were present during 2007. Click image for enlargement. Click here for visualization Credit: NASA

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.

Graph of global annual surface temperatures relative to 1951 through 1980 mean temperature. Image right: Graph of global annual surface temperatures relative to 1951-1980 mean temperature. Air and ocean data from weather stations, ships and satellites. The 2007 point is the 11-month anomaly. Click image for enlargement. Credit: GISS

"As we predicted last year, 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 NASA GISS.

A minor data processing error found in the GISS temperature analysis in early 2007 does not affect the present analysis. The data processing flaw was failure to apply NOAA adjustments to United States Historical Climatology Network stations in 2000-2006, as the records for those years were taken from a different data base (Global Historical Climatology Network). This flaw affected only 1.6% of the Earth’s surface (contiguous 48 states) and only the several years in the 21st century.

This shows temperature anomalies for the 2007 calendar year relative to the 1951 through 1980 mean. Image right: This shows temperature anomalies for the 2007 calendar year relative to the 1951-1980 mean. Warmer areas in red, cooler areas in blue. Largest increases were in the northern hemisphere. Click image for enlargement. Credit: GISS

The data processing flaw did not alter the ordering of the warmest years on record and the global ranks were unaffected. In the contiguous 48 states, the statistical tie among 1934, 1998 and 2005 as the warmest year(s) was unchanged. In the current analysis, in the flawed analysis, and in the published GISS analysis, 1934 is the warmest year in the contiguous states (but not globally) by an amount (magnitude of the order of 0.01°C) that is an order of magnitude smaller than the certainty.

Related Links:

> GISS 2007 Temperature Analysis
> NASA Web Story: 2006 Was Earth’s Fifth Warmest Year
> Web Video Short: Taking the Earth's Temperature

 
 
Leslie McCarthy
Goddard Institute for Space Studies