NASA finds 2011 ninth warmest year on record; GISS team concludes slowdown of warming likely to prove illusory
The global average surface temperature in 2011 was the ninth warmest since 1880, according to NASA scientists; nine of the 10 warmest years in the modern meteorological record have occurred since the year 2000.
NASA’s Goddard Institute for Space Studies (GISS) in New York, which monitors global surface temperatures on an ongoing basis, released an updated analysis that shows temperatures around the globe in 2011 compared to the average global temperature from the mid-20th century. The average temperature around the globe in 2011 was 0.92 degrees F (0.51 °C) warmer than the mid-20th century baseline.
The difference between 2011 and the warmest year in the GISS record (2010) is 0.22 degrees F (0.12 C). Because of the large natural variability of climate, scientists do not expect temperatures to rise consistently year after year. However, they do expect a continuing temperature rise over decades.
2011 was only the ninth warmest year in the GISS analysis of global temperature change, yet nine of the ten warmest years in the instrumental record (since 1880) have occurred in the 21st century. The past year has been cooled by a moderately strong La Nina. The 5-year (60-month) running mean global temperature hints at a slowdown in the global warming rate during the past few years. However, the cool La Nina phase of the cyclically variable Southern Oscillation of tropical temperatures has been dominant in the past three years, and the deepest solar minimum in the period of satellite data occurred over the past half dozen years. We conclude that the slowdown of warming is likely to prove illusory, with more rapid warming appearing over the next few years.—Hansen et al.
The temperature analysis produced at GISS is compiled from weather data from more than 1,000 meteorological stations around the world, satellite observations of sea surface temperature and Antarctic research station measurements. A publicly available computer program is used to calculate the difference between surface temperature in a given month and the average temperature for the same place during 1951 to 1980. This three-decade period functions as a baseline for the analysis.
James Hansen, Reto Ruedy, Makiko Sato and Ken Lo (2012) Global Temperature in 2011, Trends, and Prospects