Figure Global mean temperature changes over the last decade in context. (gray curve) monthly global mean temperature anomalies (with respect to 1961–90 climatology) since 1975, derived from the combined land and ocean temperature data set HadCRUt3. (topblue curve) the global mean after the effect of El Niño-Southern Oscillation (ENSO) that has been subtracted. (bottom blue curve, offset by 0.5°C) the ENSO contribution itself. Least squares linear trends in the ENSO and ENSO-removed components for 1999–2008 and their two standard deviation uncertainties are shown in orange

Editor's commentsThe latest research reported here is an attempt based on observation interpreted by modeling to explain the apparent slowing down of the rise in global surface temperature since 2000. Some researchers believe that this is only part of the answer to why the rise in surface temperatures has apparently slowed.


In the State of the Climate in 2008 , it was reported that based on experimental observations it appears that the global temperature rise has slowed in the decade after 2000. The trend for January 1999 to December 2008 is +0.07±0.07°C per decade, much less than the 0.18°C per decade recorded between 1979 and 2005.

A number of studies have attempted to explain the apparent pause. A new study attributes the slowdown to an increase in ocean heat uptake and reports that most of the excess energy was absorbed in the top 700 m of the ocean, 65% of it in the tropical Pacific and Atlantic oceans.

The new study, which is based on observations and computer models, showed that natural La Nina weather events in the Pacific around the year 2000 brought cool waters to the surface that absorbed more heat from the air.

According to a Reuters article , Kevin Trenberth, of the U.S. National Center for Atmospheric Research, has said that warmth is spreading to ever deeper ocean levels and that pauses in surface warming could last 15-20 years. A very recent observational-based reanalysis of the time evolution of the global ocean heat content for 1958 through 2009 has shown that ocean heating has continued during the recent upper-ocean-warming hiatus, but the heat has been absorbed in the deeper ocean. In the last decade, about 30% of the warming has occurred below 700 m, contributing significantly to an acceleration of the warming trend.

The latest observed global temperature anomalies from the Climate Research Unit and the Hadley Centre of the UK Met Office based on HadCRUT4 data.