2011: world’s 10th warmest year, warmest year with La Niña on record, second-lowest Arctic sea ice extent
Global temperatures in 2011 have not been as warm as the record-setting values seen in 2010 but have likely been warmer than any previous strong La Niña year, based on preliminary data from data sources compiled by the World Meteorological Organisation (WMO). The global combined sea surface and land surface air temperature for 2011 (January–October) is currently estimated at 0.41°C ± 0.111°C (0.74°F ± 0.20°F) above the 1961–1990 annual average of 14.00°C/57.2°F. At present, 2011’s nominal value ranks as the equal 10th highest on record, and the 13 warmest years have all occurred in the 15 years between 1997 and 2011. Model reanalysis data from the European Centre for Medium-Range Weather Forecasts (ECMWF) are also consistent with this ranking. The 10-year average for the period 2002-11, at 0.46°C above the long-term average, equals 2001-10 as the warmest 10-year period on record. Final annual figures for 2011 will be available once November and December data are available in early 2012.
Global climate in 2011 was heavily influenced by the strong La Niña event which developed in the tropical Pacific in the second half of 2010 and continued until May 2011. This event, which on most measures was one of the strongest of at least the last 60 years, was closely associated with many of the year’s notable regional climate events, including drought in east Africa, the central equatorial Pacific and the southern United States, and flooding in southern Africa, eastern Australia and southern Asia. Strong La Niña years2 are typically 0.10 to 0.15°C cooler than the years preceding and following them. 2011’s global temperatures followed this pattern, being lower than those of 2010, but were still warmer than the most recent moderate to strong La Niña years, 2008 (+0.36°C), 2000 (+0.27°C) and 1989 (+0.12°C). La Niña conditions have redeveloped in recent weeks but are not expected to approach the intensity seen in late 2010 and early 2011.