NOAA 2011 - 11th warmest year on record

While NASA placed 2011 as the 9th warmest year, NOAA placed it as the 11th warmest year tied with 1997.


Global Highlights

• This year tied 1997 as the 11th warmest year since records began in 1880. The annual global combined land and ocean surface temperature was 0.51°C (0.92°F) above the 20th century average of 13.9°C (57.0°F). This marks the 35th consecutive year, since 1976, that the yearly global temperature was above average. The warmest years on record were 2010 and 2005, which were 0.64°C (1.15°F) above average.
• Separately, the 2011 global average land surface temperature was 0.8°C (1.49°F) above the 20th century average of 8.5°C (47.3°F) and ranked as the eighth warmest on record. The 2011 global average ocean temperature was 0.40°C (0.72°F) above the 20th century average of 16.1°C (60.9°F) and ranked as the 11th warmest on record.
• La Niña, which is defined by cooler-than-normal waters in the eastern and central equatorial Pacific Ocean that affects weather patterns around the globe, was present during much of 2011. A relatively strong phase of La Niña opened the year, then dissipated in the spring before re-emerging in October and lasting through the end of the year. When compared to previous La Niña years, the 2011 global surface temperature was the warmest observed during such a year.
• The 2011 globally-averaged precipitation over land was the second wettest year on record, behind 2010. Precipitation varied greatly across the globe. La Niña contributed to severe drought in the Horn of Africa and to Australia?s third wettest year in its 112-year period of record.

Global Temperatures

The year 2011 tied with 1997 as the 11th warmest year since records began in 1880. The annually-averaged temperature over global land and ocean surfaces was 0.51°C (0.92°F) above the 20th century average of 13.9°C (57.0°F). This marks the 35th consecutive year (since 1976) that the yearly global temperature was above the 20th century average. The warmest years on record were 2010 and 2005, which were 0.64°C (1.15°F) above average. Including 2011, all eleven years in the 21st century so far (2001–2011) rank among the 13 warmest in the 132-year period of record. Only one year during the 20th century, 1998, was warmer than 2011.
21st Century (2001–2011) Annual Temperature Ranks

The following table list the global combined land and ocean annually-averaged temperature rank and anomaly for each of the years to date in the 21st century.

21st Century Year	Rank 1 = Warmest Period of Record: 1880–2011	Anomaly °C	Anomaly °F
2011	11	0.51	0.92
2010	1 (tie)	0.64	1.15
2009	7 (tie)	0.58	1.04
2008	13	0.50	0.90
2007	7 (tie)	0.58	1.04
2006	6	0.59	1.06
2005	1 (tie)	0.64	1.15
2004	9	0.56	1.01
2003	4	0.61	1.10
2002	5	0.60	1.08
2001	10	0.54	0.97

Natural climate patterns that persist for days, months, or even years can affect weather patterns around the world and impact the average global temperature. One such well-known global-scale pattern—the El Niño-Southern Oscillation (ENSO)—is a natural episodic fluctuation in sea surface temperature (El Niño) and the air pressure of the overlying atmosphere (Southern Oscillation) across the equatorial Pacific Ocean. Over a period of months to a few years, ENSO fluctuates between warmer-than-average ocean surface waters (El Niño) and cooler-than-average ocean surface waters (La Niña) in that region.

Two separate cool-phase La Niña events took place in 2011, according to NOAA's Climate Prediction Center (CPC). These events affected weather patterns in many parts of the world during the year and dampened the global temperature compared with the record warmth of the previous year, 2010 (which is tied for warmest with 2005). The coolest monthly global anomalies occurred during the beginning of the year, where both January and February each ranked as 17th warmest for their respective months. Monthly temperature anomalies increased as the La Niña episode waned and ENSO-neutral conditions emerged during May. June and July ranked as the seventh warmest for their respective months while August and September each ranked eighth warmest. La Niña conditions returned in October and moderately strengthened during the remainder of the year. Global monthly temperature anomalies during this period cooled compared to those during the middle of the year.

With CPC ENSO records dating back to 1950, 2011 ranked as the warmest "La Niña year" in the 1950–2011 period of record. Two of the three warmest years on record (2010 and 1998) are "El Niño years". A La Niña (El Niño) year is defined here as occurring when the first three months of a calendar year meet the La Niña (El Niño) criteria as defined by the CPC...[1]