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Note: The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective November 2011, the GHCN-M version 3.1.0 dataset of monthly mean temperature replaced the GHCN-M version 3 monthly mean temperature dataset. Beginning with the October 2011 Global monthly State of the Climate Report, GHCN-M version 3.1.0 is used for NCDC climate monitoring activities, including calculation of global land surface temperature anomalies and trends.
For more information about this newest version, please see the Modifications to Pairwise Homogeneity Adjustment software to address coding errors and improve run-time efficiency.
December 2011 Selected Climate
Anomalies and Events Map
The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. Effective with the July 2009 State of the Climate Report, NCDC transitioned to the new version (version 3b) of the extended reconstructed sea surface temperature (ERSST) dataset. ERSST.v3b is an improved extended SST reconstruction over version 2. For more information about the differences between ERSST.v3b and ERSST.v2 and to access the most current data, please visit NCDC's Global Surface Temperature Anomalies page.
Temperature anomalies for December 2011 and January–December are shown on the dot maps in the following section. The dot maps on the left provide a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) version 3.1.0 dataset of land surface stations using a 1961–1990 base period. The dot maps on the right are a product of a merged land surface and sea surface temperature (SST) anomaly analysis developed by Smith et al. (2008). For the merged land surface and SST analysis, temperature anomalies with respect to the 1971–2000 average for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC's Global Surface Temperature Anomalies page.
In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth's surface. The average position of the upper-level ridges of high pressure and troughs of low pressure—depicted by positive and negative 500-millibar height anomalies on the
December 2011 map—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.
The December 2011 globally-averaged temperature across land and ocean surfaces was 0.48°C (0.86°F) above the 20th century average of 12.2°C (54.0°F), making this month the 10th warmest December since records began in 1880. This anomaly is significantly lower than the record December warmth in 2006, which was 0.72°C (1.30°F) above average.
Separately, the worldwide average land surface temperature anomaly was 0.88°C (1.58°F), the eighth warmest on record for the month of December. It was most notably warmer than average across much of the higher latitudes in the Northern Hemisphere, including Canada, Scandinavia, most of northern Russia, and the U.S. state of Alaska, which were more than 5°C above normal in many locations, as indicated by the dot maps above. It was also much warmer than normal across the eastern two-thirds of the United States and nearly all of Europe.
It was colder than average in the western United States, southern Greenland, Iran, Central Asia, Mongolia, northern and southeastern China, and most of Australia.
The El Niño-Southern Oscillation (ENSO) is a periodic fluctuation in sea surface temperature (El Niño) and the air pressure of the overlying atmosphere (Southern Oscillation) across the equatorial Pacific Ocean. A weak-to-moderate cold phase (La Niña) ENSO persisted through December as sea surface temperatures in the central and eastern equatorial Pacific Ocean remained cooler than normal. The December 2011 globally-averaged ocean temperature anomaly of 0.32°C (0.58°F) was the 16th warmest on record for December but was the lowest positive anomaly for any month since March 2008, also a La Niña month. The average Northern Hemisphere ocean temperature anomaly was the coolest since April 2011 while the Southern Hemisphere was the coolest since January 2008. According to NOAA's Climate Prediction Center, La Niña is expected to peak during the December–February period and continue into the Northern Hemisphere spring 2012. In addition to the equatorial Pacific, ocean temperatures were also cooler than average across the northeast Pacific, the north central and south Atlantic Ocean, and parts of the mid-latitude Southern oceans. It was notably warmer than average in the north central Pacific Ocean, the eastern Indian Ocean, and parts of the mid-latitude southern oceans. Images of sea surface temperature conditions are available for all weeks during 2011 from the weekly SST page.
| December | Anomaly | Rank (out of 132 years) |
Records | |||
|---|---|---|---|---|---|---|
| °C | °F | Year(s) | °C | °F | ||
| Global | ||||||
| Land | +0.88 ± 0.14 | +1.58 ± 0.25 | 8th Warmest | Warmest: 2006 | +1.37 | +2.47 |
| 125th Coolest | Coolest: 1929 | -1.21 | -2.18 | |||
| Ties: 1979 | ||||||
| Ocean | +0.32 ± 0.04 | +0.58 ± 0.07 | 16th Warmest | Warmest: 1997, 2009 | +0.58 | +1.04 |
| 117th Coolest | Coolest: 1909 | -0.53 | -0.95 | |||
| Ties: 1972 | ||||||
| Land and Ocean | +0.48 ± 0.09 | +0.86 ± 0.16 | 10th Warmest | Warmest: 2006 | +0.74 | +1.33 |
| 123rd Coolest | Coolest: 1916 | -0.56 | -1.01 | |||
| Ties: 1987, 2004 | ||||||
| Northern Hemisphere | ||||||
| Land | +1.05 ± 0.13 | +1.89 ± 0.23 | 9th Warmest | Warmest: 1939 | +1.79 | +3.22 |
| 124th Coolest | Coolest: 1929 | -1.53 | -2.75 | |||
| Ocean | +0.37 ± 0.05 | +0.67 ± 0.09 | 11th Warmest | Warmest: 2009 | +0.60 | +1.08 |
| 122nd Coolest | Coolest: 1909 | -0.58 | -1.04 | |||
| Land and Ocean | +0.63 ± 0.11 | +1.13 ± 0.20 | 7th Warmest | Warmest: 2006 | +0.98 | +1.76 |
| 126th Coolest | Coolest: 1917 | -0.73 | -1.31 | |||
| Southern Hemisphere | ||||||
| Land | +0.42 ± 0.11 | +0.76 ± 0.20 | 18th Warmest | Warmest: 1972 | +0.85 | +1.53 |
| 115th Coolest | Coolest: 1909 | -0.79 | -1.42 | |||
| Ocean | +0.30 ± 0.04 | +0.54 ± 0.07 | 25th Warmest | Warmest: 1997 | +0.62 | +1.12 |
| 108th Coolest | Coolest: 1910 | -0.48 | -0.86 | |||
| Land and Ocean | +0.32 ± 0.06 | +0.58 ± 0.11 | 25th Warmest | Warmest: 1997 | +0.65 | +1.17 |
| 108th Coolest | Coolest: 1909 | -0.51 | -0.92 | |||
| Ties: 1983 | ||||||
The
January–December map of temperature anomalies shows that warmer-than-average temperatures occurred across much of the globe during 2011. La Niña events at both the beginning and end of the year influenced global temperatures, dampening them from the record warmth observed during 2010 (which tied with 2005). Overall, the worldwide combined land and ocean surface temperature was 0.51°C (0.92°F) above the 20th century average, ranking as the 11th warmest year on record and the coolest year since 2008. This temperature anomaly is 0.13°C (0.23°F) less than the record warmth of 2010 and 2005. Separately, the 2011 average global land surface temperature ranked as the eighth warmest on record and the ocean surface ranked as the 11th warmest.
The greatest above-average annual temperature anomalies occurred across the Northern Hemisphere high latitude land areas, particularly central and northern Russia, Scandinavia, and Canada. Also noteworthy, it was warmer than average across the eastern half of the United States, Mexico, most of Europe and Africa, and the north central Pacific Ocean. Temperatures were below normal across the eastern and central Pacific Ocean, west central North America, and north and central Australia. Please refer to the NCDC State of the Climate Annual Global Analysis report for more detailed information.
| January–December | Anomaly | Rank (out of 132 years) |
Records | |||
|---|---|---|---|---|---|---|
| °C | °F | Year(s) | °C | °F | ||
| Global | ||||||
| Land | +0.83 ± 0.18 | +1.49 ± 0.32 | 8th Warmest | Warmest: 2007 | +1.05 | +1.89 |
| 125th Coolest | Coolest: 1907 | -0.56 | -1.01 | |||
| Ocean | +0.40 ± 0.03 | +0.72 ± 0.05 | 11th Warmest | Warmest: 2003 | +0.52 | +0.94 |
| 122nd Coolest | Coolest: 1909 | -0.45 | -0.81 | |||
| Ties: 2007 | ||||||
| Land and Ocean | +0.51 ± 0.08 | +0.92 ± 0.14 | 11th Warmest | Warmest: 2005, 2010 | +0.64 | +1.15 |
| 122nd Coolest | Coolest: -0.42 | -0.76 | 0.06 | |||
| Ties: 1997 | ||||||
| Northern Hemisphere | ||||||
| Land | +0.94 ± 0.24 | +1.69 ± 0.43 | 6th Warmest | Warmest: 2007 | +1.19 | +2.14 |
| 127th Coolest | Coolest: 1884 | -0.65 | -1.17 | |||
| Ocean | +0.39 ± 0.04 | +0.70 ± 0.07 | 13th Warmest | Warmest: 2005 | +0.54 | +0.97 |
| 120th Coolest | Coolest: -0.46 | -0.83 | 0.05 | |||
| Land and Ocean | +0.60 ± 0.14 | +1.08 ± 0.25 | 10th Warmest | Warmest: 2010 | +0.75 | +1.35 |
| 123rd Coolest | Coolest: -0.43 | -0.77 | 0.06 | |||
| Ties: 2001 | ||||||
| Southern Hemisphere | ||||||
| Land | +0.52 ± 0.11 | +0.94 ± 0.20 | 14th Warmest | Warmest: 2005 | +0.87 | +1.57 |
| 119th Coolest | Coolest: 1917 | -0.71 | -1.28 | |||
| Ties: 1991 | ||||||
| Ocean | +0.41 ± 0.03 | +0.74 ± 0.05 | 11th Warmest | Warmest: 1998 | +0.54 | +0.97 |
| 122nd Coolest | Coolest: 1911 | -0.46 | -0.83 | |||
| Land and Ocean | +0.43 ± 0.06 | +0.77 ± 0.11 | 12th Warmest | Warmest: 1998 | +0.58 | +1.04 |
| 121st Coolest | Coolest: 1911 | -0.47 | -0.85 | |||
The most current data may be accessed via the Global Surface Temperature Anomalies page.
The maps below represent anomaly values based on the GHCN version 2 dataset of land surface stations using a base period of 1961–1990. During December 2011, above-average precipitation fell over areas that included much of Australia, Alaska, the south central United States, northern Mexico, Central America, northwestern South America, and Western and Northern Europe. Drier-than-average conditions were present across the northern and far western United States, southern South America, Southern Europe, much of South and East Asia, and parts of North and West Africa.
Global precipitation over land in 2011 was well above the 1961–1990 average for the second year in a row, ranking as the second wettest year on record, behind 2010. Precipitation anomalies were variable across the globe. It was wetter than normal across much of the northeastern United States, Central America, much of coastal South America, Australia, and northwestern China. It was particularly drier than normal in the south central United States, southern and northeastern China, and Mongolia. Please refer to the NCDC State of the Climate Annual Global Analysis report for more detailed information.
Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.
Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.
Smith, T.M., and R.W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.
Smith, et al (2008), Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006), J. Climate., 21, 2283-2293.
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