State of the Climate
Global Analysis
December 2008

National Oceanic and Atmospheric Administration

National Climatic Data Center

Use the form below to access monthly reports.

« November 2008
Global Analysis Report

Annual 2008 »
Global Analysis Report

Report:

Year: Month:

Global Highlights:

Based on preliminary data, the globally averaged combined land and sea surface temperature was the eighth warmest on record for December and the January-December period.
December 2008 temperatures were above average in Iceland, Fenno-Scandinavia, western and eastern Russia, western Alaska, the eastern contiguous U.S., western and southeastern Africa, eastern Europe, western Australia, and most of Mexico, South America, and southern and southeastern Asia. Meanwhile, cooler-than-average conditions were present across Canada, the north-central and northwestern continental U.S., central Russia, western Europe, western and southern Australia, and parts of the Middle East Region.
Precipitation during December 2008 was variable in many areas. In general, precipitation was above average in the Hawaiian Islands, the eastern continental U.S., western Australia, and across parts of South America and central Europe. Drier-than-average conditions were observed across the south-central contiguous U.S., Alaska's panhandle, eastern Australia, southeastern Africa, and most of South America, Europe, and southeastern Asia.
Neutral phase El Niño-Southern Oscillation (ENSO) conditions persisted across the equatorial Pacific Ocean, although characteristics of a developing La Niña were present.

The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. The most current data may be accessed via the Global Surface Temperature Anomalies page.

Introduction

Temperature anomalies for December 2008 are shown on the dot maps below. The dot map, below left, provides a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. The dot map, below right, is a product of a merged land surface and sea surface temperature anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 mean for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

December's Land Surface Temperature Anomalies in degree Celsius

December's Land Surface Temperature
Anomalies in degrees Celsius

December's Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

During December, anomalous warm conditions were present over much of the world's land surface, especially across Fenno-Scandinavia, western and eastern Russia, and western Alaska, where temperatures were 2°-6°C (4°-11°F) above the 1961-1990 mean. Above average temperatures were also observed across Iceland, the eastern contiguous U.S., western and southeastern Africa, eastern Europe, western Australia, and most of Mexico, South America, and southern and southeastern Asia. Elsewhere, cooler-than-average conditions were present across Canada, the north-central and northwestern continental U.S., central Russia, western Europe, western and southern Australia, and parts of the Middle East Region.

Sea surface temperatures (SST) during December 2008 were warmer than average across much of the Atlantic, Indian, and northwestern Pacific oceans. Cooler-than-average SSTs were present in parts of the southern oceans, the equatorial and northeastern Pacific Ocean, and parts of the Atlantic and Indian oceans. SST anomalies decreased in all Niño regions during December 2008, however neutral ENSO conditions persisted. Please see the December 2008 ENSO discussion for additional information.

Anomalously warm temperatures covered much of the world's land surface during January-December 2008. The year-to-date map shows the presence of warmer-than-average temperatures across all land areas, with the exception of Colombia, parts of Alaska, central Canada, and the midwestern continental U.S. Warmer-than-average SST conditions were present in the Atlantic and Indian oceans, and across parts of the Pacific oceans. Cooler-than-average conditions were observed in the central equatorial and northeastern Pacific oceans and parts of the southern oceans.

The mean 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 map, respectively) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products, please see the Climate Monitoring Global Products page.

Images of sea surface temperature conditions are available for all weeks during 2008 at the weekly SST page.

[ top ]

Temperature Rankings and Graphics

Current Month / Year-to-date

Effective with the February 2006 report, NCDC transitioned from the use of the Operational Global Surface Temperature Index (Quayle et al. 1999) to the blended land and ocean dataset developed by Smith and Reynolds (2005). The differences between the two methods are discussed in Smith et al. (2005). The ranks found in the tables below are based on records that began in 1880.

The combined global land and ocean surface temperature was the eighth warmest on record in December and for the January-December period. The global average ocean SST in December tied with 2001 and 2005 as the sixth warmest on record.

December	Anomaly	Rank (out of 129 years)	Warmest (or Next Warmest) Year on Record
Global Land Ocean Land and Ocean	+0.68°C (+1.22°F) +0.41°C (+0.74°F) +0.48°C (+0.86°F)	14^thwarmest 6^th warmest 8^th warmest	2006 (+1.37°C/2.47°F) 1997 (+0.56°C/1.01°F) 2006 (+0.74°C/1.33°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.69°C (+1.24°F) +0.37°C (+0.67°F) +0.49°C (+0.88°F)	19^th warmest 8^th warmest 11^th warmest	1939 (+1.82°C/3.28°F) 2006 (+0.55°C/0.99°F) 2006 (+0.95°C/1.71°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.62°C (+1.12°F) +0.45°C (+0.81°F) +0.47°C (+0.85°F)	7^th warmest 5^th warmest 6^th warmest	1972 (+0.79°C/1.42°F) 1997 (+0.60°C/1.08°F) 1997 (+0.62°C/1.12°F)

December's Global Land and Ocean plot

December's Global Hemisphere plot

January- December	Anomaly	Rank (out of 129 years)	Warmest Year on Record
Global Land Ocean Land and Ocean	+0.81°C (+1.46°F) +0.37°C (+0.67°F) +0.49°C (+0.88°F)	6^thwarmest 10^th warmest 8^th warmest	2007 (+1.02°C/1.84°F) 2003 (+0.48°C/0.86°F) 2005 (+0.61°C/1.10°F)
Northern Hemisphere Land Ocean Land and Ocean	+0.89°C (+1.60°F) +0.40°C (+0.72°F) +0.59°C (+1.06°F)	5^th warmest 9^th warmest 8^th warmest	2007 (+1.18°C/2.12°F) 2005 (+0.54°C/0.97°F) 2005 (+0.72°C/1.30°F)
Southern Hemisphere Land Ocean Land and Ocean	+0.54°C (+0.97°F) +0.35°C (+0.63°F) +0.38°C (+0.68°F)	6^th warmest 10^th warmest 9^th warmest	2005 (+0.81°C/1.46°F) 1998 (+0.50°C/0.90°F) 1998 (+0.53°C/0.95°F)

January-December Global Land and Ocean plot

January-December Global Hemisphere plot

The most current data may be accessed via the Global Surface Temperature Anomalies page.

[ top ]

Precipitation

The maps below represent anomaly values based on the GHCN data set of land surface stations using a base period of 1961-1990. Precipitation during December 2008 was above average over areas that include the Hawaiian Islands, the eastern continental U.S., western Australia, and across parts of South America and central Europe. Drier-than-average conditions were observed across the south-central contiguous U.S., Alaska's panhandle, eastern Australia, southeastern Africa, and most of South America, Europe, and southeastern Asia.

December's Precipitation Anomalies in Millimeters

December Precipitation Percent Departures

December's Precipitation Percent Departures

Details on flooding and drought can also be found on the December Global Hazards page.

[ top ]

ENSO SST Analysis

First week of December's ENSO condtions Map

Click here for animated loop

As shown in the adjacent animation, SST anomalies decreased across all Niño regions during December 2008. Although characteristics of a developing La Niña were present, neutral phase ENSO conditions remained across the equatorial Pacific Ocean. A comprehensive summary of December 2008 ENSO conditions can be found on the ENSO monitoring page. For the latest advisory on ENSO conditions go to NOAA's Climate Prediction Center (CPC) and the CPC ENSO Diagnostic Discussion.

Images of sea surface temperature conditions are available for all weeks since 2003 at the weekly SST page.

[ top ]

Northern Hemisphere Snow Cover Extent

Northern Hemisphere Snow Cover Extent
for December 2008

As shown in the time series to the right, the mean Northern Hemisphere snow cover extent during December 2008 was above average. The Northern Hemisphere had the 22^nd largest snow cover extent on record. The mean Northern Hemisphere December snow cover extent for the 1967-2008 period of record was 43.5 million square kilometers.

North America Snow Cover Extent
for December 2008

Across North America, snow cover for December 2008 was above average, the 7^th largest extent since satellite records began in 1967. The mean North America December snow cover extent was 16.6 million square kilometers for the 1967-2008 period of record. Significant winter storms brought heavy snow, breaking over 2,000 daily snowfall records across parts of the U.S. For more information on the U.S. December snow events, please visit the U.S. 2008-2009 Snow Season Summary page.

Eurasia Snow Cover
Extent for December 2008

As depicted in the time series to the right, Eurasia's snow cover extent during December 2008 was below average. This was the 12^th least snow cover extent over the 41-year historical period. Much of this can be attributed to the above normal temperatures that covered most of the Asian continent. On average, the Eurasian snow cover extent in December was 26.9 million square kilometers for the 1967-2008 period of record.

Data were provided by the Global Snow Laboratory, Rutgers University.

[ top ]

Troposphere

Temperatures above the Earth's surface are measured within the lower troposphere, middle troposphere, and stratosphere using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time). Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

Lower Troposphere

Current Month / Year-to-date

These temperatures are for the lowest 8 km (5 miles) of the atmosphere. Information on the UAH and RSS sources of troposphere data is available.

December	Anomaly	Rank (out of 30 years)	Warmest (or Next Warmest) Year on Record	Trend
UAH low-trop	+0.18°C/+0.32°F	11^th warmest	2003 (+0.47°C/+0.85°F)	+0.13°C/decade
*RSS low-trop	+0.17°C/+0.31°F	10^th warmest	2003 (+0.49°C/+0.88°F)	+0.13°C/decade

*Version 03_0

January- December	Anomaly	Rank (out of 30 years)	Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record	Trend
UAH low-trop	+0.05°C/+0.09°F	16^th warmest	1998 (+0.51°C/+0.92°F)	+0.13°C/decade
*RSS low-trop	+0.09°C/+0.16°F	12^th warmest	1998 (+0.55°C/+0.99°F)	+0.16°C/decade

*Version 03_0

Mid-troposphere

Current Month / Year-to-date

These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 3-10 km (2-6 miles) above the Earth's surface), which also includes a portion of the lower stratosphere. (The MSU channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 10 km (6 miles).) Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, may create an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004) (RATPAC). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.

RATPAC January-December plot

Radiosonde measurements indicate that for the January-December year-to-date period, temperatures in the mid-troposphere were 0.21°C (0.38°F) above average, resulting in the 17^th warmest January-December since global measurements began in 1958. However, as shown in the table below, satellite measurement of the January-December year-to-date period for the middle troposphere varied from seventh coolest (24^th warmest) to eleventh coolest (20^th warmest) on record.

The global mid-troposphere temperatures were near average in December 2008. As shown in the table below, satellite measurement for December 2008 ranked from 13^th warmest to 19^th warmest on record.

December	Anomaly	Rank (out of 30 years)	Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record	Trend
UAH mid-trop	-0.05°C/-0.09°F	18^th warmest (13^th coolest)	1987 (+0.36°C/+0.65°F) [1995 (-0.27°C/-0.49°F)]	+0.02°C/decade
*RSS mid-trop	-0.03°C/-0.05°F	19^th warmest (12^th coolest)	1987 (+0.40°C/+0.72°F) [1985 (-0.24°C/-0.43°F)]	+0.05°C/decade
**UW-UAH mid-trop	+0.09°C/+0.17°F	14^th warmest	2003 (+0.43°C/+0.77°F)	+0.10°C/decade
*UW-RSS mid-trop	+0.09°C/+0.16°F	13^th warmest	2003 (+0.49°C/+0.88°F)	+0.12°C/decade

*Version 03_0

January- December	Anomaly	Rank (out of 30 years)	Warmest [Coolest] (or Next Warmest [Coolest]) Year on Record	Trend
UAH mid-trop	-0.11°C/-0.20°F	24^th warmest (7^th coolest)	1998 (+0.45°C/+0.81°F) [1984 (-0.20°C/-0.36°F)]	+0.04°C/decade
*RSS mid-trop	-0.06°C/-0.11°F	22^nd warmest (9^th coolest)	1998 (+0.49°C/+0.88°F) [1985 (-0.23°C/-0.41°F)]	+0.09°C/decade
**UW-UAH mid-trop	-0.01°C/-0.02°F	22^nd warmest (9^th coolest)	1998 (+0.59°C/+1.06°F) [1984 (-0.25°C/-0.45°F)]	+0.11°C/decade
*UW-RSS mid-trop	+0.04°C/0.07°F	20^th warmest	1998 (+0.62°C/+1.12°F)	+0.16°C/decade
RATPAC	+0.21°C/+0.38°F	17^th warmest (out of 51 years)	1998 (+0.74°C/+1.33°F)	+0.15°C/decade

*Version 03_0

[ top ]

Stratosphere

Current Month

The table below summarizes stratospheric conditions for December 2008. On average, the stratosphere is located approximately 16-23 km (10-14 miles) above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in part due to the depletion of ozone. The large positive anomaly in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the sharp jump in temperature in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. In both cases the temperatures returned to pre-eruption levels within two years.

December	Anomaly	Rank (out of 30 years)	Coolest Year on Record
UAH stratosphere	-0.78°C (-1.40°F)	2^nd coolest	2000 (-0.84°C/-1.51°F)
*RSS stratosphere	-0.68°C (-1.22°F)	3^rd coolest	2000 (-0.78°C/-1.40°F)

*Version 03_0

[ top ]

For additional details on precipitation and temperatures in December, see the Global Hazards page.

References

Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology, 17, 1153-1170.

Free, M., D.J. Seidel, J.K. Angell, J. Lanzante, I. Durre and T.C. Peterson (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series, J. Geophys. Res., 10.1029/2005JD006169.

Free, M., J.K. Angell, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel(2004), Using first differences to reduce inhomogeneity in radiosonde temperature datasets, J. Climate, 21, 4171-4179.

Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature, 429, 55-58.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003a), Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology, J. Climate, 16, 224-240.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003b), Temporal homogenization of monthly radiosonde temperature data. Part II: trends, sensitivities, and MSU comparison, J. Climate, 16, 241 262.

Mears, Carl A., M.C. Schabel, F.J. Wentz, 2003: A Reanalysis of the MSU Channel 2 tropospheric Temperature Record. J. Clim, 16, 3650-3664.

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.

[ top ]