National Climatic Data Center
14 January 2009
The global January-December temperature for combined land and ocean surfaces was 0.49°C (0.88°F) above the 20th century average, tying with 2001 as the eighth warmest since records began in 1880. Globally averaged land temperatures were 0.81°C (1.46°F) above average, while the ocean temperatures were 0.37°C (0.67°F) above average, ranking as the sixth warmest and tenth warmest, respectively. Eight of the ten warmest years on record have occurred since 2001, part of a rise in temperatures of 0.5°C (0.9°F) since 1880. See the global time series.
| Global Top 10 Warm Years (Jan-Dec) | Anomaly °C | Anomaly °F |
|---|---|---|
| 2005 | 0.61 | 1.10 |
| 1998 | 0.58 | 1.04 |
| 2002 | 0.56 | 1.01 |
| 2003 | 0.56 | 1.01 |
| 2006 | 0.55 | 0.99 |
| 2007 | 0.55 | 0.99 |
| 2004 | 0.53 | 0.95 |
| 2001 | 0.49 | 0.88 |
| 2008 | 0.49 | 0.88 |
| 1997 | 0.46 | 0.83 |
The year began with a cold phase (La Niña) El Niño-Southern Oscillation (ENSO) which developed during late 2007, transitioned to a neutral phase in June 2008, and remained neutral through the end of the year. The presence of a strong La Niña dampened ocean sea surface temperatures (SSTs) and contributed to a February global average temperature that was the coolest since the La Niña episode of 2000-2001. During March, sea surface temperature (SST) anomalies were cooler-than-average in all Niño regions, with the exception of the Niño 1+2 region where the monthly temperature anomaly rose to +0.82°C (+1.48°F). Temperatures across Niño 3.4 and Niño 4 regions increased slightly but the anomalies remained below average. These conditions indicated the first signs of weakening of the cold event (La Niña), however a moderate La Niña remained across the equatorial Pacific Ocean. By June, temperatures across the Niño 3.4 and Niño 4 regions continued to warm and the Oceanic Niño Index threshold [3-month (April-June) running mean] was -0.50°C (-0.90°F), indicating a transition into a neutral phase. By the end of December, neutral phase ENSO conditions persisted across the equatorial Pacific Ocean, although characteristics of a developing La Niña were present. According to the latest information from NOAA's Climate Prediction Center, La Niña conditions could develop into early 2009. For more information on the state of ENSO during 2008, please see the ENSO monitoring annual summary.
| January- December |
Anomaly | Rank | Warmest Year on Record |
|---|---|---|---|
GlobalLandOcean Land and Ocean |
+0.81°C (+1.46°F) +0.37°C (+0.67°F) +0.49°C (+0.88°F) |
6thwarmest 10th warmest 8th warmest |
2007 (+1.02°C/1.84°F) 2003 (+0.48°C/0.86°F) 2005 (+0.61°C/1.10°F) |
Northern HemisphereLandOcean Land and Ocean |
+0.89°C (+1.60°F) +0.40°C (+0.72°F) +0.59°C (+1.06°F) |
5th warmest 9th warmest 8th warmest |
2007 (+1.18°C/2.12°F) 2005 (+0.54°C/0.97°F) 2005 (+0.72°C/1.30°F) |
Southern HemisphereLandOcean Land and Ocean |
+0.54°C (+0.97°F) +0.35°C (+0.63°F) +0.38°C (+0.68°F) |
6th warmest 10th warmest 9th warmest |
2005 (+0.81°C/1.46°F) 1998 (+0.50°C/0.90°F) 1998 (+0.53°C/0.95°F) |
The 1901-2000 average combined land and ocean annual temperature is 13.9°C (56.9°F), the annually averaged land temperature for the same period is 8.5°C (47.3°F), and the long-term annually averaged sea surface temperature is 16.1°C (60.9°F).
During the past century, global surface temperatures have increased at a rate near 0.05°C/decade (0.09°F/decade), but this trend has increased to a rate of approximately 0.16°C/decade (0.29°F/decade) during the past 30 years. There have been two sustained periods of warming, one beginning around 1910 and ending around 1945, and the most recent beginning about 1976. Temperatures during the latter period of warming have increased at a rate comparable to the rates of warming projected to occur during the next century with continued increases of anthropogenic greenhouse gases.
Temperature measurements have also been made above the Earth's surface over the past 51 years using balloon-borne instruments (radiosondes) and for the past 30 years using satellites. These measurements support the analyses of trends and variability in the troposphere (surface to 10-16 km) and stratosphere (10-50 km above the earth's surface).
The best source of upper air in-situ measurements for studying global temperature trends above the surface is the Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) dataset.
Data collected and averaged between the 850-300 mb levels (approximately 5,000 to 30,000 feet above the surface) indicate that 1958-2008 global temperature trends in the middle troposphere are similar to trends in surface temperature; 0.13°C/decade (0.23°F/decade) for surface and 0.16°C/decade (0.29°F/decade) for mid-troposphere. Since 1976, mid-troposphere temperatures have increased at a rate of 0.17°C/decade (0.31°F/decade). For the January-December 2008 period, global mid-troposphere temperatures were 0.13°C (0.23°F) above the 1971-2000 mean and the 17th warmest.
Since 1979, NOAA's polar orbiting satellite measurements have also been used to measure temperatures in the troposphere and stratosphere. Microwave Sounding Unit (MSU) data are analyzed for NOAA by the University of Alabama in Huntsville (UAH), Remote Sensing Systems (RSS, Santa Rosa, California) and the University of Washington (UW). These observations show that the global average temperature in the middle troposphere (the layer which is centered at an altitude of 2 to 6 miles, but which includes the lower stratosphere) has increased, though differing analysis techniques have yielded similar but different trends (see below).
In all cases these trends are positive. The analysis performed by RSS reveals a trend of 0.09°C/decade (0.17°F/decade) while the UAH analysis reveals a lower trend of 0.04°C/decade (0.08°F/decade). When adjusted by University of Washington scientists to remove the stratospheric influences from the RSS and UAH mid-troposphere average, the trends increase to 0.15°C/decade (0.28°F/decade) and 0.11°C/decade (0.20°F/decade), respectively. (A journal article is available that describes the University of Washington adjustments to remove the stratospheric influence from mid-troposphere averages.) Trends in these MSU time series are similar to the trend in global surface temperatures, which increased at a rate near 0.16°C/decade (0.29°F/decade) during the same 30-year period.
The MSU anomalies for the January-December period were the coolest since 2000, breaking the streak of consecutive warmer-than-average temperatures.
While middle tropospheric temperatures reveal an increasing trend over the last three decades, stratospheric temperatures (14 to 22 km / 9 to 14 miles above the surface) have been below average since the warming effects from the 1991 Mt. Pinatubo eruption dissipated in 1993. January - December 2008 was the 16th consecutive year with below-average temperatures (an anomaly of -0.62°C/-1.12°F), the second coolest year behind 1996 which had an anomaly of -0.64°C/-1.15°F. The below-average stratospheric temperatures are consistent with the depletion of ozone in the lower stratosphere and the effects of increasing greenhouse gas concentrations. The large temperature increase in 1982 is attributed to the volcanic eruption of El Chichon, and the increase in 1991 was associated with the eruption of Mt. Pinatubo in the Philippines.
Warmer-than-average temperatures occurred throughout the year in most land areas of the world, with the exception of cooler-than-average conditions across Colombia, parts of Alaska, central Canada, and the midwestern continental U.S. The warmest above-average temperatures occurred throughout high latitude regions of the Northern Hemisphere including much of Europe and Asia. Temperature anomalies in these regions ranged from 2-4°C (3.6-7.2°F) above the 1961-1990 average.
The map, above left, is created using data from the Global Historical Climatology Network (GHCN), a network of more than 7,000 land surface observing stations. The map, above 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.
Notable temperature extremes in 2008 include the below average temperatures across the Middle East, central Asia, and southeast China during January 2008. Parts of Turkey experienced their coldest January nights in 50 years (WMO). Freezing temperatures and heavy snowfall affected over 78 million people and resulted in 60 fatalities across China. The anomalously cool conditions over central Asia and southeast China were associated with the largest January snow cover extent on record for the Eurasian continent and for the Northern Hemisphere. In contrast, above average temperatures during January were observed across Australia, Europe, and northern Asia. Temperatures in Australia were 3-5°C (5-7°F) above average across large areas in Western and Central Australia. For the nation as a whole, the January 2008 average temperature was 1.23°C (2.21°F) above the 1961-1990 mean, making it the warmest January on record [Australia's Bureau of Meteorology(BoM)]. Most parts of the Fenno-Scandinavia region had their warmest winter since records began (WMO).
In March, South Australia experienced a record heat wave which brought scorching temperatures across the state. Adelaide, South Australia's capital, experienced its longest running heat wave on record, with 15 consecutive days of maximum temperatures above 35°C (95°F). This shattered the previous record of 8 consecutive days which was tied on numerous occasions, most recently in February 2004. Also, Adelaide set a new record as having the longest number of consecutive days exceeding 35°C (95°F) for all Australian state capital cities. The second longest such streak was 10 days, set in February 1988 in the city of Perth. Overall, South Australia had its third warmest March since records began with 2.35°C (4.23°F) above the 1961-1990 average (BoM).
During the second and third weeks of September, Hungary saw a marked contrast in temperatures. The city of Szeged set a new maximum temperature record for September 7 when temperatures rose to 37.6°C (100°F), surpassing the 1946 record of 36.7°C (98°F). Meanwhile, on September 15, a new national record was set when the city of Sopron, Hungary recorded its coldest temperature of 8.6°C (47°F), surpassing the previous record set in Zalaegerszeg in 1925 when temperatures fell to 10.5°C (51°F).
Additional information on other notable weather events can be found in the Significant Events section of this report, or through the monthly Climate Perspectives reports.
According to the National Snow and Ice Data Center, the September Northern Hemisphere average sea ice extent, which is measured from passive microwave instruments onboard NOAA satellites, was 4.67 million square kilometers (34 percent below the 1979-2000 mean), the second lowest on record behind 2007. The Northern Hemisphere sea ice extent time series to the right depicts the decrease of the sea ice extent from June-September. It is seen that from May to June, the sea ice extent was similar to 2005 and 2007. However, by early August, the 2008 sea ice extent surpassed the 2005 extent but was nearly nine percent above the 2007 record. The lowest Northern Hemisphere sea ice extent in the seasonal cycle occurs in September each year. The average September rate of sea ice decline is 11.7 percent per decade. A complete summary of the 2008 Northern Hemisphere sea ice extent is available, courtesy of the National Snow and Ice Data Center.
In contrast, the 2008 Southern Hemisphere sea ice extent saw several monthly records when it was the largest sea ice extent for January, March, and April 2008. It also was the second largest sea ice extent for February (behind 2003) and June (behind 1979), and third largest May (behind 2000 and 1996).
For further information on Northern and Southern Hemisphere snow and ice conditions, please see the NSIDC News page, provided by the NOAA's National Snow and Ice Data Center (NSIDC).
Arctic sea ice conditions are inherently variable from year to year in response to wind, temperature and oceanic forcings. Quite often a "low" ice year is followed by recovery the next year. But increasing surface temperatures in high latitudes have contributed to progressively more summer melt and less ice growth in the fall and winter. While natural variability is responsible for year-to-year variations in sea ice extent, three extreme minimum extent years along with evidence of thinning of the ice pack suggest that the sea ice system is experiencing changes that may not be solely related to natural variability.
As shown in the time series to the right, the mean Northern Hemisphere snow cover extent during the boreal winter (December 2007-February 2008) was above average. This can be primarily attributed to the multiple snow and ice storms that affected much of the Northern Hemisphere during the winter. This resulted in the fourth largest snow cover extent on record. The mean Northern Hemisphere winter snow cover extent for the 1967-2008 period of record is 45.5 million square kilometers.
Across North America, snow cover for winter 2007/2008 was above average, the sixth largest extent since satellite records began in 1967. A series of snow and ice storms struck the U.S. throughout the winter. The heavy snowfall during the winter prompted more than 4,700 new daily snowfall records and several new seasonal records across the contiguous U.S. The mean North America winter snow cover extent for the 1967-2008 period of record is 17.1 million square kilometers.
Mean Northern Hemisphere snow cover extent during spring 2008 was below average, resulting in the third least snow cover extent on record, behind 1968 and 1990. Much of this was due to anomalously warm conditions across Asia, Europe, and parts of Alaska and Canada during the boreal spring (March-May). The mean Northern Hemisphere spring snow cover extent for the 1967-2008 period of record is 30.8 million square kilometers.
Snow cover for boreal spring 2008 across North America was slightly above average, due to a series of snow storms that struck the U.S. early in the season. This resulted in the 14th largest extent since satellite records began in 1967. The mean North American spring snow cover extent for the 1967-2008 period of record is 12.9 million square kilometers.
Data were provided by the Global Snow Laboratory, Rutgers University.
Global precipitation in 2008 was above the 1961-1990 average. Precipitation throughout the year was variable in many areas. Regionally, drier than average conditions were widespread across the Hawaiian Islands, the western and south-central contiguous U.S., southwestern Alaska, southeastern Africa, southern Europe, northern India, and parts of Argentina, Uruguay, eastern Asia, the eastern coast of Brazil, and southern Australia. Most of Europe, western Africa, the northeastern and central contiguous U.S., parts of northern South America and southeastern Asia experienced wetter than average conditions.
The Philippine Islands received much-above-average precipitation in 2008 due to several tropical cyclones that made landfall in the region during the active season, dumping heavy precipitation which led to widespread floods and landslides on the islands. In southern China, severe storms and Typhoon Fengshen brought heavy rain across the area, causing widespread floods and landslides. The copious rainfall across southern China made June 2008 the wettest month on record for Hong Kong, Guangzhou, and Macao, according to the Hong Kong Observatory. Records began in 1884.
Precipitation across Australia was 73 percent below normal during May, resulting in the driest May on record. May 2008 had a national average of 7.86 mm (0.31 inches) of rain, supplanting the 1961 record of 8.27 mm (0.32 inches). During March-May, Australia, as a whole, experienced 53 percent below-normal precipitation, resulting in the eighth driest austral autumn (March-May). Parts of Australia have been experiencing drought conditions for over a decade.
In the U.S., heavy rain fell across much of the Midwest during the first half of June, causing the worst floods in 15 years and setting numerous new record river crest levels. For more information, please visit the June Midwest Flooding page.
Unsettled weather affected the British Isles during the boreal summer (June-August), resulting in a summer rainfall total that was much above the 1971-2000 mean. June-August 2008 period ranked as one of the top 10 wettest summers since records began there in 1914. Northern Ireland experienced its second wettest boreal summer when a total of 393.7 mm (15.5 inches) of rain fell. The wettest boreal summer for Northern Ireland was set in 1958 when 404.0 mm (15.9 inches) of rain fell.
Prolonged drought (January-September) across parts of Argentina, Paraguay, and Uruguay significantly affected agriculture. Some areas experienced their worst drought in over five decades.
During September 2008, Hurricanes Gustav, Hanna, and Ike, and Tropical Storm Kyle brought torrential rain across the Caribbean and parts of the continental U.S., triggering fatal floods and wreaking havoc across the affected areas.
For more information about precipitation extremes during 2008, see the annual report of Significant Events.
Additional information on other notable weather events can be found in the Significant Events section of this report, or through the monthly Climate Perspectives reports.
NOAA's National Climatic Data Center is the world's largest active archive of weather data. The temperature and precipitation rankings are available from the center by calling: 828-271-4800.
NOAA works closely with the academic and science communities on climate-related research projects to increase the understanding of El Niño and improve forecasting techniques. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts.
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.
For all climate questions, other than questions concerning this report, please contact the National Climatic Data Center's Climate Services and Monitoring Division:
Climate Services and Monitoring Division
http://www.ncdc.noaa.gov/oa/climate/research/2008/ann/global.html 
