The global surface temperature for all of 2003 is expected to be +0.45°C above the 1961-90 annual average, according to the records maintained by Members of the World Meteorological Organization (WMO). This value makes 2003 the third warmest year just behind 2002 (+0.48°C). The warmest year remains 1998 (+0.55°C).
Calculated separately for both hemispheres, the 2003 temperatures for the Northern Hemisphere (+0.57°C) and for the Southern Hemisphere (+0.33°C) are both likely to be the third warmest in the instrumental record from 1861 to present.
The high temperatures recorded over land influenced the overall values in 2003. Europe experienced unprecedented heat during June, July and August. The Mediterranean and Near East region (40-30N, 20W-60E) had the warmest land and Sea Surface Temperature (SST) anomaly on record for June and July. The Northern Hemisphere had the warmest land and SST anomaly on record for September and October.
The global surface temperature has increased since the beginning of the instrumental record in 1861. Over the 20th century the increase was greater than 0.6°C. The rate of change for the period since 1976 is roughly three times that for the past 100 years as a whole. Analyses of proxy data for the Northern Hemisphere indicate that late 20th century warmth is unprecedented for at least the past millennium. In the Northern Hemisphere, the 1990s were the warmest decade and 1998 the warmest year in the past 1000 years.
Strong regional temperature differences
Much of Europe was affected by heat waves during the summer (June, July, August) of 2003. Nationwide seasonal temperatures were warmest on record in Germany, Switzerland, France and Spain. The heat wave resulted from a zone of strong high pressure over Western Europe related to a marked ridge of high pressure in the large-scale upper atmospheric wind flow. Such «blocking highs» that persist for many days are not rare in Europe during summer. They usually bring warm and sunny weather. However, in this situation heated air from the south reinforced the strength and persistence of the heat wave.
In the European Alps, the average thickness loss of glaciers reached about 3 metres water equivalent, which was nearly twice as much as during the previous record year 1998 (1.6 metres).
During the Northern Hemisphere winter, large areas in central and Eastern Europe saw episodes of very cold temperatures. January temperatures in the Russian Federation reached -45°C. For the third year in a row Mongolia experienced a cycle of dry summer/cold winter. The Northern Hemisphere snow cover extent for 2003 was the second greatest on record.
More extensive, updated information will be made available in the annual WMO Statement on the Status of the Global Climate in 2003, to be published in early March 2004.
Source: World Meteorological Organization WMO