State of the Climate in 2003

Abstract

The earth's climate was influenced by a moderate El Niño in the tropical Pacific Ocean at the beginning of 2003. This ENSO warm event developed during October?November of 2002, and eventually dissipated during March?April 2003, giving way to near-neutral ENSO conditions for the remainder of the year. Despite the cessation of El Niño during the boreal spring, the ENSO warm event affected regional precipitation anomalies over a broad area of the Pacific basin, including wet anomalies along the west coast of South America, and dry anomalies in eastern Australia, the southwest Pacific, and Hawaii. The global mean surface temperature in 2003 was within the highest three annual values observed during the period of regular instrumental records (beginning in approximately 1880), but below the 1998 record-high value. Global surface temperatures in 2003 were 0.46°C (0.83°F) above the 1961?90 mean, according to one U.K. record, which ranked as third highest in this archive. In the U.S. temperature archive, the 2003 anomaly was also 0.46°C (0.83°F), equivalent to the 2002 value, which ranked second over the period of record. Similar to the surface temperature anomalies, satellite retrievals of global midtropospheric temperatures ranked 2003 as third warmest relative to the 1979?98 mean value. The hurricane season was extremely active in the Atlantic basin, with a total of 16 tropical storms, seven hurricanes, and three major hurricanes in 2003. Five of these tropical cyclones made landfall in the United States, three made landfall in northeastern Mexico, and a tropical storm affected Hispañola. In addition, Nova Scotia and Bermuda experienced devastating impacts from hurricanes in 2003. Another notable aspect of the season in the Atlantic was the formation of five tropical storms over the Gulf of Mexico, which tied the season high observed in 1957. In addition, three tropical storms formed outside of the normal (June?November) hurricane season in 2003?one in April and two in December?which made this the first season since 1887 that two tropical storms have formed during December in the Atlantic basin. Also of note was the below-normal activity in the eastern North Pacific basin. There were no major hurricanes in this basin during the 2003 season, which made this the first year since 1977 with no category 3?5 storms. Despite the below-normal activity, four tropical cyclones made landfall on the Pacific coast of Mexico, two as hurricanes and two as tropical storms, which was twice the long-term mean. The summer of 2003 was one of the warmest on record across parts of Europe, where a heat wave affected most of Central and Western Europe. Two distinct periods of exceptional heat occurred during the season?the first in June and the second during the latter half of July and the first half of August. The July?August heat wave was the more serious of the two, since it coincided with the normal peak in summer temperatures and was accompanied by an almost complete absence of rainfall. The high temperatures and dry conditions exacerbated forest fires that burned across southern France and Portugal in July and August. The record heat wave spread across most of Western Europe in August, and it was likely the warmest summer since 1540 in parts of Central Europe. In France, 11,000 heat-related deaths were reported between late July and mid-August. In Germany, both June and August were the warmest such months since at least the beginning of the twentieth century. The summer was also the hottest in Germany since 1901, and, with the exception of some stations in northern and northwestern Germany, it was the hottest summer since the beginning of recorded measurements. Other climatic events of note during 2003 included 1) record wet conditions across parts of the southeast, mid-Atlantic, and eastern coast of the United States; 2) record cold temperatures and anomalous June snowfalls in European Russia; 3) 546 tornadoes during May 2003 in the United States, which was an all-time record of reported tornadoes for any month; 4) continuing drought conditions across the western United States, with some areas experiencing their fourth and fifth years of significant precipitation deficits; 5) severe bushfires in eastern Australia in January, the worst wildfire season on record in British Columbia during August, as well as severe wildfires across southern California in October; 6) above-average rainfall across West Africa and the Sahel, which had its second wettest rainy season since 1990; 7) a return to normal rainfall across the Indian subcontinent during the summer monsoon; and 8) a near-record extent of the Antarctic ozone hole, which was 28.2 million km2 at its maximum in September 2003.