Climate and Global Change Issues: Surface Temperatures
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Global surface temperature anomalies during 1994 were 0.4C warmer than normal based on land-only measurements, and slightly greater than 0.3C warmer than normal based on combined land-sea measurements. This return of relatively large, positive global temperature anomalies after a two-year hiatus coincides with a return to near-normal stratospheric aerosol concentrations as the effects of the June 1991 eruption of Mt. Pinatubo greatly diminished.
A return to warm episode [El Nino/Southern Oscillation (ENSO)] conditions in the tropical Pacific during the second half of the year also contributed to the above-normal global temperatures described above. The recurrence of warm episode conditions for the third time in four years, while not unprecedented, has spurred some climate researchers to reexamine the basic assumptions and presumed mechanisms for generation and maintenance of warm episodes. During 1994, ENSO-related shifts in tropical convection contributed to: (1) extreme drought over much of Australia, (2) significantly below-normal precipitation throughout Indonesia, (3) a delayed start to the rainy season in southern Africa, and (4) abnormal weather patterns across the North Pacific and North America by the end of the year.
Other regional climate anomalies during 1994 included above-normal precipitation in the Sahel and extreme warmth in Europe. During the 1994 Sahel rainy season (May to September), much of western tropical Africa recorded more than 120% of normal precipitation, making this their wettest season in over two decades. In Europe, above-normal temperatures prevailed from July through December, and extreme warmth dominated during July and November. For example, Vienna, Austria recorded its highest annual temperature in over 200 years, while Hamburg, West Germany recorded its warmest July since 1850 and central England reported its warmest November in 336 years.
The year also witnessed near-record low ozone amounts in the Southern Hemisphere stratosphere. The "ozone hole" during October 1994 was comparable in magnitude and spatial extent to the record values observed during 1992 and 1993. In the Northern Hemisphere, the January-February ozone minimum was not as severe as observed in 1993.
Climate and Global Change Issues: Surface Temperatures
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