The earth’s surface air temperature in 1999 was the fifth warmest in the record of observations stretching back to 1860.
The final analysis confirmed the global mean temperature was 0.33°C above the recent long-term average based on the period 1961-1990. This makes the 1990s the warmest decade of the century, and probably the warmest decade of the millennium. Both the Northern and Southern Hemispheres recorded warm years; respectively 0.45°C and 0.20°C warmer than normal.
These year-end analysis results were announced today by NIWA (National Institute of Water and Atmospheric Research) in conjunction with UK’s Hadley Centre and the University of East Anglia’s Climate Research Unit.
Dr Jim Salinger, NIWA Senior Climate Scientist, said, "Global temperatures in 1999 were about 0.7°C higher than those at the end of the 19th century, and seven of the top 10 warmest years of the century have been in the 1990s. 1999 will have been the 21st consecutive year with an above normal global surface temperature, and the ten warmest years have all occurred since 1983.
"The rapid cooling of seas in the eastern equatorial Pacific, the La Nina, has contributed to 1999 being significantly cooler than 1998, the hottest year on record.
"Although we do not have instrumental records going back further than the middle of the 19th century, our analysis of tree rings, ice cores, corals and historical records from around the world indicates that the 1990s were the warmest decade of the millennium.
"In the New Zealand region mean surface temperature calculated by NIWA was 13.34°C, 0.80°C above the 1961–90 average, following the record 13.40°C of 1998," said Dr Salinger. "This was caused by the current La Niña event in the tropical Pacific Ocean, and warm seas around New Zealand. La Nina events typically give New Zealand warm weather. The combination produced the most anticyclonic conditions ever, and few characteristic ‘roaring forties’.
"Across the Tasman in Australia the 1990s were the warmest decade in the ninety years for which high-quality records are available since 1910. The Australian mean temperature for 1999 was 21.92°C, 0.11°C higher than the average for the 1961 - 90 average period. Like New Zealand and the globe, their warmest year occurred in 1998, which was 0.83°C above average."