PACIFIC WARMING SURPRISES SCIENTISTS

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NATIONAL INSTITUTE OF WATER AND ATMOSPHERIC RESEARCH Taihoro Nukurangi Auckland, New Zealand

 

ASIA PACIFIC NETWORK FOR GLOBAL CHANGE RESEARCH

NEWS RELEASES November 11, 2001

New figures compiled from detailed Pacific island weather records show that over the last fifty years, many parts of the Pacific warmed much faster than the global average warming.

Pacific island meteorologists attending last week’s National Institute of Water and Atmospheric Research / Asia-Pacific Network for Global Change Research workshop in Auckland compiled all their national measurements to produce a regional picture of Pacific climate from 1950 - 2000.

Workshop convenor Dr. Jim Salinger said this amount of detail had not been available before. The resulting picture of the Pacific’s climate over the second half of the 20th century surprised climate scientists at the workshop.

Dr. Salinger said it became immediately plain that there has been an unusually strong warming in the South Pacific. "For the whole of the last century, the global average temperature rise was 0.6 degrees Celsius," Dr. Salinger said. "But in the Pacific, temperatures rose higher than that in the second half of the century alone."

The daily temperature records show that in Australia, the Cook Islands, Fiji, French Polynesia, New Caledonia, the Solomon Islands and Vanuatu, temperatures rose by half to one degree Celsius in the second half of the 20th century. Elsewhere in the Pacific, the warming was similar to the global average warming.

"This shows that global warming is alive and well," Dr. Salinger said. He said the higher than expected temperature rises would have been accentuated by the greater number of El Niños which developed in the last quarter of the 20th century, between 1976 and 1998.

The regional view of Pacific island weather data also revealed a significant reduction in rainfall in many parts of the Pacific. "While this was not as widespread as the unusual warming, it is also evidence of long-term changes in climate," Dr. Salinger said.

 

LONG-TERM CLIMATE SHIFT IN PACIFIC

Climate scientists are now convinced that a long-term climate pattern in the Pacific ocean recently changed to its opposite phase, and that this means long-term changes in the weather, in the Pacific and globally.

Dr. Jim Salinger, a senior climate scientist with New Zealand’s National Institute of Water and Atmospheric Research, last week convened a NIWA / Asia-Pacific Network for Global Change Research workshop in Auckland, where meteorologists from Pacific island and Pacific rim countries put together detailed information about temperature and rainfall in the South Pacific region since 1950.

Dr. Salinger said the workshop clarified knowledge about the Interdecadal Pacific Oscillation, a climate pattern that works like a pendulum. "It stays in the same state for two or three decades, then it suddenly shifts to the opposite phase." He said it was now plain that the Interdecadal Pacific Oscillation switched to its opposite phase in 1998.

Dr. Salinger said the change in the IPO meant that the north and northeast Pacific would be drier. "We’re already seeing that. Tuvalu and Western Kiribati are suffering massive droughts, while countries further west, like Fiji, Vanuatu, Tonga and New Caledonia have become wetter."

He said it is also likely that there will be fewer intense El Niños in the next couple of decades, and more La Niñas. The warmer than usual temperatures in the southern Cook Islands, Fiji, New Caledonia, New Zealand, Niue, Tonga, and Vanuatu will probably continue as well.

Dr. Salinger said new research studying long-lived corals in Rarotonga appears to confirm the IPC decadal changes. "The coral samples show similar decadal changes in water temperature going back to the 1700s.

"Last century, the IPO was in a positive phase from 1922 to 1944, then a negative phase from 1946 to 1977, then it switched back to positive between 1978 and 1998. Now it’s back to negative, and that change is likely to last for the next 25 to 30 years.

Dr. Salinger said in New Zealand, the 1998 change in the IPO meant slightly wetter weather in the north and east of the North Island, and drier conditions in the south and west of the South Island. "We’re certainly seeing that now, for example, in the Southern hydro lakes," he said.

For further information contact Dr. Jim Salinger: 025 540 707, or Jan Sinclair: 025 221 3228 and [email protected]

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