SINKING OR RISING, FUTURE OF PACIFIC ATOLLS ALL IN THE ENTRAILS OF

admin's picture

STATISTICAL ANALYSIS

By Michael Field

AUCKLAND, New Zealand (August 25, 2002 – Agence France-Presse)---Bob Dylan's Subterranean Homesick Blues could be the national anthem for Tuvalu, the Pacific's smallest nation and said to be sinking beneath the ocean.

That Dylan line "you don't have to be a weatherman to know which way the wind blows" sounds like Tuvalu, cursed to live an unscientific antidote because one key measuring instrument is sinking and the other has only been there too short a time.

Tuvalu has become Greenpeace's poster-victim for the dangers of global warming and one of its main weapons for beating up Australia, which is not ratifying the Kyoto Protocol on carbon emissions.

Tuvalu's 10,500 Polynesians live on just 26 square kilometers (10 square miles) over nine islands, none more than five meters (16 feet) above sea-level -- and if it rises they are doomed.

Earlier this month Saufatu Sopo'aga became prime minister, taking over from defeated Koloa Talake, who earlier this year at the Commonwealth Heads of Government Meeting announced he was getting lawyers to sue Australia and the United States for their global emissions which, he said, were leading to the sinking of his island.

Sopo'aga went to the Pacific Forum Summit in Fiji last week and said the legal option was no longer being considered. But he was adamant Funafuti was sinking, pointing out that just after he left "a surge of sea waves came across the ocean side of the airfield ... surging across the runway. A couple of families have had to be relocated."

The problem with Sopo'aga's story is that such storm surges have always occurred and are part of any atoll's legends and lifestyles. And going to the weathermen at this point does not help too much.

Since 1977, the University of Hawai‘i Sea Level Center has had a tide gauge at Funafuti. The 14-nation Australian funded South Pacific Sea Level and Climate Monitoring Project installed a more accurate gauge there in 1993. The latter is operated for the project by Australia's National Tidal Facility (NTF).

Hawai‘i's gauge has produced erratic data, suggesting it is sinking or getting knocked about by the wind.

In March, NTF caused drama with the statement: "The historical record shows no visual evidence of any acceleration in sea level trends."

Coastline degradation and sinking islets in Funafuti, it suggested, were the result of entirely local conditions.

NTF's statement has been used by critics of the global warming theory and by skeptics of the Intergovernmental Panel on Climate Change (IPCC), which predicted global sea level rises.

At this month’s Pacific Islands Forum summit, John Hunter, of the Antarctic Cooperative Research Center in Tasmania, briefed leaders, saying to assert that there was no sea level rise at Tuvalu was completely wrong.

"I do also believe that the way in which the NTF has released figures has been unhelpful to climate scientists but very helpful to greenhouse skeptics," he told AFP.

Applying various statistical techniques he has been able to adjust for the Hawai‘i gauge sinking and the more dramatic impact of El Niño, which in Tuvalu produces dramatic drops in sea level.

"A cautious estimate of present long-term relative sea level change at Funafuti, which uses all the data, is a rate of 0.8 plus or minus 1.9 mm/year relative to the land," he says in a paper.

"This indicates that there is about a 68 percent probability of the rate of rising being between -1.1 and 2.7 mm per year."

Hunter says the relative sea level change at Funafuti is not directly comparable with the IPCC estimates of global average sea level rise during the 20th Century of 1 to 2 mm per year. "It is interesting to note that they are of similar magnitudes."

He concedes though that the data is of "little value" at the moment because NTF is too recent and strongly affected by El Niño.

"Even using the full 24 years of available data, the uncertainties in estimated trends are presently undesirably large.

Hunter says a useful estimate of sea level rise may be possible after a further 40 years.

"As with much climate data, we do not have as much as we would like and the uncertainty is undesirably high," he said. "However, we have to use what we have got."

Hunter has also studied the extremes of sea level, which are causing the problems.

If the top 0.1 percent of the sea levels each year they show a rate of rise of about 5 plus or minus 2 mm per year: "a rate that is five times the rate of increase in mean sea level."

Hunter: "This increase in the extremes may be attributable to global warming or it might not. We just don't know at the moment. Also, it may not be a long-term trend but just part of a long multi-decadal cycle. Again, we don't know."

Michael Field New Zealand/South Pacific Correspondent Agence France-Presse E-mail: afp.nz@clear.net.nz  Phone: (64 21) 688438 Fax: (64 21) 694035 Website: http://www.afp.com/english/  Website: http://www.michaelfield.org 

Rate this article: 
Average: 4 (1 vote)

Add new comment