By MARIA CHENG
2009-05-17 08:14 AM
Do they really need to rush?
Scientists have long warned that the Maldives, an archipelago nation of nearly 1,200 islands in the Indian Ocean, will be wiped out by rising sea levels in the coming decades. President Mohamed Nasheed is so convinced of his nation's demise he has proposed relocating all 350,000 inhabitants to other countries. On average, the islands are 7 feet (2.1 meters) above sea level, making them the lowest-lying nation on Earth.
Most experts agree the Maldives have plenty to worry about: In the worst-case scenario, if global sea levels rise higher and faster than expected, the islands may indeed be swallowed up.
But some recent data challenge the widespread belief that the islands are destined to disappear _ and a few mainstream scientists are even cautiously optimistic about their chances for surviving relatively intact beyond the next century.
"The outlook for the Maldives is not all doom and gloom," said Paul Kench of the University of Auckland in New Zealand. "The islands won't be the same, but they will still be there."
Kench said his studies of the Maldives show the islands can adjust their shape in response to environmental changes, such as the rising seas and warmer temperatures predicted in the next century.
Kench suggests the islands might move onto their reefs and build vertically, offsetting the potential threat of sea level rises. His research _ published together with other scientists from Australia, New Zealand and the Maldives _ shows some islands have rebuilt themselves as much as 1.6 feet (49 centimeters) higher. Their studies have been published in recent years in journals including Geology and the Journal of Geophysical Research.
"It's quite convincing work and seems to be quite widely accepted by the scientific community," said Andrew Cooper, a professor of coastal studies at the University of Ulster in Northern Ireland.
"They have detailed geological evidence that this kind of growth has happened before in the past. ... I think the question of the Maldives being completely wiped out may be overstated."
Following the devastating 2004 Asian tsunami, many scientists assumed the Maldives would be damaged. But Kench and his colleagues not only found little evidence of island erosion, but also that the tsunami had washed sediment ashore, making some islands taller than they were before the catastrophe.
Kench warned, however, that while only a small number of Maldivian islands may not be able to adapt to rising sea levels, those are unfortunately the ones where many people live: Male, the nation's capital, and Hulule. Residents of those islands will probably need to relocate to another country or move to other Maldivian islands that won't disappear so quickly, he said.
Building taller and moving to higher ground are examples of a hot trend in climate change policy: emphasizing adaptation.
While much global warming work aims to limit emissions, adaptation advocates argue for the need to combat the inevitable effects of climate change through forward planning and construction. That includes moving people, building sea walls, and new construction techniques.
Sea levels worldwide have been steadily rising, except in a handful of places, including the Maldives. But in the last 50 years, some data from satellite pictures and tide measurements suggest sea levels in the Maldives have dropped by as much as 12 inches (30 centimeters).
"That was definitely unexpected," said Jonathan Overpeck, director of the Institute for the Study of Planet Earth at the University of Arizona. Overpeck said the decline in the Maldives' sea levels is probably due to local factors like ocean temperatures and currents.
Such data is inconclusive, however _ and with few available records, the Indian Ocean remains one of the world's least understood oceans.
Jianjun Yin, an assistant research scientist who monitors sea levels at Florida State University, said the drop in the Maldives could be caused by increased evaporation in the Indian Ocean. Evaporation makes water more dense, thus lowering sea levels.
Yin said the Maldives' defiance of the global trend of rising sea levels could be temporary. "I don't think the Maldives will disappear in a few decades, but maybe in another hundred years it will become a very serious situation," he said.
Other scientists think coral reefs may help save the islands. Under normal conditions, reefs can grow inches (centimeters) every year, allowing them to keep up with at least some sea level rise. The reefs form natural barriers that protect islands from being eroded by rising sea levels.
But rising tides and temperatures may conspire to stunt the corals' growth. As sea levels rise, light conditions underwater worsen, making it difficult for the reefs to expand; their health also depend upon relatively cool waters.
"One of the $64,000 questions is whether corals will be able to grow fast enough to keep up with sea level rises," Cooper said.
Many scientists estimate that by 2100, global sea levels will rise by 3 feet (91 centimeters), due to melting ice caps in Greenland and Antarctica. But because no one knows how fast these will melt, that figure comes with a significant margin of error.
"That is a huge question which limits our ability to predict what is going to happen in the Maldives," said Steve Nerem, a professor at the Colorado Center for Astrodynamics Research.
Scientists are unsure if water from the melting ice caps might hang around Greenland and Antarctica, or if they will spread out across the Earth's oceans _ and if they do, how fast that spread will happen.
Though uncertainty about future sea level rises may be good news for the Maldives _ and for tourists seeking their sandy beaches _ most scientists urge the country to make contingency plans.
"We just don't know enough to be confident one way or the other," Overpeck said. "And in this case, if you make a mistake, you lose an island. You lose a nation."