Climate-change study reveals unusual rainfall changes

Published on July 23, 2007

Without melting ice and starving polar bears, how can Thailand tell if the impact of climate change is upon us?

A senior climate-change researcher recently looked at five decades of rainfall records in the Kingdom and found a remarkable change in the pattern over the past 25 years.

"I used the country's average annual rainfall charts from 1951 to 2006 to calculate the average over the period and how much rainfall each year deviates from the average value," says Suppakorn Chinvanno of the Southeast Asian Bureau of the Global Change System Analysis, Research and Training Centre (SEA-Start).

"The results show that the deviation from the average is greater in both magnitude and frequency in the past 25 years compared with the earlier 25 years. If it's not a year of drought, then it's a year of flood. Where are the normal years?"

The centre has just completed its first study of climate change impact in Thailand and the Mekong region. Another is on its way.

Although there has been no significant change in average annual rainfall (1,600 millimetres), Suppakorn believes the increasing magnitude and frequency of extreme events will extend in the future. In other words, weather anomalies are becoming normal.

"I can't say with confidence that this is the result of climate change," he says.

"This is just simple playing with numbers. There are many other factors to consider when it comes to climate. The rain fluctuation may be from the influence of El Nino and La Nina, which created unusually dry or wet years.

"However, this shows that the change in climate variability is real and we should think about how to cope with it."

Thailand needs many more studies. Scientists working on Africa undertook 14 different studies before they could reach a consensus on the impact of climate change over the continent, Suppakorn adds.

Recently Dr Anond Sanidvongs, SEA-Start's director, reported that warmer

temperatures and shorter winter periods had been observed in Thailand, particularly in mountainous areas. He also pointed to a few millimetres' annual rise in sea levels at measuring stations in the Gulf of Thailand and the Andaman Sea as evidence of climate change in Thailand.

So far, scientists generally agree that sea levels rising at those rates are not yet a threat to Thailand. However, marine biologist Thorne Thamrongnavasawadi of Kasetsart University asserts that there is a need to look into the detail. He recently observed some peculiar phenomena in the seas around the Kingdom.

For example, fishermen from different provinces on the Andaman coast earlier this year reported mass fatalities of fish, many of which had been washed ashore. There were no incidents of oil spillage or other pollution, he says.

"One possibility is what we call 'internal wave' attacks, which bring an abrupt drop in water temperature from say 26 to 15 degrees Celsius," Thorne says. "This is a new phenomenon to this region. It's too early to say where the 'waves' come from and why it happened, but I'm convinced that this may have a lot to do with climate change."

Thorne also warns of mass extinction in crustacean and mollusc species that produce external calcium carbonate shells because the sea is becoming more acidic due to increasing levels of carbon dioxide in the atmosphere.

"But our scientists are left in the dark when it comes to technology and tools to study climate change," Thorne notes. "It's sad that no one here is capable of doing any specific research to determine the impact on our ocean because of the lack of technical and financial support."

Suppakorn faces a similar problem, but he says governments in developing countries should not be left to shoulder the costs of adaptation to climate change alone. There should be a global mechanism at the level of the Kyoto Protocol by which industrialised nations pay to help alleviate the impact of climate change in the developing world.

"The Thai government has spent up to Bt13 billion annually on flood and/or drought relief over the past decade," he argues. "Preparedness to cope with the impact of climate change will need a holistic approach and we need help both in terms of money and technology transfer."

He hopes the issue will take centre stage at the next international meeting on climate change in Bali, Indonesia, in December when scientists and politicians convene to discuss the post-Kyoto arrangement.

Nantiya Tangwisutijit

The Nation