Michael Richardson, Straits Times 13 Jul 09;
IN NORMAL conditions, the vast swathe of tropical forest and peatland swamp that covers much of insular South-east Asia is immune to fire. Beneath the dense forest canopy lies a water-saturated world, teeming with plant, animal and insect life.
But these are not normal times. Nature is conspiring with man to put unprecedented stress on the forest, raising the risk of devastating fire and a big jump in the region's greenhouse gas emissions.
Scientists blame such emissions, mainly of carbon dioxide (CO2), for warming the planet. They say that the average surface temperature around the world rose by about 0.7 deg C in the 20th century as a result of human activity, mainly the burning of carbon-based fossil fuels and the clearing of forests for timber and agriculture.
Trees soak up and store CO2 when they grow and release it when they rot or are burnt. Emissions from cutting or burning forests in South-east Asia, Brazil and equatorial Africa account for around 20 per cent of global CO2 emissions, about the same as from the transport sector.
Reflecting scientific warnings, G-8 leaders meeting in Italy last week agreed not to allow the global temperature to increase more than 2 degrees C above pre-industrial levels, although they made no binding commitments.
Two degrees C is seen as a threshold for severe, perhaps irreversible, climate change, including more extreme weather, food shortages, sea level rise and the extinction of some species of plants and animals.
On top of man-made temperature increase in South-east Asia and other parts of the world, weather forecasters are now predicting the return of El Nino, a natural cycle that occurs every few years, bringing drier-than-normal conditions, and sometimes drought, to South-east Asia.
It is not yet clear whether this El Nino will be moderate, as in 2002 and 2006, or severe, as in 1997-98 when fires that were started to clear land for plantations in Indonesia raged out of control for months, blanketing South-east Asia in a choking haze of pollution that cost an estimated US$9 billion (S$13 billion) in disruption and damages.
What made one of the region's driest seasons on record especially damaging was the prior draining and cutting of large areas of peatland forest, where the remains of past plant life have been submerged for centuries in water-saturated layers up to 20m thick.
Peatland covers over 27 million hectares of Indonesia, Malaysia, Brunei and Papua New Guinea, with around 83 per cent of that in Indonesia, mainly Kalimantan, Sumatra and Papua.
In recent years, surging global demand for timber, wood pulp, cooking and food-processing oil as well as biofuel has hastened the draining and conversion of previously ignored peatland for agriculture, particularly palm oil plantations.
Peatland is a major store of CO2. As it dries out, it oxidises and releases the gas. Worse still, it becomes susceptible to fire.
A team of United States and European scientists used satellites to measure levels of CO2 and carbon monoxide (a good indicator of the occurrence of fire) in the atmosphere above South-east Asia between 1997 and 2006. They published the results of their study in December.
They found that between 2000 and 2006, average CO2 emissions from the region accounted for about 2 per cent of global fossil fuel emissions and 3 per cent of the worldwide increase in atmospheric CO2.
But during moderate El Nino years in 2002 and 2006, when dry season rainfall was half of normal, CO2 emissions from fire rose 10 times.
In the severe El Nino of 1997-98, fire emissions from the region were much higher. They contributed 15 per cent of global fossil fuel emissions and 31 per cent of the global atmospheric increase of CO2 over the two-year period.
Other studies have also shown that if drought becomes more frequent with climate change, more fires can be expected in equatorial forests and peatland. As more CO2 is released into the atmosphere, it will thicken the blanket of heat-trapping gases near earth's surface, leading to more drying and more fires.
According to some recent computerised climate models, loss of tropical forests to fire, cutting and other causes could increase atmospheric CO2 concentrations by as much as 100 parts per million by the end of this century. This would be a significant increase, given that the level of CO2 in the atmosphere is currently about 380 parts per million, the highest in 650,000 years.
With a warmer world, many forested areas that have been storing carbon will instead release the gas. 'Essentially, we could see a forest-carbon feedback that acts like a foot on the accelerator pedal for atmospheric CO2,' Professor Chris Field, director of global ecology at Stanford University's Carnegie Institution, told the annual meeting of the American Association for the Advancement of Science in Chicago in February.
No one knows how strong any feedback will be. But if the looming El Nino cycle in South-east Asia turns out to be severe, it may be a harbinger of the region's climate future.
The writer is a visiting senior research fellow at the Institute of Southeast Asian Studies.
