Excessive logging threatens Asian peat swamps and global carbon levels

Satellites have detected large amounts of carbon dioxide released into the atmosphere by the 1997 fires in Indonesia’s tropical bush. An international study shows that recurrent fires from poor logging practices on Asian peat land could continue to boost atmospheric CO2 levels and destroy Borneo’s peat swamps.

A team of European and Indonesian scientists used satellite imagery to measure the amount of CO2 gas released from fires in Southeast Asia. Extended drought from reduced rainfall caused by the El Niño weather phenomenon, combined with poor land management, was thought to have triggered the 1997 Indonesian fires that released a yellow haze covering thousands of kilometres for months.

Estimates of the economic damage to Asia totalled more than €2 billion.

The study, published in the latest issue of Nature, focused on Asian tropical peat swamp forests which have peat layers up to 20 metres deep. Because of the high carbon content of the soil, surface fires spread underground into the peat layer, burning incompletely and producing huge amounts of smoke and fine particles. The peat swamp forests represent approximately 40% of the total area burned in Indonesia.

Scientists compared images and data from 2.5 million hectares of land before and after the 1997 fire. They found that the fires released upwards of 2.57 gigatonnes of carbon, 40% of the mean carbon emissions released annually from fossil fuels. The fires thus contributed to the largest annual increase in atmospheric CO2 since records began in 1957, says the report.

Recurrent fires may see tropical peat stores continuing to release huge amounts of carbon, warns the report. “Forests in Indonesia have again been burning during this year’s extended dry season, caused by a weak El Niño weather event,” says Dr Florian Siegert, managing director of Remote Sensing Solutions GmbH. “Unfortunately the world does not pay attention to that.”

However, the team argues that dried-out peat swamps will not necessarily catch fire, even after three months without rain – a typical El Niño effect. Fires are most likely to be triggered from a combination of drought and poor land use practices, such as excessive logging and swamp drainage, that make peat ecosystems susceptible to fire.

The report concludes that unless land use policies are tightened to control logging, recurrent fires will lead to a complete loss of Borneo’s peat swamp forests and continued high emissions of CO2. Scientists are calling for intensive national and international efforts to avoid further fires in the tropical peat swamp forests in Southeast Asia.

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