Tropical peatlands 'haemorrhage' fossil carbon

EMBARGOED until 1800 GMT on Wednesday 30 January
The quantities of carbon dioxide leaking out of deforested peatlands in south-east Asia constitute “a globally significant environmental disaster”, scientists say. 

LONDON, 30 January – Deforestation is causing carbon dioxide to leak from tropical forests far faster than anyone had suspected, says a team of scientists who have studied the process in south-east Asia.

The team, led by researchers from the UK’s Open University, say what is happening is a little-known problem which amounts to a disaster of worldwide significance. Their study is published in the journal Nature.

Tropical peatlands, with their high water tables and low decomposition rates, store huge quantities of organic carbon tens of metres thick. Most of these peatlands are in Indonesia, where the natural swamp forests are increasingly being felled for timber and to allow food to be grown.

Once felled, the forests are often drained and burnt.  A common crop is oil palm, used in food and particularly valuable as well for producing biofuels.

Dr Sam Moore, lead author of the study, says: “We measured carbon loss in channels draining intact and deforested peatlands, and found it is 50% higher from deforested swamps.

Ancient deposits vanishing

“Dissolved organic carbon released from intact swamps mainly comes from fresh plant material, but carbon from the deforested swamps is much older – centuries to millennia – and comes from deep within the peat column.”

Dr Vincent Gauci, senior lecturer in earth systems and ecosystem science at the Open University, and one of the study’s authors, said: “The destruction of the Asian peat swamps is a globally significant environmental disaster, but unlike deforestation of the Amazon, few people know that it is happening”.

“The scary part of what is happening is the age of the carbon that’s being lost”

Carbon lost from the drainage systems of deforested and drained peatlands is often not considered in ecosystem exchange carbon budgets, but the researchers found it increased the estimated total carbon lost from deforested peatlands by 22%

Changes in the water cycle seem to be the main driver of this increase.  Much of the rain that falls would normally leave the ecosystem through transpiration in vegetation, but deforestation forces it to leave through the peat, where it dissolves fossil carbon on its way.

Dr Gauci told the Climate News Network: “The scary part of what is happening is the age of the carbon that’s being lost.

“No-one had realised before now the real extent of the loss, because researchers had looked only at how much carbon was being lost from the land surface. Now we can see that fossil carbon is disappearing too.

Better off burning fossil fuels

“The pressure on south-east Asia for food, timber and oil palm is huge. Carbon loss following deforestation is also under way in Latin America, though it is not too severely affected yet.”

Dr Gauci said the team had been prompted to investigate what was happening in south-east Asia by studies of peatlands in high northern latitudes, including the UK, which revealed a similar process at work.

Long-term research in this area by a co-author of the report, Professor Sue Page, has shown that clearing and draining these ecosystems to grow biofuels is essentially pointless.

Dr Gauci said: “It’s really no better to grow oil palm to produce biofuels than to to use the fossil fuels they are intended to replace.

“It releases more carbon dioxide into the atmosphere than the fossil fuels would have done, and it destroys biodiversity, including the orang-utans.” – Climate News Network

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