Peatlands, especially those in tropical regions, sequester gigantic amounts of organic carbon. Human activities are now having a considerable impact on these wetlands. For example, drainage projects, in combination with the effects of periodic droughts, can lead to large-scale fires, which release enormous amounts of carbon dioxide into the atmosphere, and thus contribute to global warming.
Using laser-based measurements, Florian Siegert and his research group at Ludwig-Maximilians-Universität (LMU) in Munich have estimated the volume of peat burned in such fires with unprecedented accuracy.
Our work once again underlines the decisive role played by acutely endangered tropical wetland ecosystems in the context of global warming, said Siegert. The study also provides important data for the upcoming World Climate Conference in Copenhagen. One of the goals of that meeting is to reach agreement on how financial and other incentives can be employed for the protection of tropical wetlands, and so help preserve their enormous capacity for carbon storage.
Over the course of millions of years, plant material can be converted into coal. The first step in this process leads to the formation of peat, an organic material that is combustible and is harvested for heating purposes in many parts of Europe. As a condensed form of plant mass, peat is also an important storage form of carbon at near-surface levels.
It is estimated that, in the tropics, peat swamps cover an area of 30 to 45 million hectares, said Siegert. This corresponds to about 10 per cent of the total area of peatlands in the world, and means that tropical peatlands represent one of the largest near-surface storage sites for organic carbon that we have.
Almost half of all that tropical peatland is located in just one country: Indonesia.
Many of the coastal peatlands on Borneo formed over 20,000 years ago. Since that time as in most tropical peatlands convex domes of peat, up to 20 metres thick, have developed. They serve as the basement layer of tropical peat swamp forests and possess a huge capacity for storing carbon. In fact, the total amount of carbon locked in the peatlands of Indonesia alone is thought to be more than 50 gigatonnes.
These areas, though, are in imminent danger. Left in their natural state, they are simply too wet to burn. But drainage measures and deforestation disturb their ecological equilibrium and make them vulnerable to fire, which is almost always caused by human activities. Private companies often exploit fires to prepare the ground for the establishment of large-scale plantations for the production of wood pulp and palm oil,.
Such fires are doubly dangerous. The smoke they produce contains tremendous amounts of aerosols and toxic gases, which can lead to serious health problems in many areas of Southeast Asia. Furthermore, the soil-bound organic carbon is transformed into carbon dioxide, a greenhouse gas that plays a leading role in global warming.
These problems are made even worse during dry periods that increase the combustibility of the peat. For instance, during the drought associated with the El Niño phenomenon in 1997-98, up to 2.57 gigatonnes of carbon was released from the wetlands of Indonesia alone.
The regular occurrence of large-scale forest fires alone makes Indonesia one of the largest producers of atmospheric CO2 in the world. However, this significant source of emissions has yet to be taken into account by the Intergovernmental Panel on Climate Change (IPCC) or incorporated into computer models of regional and global climate.
(G)rowth of the market for palm oil, stimulated by increased demand for cheap biofuels, will make the situation worse, as the incidence of fires this year has already shown, Siegert said. This is something that should have repercussions for European policies in the area of renewable energy sources. Also on the agenda in Copenhagen are programmes such as REDD (for Reduced Emissions from Deforestation and Degradation in developing countries), which is designed to provide monetary incentives aimed at protecting tropical peat swamp forests and their giant carbon stores.