New research suggests the greenhouse gas emissions impact of rainforest deforestation for palm oil plantations could be worse than thought.
For a study recently published in the journal Nature Communications, scientists from Ecole Polytechnique Federale de Lausanne (EPFL) and the Swiss Federal Institute for Forest, Snow and Landscape research (WSL) set out to determine the impact palm oil farming can have on the environment.
Palm oil is used as a feedstock for biofuels production, and in processed foods and cosmetics.
Using data gathered by University of Gottingen on the soil and vegetation in central Sumatra they compared the impact of oil palm monoculture with that of intensive and extensive rubber cultivation practices.
The team discovered that converting rainforest land into palm oil plantations leads to the biggest carbon emissions: one hectare of converted land equates to a loss of 174 tonnes of carbon, most of which will end up in the air as CO2.
“The quantity of carbon released when just one hectare of forest is cleared to grow oil palms is roughly equivalent to the amount of carbon produced by 530 people flying from Geneva to New York in economy class," said Thomas Guillaume, lead author of the study, in an EPFL press release.
This figure is higher than that published by the Intergovernmental Panel on Climate Change (IPCC) to quantify the amount of greenhouse gases emitted by oil palm farming.
Intensive rubber farming is associated with a loss of 159 tonnes, and extensive rubber production 116 tonnes. The difference with oil palms explained by rubber plants’ longer plantation rotation times. On the other hand, oil palm farming is more efficient in terms of the amount of biomass produced each year versus the loss of carbon.
Significantly, the study also found that with palm oil, the amount of palm oil that returns to the soil to feed living organisms in the ground is up to 90% lower than in a rain forest.
“The quantity of biomass that humans take away in order to produce palm oil compared to the quantity left for the ecosystem sheds real doubt on the sustainability of this form of farming,” Guillaume explains in a press release.
The study also delivers practical advice on lowering the short term impact of both rubber tree and oil palm monocultures. It sets out several considerations:
- Deforestation should be done only if the wood that is felled can then be used without being burnt
- A more abundant layer of vegetation should be left on the ground as a natural fertiliser
- The waste from palm oil mills should be returned to the soil as another form of fertiliser
Longer-term, Guillaume notes the OPAL project (Oil Palm Adaptive Landscapes), funded by the Swiss National Science Foundation and the Swiss Agency for Development and Cooperation. This project is studying the carbon footprint of oil palm plantations that do not require deforestation. For example, the team, led by Professor Alexandre Buttler, the director of EPFL’s ECOS lab, are researching plantations set up in grassland plains or in the savanna in Colombia, as well as intercropped plantations in Cameroon.