When a Rainforest Is Cleared for Palm Oil, a Jetliner of Carbon Is Produced

How much is 174 tons of carbon? 

A passenger jet.

The production of palm oil, the vegetable oil used in thousands of modern products, has immense environmental consequences, and a new study puts an exact figure on one aspect of it: 174 tons.

When rainforests are replaced with palm oil plantations, the clearing of one hectare (2.471 acres) of forest equates to the production of 174 tons of carbon, according to a study published Tuesday in Nature Climate Change. Much of that carbon is released into the atmosphere via CO2.

Used in biofuels, cosmetics, packaging, and food, palm oil production takes up an approximate 30 million hectares of land across the globe.

This domination of land use in the tropics (specifically the Indonesian island of Sumatra), a new study suggests, comes with a heavy environmental toll. Most of the carbon released from palm oil production turn into CO2, a greenhouse gas emission that contributes to climate change.

“Land use change is a commonly overlooked source of greenhouse gas emissions,” explains climate science researcher Rose Abramoff, Ph.D. to Inverse. Abramoff, a specialist in soil organic matter, was not a part of this study. “Soils are the largest pool of carbon on land, but they can also be very sensitive to disturbance.”

To put the new data another way, 174 tons of carbon is roughly equivalent to the amount of carbon produced by 530 people flying to Geneva from New York in economy class.

To get a sense of the scale, that’s one Air Bus Airbus A380 flying for Air France, which the airline outfits to carry around 515 people per flight.

For every 2.471 acres of rainforest that are replaced with palm oil trees, the same amount of carbon is produced as "530 people flying from Geneva to New York in economy class."
For every 2.471 acres of rainforest that are replaced with palm oil trees, the same amount of carbon is produced as "530 people flying from Geneva to New York in economy class."

Despite the recent dip in Malaysian palm oil price value, its lowest in two years, palm oil production remains high — that drop was largely driven by changing energy prices.

The study’s lead author, Thomas Guillaume, Ph.D., a postdoctoral researcher a EPFL and the Swiss Federal Institute for Forest, Snow, and Landscape Research, tells Inverse that while most studies on this subject are on specific components of Sumatra’s ecosystem, “our strength was that all data had been collected on the same research sites, giving a comprehensive overview.”

Sumatra, Indonesia
Lead author Thomas Guillaume collecting samples in Sumatra, Indonesia.

Guillaume presses that this study emphasizes the importance of carbon loss in soil. Soil sucks in and acts as a sink for greenhouse gases, including CO2, methane, and nitrous oxide. As demonstrated here, deforestation and land use change can cause carbon loss in the soil, which then enters the atmosphere.

Scientists estimate that approximately two-thirds of the total increase in atmospheric CO2 is caused by the burning of fossil fuels, while the remainder stems from soil organic carbon loss.

“The dark, secret world hidden beneath our feet”

“The dark, secret world hidden beneath our feet is an important, but perhaps easy to overlook, component of the global carbon cycle,” says ecosystem ecologist Colleen Iversen, Ph.D., who was not a part of this research. “There is more carbon stored below ground in the soil than in plants and the atmosphere combined. As this study shows, the conversion of tropical rainforest to agricultural use can result in a loss of carbon from the soil to the atmosphere, which in turn can contribute to the warming of the planet.”

Guillaume and his team came to the realization that one hectare of land converted means the loss of 174 tons of carbon by collecting two years’ worth of data on the soil and vegetation in Sumatra. Malaysia and Indonesia account for 85 percent of global palm oil production and in 2012, Indonesia was determined to have the highest deforestation rate in the world.

deforestation
Land cleared for palm oil plantations in Borneo, Indonesia.

The research team measured carbon pools 50 centimeters deep into the forest floor, and compared that data to carbon measurements pulled from replicate plots that contained things like litter decomposition and dead wood. After synthesizing the data, they looked at the carbon fluxes established by other research groups that had worked in the same Indonesian plots — a process that revealed the carbon rate loss from palm oil production, as well as the additional losses from rubber farming (which equates to a loss of 159 tons of carbon).

The loss estimate established here, the study authors write, is higher than previous estimates used by the Intergovernmental Panel on Climate Change (IPCC) to quantify the rate greenhouse gases emitted by oil palm farming and the figure used by sustainable palm oil certification groups. The later is integral to balancing what is environmentally feasible to the needs of farms: Tropical countries rely on oil palm crops to increase their economic welfare.

Those numbers, Guillaume explains, “are quite old” and based off a few studies and a lot of uncertainty. This study joins a growing body of research published in the past few years, establishing the rate of soil carbon losses.

“I don’t know what will happen now, but the inertia of the politics over scientific findings is quite important,” Guillaume asserts. “A former professor of mine was saying that, in Switzerland, scientific findings take 20 years to reach the politics.”