Palm oil is the elephant in the greenhouse

Posted Wednesday, 6 June 2018, 11:49

Palm oil isn’t as bad for climate as you think. It’s worse.

The oil palm industry is expanding quickly into tropical rainforest, and increasingly into peat swamp forest. The total land area planted with oil palm in Indonesia and Malaysia, where almost the entire world’s supply of palm oil is grown, has more than doubled since 2000 to nearly 17 million hectares in 2015. This is terrible for orangutans, indigenous peoples, and especially the climate. Besides housing some of the most bio-diverse ecosystems in the world, Indonesia’s forests hold large carbon stocks – but that’s nothing compared to what’s in the soil. One-third of all new oil palm plantations expand onto waterlogged peat soils packed with preserved organic matter accumulated over millennia. When peat soils are drained for oil palm plantations, the greenhouse gas (GHG) emissions are several times larger than the carbon loss from the forest biomass when averaged over 30 years.

The GHG emissions from palm-driven land use change are so big they contribute significantly to global warming. In a back-of-a-large-envelope calculation using the data sources in the table below, we can estimate total land use change emissions from palm oil in Indonesia and Malaysia, as well as their share of global net GHG emissions in the figure. We see that palm oil emissions as well as their contribution to global warming have been rising as the oil palm industry has continued to expand. Averaged over the last three years for which data is available, palm-driven land use change in Indonesia and Malaysia has emitted roughly 500 million tonnes of CO2e each year, contributing 1.4% of global net CO2e emissions. This is almost as high as global emissions from the aviation sector and more than the total GHG emissions from the state of California.

Palm oil contribution to global warming

The worst part of this scenario is that the massive climate impact of palm oil is completely unnecessary. A good chunk of palm oil is used to produce biofuels, where it actually increases GHG emissions from the transport sector compared to petroleum. No other major oil crop in the world has a carbon footprint as bad as palm. And even palm oil itself could be produced much more sustainably if the Indonesian government would enforce moratoriums on deforestation and peat conversion. Global palm oil demand continues to rise, and if nothing is done to change course, the palm oil problem is going to make it increasingly hard to meet any kind of climate target.

 

Assumptions and data sources used in this analysis
Category Parameter Value used in analysis Sources
Oil Palm Expansion Total planted oil palm area in Indonesia 3.9-11.3 million hectares from 1999-2015* Indonesia Central Bureau of Statistics
Total planted oil palm area in Malaysia 3.3-5.6 million hectares from 1999-2015 Malaysia palm oil board
Area of oil palm on peatland 0.3-3.1 million hectares from 1990-2015 Miettinen et al. (2012) and Miettinen et al. (2016)
Share of oil palm expansion on peat 19-33% Searle (2018)
Natural biomass loss Primary (virgin) forest: above-ground carbon loss from conversion 350 dry tonnes biomass per hectare IPCC 2006 Guidelines for National Greenhouse Gas Inventories: Forest. Value for tropical rainforest Asia insular from Table 4.7
Secondary (degraded) forest: above-ground carbon loss from conversion 175 dry tonnes biomass per hectare IPCC (2006). Assumed to be the same as the average value for tropical rainforest plantation Asia broadleaf and Asia other from Table 4.8
Root: above ground biomass ratio for forest; 0.37 IPCC (2006). Value for tropical rainforest from Table 4.4
Grassland: above and below-ground carbon loss from conversion 12.4 tonnes dry biomass per hectare IPCC (2006): Grassland. Average value for tropical dry and tropical moist & wet from Table 6.4
Primary forest loss as share of total land expansion for oil palm 0.35 Assumed to be half of total expansion on forest and “other land” in Southeast Asia in palm biodiesel scenario in Valin et al. (2015), page 63
Secondary forest loss as share of total land expansion for oil palm 0.35 Assumed to be half of total expansion on forest and “other land” in Southeast Asia in palm biodiesel scenario in Valin et al. (2015), page 63
Grassland loss as share of total land expansion for oil palm 0.3 Remainder of land
Carbon content of biomass 0.47 Default value from Table 4.3 from IPCC (2006)
Conversion: carbon to CO2 3.67 Molecular weight of CO2 (44) divided by molecular weight of carbon (12)
Plantation biomass increase Above-ground carbon gain from oil palm trees 24 tonnes carbon per hectare Murdiyarso et al. (2010)
Root: above ground biomass ratio for oil palm 0.37 Assumed to be the same as for forest
Soil carbon Area-weighted average soil carbon stock for mineral soils in Asia 36 tonnes carbon per hectare Calculated using data from the Harmonized World Soil Database, data downloaded in 2011
Share of mineral soil carbon stocks lost upon land conversion 0.13 Value for native forest to plantation conversion from Guo & Gifford (2002)
Peat soil: carbon loss from conversion 95 tonnes CO2e per hectare per year Value using 30-year amortization from Page et al. (2011)
Global CO2 emissions   25-36 billion tonnes CO2e per year from 2000-2015 CO2.earth, U.S. EPA, and Pidcock (2016)

*Note: range reflects values over time, for example total planted oil palm area in Indonesia was 3.9 million hectares in 1999 and 11.3 million hectares in 2015.