Palm oil production may have many benefits, but rapidly increasing plantation comes at a high cost to local and global environments.
Palm oil makes a big contribution to modern life as one of the most-widely used substances in food, cooking, cosmetics, medicines and a range of chemicals. But the industry that produces it is seriously harming the planet.
That is the conclusion of a study of nearly 1,000 scientific papers about oil palm plantations, published in Biological Reviews journal.
Over the last few decades, the scale of destruction of forests and peat lands so as to expand the highly-profitable oil palm plantations − mainly in Southeast Asia − has been immense.
Although deliberately starting fires to clear pristine forests for plantations is illegal, the practice still continues and has contributed to serious air pollution across the region, causing breathing difficulties.
Oil palms are now a highly-profitable cash crop grown throughout the humid tropical lowlands in 43 countries, with 18.1million hectares in cultivation. Indonesia (7.1m ha) and Malaysia (4.6m ha) account for 85 per cent of global production, and the number of their plantations is steadily increasing.
Although the study − by Germany’s University of Göttingen, and Helmholtz Centre for Environmental Research (UFZ), and Bogor Agricultural University in Indonesia − accepts that the plantations provide food and many other useful products, the harm they cause to the planet is undeniable.
Their defenders say the growing palm trees reduce the carbon dioxide in the atmosphere. But the researchers counter that this never compensates for the losses incurred when the forests were cleared in the first place.
This is particularly true when plantations are on land previously occupied by peat bogs. The CO2 produced when the land is drained can never be offset by growing trees, the report says.
Apart from these increased greenhouse gas emissions, the plantations also emit volatile organic compounds, precursors to ozone, which is itself a serious air pollutant near ground level.
Because the structure of a plantation differs from that of a forest, it will have higher air and soil temperatures at ground level – as much as 6.5°C – and lower air humidity.
“Risks of flooding, drought, landslides, and wildfires are all higher in oil palm plantations and surrounding areas than in forests and their surroundings,” the report says.
Plantations can also badly affect water supplies − both the storage of water and its quality in streams and rivers. Forests store more water in soil and foliage, and when they release it to streams it is cleaner. Because oil plantations are susceptible to drought during dry periods, growers have to resort to irrigation.
Peat acts as a giant sponge, slowly releasing water, so draining it worsens the impact of a plantation. Its loss can lead both to flooding and drought.
Because the run-off from plantations after heavy rain is far greater and the soil is not held in place by undergrowth, the water picks up sediment. This can be a severe threat to the health of rivers, as well as causing serious erosion.
The negative effects of destroying peat bogs for plantations are irreversible, but the study says they can sometimes be mitigated. Measures such as planting an understory of vegetation − the underlying layer of vegetation between the forest canopy and the forest floor − can reduce the worst effects and improve water storage and quality.
Palm oil products
The study looks at other consequences of oil palm plantations, including the many products that the oil is used for. Palm oil is the clear choice for many manufacturers. It grows from three to eight times better than rapeseed and soya, for instance, depending on the growing conditions. And this proportion could be improved even further, scientists say.
But the study points out that the forests’ destruction means the loss of many of their products and services − for example, many timber and fruit trees. This can have adevastating effect on indigenous peoples living in the forests.
One of the biggest losses is in medicinal plants. Over 2,000 southeast Asian forest species are used in women’s healthcare, and Indonesian local healers use more than 250 medicinal plants.
Although many of the worst effects of oil plantations − for example, burning forests and draining peat bogs − are now discouraged or banned, they still persist, prompting demands for more enforcement. Researchers also say much more work is needed on how to mitigate the plantations’ effects.