A team of international researchers, led by Clifton Sabajo and Alexander Knohl from the University of Göttingen in Germany, published a new study showing that the growth of oil palm and other cash crops in Sumatra, Indonesia has made the region warmer.
“Land use change from forest to cash crops such as oil palm and rubber plantations does not only impact biodiversity and stored carbon, but also has a surface warming effect, adding to climate change,” says Knohl, who is a professor in bioclimatology.
Palm oil which is the most widely used vegetable oil in the world, appears in the ingredients’ list of many consumer goods, from chocolate to soap.
The team used satellite data collected between 2000 and 2015 by the NASA Landsat missions and the MODIS instrument, as well as data collected on the ground to study the differences between in surface temperature for various types of land cover, such as forests, clear-cut land, and cash crops, in the Jambi province of Sumatra.
They found that clear-cut land, which is mainly used for agriculture, was up to 10 °C warmer than forests.
“Clear-cut land is the phase between forest and other land cover types, such as small-holders [small-scale family farms] or commercial plantations,” says Sabajo.“From field observations, we know that the landscape is so dynamic that there are continuous land use changes all the time, so clear-cut land is always present.”
“We compared the average land-surface temperature increase in the province with a site that was covered by forest over the entire period and that can be considered as a control, unaffected by direct land-use change. The land-surface temperature of the forest sites (at 10:30am) only increased by 0.45 °C, suggesting that at least 0.6 °C of the 1.05 °C increase is due to land-use change,” says Knohl.
“The strong warming effect we show for the Jambi province may serve as an indication of future changes in land-surface temperature for other regions of Indonesia that will undergo land transformations towards oil palm plantations,” the scientists write in the study. The Indonesian government plans to substantially expand the country’s production of oil palm, as the demand for this product increases around the world.
“We think that current land-use developments in Indonesia need to carefully evaluate all aspects of environmental and socio-economic consequences. Land-surface temperature and microclimate should be considered,” says Knohl.
The research is part of a large German-funded project, the Collaborative Research Centre 990: Ecological and Socioeconomic Functions of Tropical Lowland Rainforest Transformation Systems (Sumatra, Indonesia).
Read more on https://www.biogeosciences.net/14/4619/2017