Forest on Borneo in Indonesia, cut down for an oil palm plantation JAMI TARRIS/MINDEN PICTURES

News from Science | Article By Erik Stokstad

A new analysis of global forest loss—the first to examine not only where forests are disappearing, but also why—reveals just how much industrial agriculture is contributing to the loss. The answer: some 5 million hectares—the area of Costa Rica—every year. And despite years of pledges by companies to help reduce deforestation, the amount of forest cleared to plant oil palm and other booming crops remained steady between 2001 and 2015.

The finding is “a really big deal,” says tropical ecologist Daniel Nepstad, director of the Earth Innovation Institute, an environmental nonprofit in San Francisco, California, because it suggests that corporate commitments alone are not going to adequately protect forests from expanding agriculture.

Researchers already had a detailed global picture of forest loss and regrowth. In 2013, a team led by Matthew Hansen, a remote-sensing expert at the University of Maryland in College Park, published high-resolution maps of forest change between 2000 and 2012 from satellite imagery. But the maps, available online, didn’t reveal where deforestation—the permanent loss of forest—was taking place.

For the new analysis, Philip Curtis, a geospatial analyst working with The Sustainability Consortium, a nonprofit headquartered in Fayetteville, Arkansas, trained a computer program to recognize five causes of forest loss in satellite images: wildfire, logging of tree plantations, large-scale agriculture, small-scale agriculture, and urbanization. To teach the software, Curtis spent weeks staring at thousands of images from Google Earth that showed deforestation with a known cause. “It was some of the most distressing part of the work,” he says, especially when looking at Southeast Asia. “The scale of the loss was staggering.”

All told, about 27% of the total loss between 2001 and 2015 was due to large-scale farming and ranching

The program’s decisions were based on mathematical properties of the images, which can help distinguish the larger blocky shapes of industrial agriculture from the smaller, irregular fields in shifting subsistence farming, for example. All told, about 27% of the total loss between 2001 and 2015 was due to large-scale farming and ranching, Curtis and his colleagues report today in Science. Such farming includes industrial plantations for palm oil, a valuable biofuel and a major ingredient in food, cosmetics, and other products. Forest cleared for those plantations is gone for good, whereas forest cleared for other purposes, including small-scale farming, typically grows back. (Urbanization, also a permanent conversion, made up just 1% of the total loss of forest.)

Deforestation from commodity-driven agriculture held steady between 2001 and 2015, the span of the analysis. But the trends vary by region. In Brazil, large swaths of Amazonian forest have been cut down for cattle ranches or soybean farms. The good news is that the rate of deforestation there fell by half between 2004 and 2009, because of enforcement of environmental laws, pressure from purchasers of soybeans, and other factors. But in Malaysia and elsewhere in Southeast Asia, laws against deforestation are often lacking or poorly enforced, and ever more forests have been cut down for palm oil plantations. “We’ve known this [was happening], but we didn’t have the numbers to show it consistently across the globe,” Curtis says.

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