From oil palm to sugar to coffee and cocoa, commercial agriculture is expanding across the tropics, destroying valuable tropical rainforests, which store immense amounts of carbon and support half of the Earth’s plants and animals; at the same time, responsible producers are looking for solutions. 

Findings published today in the journal Conservation Letters show commodity crop producers how and where they can redirect crop production to minimize environmental damage to remaining tropical rainforests.

Researchers at RESOLVE, Woods Hole Research Center, World Wildlife Fund, and University of Minnesota have identified 125 million hectares (309 million acres) of degraded lands that could support expansion of commercial agriculture for another 25-50 years without clearing more pristine rainforest. About half of this area is in tracts larger than 5,000 ha and below 500 meters elevation, prerequisites for commercial-scale oil palm production, the fastest-growing industrialized commodity crop in the tropics.

Limiting commodity crop production to these already-degraded areas will keep over 13 billion tons of CO2 from entering the atmosphere – almost enough to fuel the world’s coal power plants for a year.

“The simplicity and transparency of this easily-monitored metric could prove useful to producers, governments, investors, environmental stewards, and consumers and enhance good governance in tropical regions,” said the study’s lead author, Eric Dinerstein, Director of RESOLVE’s Biodiversity and Wildlife Solutions program and senior fellow at the World Resources Institute.

Over the last century, industrial-scale agriculture has expanded rapidly into tropical rainforests.  The loss of trees degrades the structure of the forest – far fewer species can survive in areas after the trees have been cut – and the clearing of tropical rainforests causes roughly 10-15% of global human-caused carbon emissions.  Redirecting the planting of oil palm and other crops to areas already damaged by logging would substantially lower carbon emissions and the loss of rainforest species.

Co-author Alessandro Baccini, Associate Scientist at Woods Hole Research Center, explained, “The accurate estimates of carbon density in this new data set provide a strong foundation for estimating carbon emissions from forest loss across the tropics and can guide development away from areas of high forest carbon density.”

To identify the degraded areas, the study used a measure of the amount of carbon stored in trees in tropical rainforests (which differs from the amount of carbon stored in other ecosystems), called Above Ground Carbon Density (AGC).   Intact tropical rainforests have an AGC of approximately 250 metric tons per hectare (2.5 acres), a figure that decreases as trees are cut down.  Areas considered in this study to be degraded were those with an AGC of 40 metric tons or less, a value agreed-upon by various organizations and oil palm producers as a guideline to avoid clearing high-carbon forests, as these tend to be the places with the highest diversity of plants and animals as well.

The researchers added several safeguards that excluded protected areas, steep slopes, existing urban areas and agriculture, and sites with rare habitats or species found nowhere else from consideration.

Production of three key crops – oil palm, sugar cane, and natural rubber – alone is projected to increase 17% to 29%, and the estimated 60-66 million hectares (148-163 million acres) needed to accommodate the increase could easily fit within the degraded, low-carbon lands identified in this study for years to come.

A key point in this analysis is that it not only guides commodity production away from sensitive, high-biodiversity areas but also provides alternative locations for production, toward lands that are already low in carbon and biodiversity yet still suitable for agriculture.  These systems are complex and, once they have been degraded, may take decades, or centuries, to recover. 

In commenting on the analysis, Nigel Sizer, Global Director of World Resources Institute’s Forests Program said, “The study’s concrete recommendations will help to guide commodity producers, some of which are already taking steps to reduce their environmental footprint. By redirecting projected expansion to areas of lower conservation value,  producers can help ensure more responsible and sustainable supply chains.”