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Carbon emissions from loss of intact tropical forest a ‘ticking time bomb’

  • When undisturbed tropical forests are lost the long-term impact on carbon emissions is dramatically higher than earlier estimates suggest, according to a new study.
  • Between 2000 and 2013, about 7 percent of the world’s intact tropical forests were destroyed, leading not just to direct carbon emissions but also “hidden” emissions from logging, fragmentation and wildlife loss.
  • Another key difference between the old and new estimates is that the latter take into account the diminished carbon sequestration potential of these forests.
  • The authors write that the indigenous communities who live in and protect about 35 percent of these forests will have a bigger role to play in the fight against climate change.

Losing undisturbed tropical forests is more devastating for the planet than previously thought, according to new research published in the journal Science Advances.

“Our results revealed that continued destruction of intact tropical forests is a ticking time bomb for carbon emissions,” lead author Sean Maxwell, from the Wildlife Conservation Society and the University of Queensland, Australia, said in a statement. “There is an urgent need to safeguard these landscapes because they play an indispensable role in stabilizing the climate.”

There were 549 million hectares (1.36 billion acres) of intact tropical forests in 2013, an area half the size of the U.S. Each of these patches of forest remains free of large-scale human interference observable by satellites and are at least 50,000 hectares (123,550 acres) in size. Though intact forests constitute only about 20 percent of all tropical forests, they lock away as much as 40 percent of above-the-ground carbon stored in tropical forests.

Forest in the Bolivian Amazon. Photo by Rhett A. Butler for Mongabay.
Primary tropical forests, like in this forest in Bolivia, store vast amounts of carbon and serve as habitat for perhaps half of the planet’s terrestrial species. Photo by Rhett A. Butler for Mongabay.

The researchers assessed the long term impact, through 2050, of the loss of 7.2 percent of intact tropical forests between 2000 and 2013. They found that the carbon footprint, direct and indirect, was more than six times greater than earlier estimates had suggested. When only emissions generated directly by forest clearing are taken into account, the carbon footprint is pegged at 338 million metric tons. The new paper revises this to nearly 2.12 billion metric tons. By comparison, forests in the U.S. sequester 236 million metric tons of carbon every year.

One of the crucial differences between the two estimations is the inclusion of carbon storage benefits that are relinquished when these forests are destroyed. “Intact tropical forests appear to be a net carbon sink, assume that this sink persists until 2050 and therefore account for this forgone carbon sequestration,” Yadvinder Malhi, a professor of ecosystem science at the University of Oxford and co-author of the paper, told Mongabay. “Conventional approaches just look at the immediate carbon stock loss.”

These earlier estimates also failed to capture the impacts of degradation due to selective logging, forest edge effects, and wildlife loss. Initial logging in previously undisturbed forests opens the way for further incursions and selective removal of the biggest, tallest trees from the forest, which also diminishes carbon sequestration potential.

Deforestation in Borneo. Photo by Rhett A. Butler.
Deforestation in Borneo. Photo by Rhett A. Butler.

Roads and pathways built to facilitate logging can intensify hunting pressure and precipitate the loss of animals critical to forest regeneration, such as elephants and hornbills. “Fragmentation results in the creation of edges where the microclimate changes and this seems to increase tree death and biomass loss,” Malhi said.

The study could prompt a reassessment of the importance of retaining intact forests for tackling climate change. It suggests that in programs like REDD+, which offer financial incentives for countries to keep their forests standing, the focus remains on deforestation frontiers — areas that historically report high rates of forest clearing — and not enough attention is paid to intact forest.

Tom Evans, another study co-author from the WCS, says these relatively undisturbed forests serve as refuges for biodiversity, protect watersheds, influence regional climates, and even safeguard human health, because the risk of disease transmission increases when forests are opened up.

At least 35 percent of the intact forests studied are home to and protected by indigenous peoples, who face a precarious future themselves. The ability of indigenous communities to protect their lands and the forests is constantly challenged; in recent months, the struggle by indigenous communities in Brazil to protect their land and their rights in the face of a hostile government has captured international attention.

Maxwell echoed the view that indigenous communities are at the center of the fight to protect these forests. “Intact forests are often critical to the material and spiritual aspects of traditional cultures, and strengthening the land tenure of Indigenous and traditional peoples is a powerful way to protect intact forests,” he said.

Lowland rainforest in Sulawesi’s Tangkoko Reserve, Indonesia. Photo by Rhett A. Butler for Mongabay.


Maxwell, S. L., Evans, T., Watson, J. E. M., Morel, A., Grantham, H., Duncan, A., … Malhi, Y. (2019). Degradation and forgone removals increase the carbon impact of intact forest loss by 626%. Science Advances5(10). doi:10.1126/sciadv.aax2546

Banner Image of tropical rainforest in Sulawesi, Indonesia, by Rhett A. Butler/Mongabay.

Malavika Vyawahare is the Madagascar staff writer for Mongabay. Find her on Twitter: @MalavikaVy

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