More than 30% of Borneo's rainforest was destroyed in the four decades after 1973, according to a Landsat satellite study published in PLoS ONE.1 Bornean orangutans lost much of their habitat too: one study estimates a loss of about 148,500 individuals between 1999 and 2015.2
Key points
- Borneo lost more than 30% of its rainforest between 1973 and 20101
- Sabah lost the largest share (40%); Kalimantan, the Indonesian part, lost the largest area (123,941 km²)1
- Oil palm and timber plantations covered about 10% of the island by 20101
- At least 271,819 km of logging roads were opened between 1973 and 20101
A note on dates: the most detailed island-wide measurements we can verify end in 2010. This post uses them as the long-run baseline. For recent Indonesian figures, see deforestation in Indonesia.
The numbers: who lost what
Borneo is shared by three countries: Indonesia (Kalimantan), Malaysia (Sabah and Sarawak) and Brunei. The study found large differences between them.1
What cleared the forest
By 2010, industrial oil palm covered 64,943 km² of Borneo and timber plantations another 10,537 km², together about 10% of the island.1 Many of those plantations stand where rainforest used to be. See the true cost of palm oil for how that connects to what we buy.
Logging opened the way. The study mapped at least 271,819 km of logging roads built between 1973 and 2010.1 Roads let loggers in, and then farmers, hunters and fire. For the full list of drivers worldwide, see the causes of deforestation.
The orangutan question
A 2018 study in Current Biology compared nest counts across Borneo and estimated a loss of about 148,500 orangutans between 1999 and 2015. It projected at least 45,300 more by 2050 if current trends continue.2
The cause is not only lost forest. The study's authors point to habitat loss as the main driver, very likely accompanied by killing. In primary and selectively logged forests, which accounted for 67% of the total loss, they saw a large role for killing.2 Protecting the trees alone is not enough; protecting the animals living in them matters too. Read more on Indonesia and its orangutans.
What would help
The pattern across Borneo is that forest loss follows roads, concessions and plantations. That points to the same solutions as elsewhere: protect the forest that remains, hold supply chains to account, and restore degraded land. See solutions to deforestation, and compare with how Brazil cut Amazon clearing to a record low.
Watch the film to see what is at stake, then choose how the story ends.
Questions people ask
How much of Borneo's rainforest has been lost?
More than 30% between 1973 and 2010, according to a satellite study. Sabah lost about 40% of its 1973 forest, Kalimantan 31%, Sarawak 23% and Brunei 8%.1
What is causing deforestation in Borneo?
Industrial oil palm and timber plantations covered about 10% of the island by 2010, and logging roads, at least 271,819 km of them, opened up remote forest.1
How many Bornean orangutans have been lost?
A 2018 study estimated a loss of about 148,500 between 1999 and 2015, and projected at least 45,300 more by 2050 under current trends.2
Which part of Borneo lost the most forest?
Kalimantan lost the largest area, 123,941 km², and Sabah lost the largest share, about 40% of its 1973 forest.1
Sources
- Mongabay (2014). 30% of Borneo's rainforests destroyed since 1973, reporting Gaveau, D.L.A. et al. (2014), Four decades of forest persistence, clearance and logging on Borneo, PLoS ONE. Accessed 22 October 2026.
- Mongabay (2018). Borneo, ravaged by deforestation, loses nearly 150,000 orangutans in 16 years, study finds, reporting Voigt, M. et al. (2018), Current Biology. Accessed 22 October 2026.