The final remnants of Borneo’s ancient forests, home to the world’s last remaining orangutans, have been ravaged by extreme rainfall events that scientists are directly linking to a warming climate. A new study led by researchers at the University of Cambridge, published today in *Nature Climate Change*, presents grim data: populations of the critically endangered Bornean orangutan have declined by up to 50% in regions hit by consecutive years of deluge, with flooding destroying nesting sites and food sources. The paper’s lead author, Dr. Helen Sharp, stated that the findings are a “clear signal” that even the most resilient species cannot adapt to the rapid pace of anthropogenic change. “We are witnessing a biological collapse in real time,” she said, her voice carrying the calm urgency that defines the scientific community’s response to this unfolding crisis.
The study analysed satellite data and ground surveys from 2015 to 2025, a period during which Borneo experienced a 300% increase in extreme rainfall events, exceeding the global average. These events, characterised by more than 200 millimetres of rain in 24 hours, trigger landslides and river flooding that can wipe out entire forest patches. The data reveals that orangutans, which rely on a steady supply of fruit, leaves, and bark, are unable to find sufficient food in the aftermath. “It’s like a bomb has gone off in their larder,” explained Sharp. “The trees that survive the flood are often stripped of their fruits by the torrent, and the remaining seeds rot in the saturated soil.” The decline is most severe in lowland areas, where deforestation for palm oil has already fragmented habitats, leaving the apes with nowhere to flee.
The British government’s chief scientific adviser, Sir Andrew Morley, has called for an immediate halt to palm oil imports from regions where deforestation is occurring, a move that would affect nearly a quarter of the UK’s supply. “We cannot claim to care about biodiversity while our consumption drives its destruction,” he said in a statement. But the fires and floods of the past decade have made one thing clear: conservation efforts alone are insufficient. The world’s average temperature has risen by 1.45°C above pre-industrial levels, pushing the hydrological cycle into a frenzy. For every degree of warming, the atmosphere can hold 7% more moisture, turning what were once once-in-a-century storms into annual occurrences. The result is a world where the very fabric of life, the biosphere, is being torn asunder.
The political will to address this crisis remains, however, as fragile as the peat swamp forests that the orangutans call home. At the COP30 summit in Brazil later this year, pressure is mounting for a global treaty that would penalise nations failing to meet their emission reduction targets. But as Sharp noted, “Even if we stopped all emissions today, the inertia in the system means we will still see decades of intensifying weather.” The technology for carbon capture and renewable energy exists, but the pace of implementation is sluggish. The United Kingdom, for example, has increased its wind capacity by 40% since 2020, yet still relies on gas for 30% of its electricity. The energy transition is a marathon, not a sprint, but for the orangutans of Borneo, time is measured in years, not decades.
The emotional toll on the scientists is palpable. “We are documenting the end of a species,” said Sharp, pausing to collect herself. “My children are the same age as some of the infants we’ve rescued from flooded villages. They ask me why the monkeys are dying. How do you explain climate change to a six-year-old?” The answer, perhaps, lies in the data. The study projects that under a business-as-usual scenario, the Bornean orangutan will be functionally extinct in the wild by 2050. To prevent this, global emissions must peak within five years and decline by 50% by 2035. A tall order, but one that the British scientists insist is achievable with existing technology. “There is no time for despair,” Sharp concluded. “Only action.”
