Earth is always changing. Throughout the planet’s long history, continents have assembled and broken apart, climates have warmed and cooled, volcanoes have erupted, species have emerged, and others have retreated from the evolutionary stage. But recent research suggests that Earth’s future holds an extreme chapter that seems increasingly unavoidable: a steadily warming planet that pushes tropical regions—the areas with the richest biodiversity on Earth—toward becoming zones of intense heat that are nearly uninhabitable.
This research, which has sparked wide attention, is led by Alexander Farnsworth of the University of Bristol, together with scientists from several international institutions. Their study, titled “Climate extremes likely to drive land mammal extinction during next supercontinent assembly”, was published in October 2023 in Nature Geoscience. Using long-term climate models that integrate projections of continental shifts, increasing solar radiation, and changes in atmospheric carbon dioxide, the researchers attempt to visualize Earth’s climate roughly 250 million years from now, when all continents are expected to merge again into a new supercontinent known as Pangea Ultima.
Extreme in Tropics
Although the primary aim of the study was to understand whether mammals could survive under those conditions, the most compelling insight actually concerns a region very familiar to us, the tropics. According to their simulations, the tropics will experience extreme increases in heat and humidity that far exceed the tolerance limits of warm-blooded organisms and the ecosystems that depend on climate stability.
Under what the researchers call a moderate scenario, land surface temperatures rise sharply, while high humidity prevents heat from dissipating. This combination of heat and moisture is measured through the wet-bulb temperature, an indicator that reflects the body’s ability to expel heat. In the tropics, wet-bulb temperatures are already high under present-day conditions. A modest increase in temperature is enough to push tropical regions beyond biological comfort limits.
The researchers’ comments on this point are direct. Farnsworth explains, “The tropics naturally sit close to the physiological heat threshold. When you raise global temperatures even slightly, these regions quickly exceed biological comfort zones. The effects are very rapid and very severe.”
He also emphasizes that the tropics are not only hot but also humid, and this combination creates extreme heat stress far more dangerous than dry heat.
His colleague, Professor Benjamin Mills of the University of Leeds, adds that tropical regions on the future supercontinent will face a double burden. First, they will sit under stronger solar radiation, and second, they will lose the moderating influence of the oceans as landmasses expand.
“The interior of a supercontinent tends to become a giant hot desert,” Mills says. “But the tropical belt surrounding it would transform into an intensely hot-humid zone. These two combinations create a recipe for extreme climatic stress not seen on Earth for hundreds of millions of years.”
250 Million Years in The Future
These conditions arise not only because the climate of the future will be hotter, but because of natural geological and astronomical processes. As continents merge, much of the land will lie far from the ocean. Regions that today sit along lush coastlines—such as Southeast Asia, West Africa, the Amazon, and the Indonesian archipelago—would find themselves deep within the continental interior. Without the cooling influence of nearby seas, temperatures would soar. Models also show that by then the Sun will shine about 2.5 percent brighter than today, adding significantly more heat to Earth’s surface.
The result is a world that feels alien compared to the Earth we know today. Tropical rainforests, currently the planet’s lungs, would face intense thermal stress and prolonged drought. Major river systems would lose their sources of water. Tropical vegetation—highly sensitive to fluctuations in heat and moisture—may struggle to regenerate.
“What we see in these simulations is a world profoundly unfriendly to the tropical ecosystems we are familiar with,” Farnsworth notes.
Although these projections describe a world 250 million years in the future, their relevance to the present is surprisingly strong. The study underscores how deeply vulnerable tropical regions are to even the slightest changes in the global climate system. We already see the early sign, extreme heatwaves in South and Southeast Asia, oppressive humidity that makes heat feel unbearable, and tropical nights where temperatures no longer fall below 30°C. On a smaller scale, this pattern echoes the long-term supercontinent scenario, though at a much reduced intensity.
Farnsworth and his team remind us that life in the tropics—including human life—depends on a delicate climatic balance. The tropics may be the world’s biological epicenter, but they are also the regions that feel the impacts of warming the fastest. If the planet continues to heat up, the tropics will stand on the front lines of that transformation. And from here, the story of Earth’s hotter future begins. (Sulung Prasetyo)
Read also:
From mountains to oceans, delivered to you. Follow us on Lingkar Bumi WhatsApp Channel.
