Deep within the dense, vibrant heart of the Amazon rainforest, a remarkable phenomenon exists that many would find difficult to believe: a river so hot it can boil. Known as the Shanay-Timpishka, which translates from the local indigenous language as “boiled with the heat of the sun,” this unique tributary in eastern-central Peru has temperatures reaching up to 200°F (93°C) in certain areas. Its waters, heated by geological cracks beneath the Earth’s crust, form part of the Amazon River’s vast network, but its environment is far from hospitable to most forms of life.
This boiling river is not only an extraordinary natural feature in its own right, but it also offers scientists an unprecedented opportunity to explore the potential impacts of climate change on tropical ecosystems. In recent years, biologists from the University of Miami have turned their attention to this heated waterway, studying how plant and tree communities are adapting to the extreme temperatures. Their findings suggest that the river may provide a glimpse into the future of tropical rainforests, including the Amazon, as climate change pushes global temperatures higher.
A Natural Laboratory for Climate Change
The unique characteristics of the Shanay-Timpishka make it a natural laboratory for studying the effects of rising temperatures on plant communities. In 2021, a team of researchers led by Riley Fortier, a graduate student in Professor Kenneth Feeley’s Jungle Biology lab, conducted an in-depth study of the area to investigate how temperature impacts forest composition. Their research, published in the journal Global Change Biology, highlights the river as a “window into the future” for understanding how tropical ecosystems could evolve as the Earth continues to warm.
Fortier explained the significance of their study by saying, “It really provides us a window into the future because the Amazon will get hotter whether we like it or not, so this allows us to understand what increases in temperature will do to the forest composition.” This statement encapsulates the core of the research: the boiling river offers a rare, natural example of how temperature shifts can affect plant diversity and forest ecosystems, offering clues to how tropical forests might adapt—or fail to adapt—under the pressures of climate change.
Mapping the River’s Impact on Forest Composition
In 2022, the research team returned to the region to extend their investigation, mapping the vegetation along the river from cooler, upstream areas to the hottest points near the boiling waters. The team surveyed 70 different locations along the river, using temperature sensors to monitor the varying degrees of heat and noting the types of plants and trees found in each area. The results were striking and revealing.
The team found that plant diversity sharply decreased as temperatures rose, particularly in the areas closest to the boiling river. Specifically, they observed an 11% decrease in tree diversity for each degree of warming. In the hottest sections of the river, only plant species that are highly adapted to warm, tropical climates were able to survive, making the river’s environment quite different from the rich, biodiverse jungles that characterize much of the Amazon.
Insights into Future Tropical Forests
The data collected from the boiling river suggests that global warming could have profound consequences for the future of tropical forests, particularly in regions like the Amazon. The team found that the composition of plant species changed significantly as the temperature increased, with cooler spots in the forest exhibiting much more plant diversity than the hotter zones. As temperatures rose, the forest became more homogeneous, with fewer species able to thrive.
One of the most surprising findings of the study was the directional shift in forest composition along the river’s path. As the temperature climbed toward the boiling river’s hottest section, the species diversity shrank rapidly, with many species that are commonly found in hotter parts of the Amazon replacing those typical of cooler, more humid regions. This transition occurred remarkably quickly—within less than a mile—signaling how sharply climate change could reshape ecosystems in a short time frame.
For Fortier, the quick shift in plant species was particularly striking. “We saw a very directional change in composition, where the hottest part of the forest along the river had a greater representation of species that grow in hotter areas of the Amazon,” he noted. “Then, there was a drastic change in species as you moved away from the hottest part of the river. Usually, you wouldn’t see such a clear change in the species composition over such a short distance.”
Drier, Scrubbier Vegetation in Hotter Zones
As the researchers moved closer to the boiling river’s hottest section, they noticed a stark contrast in the types of vegetation present. The hotter areas were drier and harbored more scrubby vegetation and vines than the lush, tree-dense areas farther upstream. The trees in these zones were also smaller and less diverse, creating an environment that resembled a transition zone between a forest and a savanna. Despite being within a small stretch of the jungle, the change in the landscape was stark and drastic.
“We saw a shift in vegetation that was so clear, it was like moving between two completely different ecosystems,” Fortier remarked. The team observed that the hottest parts of the forest, although still within the Amazon, seemed to resemble the savanna ecosystems typically found in hotter, drier parts of the world. Trees shrank in size, and plant diversity decreased sharply, much like what one might expect to find over dozens of miles in a typical forest, but all within just a mile of the boiling river.
The Uniqueness of the Boiling River as a Research Tool
What makes the Shanay-Timpishka even more valuable as a natural research system is its ability to isolate temperature as the key variable affecting plant communities. Unlike other regions of the Amazon, where changes in vegetation are influenced by multiple factors like rainfall, soil type, and humidity, the boiling river offers a natural environment where these other variables remain constant, and temperature is the dominant influence.
This allows researchers to isolate the effects of warming and observe how temperature alone impacts an entire ecosystem. Fortier highlighted this unique aspect of the research: “At the boiling river, the rainfall, soil, and humidity are constant, but what we see is that as global warming happens, everything will change.” This ability to study the isolated effects of temperature on forest communities makes the Shanay-Timpishka an unparalleled natural experiment in understanding the potential consequences of climate change.
Continuing Research and Global Implications
Fortier and his team are not finished with their work at the boiling river. Their findings are just the beginning of a more extensive, ongoing study into how extreme temperature fluctuations could reshape tropical ecosystems in the coming decades. As climate change accelerates, researchers will continue to monitor how these unique natural systems might offer further insights into the effects of warming on biodiversity and forest composition.
The boiling river’s exceptional nature also means it cannot be replicated in a laboratory or under controlled conditions. The “coolest” aspect of this natural system, Fortier argued, is that the river itself acts as a “natural experiment.” “You can’t heat a whole forest, at least not artificially,” he explained. “We can isolate temperature as having such an important effect on an entire plant community.”
As the Amazon rainforest—and rainforests around the world—face the threat of global warming, the Shanay-Timpishka is offering scientists a rare opportunity to glimpse into the future. By studying how this natural hotspot is changing, researchers can better predict how the Amazon and other tropical rainforests will cope with the increasing heat. Understanding the consequences of these temperature changes is critical, as tropical forests play a vital role in regulating the Earth’s climate by absorbing large amounts of carbon dioxide and providing habitats for countless species.
Conclusion
The boiling river of the Amazon is more than just a geological curiosity; it is a living laboratory that offers essential clues about how our planet’s ecosystems will react to the escalating temperatures caused by climate change. As global temperatures rise, tropical rainforests like the Amazon will likely face substantial changes, with profound effects on biodiversity and the broader environment. The unique conditions around the Shanay-Timpishka give scientists an invaluable opportunity to study how these changes could unfold, offering critical insights that could help guide conservation and climate mitigation efforts in the years to come.
Ultimately, the boiling river in Peru may be one of the most important places to watch as we seek to understand and prepare for the increasingly hot world that climate change is making a reality.
Reference: Riley P. Fortier et al, Hotter Temperatures Reduce the Diversity and Alter the Composition of Woody Plants in an Amazonian Forest, Global Change Biology (2024). DOI: 10.1111/gcb.17555