Significant drying and warming of the waters of Lake Teifi in 2023, reaching more than 40 °C in the entire water column at the monitoring site. credit: sciences (2025). doi: 10.1126/science.adr4029
During the extreme drought and heat wave of 2023, Amazon lakes reached the highest temperatures on record. Water temperatures in some areas rose to a staggering 41 degrees Celsius (105.8 degrees Fahrenheit), and led to the death of thousands of aquatic animals, including dozens of river dolphins.
Scientists have long known that the Amazon is warming, but 2023’s extreme event, caused by the worst drought on record, created water conditions deadly for some wildlife. The sight of more than 200 freshwater dolphin carcasses floating in Lake Teifi immediately prompted researchers to study bodies of water throughout the Amazon.
The team, led by Ian Fleischmann of the Mamiroa Institute for Sustainable Development in Brazil, conducted in situ measurements of 10 Amazonian lakes during the 2023 drought, and analyzed satellite data from 24 lakes to assess warming trends over three decades. In addition, scientists conducted hydrodynamic computer models to determine the exact causes of the extreme heat.
Life-threatening temperatures
According to the study, temperatures in five of the ten lakes monitored exceeded 37 degrees Celsius (98.6 degrees Fahrenheit). published In the magazine sciences. There were also large daily temperature fluctuations of up to 13 °C (23.4 °F), resulting in severe heat stress on fish and other aquatic animals.
Modeling revealed that a perfect storm of circumstances caused this environmental disaster. These were high solar radiation, very low water depth, turbid water (which absorbed sunlight rather than reflecting it), and low wind speeds.
Unfortunately, the heat reached the bottom of Lake Teifi, so the dolphins and fish couldn’t escape it. The 2023 drought also occurred amid warming Amazon lakes. According to the researchers, temperatures have risen by 0.6 degrees Celsius every decade over the past three decades.
Warning for the future
As climate change shows no signs of slowing down, life-threatening extreme temperatures may become more common. “These observations highlight major threats that are likely to affect people and biodiversity in the Amazon and other tropical waters in the coming years,” the researchers wrote in their paper.
Therefore, the study authors warn that urgent action is needed to monitor and protect these vulnerable areas. “Developing consistent, long-term ecological monitoring of vulnerable lake ecosystems such as Lakes Teifi and Kawari is essential for them to be effective sentinels of climate change and to develop management strategies of value to the people of the region.”
Written for you by our author Paul Arnoldedited by Gabe ClarkIt has been previously examined and reviewed Robert Egan– This article is the result of careful humanitarian work. We depend on readers like you to keep independent science journalism alive. If this report interests you, please consider a gift (especially monthly). You will get Ad-free An account as a thank you.
More information:
Ian Santos Fleishman et al., Extreme Warming of Amazon Waters in a Changing Climate, sciences (2025). doi: 10.1126/science.adr4029
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