The historic drought and heat wave that struck the Amazon in 2023 led to alarming warming in its waters, presenting dire consequences for local ecosystems and communities. A recent study published in *Science* reveals that temperatures in key lakes soared to lethal levels, particularly affecting fish and river dolphins.
Extreme Temperature Peaks
Many might assume that heat waves dissipate without lasting effects. However, the reality in the Amazon was starkly different. Monitoring of ten lakes indicated that five of them surpassed 37ºC during the day, while one recorded an unprecedented 41ºC—akin to a spa pool. This extreme heat extended down to approximately two meters deep, eliminating any cooler zones for aquatic life.
Lake Tefé: The Heart of the Crisis
Lake Tefé, typically spanning over 7 km in width, captured national and international headlines when its surface area dwindled by 75% from September to October 2023. This drastic shrinkage startled both residents and wildlife alike. Coinciding with this shrinkage was a “massive and unprecedented mortality” among river dolphins—209 carcasses were discovered in a short span, including 70 found on September 28 when temperatures first soared to 39.5 °C.
Unexpected Temperature Fluctuations
Researchers also documented extreme daily temperature variations, reaching up to 13.3°C. This meant that water temperatures transitioned from a hot tub-like warmth during the day to a drastic chill at night, significantly altering the local ecosystem and rendering survival increasingly difficult for its inhabitants.
Unpacking the Causes of Extreme Heat
The study identified multiple factors contributing to this alarming rise in temperatures. Clear skies allowed excessive solar radiation to penetrate, while shallow water depth and reduced wind speeds limited cooling effects through evaporation. This unique combination created what researchers termed a “perfect storm” for extreme warming.
A Long-term Crisis
While the events of 2023 were particularly extreme, they are not isolated incidents. Long-term data reveals a concerning warming trend in the region, with lake temperatures increasing by 0.6 degrees per decade from 1990 to 2023. This trend raises serious alarms about the future stability of the Amazon’s ecosystem.
Broader Ecological Impacts
The crisis extends beyond river dolphins. Significant fish mortality has been reported due to their limited temperature tolerance; even minor increases can prove fatal. The human populations in nearby riverside communities are facing equally severe repercussions, as drought and excessive heat have isolated thousands, depriving them of access to food, clean drinking water, and essential medicines.
The situation remains critical, demanding immediate attention and action from local and global communities alike. Continuous monitoring and proactive measures are essential to understanding and mitigating the impact of climate change on the Amazon and its inhabitants.
Images | Natalia Pedraza