During 2023, an intense period of drought caused several Amazonian lakes to reach temperatures surpassing those of a heated spa. Brazil’s Lake Tefé registered a staggering 41.0 °C (105.8 °F).
The resultant environmental catastrophe led to the demise of over 200 dolphins, an immeasurable quantity of fish, and thousands upon thousands of other aquatic organisms.
From the planet’s coral reefs to aquatic eels, avian species, and even African elephants, this serves as yet another stark instance of a large-scale die-off among Earth’s wildlife, now definitively linked to the escalating climate crisis.
“The climate emergency is undeniably upon us; there is no room for doubt,” declared hydrologist Ayan Fleischmann, dispatched to investigate the lake phenomenon, as he communicated to AFP.
Fleischmann, affiliated with the Mamirauá Institute for Sustainable Development in Brazil, in collaboration with his colleagues, analyzed satellite imagery alongside direct water temperature measurements from the region’s lakes throughout the 2023 drought.
Their findings indicated that a convergence of meteorological and hydrological factors contributed to the calamitous state of the Amazonian lakes. These included reduced wind velocities, diminished water levels, exceptionally intense solar radiation during an eleven-day period devoid of cloud cover, and water turbidity that facilitated greater sunlight absorption.
“This drought’s unprecedented severity has been ascribed to climate change, encompassing the widespread warming of the world’s oceans, particularly the North Atlantic, compounded by a moderate to strong El Niño event,” the research team published in their findings.
Water temperatures surpassed 37 °C in five of the ten lakes under examination. However, the researchers posit that the extreme diurnal temperature fluctuations, occasionally reaching up to 13 °C, were most likely the critical factor inducing fatal thermal shock in the wildlife.
“An escalation of 10 °C in water temperature is unprecedented,” commented University of Greenwich ecologist Adrian Barnett, who was not involved in the study. He shared with journalist Phoebe Weston of The Guardian, “The sheer magnitude of energy required to elevate temperatures in such vast bodies of water is astonishing.”
At the time of the event, the World Wildlife Fund reported a significant loss, with approximately 10 percent of the local dolphin population perishing within a single week. This included 130 Amazon river dolphins (Inia geoffrensis) and 23 tucuxi dolphins (Sotalia fluviatilis), both species classified as endangered.
The mortality figures continued to escalate, with an estimated total of 330 dolphin carcasses discovered in the vicinity of the lakes.
“When water temperatures reach 41 °C, the physiological functions of fish cease: their enzymes become inhibited, their metabolic processes collapse, and they succumb,” explained Adalberto Val, a biologist from the Brazilian Amazon Research Institute, in his statement to Noticias Ambientales.
This ecologically vital region, which encompasses the planet’s most extensive remaining expanse of tropical rainforest, harbors approximately one-fifth of Earth’s freshwater resources. However, the shifting climatic patterns are precipitating a significant depletion of these reserves.
Scientific projections have already sounded alarms regarding the imminent collapse of the Amazon rainforest. Now, Fleischmann and his colleagues have documented that the average water temperatures of flood-plain lakes in the central Amazon have risen by 0.6 °C per decade since 1990.
“We hold significant concerns that these extreme conditions are becoming more prevalent,” stated John Melack, an ecologist at UC Santa Barbara. “The ramifications for biodiversity and the livelihoods of local populations are substantial.”
This escalating crisis is not confined to regional solutions, as researchers emphasize the imperative for a global, concerted effort to curtail fossil fuel consumption. Without such action, humanity faces the continued extinction of increasingly vast segments of the most extraordinary life forms in the known cosmos, including ourselves.
