The Amazon lakes have reached high temperatures during the last droughts even above 41ºC. They have become authentic ‘spas’, in the words of scientists who have monitored the water temperature.
Consequently, hundreds of pink dolphinsan emblematic species in extinction, were killed, and entire populations of fish have disappeared.
The impacts of climate change in indigenous life on the shores of these lakes and rivers is ending the resilience of what is known as the ‘tropical lung of the world‘, a function that it is ceasing to exercise: in 2024 the Amazon emitted more C02 by fires than due to deforestation.
The Taruma Acu River is barely visible in the midst of a serious drought in Manaus, Amazonas state, Photo taken on September 25, 2024. Edmar Barros
“Boiling” lakes, death of species
The data of thethe temperatures in the water in the lakes, published this week in the Science magazinewere collected during the extreme drought that the Amazon suffered in the fall of 2023. The largest river in the world lowered its flow so much that in some sections it was not navigable.
A team of scientists at the Mamirauá Institutededicated to environmental research in Brazil, monitored 10 lakes in the basin to study their situation that year. These are oxbow lakes connected with big rivers through channels that dry out and leave them isolated. Five of them had water above 37ºCwhen the average in the previous 20 years was 33.3ª. In it Tefe lakean arm of the Solimaes River – sanctuary for pink dolphins and tucuxi dolphins -, 41ºC was reached and not only on the surface but up to two meters deep.
209 dolphin carcasses were found in two months. Besides the lakes reduced their size. Tefé lost up to 75% of its surface and Badajós, 90%.
A woman carries a can of water during the heat wave in the city. Photo:Antonio Becerra Scientists attribute these temperatures to extreme heat waves, solar radiation because of the droughtthe shallow depth of these lakes, the turbidity of the water and a low wind speed, factors that converged and turned them into “boiling lakes” for days.
Your concern is how these events may affect these fragile ecosystemstaking into account that these circumstances can be repeated.
In the case of the cetaceans of Lake Tefe, they point out that they did not escape to cooler waters because the high temperatures could impact their neurological systemspreventing them from looking for a way out. Both species, the pink and the tucuxi, are in danger of extinction, according to the IUCN, also due to other factors, such as their illegal capture as fish bait or due to pollution of rivers by mercuryused for illegal gold mining.
Aerial view of the surface charred by a forest fire in Oímbra (Ourense). EFEWarming in the region has increased on average 0.6ºC each decade since 1990. Proof of this trend is that the drought and heat waves of 2023 were repeated in 2024 in the same months and the same area. Also in 2025 there was a drought in Brazilalthough this year has been more irregular and has been felt more in the south of the country, while in the Amazon there has been a ‘mix’ of floods and lack of rain, with regional fluctuations.
Ayan Fleischmann, from the Mamirauá Institute, who is the main author of the work in Science, explains to La Vanguardia the circumstances in those two previous years have to do with the El Niño phenomenonbut that “the relationship with the warming of the Tropical North Atlantic, which is linked to global climate change.”
“The reality is that the Amazon has suffered extreme events with greater frequency in recent years, droughts and floodslike the one in 2021, the largest in 120 years. Everything indicates that we will have more heat waves in the Amazon lakes in the coming years and that will impact all life in those places,” he predicts.
Playa de Leme, Rio de Janeiro during a hot spell. EFEFleischmann highlights the threat to the ecosystems, food security and economy of the region: “Not only the dolphins that could not leave Lake Tefé were also affected. other biological groups. We observed an intense proliferation of phytoplankton in the lake, which turned red on several occasions due to a bloom of Euglena sanguinea. I believe that these Amazonian lakes are not going to disappear, but their ecosystems will change if these heat waves and droughts become more frequent«This algae that you mention generates a toxin that can cause mass death of fish that indigenous communities live on.
In 2023 alone there were seven intense heat waves in the Amazon. In 2024 there were In 2024 there were around ten
The increase in emissions that you mention Jimenez-Muñoz has a lot to do with the fires: coinciding with the prolonged drought since the previous year and the heat waves, the amazon rainforest He lived his season of forest fires most destructive in two decades, according to research by the European Commission’s Joint Research Centre.
European scientists reveal how flames are destroying the ecological integrity of the Amazon foresteven in areas where logging has decreased since Brazilian Lula da Silva took office. Data from this recent work indicates that last year these Amazon fires released 791 million tons of CO2surpassing emissions from deforestation.
After a forest fire in Iranduba, metropolitan region of Manaus (Brazil). EFEIn total, last year 3.3 million hectares were burned of jungle, when extreme droughts combine with poor land management practices, such as burning of pastures and deforested lands that end up escaping into forests weakened by lack of moisture. Additionally, these forests can act as a net source of emissions for seven years or more after a fire, as they are not fire-adapted forests.
Fleischmann, who recalls that “extreme events such as those of 2023 and 2024 can be repeated, considers it essential that “appropriate policies be taken to adapt traditional Amazonian communities to this new reality, whose isolation during extreme droughts has enormous humanitarian consequences”, as seen in 2024. In fact, he points out that “concrete proposals already exist, but they must be put into practice.”
He also advises that there be monitoring programs long-term in the Amazonian water bodies, covering both the quality of that water and its ecosystems. The own indigenous communities They have been denouncing for some time that climate change and the proliferation of illegal gold mines are already causing serious problems for their health.
Rosa Rosa Martin
