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The unprecedented drought that the Amazon experienced last year caused the lowest river levels to be recorded in 120 years. Manaus and 20 other cities in Brazil had to declare a state of emergency due to low water availability, and the Lake Tefé region became famous worldwide because more than 110 dolphins floated dead there. A climate catastrophe. Several villages were cut off from communication, as the rivers they use as transportation routes dried up, and in other countries such as Peru and Colombia there were alerts due to fish mortality due to high temperatures.
At that moment the question arose as to how much the phenomenon of The boy and climate change in this extreme event. Who to blame? The suspicion then was that both. Now, a recent study prepared by the initiative World Weather Attribution (WWA), in which scientists from Brazil, the Netherlands, the United Kingdom and the United States participated, gives an accurate answer: it was climate change, and not The boythe main cause of the exceptional drought that occurred in the Amazon basin during June and November 2023.
Brazilian Regina Rodrigues, professor at the Universidade Federal de Santa Catarina and one of the co-authors of the study, explains that the definition of a drought involves several elements. There is meteorological drought, for example, in which only low precipitation or lack of rain is taken into account to analyze it. “In this case, we find that both The boy like climate change played a role in the Amazon drought, something like 50% and 50%.” But there is also what is known as agricultural drought, in which, in addition to precipitation, evotranspiration is taken into account. “If there is a lot of evaporation, the climate will be drier. And since evaporation is closely related to high temperatures, under this definition of drought we did find that it was climate change that played a greater role,” says the expert. “In a colder climate, such a drought would be extremely rare,” the researchers point out.
The study, like about 50 others that WWA has carried out to understand how climate change influenced the intensity and probability of an extreme phenomenon, uses a methodology that has been reviewed by peers and that is applied on each occasion for the event that is being carried out. is analyzing. In very short words – says Rodrigues – what is done is modeling looking at what would happen to a phenomenon (such as drought) if the quantities of tons of CO2 that have reached the atmosphere since the pre-industrial era had never been emitted. “We then compare this data statistically to what we see now and even to the future climate,” she explains.
Thus, for example, they came to the conclusion that, with the current climate, the probability of such a meteorological drought occurring in the Amazon is 1 in 100 years, while for agricultural drought the scenario changes to 1 in 50 years. . However, under a possible climate in which the average temperature of the planet does not increase more than 2°C compared to pre-industrial levels (plan B of the Paris Agreement, which aims not to exceed 1.5°C), the The probability of having a meteorological drought in the Amazon would be approximately 1 every 30 years, while for agricultural drought the risk of repeating it is 1 every 10 or 15 years. In short, they would be more frequent and probable scenarios facing a hotter planet.
This is a wake-up call for the countries that are part of the Amazon to prepare for a future that is increasingly less uncertain and, on the other hand, gives us clues that what we will experience will indeed be more extreme.
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