Floating houses and boats are seen stranded at the Negro river, city of Manaus, Amazonas State, northern Brazil, on Oct 16, 2023. The Negro river is facing the worst dry season of the last decades in the Amazon rainforest. (PHOTO / AFP)

SAO PAULO - Climate change is the main culprit for a record drought in the Amazon rainforest that has drained rivers, killed endangered dolphins and upended life for millions of people in the region, according to a study released on Wednesday.

Global warming made the drought 30 times more likely, drove extreme high temperatures and contributed to lower rainfall, according to the analysis by World Weather Attribution, an international group of scientists. The study focused on June to November last year.

The protection of the Amazon, the world's largest rainforest, is considered vital to curbing climate change because of the vast amounts of greenhouse gas that its trees absorb. The drought reduced river levels in parts of the region to their lowest points on record

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The drought that hit all nine Amazon rainforest countries - including Brazil, Colombia, Venezuela and Peru - is expected to worsen in 2024 after the rainy season begins to recede in May, scientists told Reuters last year.

The protection of the Amazon, the world's largest rainforest, is considered vital to curbing climate change because of the vast amounts of greenhouse gas that its trees absorb. The drought reduced river levels in parts of the region to their lowest points on record.

"We should be really worried with the health of the Amazon forest," said Regina Rodrigues, a study co-author and researcher at the Federal University of Santa Catarina in Brazil.

Researchers have said the drought could worsen forest fires, which when coupled with climate change and deforestation could push the Amazon more quickly toward a point of no return after which the biome dries out and ceases to be lush rainforest.

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The periodic warming in the Eastern Pacific Ocean know as El Nino also contributed to the decline in rainfall, although not to higher temperatures, the study found.

While the region has faced at least three other intense droughts in the past 20 years, this drought's scope was unprecedented and affected the entire Amazon basin, Rodrigues said.

In Brazil, a major tributary of the Amazon river fell to its lowest point since records began in 1902, with smaller streams virtually disappearing.

"Waterways dried up in a matter of months. People were forced to make huge journeys, dragging boats over dried-up sections of river to access food, medicine and other essential goods," said Simphiwe Stewart, a researcher with the Netherlands-based Red Cross Red Crescent Climate Centre and a study co-author.

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Researchers in Brazil have said low water levels and high temperatures led to the deaths of at least 178 of the endangered pink and gray Amazon river dolphins last year. Thousands of fish also have died due to low oxygen levels in Amazon tributaries.