MANAUS – Climate change was the primary culprit behind the devastating Amazon drought in 2023, while the weather phenomenon El Niño played a smaller role, scientists have found.
The drought was 30 times more likely to occur with human-caused climate change, according to a new study by World Weather Attribution (WWA), an international group of scientists that analyses extreme weather events to determine the influence of global warming. The study looked at the drought during the six-month period from June through November.
“As the Amazon drought worsened in 2023, many people pointed to El Niño to explain the event,” said Dr Ben Clarke, lead author of the study. “While El Niño did lead to even lower levels of rainfall, our study shows that climate change is the main driver of the drought through its influence on higher temperatures.”
The Amazon has recently experienced periods of rainfall, but it is still unknown whether El Niño will become stronger through the spring and whether the drought will continue.
Stretching across Brazil, Colombia, Venezuela, Ecuador, Peru and other nations, the vast Amazon rainforest is a hotspot of biodiversity and the world’s most important carbon sink, making it critical to the global climate system. Deforestation and rising temperatures have pushed the rainforest to a drier state, which threatens its capacity to absorb carbon.
The intense drought impacted 30 million people who rely on the Amazon River and its tributaries. Crops withered and boats were unable to navigate waterways to bring supplies. Communities, particularly Indigenous and river communities, found themselves isolated. Fish migration patterns changed due to warmer waters, imperilling an important food source.
The drought also contributed to the spread of wildfire and the die-off of swaths of river life, including 150 pink dolphins. Large-scale farming and cattle ranching reduced moisture retention in the soil, worsening conditions.
Dr Simone Athayde, an environmental anthropologist and researcher at the University of Florida, said local Indigenous communities recognised water levels were lower in spring 2023 but did not expect the drought to be so severe.
Based on the US Drought Monitor scale, this was an “exceptional” or level 4 drought. Without climate change, it would have been less intense and classified as a category 2 “severe drought,” according to the WWA study. The Amazon also saw severe droughts in 2005, 2010, 2015 and 2020, although the 2023 event was singular in some respects.
In a world with warming of 2 deg C above pre-industrial levels, the Amazon could see four times as many agricultural droughts of this magnitude every 10 to 15 years, meaning reduced rainfall, soil water and reservoir levels, the researchers found.
“We’re going into unprecedented territory now, and we predict in the future things are getting more intense by today’s standards. We will have to invent new categories” to classify events, Dr Clarke said.
The dry season is lengthening, a dangerous sign for the future, said Dr Regina Rodrigues, a study author and professor of oceanography and climate at Brazil’s Federal University of Santa Catarina.
The region must become better prepared for drought, said Dr Athayde, with plans for how to deliver emergency medications in isolated regions and secure food production, among other steps.
“More than ever, we need to control deforestation and promote restoration,” Dr Athayde said. “We have this window of opportunity for the Amazonian nations to connect and to coordinate on these issues.” BLOOMBERG
