Amazon faces another consecutive year of drought as wildfires reach 20-year high

The Amazonian region is grappling with a severe drought that has pushed river levels to unprecedented lows. The drought, which began in 2023, has had a devastating impact on the basin's biodiversity and communities.

On September 17, 2024, the Madeira river, a major tributary of the Amazon, dropped to 48 centimetres in Porto Velho, Brazil, compared to the normal level of 332 cm.

The Brazilian government officially declared a state of emergency in six cities in Amazonas due to the drought. 

The drought has been accompanied by record-breaking wildfires. In July, Brazil recorded 11,500 fires, followed by 38,000 in August, the highest number in 20 years. Carbon emissions from fires in the Brazilian Amazon and Pantanal biomes have been the highest since 2005, according to Mark Parrington, an atmospheric scientist at the European Centre for Medium-Range Weather Forecasts. 

In Peru, wildfires have reached unprecedented levels, with over 1,800 forest fire alerts issued. Meanwhile, Bolivia experienced over 17,700 fires this year — the highest ever recorded in the first half of any year. 

The drought conditions have been developing since last year. The period from September to November 2023 saw severe drought. “The rainy season that typically begins in October 2023 only started in January 2024 and even then, it was weak and delayed,” said Jose A Marengo, director of research and development at the National Centre for Monitoring and Early Warning of Natural Disasters in São Paulo, Brazil, told Down To Earth.

The dry winter season of 2024 (June to August in the southern hemisphere) followed an already weak rainy season, he said. “With rising temperatures (five heatwaves so far), the drought appears to have persisted since 2023,” Marengo added. 

“The floods expected in 2024 did occur (around June 2024) in central Amazon, but they did not inundate many floodplain areas that are usually affected. This means that the El Nino aand the Warmed Tropical North Atlantic impacted the rainfall in 2024. Unfortunately, La Nina has not started so far, which could bring more rainfall to the region,” Ayan Fleischmann from Mamirauá Institute for Sustainable Development told DTE.

“If the water level does not start to rise soon (and it’s unlikely to occur), the drought this year will not only be more extreme in terms of magnitude than 2023, but also longer in terms of duration. The longer the drought, the larger the impacts to the Amazon people and nature. Difficult times for us here,” Fleischmann added.

In 2023, most of the major rivers in the Amazon, including the Solimoes, Purus, Acre and Branco rivers, experienced extreme drops in water levels or completely dried up. In October 2023, the Rio Negro in Manaus recorded its lowest water level since measurements began in 1902, at 12.70 metres (compared to the average annual minimum of 17.64 metres between 1902 and 2022).

The World Weather Attribution team concluded that the severity of the 2023 drought was almost entirely attributable to increased global temperatures driven by climate change, even as the El Nino weather pattern reduced rainfall in the region to a similar degree. Furthermore, some parts of the Amazon River’s watershed received less rain between July and September last year than in any year since 1980. The region also experienced heatwaves and drier conditions.

Droughts in the Amazon are also influenced by sea-surface temperatures in the tropical Atlantic Ocean, as well as the characteristics of the land, with already dry soils exacerbating the drought to Marengo.

Rainfall is regulated by the intertropical convergence zone (ITCZ), a region near the equator where the trade winds from the Northern and Southern Hemispheres meet. The intense sun and warm waters around the equator heat the air, making it humid and buoyant. This air rises, combining with trade winds, causing it to expand and cool. This process results in thunderstorms on land. However, warm sea surface temperatures in the tropical North Atlantic push the ITCZ northwards, reducing rainfall in the Amazon.

For now, the full impacts of the two-year-long drought remain unclear. Marengo suspects that the drought could make navigation along large and small rivers and streams difficult, affecting Indigenous communities and other riverine populations who rely on waterways for transport. This could leave them isolated and without easy access to food, fuel, water and medicine.

The Pan-Amazon region, which covers nine countries and encompasses all major tributaries of the Amazon River, is home to approximately 47 million people, including Indigenous and non-Indigenous populations, as well as urban and rural dwellers. Many of these communities rely on rivers as the primary means of medium- to long-distance transportation, according to a 2024 study published in journal Communications Earth & Environment.

Scientists have observed an increase in both the frequency and intensity of droughts in the Amazon. Severe droughts have risen from four in a century to four in less than 25 years, alongside rising deforestation and global warming. Examples include the droughts of 2005, 2010, 2015-2016 and 2023. 

Droughts increase tree mortality, reducing the forest’s ability to sequester carbon. They also lead to animal deaths and heighten the risk of wildfires, according to a 2024 policy brief.