The numbers behind that conclusion are sobering. The researchers found that 10 percent of the Amazon basin, an area larger than 700,000 square kilometres and bigger than Afghanistan, has seen extreme temperatures during the dry season rise by at least 0.75 degrees Celsius per decade, accumulating to more than 3.22 degrees Celsius since 1981. That is a pace of change far exceeding the basin-wide average warming of 0.21 degrees Celsius per decade, which sits roughly in line with the global average. In other words, the climate extremes that matter most for ecosystems and people are intensifying much faster than conventional assessments of average temperature suggest, and they are concentrating in places that standard analyses have overlooked.

The methodological innovation at the heart of the study explains why. The team divided the Amazon into grid cells of 11 kilometres and combined satellite observations with data from local weather stations, allowing them to identify the dry season for every individual part of the biome. This matters because the Amazon spans the equator: areas north of it have a dry season at a different time of year from the south, meaning earlier assessments focused on the southern dry season systematically missed what was happening elsewhere. On top of this, the researchers used a new measure of water deficit that accounts for the effect of temperature on water loss, capturing how hotter air drives faster evaporation and deeper physiological stress in forests.

Crucially, the team assessed climate change in two distinct ways. The first, the ‘central tendency’, is the measure most commonly used to date and emphasises average rates of change in temperature and water deficit across all years. The second, the ‘extreme tendency’, emphasises the most exceptional years, providing a more accurate indication of how the hottest and driest periods are evolving. Professor Jos Barlow of Lancaster University, lead author of the report, explained the rationale. “We are most interested in things when they are at their hottest and driest as that is when the most harm can be caused by high temperatures,” he said. “While this has been assessed in the Southern Amazon, which shares a largely similar dry season, it has never been assessed across the whole of the Amazon, which includes regions north of the equator which have a different dry season period.”

The contrast between the two measures produced the study’s most consequential insight. When average temperature changes are considered, the Southern Amazon, which has suffered extensive deforestation and land-use change, is confirmed as the fastest warming region. But when extremes are examined, the central north Amazon emerges as the area of most rapid change. “The rates of change in climate extremes are much higher than the rates of change of average climate in the Amazon, and the most affected regions are also different for extremes and average climate,” said Dr Nathália Carvalho, post-doctoral research associate at the Lancaster Environment Centre. “This is important because we show that Amazonia’s climate is not changing uniformly. This information will be crucial when planning and implementing climate change adaptation strategies.”

Perhaps the most politically significant implication is what the geography of change rules out. The area experiencing the fastest growth in extreme temperatures lies far from the arc of deforestation, the band of forest loss along the basin’s southern and eastern edges. That means local drivers such as deforestation and land-use change cannot explain the pattern. “Given the area that is experiencing the fastest growing in extreme temperature is far from the arc of deforestation, these rapid rises cannot be explained by local changes such as deforestation and land-use changes,” Professor Barlow said. “It’s showing how the Amazon is being affected by global climate change. It’s the world’s emissions that are responsible.” For a biome often discussed in terms of national land-use policy, the finding reframes the Amazon’s fate as a genuinely global responsibility.

The biological consequences of intensifying extremes are already visible across the region. Recent exceptionally hot or dry periods have driven extensive forest fires, large-scale animal and tree deaths, and threats to human health from heat and air pollution. Recent studies cited by the research team document the first observed mass death of mammals in the Amazon, with sloths and other animals found dead on the forest floor or hanging from understorey trees, alongside reductions in the size of bird populations and measurable changes to bird lifespans, appearance and behaviour. Megafires linked to extreme heat and drought have generated air pollution that reached the Amazonian city of Manaus, while rivers that shrank during droughts disrupted the transport networks and water supplies on which forest communities depend.

The human dimension is equally stark. Dr Joice Ferreira of the Brazilian Agricultural Research Corporation, Embrapa, highlighted how extremes are eroding rural livelihoods. “Extreme climate events are impacting local livelihoods in many ways, affecting key products like açaí,” she said. “This removes the safety net that forests provide, threatening food security and weakening their role in a growing socio-bioeconomy. Most concerning, it could derail public policies currently being designed and implemented by Brazilian and state governments to drive positive transformation in the region, such as forest restoration plans. This scenario demands global action to halt climate change in the name of climate justice.” For communities whose economies and diets are woven into the forest, the loss of predictable seasonal rhythms is not an abstraction but a direct threat to food security and to emerging sustainable bioeconomies.

The timing of the findings adds urgency. With the El Niño of 2026 expected to be the largest in living memory according to the UK Met Office, the Amazon may face extremely high temperatures and drought just two years after the last major drought of 2024, leaving little time for forests, wildlife and people to recover. Scientists involved in the study warn that if the rapid increases in extreme climate events continue, the region could be pushed past critical thresholds, with cascading consequences for biodiversity, carbon storage and regional rainfall. Professor Barlow argued that adaptation measures are urgently required, including preventing factors that amplify climate risks such as deforestation, strengthening capacity to fight forest fires, and supporting local people when the rivers they rely on for navigation dry up, especially in a year with the arrival of what he described as a super El Niño.

Mike Barrett, chief scientific adviser at WWF-UK, framed the study as a call for action at both global and regional scales. “The rapidly increasing climate extremes revealed in this study highlight the urgent need for global action on climate change,” he said. “However, the new regions of risk also demonstrate the need to support other measures, including an end to deforestation and support for measures such as the Tropical Forest Forever Facility if we are to avoid critical tipping points and environmental collapse.” The study, titled ‘Rapid increase of climate extremes reveals new areas of concern in Amazonia’, also released interactive maps showing rates of change in temperature, vapour pressure deficit and precipitation across the basin, giving policymakers and researchers a tool to target adaptation where extremes are intensifying fastest. What the research makes unmistakably clear is that the Amazon’s climate is not changing uniformly, that its most exceptional years are deteriorating far faster than its averages, and that the heart of the world’s largest rainforest, once assumed to be resilient, is now squarely in the crosshairs of global warming.

Subject of Research: Rapid growth of temperature and water-stress extremes across the Amazon basin

Article Title: As El Niño looms, study finds rapid growth in climate extremes are hitting an unexpected region of the Amazon hardest

Article References: As El Niño looms, study finds rapid growth in climate extremes are hitting an unexpected region of the Amazon hardest. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Amazon, climate extremes, El Niño, drought, deforestation, forest fires, water deficit, indigenous territories, biodiversity, Communications Earth & Environment, Lancaster University, climate adaptation