Central North Amazon Dry Season Extreme Temperatures Rising 0.75°C Per Decade, Study Finds

During the dry season of 2024, the Tiaracá stream in Brazil’s Jaú National Park dropped so low that travel was only possible by paddling, stranding outboard motors in the thick mud. That localized drought in the central north Amazon is part of a broader, accelerating trend identified in a September 9, 2026 study published in the journal Communications Earth & Environment. Researchers from Lancaster University, working alongside an international team of 50 scientists, found that extreme dry-season temperatures in this specific, highly intact region are rising by at least 0.75°C per decade. That localized surge is more than triple the basin's average warming rate, exposing a hidden vulnerability in an area previously considered insulated from the worst impacts of climate change.[4][5]

The study analyzed high-resolution temperature and rainfall data across the entire Amazon basin from 1981 to 2023, dividing the vast rainforest into 11-kilometer grid cells to map localized microclimates. While average temperatures across the broader Amazon have increased by 0.21°C per decade—a figure that closely tracks the global average warming rate—the extreme temperature spikes are diverging sharply. In the central north, an area spanning 700,000 square kilometers that is larger than Afghanistan, dry-season temperature extremes have accumulated to a total increase of more than 3.22°C since 1981. These extreme spikes do not register in standard average-temperature assessments, masking the acute thermal stress placed on the ecosystem during its most vulnerable months.[2][5]

This rapid escalation in extreme heat is occurring far from the 'arc of deforestation' in the southern Amazon, which has historically been the fastest-warming region on average due to extensive land clearing. Because the central north retains extensive high forest cover, natural savannas, and vast indigenous territories, local land-use changes cannot explain the temperature spikes. '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, a post-doctoral researcher at the Lancaster Environment Centre. The data indicates that the region is bearing the brunt of global greenhouse gas emissions rather than local agricultural expansion.[3][5]

When extreme heat and severe moisture deficits compound, they fundamentally alter the physical structure and hydrology of the forest. High temperatures exponentially increase the vapor pressure deficit—the difference between the amount of moisture in the air and how much it can hold—forcing trees to close their stomata to conserve water. This physiological response reduces transpiration, which normally cools the canopy and recycles moisture back into the atmosphere to form regional rainfall. Prolonged stomatal closure leads to carbon starvation and hydraulic failure within the trees, driving large-scale mortality even in ancient, undisturbed tracts of the rainforest.[6]

The timing of these findings coincides with meteorological forecasts for a historically strong El Niño pattern developing in 2026. This natural climate phenomenon typically brings drier, hotter conditions to the Amazon basin by shifting Pacific rainfall patterns away from South America. With the basin already experiencing severe, record-breaking droughts in 2024, researchers warn that back-to-back extreme dry seasons could push the ecosystem past a critical threshold. The compounding thermal stress lowers the resilience of areas previously thought to be safe, raising the probability of a large-scale transition from dense rainforest to a degraded, savanna-like state.[1][4]

The physical changes are already manifesting in the region's biology and daily life. Recent field observations have documented the first mass deaths of mammals in the Amazon, including sloths found dead on the forest floor or hanging lifeless from understorey trees, alongside notable reductions in local bird populations. As major waterways and tributaries dry up, the aquatic ecosystems that support complex local food webs are contracting. Simultaneously, the extreme heat has fueled extensive megafires that have blanketed major urban centers like Manaus in severe, hazardous air pollution.[5]

The cascading effects extend directly to the indigenous territories and local communities residing within the central north Amazon. Dr. Joice Ferreira of the Brazilian Agricultural Research Corporation points out that extreme climate events are fundamentally disrupting the harvest of key non-timber forest products, such as açaí. The loss of these renewable resources removes a critical economic safety net for forest-dependent populations, directly threatening regional food security and destabilizing the socio-bioeconomy that relies on a predictable, stable wet and dry season cycle.[2][5]

In response to the data, conservation organizations are calling for immediate, coordinated interventions to prevent localized ecosystem collapse. Mike Barrett, chief scientific adviser at WWF-UK, emphasized that while global emissions reductions remain the primary requirement, localized defensive strategies are equally necessary. These include scaling up forest fire prevention networks, halting further degradation on the forest's edges, and deploying financial mechanisms to support communities navigating dry rivers and failing crops. Without these buffers, the structural damage to the forest canopy will only accelerate.[1][2]

The stark divergence between average warming and extreme dry-season spikes means that standard climate models may currently underestimate the immediate stress on the central north Amazon. As the 2026 El Niño develops, the 700,000-square-kilometer region will test whether an intact, mature forest canopy can withstand a 3.22°C dry-season penalty. The coming months will reveal whether the structural changes observed over the last 43 years represent a temporary strain or a permanent, irreversible shift in the basin's foundational hydrology.[3][5]