Deforestation within the Brazilian Amazon accounts for an estimated 74.5% of the documented rainfall reduction during the dry season, subtracting roughly 15.8 millimeters of annual precipitation, while global climate change underpins the remaining decrease. The forest loss also explains approximately 16.5% of the observed 2.0 °C temperature increase over the same period, with the greater share attributed to global warming originating largely from industrial activity in Northern Hemisphere nations. These findings represent a crucial “attribution partition,” quantifying the relative influence of local anthropogenic land modifications and worldwide greenhouse gas emissions on Amazonian climate fluctuations.

Professor Luiz Augusto Toledo Machado, who helmed the study from USP’s Physics Institute, emphasizes this work’s significance in disentangling the previously conflated drivers of the Amazon’s changing climate. “While many studies have documented escalating temperatures and diminishing rainfall, this is the first clear breakdown of how much is due to deforestation tied to Brazil itself, versus external global emissions,” he explains. By constructing parametric surface equations that integrate annual variability and deforestation data, the team was able to decompose the cumulative climatic shifts into their component sources, setting a new standard for ecosystem-specific climate attribution.

The researchers underline that the largest climatic disruptions occur early in the deforestation trajectory. Pronounced variations in temperature and precipitation emerge sharply once forest cover is reduced by as little as 10% to 40%. According to co-author Professor Marco Aurélio Franco, “The initial stages of deforestation impose disproportionate impacts, so preserving the standing forest is paramount. Transitioning these lands to pasture or other uses risks triggering amplified local warming and severe rainfall declines.” Their statistical analysis pinpoints this initial deforestation threshold as a climatic tipping point, beyond which recovery of ecosystem equilibrium becomes drastically more difficult.

Remote sensing datasets, including the extensive land-use classifications by the MapBiomas collaborative network, afforded the study a robust spatial and temporal scope over 35 years. These data, combined with long-term reanalyses of atmospheric greenhouse gas concentrations, revealed that atmospheric CO₂ and methane increases in the Amazon are overwhelmingly driven (>99%) by global emissions rather than local deforestation. Though deforestation reduces the forest’s capacity to sink carbon locally, this does not translate into a significant localized elevation of atmospheric CO₂ concentration, given the global scale of greenhouse gas accumulation.

The Amazon’s role in regional and global hydrological cycles is profound, often described through the concept of “flying rivers”—large atmospheric flows of moisture sustained by the forest’s transpiration processes. Trees extract groundwater and release it as vapor, driving cloud formation and precipitation not only locally but throughout South America, including the Cerrado biome. The study confirms that deforestation disrupts this vapor recycling mechanism, intensifying the dry season and exacerbating forest fire frequency, which in turn further degrade the forest’s vegetation and resilience.

Recent international research, including prior work by USP experts, has elucidated how aerosol nanoparticles generated within the Amazon’s atmosphere interplay with electrical discharges and daytime-nighttime chemical reactions to form rain-inducing clouds. This complex “aerosol machine” is tightly linked to forest health. As deforestation escalates, these processes weaken, diminishing cloud formation potential and leading to cascading rainfall deficits. Such physical-chemical insights underscore how land-cover changes ripple through atmospheric chemistry, altering weather and climate patterns in ways that threaten the rainforest’s survival.

The cumulative land degradation between 1985 and 2023 has already resulted in the loss of 14% of the Amazon’s original vegetation, an area roughly equivalent to France. While recent deforestation rates have declined slightly to 4,495 km² annually, the persistence of forest degradation—particularly from recurrent fires—continues to challenge conservationists. The dry season, stretching from June to November, remains the focal window when these impacts are most visible, as precipitation reductions and temperature rises converge to heighten vulnerability.

Looking forward, the researchers warn that the continuation of deforestation at current or higher rates threatens to push the Amazon past critical climate thresholds. Their models project accelerating precipitation declines and temperature increases during dry seasons, intensifying seasonal extremes and undermining the biome’s ecological resilience. These hydrometeorological shifts are already affecting the South American monsoon, leading to drier conditions that imperil the rainforest’s long-term stability and its essential climate regulation functions.

The implications extend beyond local ecosystems. Alterations in the Amazon reverberate across continental weather systems, influencing agriculture, water security, and biodiversity throughout Brazil and neighboring countries. Extreme drought events in 2023 and 2024 serve as ominous indicators of a rapidly shifting baseline, highlighting the urgent need for integrated strategies that address both land-use practices and global greenhouse gas emissions. This new research provides policymakers and environmental stakeholders with a precise “climate ledger” that clarifies responsibilities and informs sustainable development pathways.

This study, supported by the São Paulo Research Foundation (FAPESP) and conducted in collaboration with the Chinese Academy of Sciences, marks a breakthrough in our understanding of the Amazon’s vulnerability amid converging environmental crises. The scientific community now possesses clearer evidence tying local deforestation directly to tangible climatic consequences, alongside the overarching global warming trend. Ultimately, the findings reinforce the critical imperative to protect and sustainably manage the Amazon rainforest to secure its indispensable climate services for Brazil and the world.

—

Subject of Research: The interactive effects of deforestation and global climate change on the Amazon rainforest’s climate, with emphasis on rainfall and temperature changes during the dry season.

Article Title: How climate change and deforestation interact in the transformation of the Amazon rainforest

News Publication Date: 2-Sep-2025

Web References: https://agencia.fapesp.br/54089; https://www.fapesp.br/en

References: DOI 10.1038/s41467-025-63156-0 (Nature Communications)

Image Credits: Luiz Augusto Toledo Machado (IF-USP)

The study meticulously examines historical data from a range of sources to assess the changes in the frequency, duration, and extent of heat waves across different regions. Researchers have employed advanced statistical models and climate reanalysis data to paint a comprehensive picture of transitions in heat wave characteristics. By focusing on large-scale patterns, they aim to identify underlying drivers, revealing the systemic shifts that are altering our climate landscape.

One of the most striking findings of the research details the geographical spread of heat waves. The data shows that regions once relatively insulated from extreme heat are now experiencing increased frequency and intensity of heat waves. This shift is particularly pronounced in temperate zones, where climates traditionally characterized by moderate temperatures are now being subjected to more severe heat events. Such changes not only threaten agriculture and biodiversity but also pose serious risks to public health.

Moreover, the study highlights how urbanization plays a significant role in amplifying the effects of heat waves. As cities expand and populations grow, urban heat islands emerge, creating localized areas that suffer from significantly elevated temperatures compared to their rural surroundings. This phenomenon exacerbates the health risks associated with heat waves, particularly among vulnerable populations such as the elderly and those with existing health conditions.

Another key aspect addressed by the researchers is the role of climate variability, particularly the El Niño Southern Oscillation (ENSO) and other climatic phenomena, in modulating heat wave occurrences. Their analysis suggests that periods of high ENSO activity correlate with heightened heat wave intensity, underscoring the complexity of climate interactions. As the frequency and magnitude of these events shift over time, the implications for policy and disaster management become increasingly urgent.

In addition to the physical changes in heat wave patterns, the researchers emphasize the socio-economic implications. The rising intensity and the expanding geographic reach of heat waves can have profound effects on agriculture, water resources, and energy demand. Farmers face challenges in crop productivity, with heat stress and water scarcity potentially leading to reduced yields. On the energy front, increased air conditioning demand during intensified heat waves can strain power grids, leading to outages and increased emissions from fossil fuel-generated electricity.

Another crucial point raised in the article is the interaction between different climate-related events. The occurrence of droughts with heat waves can substantially increase fire risks, threatening both natural landscapes and human settlements. The study thoroughly discusses the interconnectedness of these phenomena, demonstrating the need for integrated approaches to climate resilience that account for multiple stressors simultaneously.

The authors also take a moment to highlight potential adaptive measures. They advocate for better urban planning and infrastructure design that can mitigate heat impacts, such as increasing green spaces and promoting reflective surfaces in buildings. By developing strategies that can withstand and adapt to heightened heat stress, communities can effectively reduce vulnerabilities and enhance quality of life for their residents.

Education and outreach are also pivotal components in combating the effects of heat waves. The research underscores the importance of informing the public about heat risks and effective preventive measures. Communities must engage in proactive dialogue about heat health, emphasizing the need for cooling centers and resources for those most at risk during extreme heat events.

Peer-reviewed studies like this one form a crucial part of the climate discourse, driving home the urgency of addressing climate change. The authors call upon policymakers to use their findings as a basis for crafting actionable strategies, reinforcing the importance of linking scientific knowledge with governance frameworks. It’s a clarion call for enhanced collaboration between scientists, government agencies, nonprofit organizations, and affected communities.

In conclusion, the study by Skinner and colleagues provides a sobering yet necessary perspective on the future trajectory of extreme heat events. By meticulously documenting shifts in heat wave patterns over the past four decades, the authors have laid the groundwork for future research and policy development. Their work serves as a powerful reminder of the need for continued vigilance in understanding how climate change reshapes our world and the urgent actions required to mitigate these shifts.

As the world grapples with the implications of climate change, studies like these are instrumental in highlighting the critical need for adaptation and resilience. The ongoing research efforts in this domain are essential to facilitate discussions about sustainable practices and innovative solutions to safeguard against increasingly hostile climate conditions.

Through collaborative efforts and informed strategies, society can hope to navigate the complexities of climate change and pave the way for a more sustainable and resilient future for generations to come.

Subject of Research: Changes in the spatial extent of heat waves over the past four decades

Article Title: The spatial extent of heat waves has changed over the past four decades.

Article References:

Skinner, C.B., Touma, D., Barlow, M. et al. The spatial extent of heat waves has changed over the past four decades.
Commun Earth Environ 6, 662 (2025). https://doi.org/10.1038/s43247-025-02661-y

Image Credits: AI Generated

DOI: 10.1038/s43247-025-02661-y

Keywords: Heat waves, climate change, urban heat islands, agricultural impact, policy implications.