Climate Change and Megafires: Wildfire Science on Heatwaves, Emissions Effects, and Environmental Policy

Climate change and megafires are reshaping the landscapes of Argentina and Chile in ways that scientists are now able to quantify with far greater precision. Recent wildfire seasons in Patagonia and southern Chile show how warming, drought, and changing land use are combining to create ideal conditions for extreme fire events.

New research rooted in wildfire science is helping to explain why these fires are becoming more intense and what this means for heatwaves, emissions effects, and environmental policy in the region.

A New Era of Fire Weather in South America

Over the last few summers, both countries have faced severe wildfires that burned forests, grasslands, and rural communities, particularly in Chile's Biobío and Ñuble regions and across the Chile–Argentina border in Patagonia.

Thousands of people were evacuated, homes were destroyed, and ecosystems including ancient Alerce forests and native grasslands suffered extensive damage. Firefighters battled dozens of simultaneous blazes under strong winds and record-breaking temperatures, while authorities declared states of catastrophe and emergency.

At the same time, a team of international researchers used attribution techniques to examine whether climate change influenced the fire weather behind these events.

Their findings suggest that the background conditions for megafires in southern Chile and Patagonia are no longer rare anomalies but are being pushed toward a new normal by human‑driven warming.

What is Causing the Wildfires in Argentina and Chile?

Wildfire science views major fire events as the result of three main ingredients: fuel, ignition, and conditions that allow a fire to spread. In the recent South American fires, all three aligned.

Long, hot, dry spells left vegetation stressed and highly flammable, especially in regions where non‑native pine plantations and invasive species have increased the amount of available fuel. Once fires started, from human activity, accidents, or deliberate burning, they quickly grew under hot, dry, and windy weather.

The attribution studies found that these "fire weather" conditions were significantly more likely in today's climate than they would have been in a pre‑industrial world.

For the central Chilean region, scientists estimated that the hot, dry, windy pattern that drove the fires was around three times more likely because of human‑induced climate change; in Patagonia, the probability was about 2.5 times higher.

This means climate change did not ignite the fires but made the window of opportunity for large, fast‑spreading burns much wider.

How Climate Change Makes Wildfires Worse

Long‑term climate records show that parts of South America, including southern Chile and Patagonia, are becoming warmer and drier, especially during the months that define the fire season.

Heatwaves have become more frequent and intense, with temperatures in some affected regions exceeding 38°C under official extreme heat warnings. These heatwaves dry out soils and vegetation, reducing moisture content and turning forests and shrublands into highly combustible fuel beds.

The same studies report that rainfall intensity during the fire season, roughly November to January, has dropped by about 25% in central Chile and around 20% in Patagonia compared with a world without human‑caused warming.

Less rain, combined with higher temperatures and increased evapotranspiration, leaves landscapes in a chronic state of dryness. According to wildfire science, this combination of heatwaves, reduced precipitation, and dry winds is a classic recipe for extreme fire weather.

What New Studies Reveal About Fire Weather

Researchers from the World Weather Attribution consortium and partner institutions applied a metric known as the Hot‑Dry‑Windy Index (HDWI) to assess the fire weather during the recent events.

HDWI blends wind speed, temperature, and humidity to indicate when conditions are primed for dangerous wildfires. By comparing current observations with climate model simulations of a world without human‑driven greenhouse gas emissions, the team calculated how much climate change shifted the odds.

They concluded that the extreme HDWI values observed in both central Chile and Patagonia, conditions that historically would have been rare, are now far more likely due to global warming.

Observational data suggested that events of this magnitude might now occur roughly once every five years in the present climate. In both study regions, the combination of persistent drought, high temperatures, and strong winds turned what might have been manageable fires into megafires that overwhelmed response efforts.

Emissions Effects and Air Quality Impacts

Megafires have powerful emissions effects that extend far beyond the burned areas. When large tracts of forest and grassland burn, they release stored carbon into the atmosphere as carbon dioxide and other greenhouse gases, temporarily turning ecosystems that usually act as carbon sinks into significant sources.

In years with intense fire activity across the Americas, burned area and associated emissions have been estimated to increase by around 30% compared with typical seasons.

Smoke from these fires also contains fine particulate matter and other pollutants that can travel hundreds or even thousands of kilometers, affecting air quality in cities and rural communities alike. Health studies from recent South American fire seasons highlight rises in respiratory and cardiovascular problems during heavy smoke episodes.

These emissions effects create a feedback loop: fires contribute to warming, which in turn increases the likelihood of future heatwaves and fire weather, especially in regions already trending toward drier conditions.

Unequal Impacts on Communities and Landscapes

Not all communities experience these megafires in the same way. Indigenous and rural populations in Patagonia and southern Chile often live closer to forested areas, rely on natural resources for their livelihoods, and have fewer resources to cope with evacuation, property loss, and long‑term recovery.

Reports from recent Argentine fire seasons describe conflicts over land, displacement of Indigenous groups, and concerns that recovery policies may not adequately support traditional land users.

At the ecosystem level, the fires have damaged habitats for vulnerable species and threatened old‑growth forests, including some of the world's oldest trees in Chile and Argentina.

The loss of native vegetation, combined with the spread of flammable plantations, can alter landscapes for decades, changing everything from biodiversity patterns to local water cycles.

Environmental Policy and Wildfire Risk

Environmental policy has become a central factor in how Argentina and Chile manage rising fire risks. In Chile, authorities have increased the wildfire budget in recent years, investing in early‑warning systems, aircraft, and equipment, and expanding efforts in forecasting and prevention.

Researchers and officials there point to the need to pair these measures with better land‑use planning, including reconsideration of large monoculture plantations that can amplify fire behavior.

In Argentina, by contrast, news reports and analyses highlight sharp cuts to the National Fire Management Service budget, with reductions of around 80% in one year and further cuts planned.

Environmental groups and scientists warn that shrinking resources for prevention, monitoring, and suppression undermine the country's ability to respond to more frequent high‑risk days.

Across both countries, experts argue that environmental policy needs to integrate wildfire science, climate targets, forest management, and community protection rather than treating fires as isolated emergencies.

Frequently Asked Questions

1. How do El Niño events interact with climate change to influence megafires in Argentina and Chile?

El Niño tends to bring hotter, drier conditions to parts of Chile and Argentina, and when layered on top of long‑term warming, it can sharply increase the chances of extreme fire weather.

2. Why are plantation forests often more fire‑prone than native forests in these regions?

Plantations of fast‑growing species like pine and eucalyptus can create dense, uniform fuel that dries quickly and burns intensely, especially during heatwaves and droughts.

3. Can prescribed burning help reduce megafire risk in Patagonia and southern Chile?

When carefully planned and monitored, prescribed burns can lower fuel loads and create strategic breaks, but they require strong local capacity, clear regulations, and favorable weather windows.

4. How might climate‑driven megafires affect tourism in southern South America?

More frequent extreme fire seasons can disrupt travel, degrade air quality, and damage iconic natural landscapes, potentially shortening peak seasons and increasing economic uncertainty for tourism‑dependent communities.