Nearly Three-Quarters of the Western United States Is Overdue for Wildfires, New Research Shows

Nearly three-quarters of the western United States is not burning as often as it historically should, according to new research presented at the American Geophysical Union (AGU) 2025 Annual Meeting in New Orleans. Scientists say this growing gap between past and present fire activity has created what they call a “fire deficit”, a condition that could make future wildfires more intense, harder to manage, and more damaging to ecosystems and communities.

Wildfires are often viewed only through the lens of destruction, but ecologists have long known that fire plays a critical ecological role. In many forests and landscapes, periodic fires clear away dead vegetation, recycle nutrients back into the soil, open space for new plant growth, and help maintain healthy forest structure. When fires are absent for too long, vegetation builds up, creating dense fuel that can feed extreme blazes when conditions finally align.

How Big Is the Fire Deficit?

The new research estimates that about 38 million hectares of land in the western U.S. are historically behind on burning. Earlier versions of the study suggested an even larger figure, but after refining their analysis, researchers updated the final number to this still-massive total. To put that into perspective, this area is larger than the size of Germany.

Based on historical fire patterns, scientists found that 74% of the western United States currently falls into a fire deficit. To make up for that deficit and bring ecosystems closer to their natural fire cycles, an estimated 3.8 million hectares of forest would need to burn every year for the next decade. That annual amount is three times greater than the forested area that burned during 2020, which remains the largest wildfire year on record in the U.S.

This doesn’t mean scientists are calling for uncontrolled fires across the West. Instead, they are pointing to the scale of the imbalance and the challenge it presents for land managers in a warming, drying climate.

Why Fire Suppression Changed Everything

For more than 150 years, the United States has invested heavily in fire suppression. Billions of dollars have gone into extinguishing wildfires as quickly as possible to protect lives, homes, and infrastructure. While this approach has saved countless communities, it has also interrupted natural fire cycles that many ecosystems depend on.

Over time, forests that once burned regularly at low or moderate intensity have become overly dense, packed with small trees, dead wood, and dry undergrowth. This accumulated fuel increases the likelihood that when fires do occur, they burn hotter, spread faster, and cause more damage than historical fires ever did.

At the same time, climate change is making conditions warmer and drier, extending fire seasons and increasing the risk of large wildfires. Researchers emphasize that today’s wildfire crisis is not caused by climate change alone, but by the combination of climate stress and decades of fire suppression.

How Scientists Measured the Fire Deficit

To understand how current fire activity compares to the past, researchers used a mix of geospatial data, including pollen records, soil samples, and historical vegetation information. These data helped reconstruct historical fire return intervals, or how often fires naturally occurred in different landscapes before modern suppression efforts.

The team relied on reconstructions from the LANDFIRE program, which models vegetation and fire regimes across the U.S. By comparing historical burn patterns with modern fire data, scientists were able to identify where fires are happening too infrequently, as well as areas where fires are now occurring more often than they once did.

The results revealed a clear and widespread fire deficit across much of the western U.S., alongside a few regions experiencing the opposite problem.

Fire Deficit vs. Fire Surplus Regions

While most of the West is behind on burning, not all ecosystems are experiencing the same trend. The study found that parts of the Southwest, particularly Southern California, are dealing with a fire surplus instead.

In shrublands and chaparral ecosystems, many fires are now human-caused and occur more frequently than they did historically. These ecosystems evolved with fire, but not with constant or repeated burning at short intervals. Too much fire can prevent shrubs and native plants from regenerating, potentially leading to ecosystem collapse or conversion to grasslands.

The research also identified parts of the Cascadia region, including areas of the Pacific Northwest, as showing early signs of a fire surplus. In this case, climate change-driven factors, such as rising temperatures and increased drought, appear to be pushing fire activity beyond historical levels sooner than scientists expected.

What Can Be Done to Address the Problem?

Closing the fire deficit will not be easy, and researchers stress that no single solution will work everywhere. Instead, they point to a combination of land management strategies that could help reduce fuel buildup while protecting communities.

One major tool is prescribed burning, where land managers intentionally set controlled fires under carefully chosen weather conditions. These burns reduce fuel loads and mimic natural fire processes without the extreme risks of uncontrolled wildfires.

Another approach is mechanical thinning, which involves physically removing excess vegetation, small trees, and dead material from forests. While expensive and labor-intensive, thinning can make prescribed burns safer and reduce fire severity near communities.

Researchers also highlight the potential of managed wildfire, allowing some naturally ignited fires to burn when conditions are safe and risks are low. Rather than suppressing every fire immediately, managers can let certain fires do ecological work, reducing fuel and restoring forest health.

Why This Matters for the Future

The scale of the fire deficit underscores how deeply fire suppression has reshaped western landscapes. Even as recent wildfire seasons feel unprecedented, many forests are still burning less than they did historically. That means the potential for extreme fires remains high unless fuel loads are addressed.

As climate change continues to intensify droughts, heat waves, and fire weather, the gap between historical and modern fire regimes could become even more dangerous. Researchers warn that without proactive management, future wildfires may grow larger, burn hotter, and threaten more communities.

Understanding where fires are overdue, where they are excessive, and how ecosystems respond differently is critical for creating smarter, region-specific fire policies. The study provides a data-driven framework to guide those decisions and highlights the urgency of rethinking how fire is managed across the western U.S.

Learning to Live With Fire Again

The research reinforces a growing consensus among ecologists: fire is not simply an enemy to be eliminated. In many ecosystems, it is a necessary natural process that, when properly managed, can reduce long-term risk rather than increase it.

Balancing ecological needs with public safety will remain one of the biggest environmental challenges of the coming decades. This study makes it clear that the question is no longer whether fire will shape the western U.S., but how intentionally and thoughtfully it will be allowed to do so.

Research paper: https://ui.adsabs.harvard.edu/abs/2025AGUFM.B42C..08H/abstract