Three Hard Truths About France's Wildfires

Worse fire weather, less fire on the ground, and mitigation benefits detectable only in models

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The pattern is very familiar: With every extreme event comes claims — from journalists, scientists, and politicians — that we can reduce the impacts of those events by quickly cutting our emissions of carbon dioxide from the burning of fossil fuels.

Here are a few examples just in the last week with respect to the wildfires across southern France:

• “[I]f we want to reduce our fire risk, the first thing we have to do is reduce our emissions;”

• “To counter this escalating threat from wildfires, societies need to re-double efforts to mitigate the effects of extreme weather and reduce carbon emissions towards net zero;”

• “The science on the cause is unequivocal . . . What needs to be done is equally clear: leave coal, oil and gas behind faster, scale up renewables and protect people where the impacts are already hitting hardest.”

The logic is attractive: emissions cause warming, warming causes fires, so cutting emissions stops the fires.

Today’s post, as in a recent THB analysis of France’s heat waves, takes such policy causality claims seriously, and asks: What effect would cutting emissions — all the way to net zero and beyond — have on wildfires in France?

This post makes three arguments that I suspect, as a set, many will want to disagree with — and I hope that we can discuss them in the comments:

• First, the fire weather climate in southern France has changed. Fire weather days (defined below) have become much more common in recent decades;

• Second, actual fire on the landscape in South France measured as area burned has not increased, and arguably has decreased, over that same period;

• Third, compared to today, aggressive mitigation is not expected to have discernible effects on the number of fire weather days this century, and perhaps much longer. Further, the benefits of mitigation are a function of faith in models not evidence from the real world.

This post considers each in turn.

A note on scope. This analysis covers Southwest France — the Landes region, home to the largest fires of recent years — and the Mediterranean coast where most of France’s big fires have historically burned. It makes no claim about the whole planet, or even the whole country.

Point one: fire weather has changed in Southern France

Fire scientists use the Fire Weather Index, or FWI — a number combining temperature, humidity, wind, and rainfall — to assess a day’s favorability for fire. A hot, dry, windy day has a high score; a cool, damp, still day has a low score. The FWI measures weather, not fire.

The figure above shows the FWI for Mediterranean France for 1980 to 2024 from the Copernicus Climate Data Store’s European Climate Data Explorer — the monthly reanalysis Fire Weather Index for the Mediterranean region.¹ This product computes the FWI from the ERA5 reanalysis, which reconstructs past weather from measured conditions.

In the data I downloaded from Copernicus, I used five months — May through September — and averaged them within each year to give one fire-season FWI value per year. You can see in the figure that the index has a lot of variability, but it is also unmistakable that there is an upwards trend over this time series.

Issues of attribution go beyond today’s post, but this evidence shows that weather conditions conducive to fire in Mediterranean France have increased over the past 45 years.

Point two: but the area actually burned did not rise

If fire weather conditions, you might expect the area burned to also increase. In France it has not.

The figures above show from two different data sources — MODIS satellite observations (2002–2024) and MODIS + VIIRS (2012-2026) — trends in area burned across France. Note that the Mediterranean region accounts for about 70% of the nation’s total area burned. The orange bar for 2026 is area burned year to date.

From 2002 to 2024 the total area burned decreased and there is no trend from 2012 to present.

How can fire weather worsen while area burned holds steady or falls?

Weather is just one ingredient for fire. Whether or not a landscape burns depends on other factors as well: how much fuel has accumulated, whether an ignition occurs (in France, humans cause about 95% of ignitions), and how effectively crews suppress fires. France invested heavily in fire prevention and firefighting, and much of Europe watched burned area fall even as the climate warmed, largely through land management and fire suppression.

Thus two things are true: a clear upward trend in fire-favorable weather and a flat-to-declining trend in actual fire on the landscape. They don’t contradict each other — they simply show that the climate does not equal the outcome.

If I had a dollar for every time this past week I saw someone posting online trends in fires in France or area burned as an argument for or against detection of changes in climate I’d be able to buy a house in Mediterranean France — with AC!

Point three: emissions reductions are not a fire risk control knob

Let’s set aside all that complexity — fuel, ignition, suppression, the divergence between climate trends and fire trends — and grant the strongest reasonable version of the mitigation argument:

Suppose we care only about fire-weather risk, and let’s assume further that it is tightly associated with cumulative carbon emissions. If we cut emissions to achieve net zero (and beyond), how much less fire-weather risk would southwest France face by the end of the century?

A 2025 study in npj Natural Hazards — Lanet et al. — gives us information we need to engage this thought experiment with numbers. That paper projected how often summer days would cross the “extreme fire-weather day” threshold — the level that days exceeded only 10% of the time during the 1991–2020 baseline period.²

The study looked at RCP2.6 and RCP4.5 (yes, RCP8.5 is in there also, but I have ignored it in this analysis — I am modeling good practice!).

In the figure below I have graphed what Lanet et al. found for the increase in the probability of extreme weather days for RCP2.6 (blue dot, typically interpreted as being consistent with hitting a 2C target) and RCP4.5 (yellow dot) versus each scenario’s cumulative carbon dioxide emissions — and drew a straight line between them. I next added the two new CMIP7 scenarios that bracket a current/pledged policy range — MEDIUM (orange diamond) and MEDIUM-LOW (green diamond) — based on their cumulative carbon dioxide emissions.

That straight line allows me to estimate changing probability of extreme fire days under the methods of Lamet et al. for the new scenarios that bracket where CMIP7 thinks the world might be currently headed.³ I also calculated the midpoint of the two CMIP7 scenarios. All this is summarized in the table below the figure.

In the table, I converted each scenario’s fire-weather probability into something more tangible: the expected number of extreme fire-weather days in a typical July or August at the end of the century, averaged over 30 years.

A present-day baseline has about 3 extreme days per month. Based on these probabilities, expected variability is about +/- 3 days per month.⁴ Under the higher-emissions baseline cases, under the methods of Lanet et al, an average August could see 6 to 7-and-a-half such days — about double today.

So the conclusion of Lanet et al. is a strong response of extreme fire weather days to accumulating carbon dioxide — which is perfect for an analysis of the effects of mitigation on their projections of fire risk.

Let’s next introduce strong mitigation — that envisioned under RCP2.6, which reaches net-zero in the 2080s and goes net-negative after that. Under that scenario, at the end of the century July and August would average about 3 extreme days per month — essentially the same as today.⁵

Mitigation, under these assumptions, provides benefits in preventing modeled risks from increasing, but mitigation does not reduce risk from today. That means if the fires in France today are a problem today, then mitigation has no potential for reducing risks from today for generations at least, if ever.

Let me say that again — Under assumptions most favorable to the fire weather impacts of mitigation,⁶ end-of-century fire weather resembles the fire weather we already live with.

The CMIP7 midpoint projects 10.8 extreme fire days in July and August, averaged over 2070-2100, while RCP2.6 projects 5.9 — about five fewer days. In the modeled results, mitigation does cut risks relative to the baseline.

So the answer to the question “does cutting carbon lower fire danger in the Landes region of France?” has two defensible answers from a single study depending on the metric: no and yes.

• No, not with respect to today’s level of risks,

• Yes, with respect to a difference between two alternative, modeled futures.

This means that the mitigation benefit — the difference from the path not taken — is unobservable. Strong mitigation has an effect between the modeled RCP2.6 world and a modeled imagined higher-emissions world. But the quantification of benefits exist only in model land — not in the real world.

The yes or no answer depends not only on which baseline is assumed but on which variable you measure. Lanet et al. track two fire-danger indices that, under the same low-emissions pathway, move in opposite directions: the daily Fire Weather Index eases (an extreme day’s odds fall from 0.12 to 0.08 in August), while the seasonal hot-dry index climbs (from 0.03 to 0.15). One risk metric falls under mitigation while another rises — from the same paper.

None of this means that mitigation would not influence future risk of fire weather, but it does mean that the benefits of mitigation only exist insofar as we trust a model to accurately represent the world and our ability to accurately project where the world is headed under alternative pathways.

Were we to introduce in our analysis more variables, more scenarios, more models, more assumptions, more baselines — the scope of plausibly defensible perspectives would multiply. We have entered the garden of forking paths.⁷

Let’s illustrate this with numbers: If we assume a baseline of RCP4.5, then a signal of mitigation by following RCP2.6 emerges 38 years after the scenarios diverge — which would be sometime well into the second half of this century.⁸ Assume a baseline that approaches RCP2.6, and the time of emergence stretches to infinity. There are many defensible positions on where the world might be headed as a baseline scenario that fall in between RCP2.6 and RCP4.5 to satisfy every proponent or opponent of mitigation.

Science cannot resolve these perspectives.

The real-world impact of mitigation on fire risk in this case is thus a function of what future one believes we are headed for — which can not be resolved empirically. This is not an argument saying that mitigation can have no benefits for reducing fire risk, but rather, an explanation why our perspectives on what that benefit might be rests on beliefs and faith, not data and science.

Where this leaves us

To their credit, the Lamet et al. study acknowledges that adaptation to fire risk is not just necessary, but essential. Unlike those quoted at the top of this post, they do not treat emissions reductions as a fire weather control knob:

Adapting to the escalating risk of wildfires necessitates a comprehensive approach that addresses the three fundamental components of risk: danger (also referred as hazard), exposure, and vulnerability. Mitigating the hazard involves decreasing the likelihood and potential severity of wildfire events. This can be achieved through public education campaigns that promote fire-safe behaviours among residents, tourists, and professionals. Fuel management practices, such as prescribed burning and mechanical thinning, have proven effective in reducing wildfire severity. Exposure can be curtailed by regulating the expansion of human settlements and infrastructure into fire-prone areas, particularly the wildland–urban interface (WUI). The WUI, where human development meets undeveloped wildland, has been identified as a zone of heightened wildfire risk. Efforts to limit development in these areas can reduce the number of structures and lives at risk. However, it is important to recognise that even without further expansion, existing exposure within the WUI remains substantial. Moreover, many peri-urban areas—often overlapping with the WUI—provide essential affordable housing, underscoring the need to balance wildfire risk reduction with broader social and economic considerations. Finally, reducing vulnerability entails enhancing the resilience of communities and systems to withstand and recover from wildfire events.

This post does not argue against accelerated decarbonization. It argues that justifying decarbonization as a fire-risk reduction policy — as so many are about France this month — misleads the public and distracts from policies that can actually make a difference.

For accelerated decarbonization to gain wide public support, its benefits must be both near-term and perceptible.

Even granting the strongest reasonable assumptions, strong mitigation leaves end-of-century fire weather in Southwest France looking much like today’s — thus, the promised risk reduction cannot be delivered, even in highly simplified models.

Further, the benefits of mitigation for fire weather risk — not actual fire on the landscape — are entirely a function and magnitude of assumptions made about counterfactual futures. That doesn’t make benefits unreal, but it does make them intangible and determined by faith in models and beliefs about the future.

There are many better reasons for accelerating decarbonization of our economies than reducing fire risk in France. If those good reasons for accelerating decarbonization have a potential side benefit of contributing to lower fire risks, even if not completely quantifiable, so much the better.

My advice to climate advocates: Lead with the better arguments. Don’t preach weather control. That is bad science and a false promise.

Mitigation matters, justifications for it should matter too.

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