Are global wildfires decreasing?

Question

According to the World Health Organization,

Climate change is directly contributing to humanitarian emergencies from heatwaves, wildfires, floods, tropical storms and hurricanes and they are increasing in scale, frequency and intensity.

However, this New York Post opinion piece by Bjørn Lomborg, a noted opponent to climate change mitigation, claims that global wildfires are actually decreasing:

One of the most common tropes in our increasingly alarmist climate debate is that global warming has set the world on fire.

But it hasn’t.

For more than two decades, satellites have recorded fires across the planet’s surface.

The data are unequivocal: Since the early 2000s, when 3% of the world’s land caught fire, the area burned annually has trended downward.

In the piece, Lomborg claims that wildfires have increased in some parts of the world but decreased in other parts. In total, they are decreasing. The media never gives the full picture, but only shows the disasters. This would then create the illusion that global wildfires are increasing.

Is this true?

Answer 1

Yes, they are decreasing

Joe W's answer has misread its source. There has indeed been an increase in tree cover lost to forest fires, but the original claim was about wildfires. Not all wildfires occur in forests; many occur in grasslands.

When we look at all wildfires, we see that the claim of the original article was correct; the annual global area burned by wildfires has indeed been trending downwards. Researchers attribute this to changes in human agricultural practices.

DISCLAIMER (and I really shouldn't have to add this at all): This is not intended as an argument about how severe or mild the impacts of climate change are or will be. OP has asked a narrow, yes-or-no question, and I am answering that specific question.

The research

I was not able to find a dataset that went all the way up to 2022. However, there was a paper in Science in 2017 that looked at the timespan from 1998 to 2015:

Fire is an essential Earth system process that alters ecosystem and atmospheric composition. Here we assessed long-term fire trends using multiple satellite data sets. We found that global burned area declined by 24.3 ± 8.8% over the past 18 years. The estimated decrease in burned area remained robust after adjusting for precipitation variability and was largest in savannas. Agricultural expansion and intensification were primary drivers of declining fire activity. Fewer and smaller fires reduced aerosol concentrations, modified vegetation structure, and increased the magnitude of the terrestrial carbon sink. Fire models were unable to reproduce the pattern and magnitude of observed declines, suggesting that they may overestimate fire emissions in future projections. Using economic and demographic variables, we developed a conceptual model for predicting fire in human-dominated landscapes.

...

... Our analysis showed that the evolution of human-dominated fire regimes follows predictable patterns, with the transition from natural to managed landscapes in forest and savanna regions generating markedly different burned area trajectories (28) (figs. S12 and S13). For humid tropical forests, frequent fires for deforestation and agricultural management yielded a sharp rise in fire activity with the expansion of settled land uses, providing quantitative evidence for rapid ecosystem transformation during early land-use transitions described in previous work (31, 32). However, in semi-arid savannas and grasslands, the transition from natural landscapes with common land ownership to agriculture on private lands generated a nonlinear decrease in fire activity, even in areas without large-scale land cover conversion. The reorganization of land cover and fire use on the landscape also altered the contributions from different fire types to total burned area (Fig. 5). For both forested and savanna regions, the most rapid changes in both land cover and total burned area occurred for transitions at very low levels of per capita GDP (<$5000 km−2 year−1, figs. S12 and S13).

With an expanding human presence on the landscape, increasing investment in agricultural areas reduced fire activity in both savannas and forests (Fig. 5). In highly capitalized regions, burned area was considerably lower, likely as a consequence of both mechanized (fire-free) management and fire suppression to protect high-value crops, livestock, homes, infrastructure, and air quality (13) (Figs. 4 and 5 and fig. S11). Livelihoods change drastically along this trajectory of fire use, as does the perception of fire and smoke (23). Regulation to improve air quality has significantly reduced cropland burning in the western United States (33). By contrast, fire activity increased in some densely populated agricultural regions of India and China (Figs. 1 and 4), suggesting that without investments in air quality management, agricultural intensification may increase fire activity in regions where crop residue burning is the dominant fire type. Agricultural expansion and intensification are likely to continue in coming decades (21), with the largest changes expected in the tropics, as development shifts vast areas of common land or extensive land uses toward more capital-intensive agricultural production for regional or global markets (21, 32). These changes in land use suggest that observed declines in burned area may continue or even accelerate in coming decades.

^{N. Andela et al., A human-driven decline in global burned area. Science 356, 1356-1362 (2017). DOI: 10.1126/science.aal4108}

The paper doesn't spend a lot of time talking about climate change. Where it does, it holds that climate change generally increases fire risks, though perhaps not in every region of the globe.

... Climate feedbacks on fire activity are complex and vary by biome and level of fire suppression (11). Given projected increases in fire risk from climate change (12), fire management will be increasingly important for maintaining ecosystem function, air quality, and other services that influence human well-being (13).

Climate is a dominant control on fire activity, regulating vegetation productivity and fuel moisture. ... Climate change may increase fire risk in many regions (12, 16), given projected warming and drying in forests and other biomes with sufficient fuel loads to support fire activity. Ultimately, the interactions among climate, vegetation, and ignition sources determine the spatial and temporal pattern of biomass burning (17).

^Ibid.

Answer 2

Global fires are becoming more of a problem over the last 20 years and studies are indicated it is caused by climate change.

The Latest Data Confirms: Forest Fires Are Getting Worse

The latest data on forest fires confirms what we’ve long feared: Forest fires are becoming more widespread, burning nearly twice as much tree cover today as they did 20 years ago.

Using data from a recent study by researchers at the University of Maryland, we calculated that forest fires now result in 3 million more hectares of tree cover loss per year compared to 2001 — an area roughly the size of Belgium — and accounted for more than one-quarter of all tree cover loss over the past 20 years.

2021 was one of the worst years for forest fires since the turn of the century, causing an alarming 9.3 million hectares of tree cover loss globally — over one-third of all tree cover loss that occurred that year. Though down from the previous year, over 6.6 million hectares of tree cover was lost to forest fires in 2022, similar to other years over the past decade. And in 2023, the world has already seen heightened fire activity, including record-breaking burns across Canada and catastrophic fires in Hawaii.

Climate change is one of the major drivers of increasing fire activity. Extreme heat waves are already 5 times more likely today than they were 150 years ago and are expected to become even more frequent as the planet continues to warm. Hotter temperatures dry out the landscape and help create the perfect environment for larger, more frequent forest fires. This in turn leads to higher emissions from forest fires, further exacerbating climate change and contributing to more fires as part of a “fire-climate feedback loop.”

This feedback loop, combined with the expansion of human activities into forested areas, is driving much of the increase in fire activity we see today.