One line of evidence is how fires reacted to different levels of mobility loss, based on fire counts in 0.5-degree grid cells. In countries with fewer fires, fire declined in almost a straight line as mobility decreased. But countries that experienced more fires showed a slow increase that leveled off at about 27 percent on average as mobility fell. The researchers interpreted this as a sign that different mechanisms were at work. The steady decline fits fewer human-driven ignitions, while the gradual rise points to weakened suppression. But Wang mentioned that there could be other reasons, such as changes in local land use.
Mobility restrictions may also have disrupted fire management activities, which could mean that fewer fires were set for management purposes. The researchers examined 12 countries with records of prescribed burning. The area burned by prescribed fires in 2020 decreased by about half compared to the 2013–2019 average. Of course, the locations and sizes of prescribed burns also shift from year to year with fire return intervals and land-management cycles, which complicates this analysis.
When areas subjected to prescribed burning were excluded in those 12 countries, the decline in fires there shrank from 45.3 percent to 27.8 percent.
This research has limits partly because it relied on mobile phone data to track human movement. This kind of data might not capture human activity in rural areas where coverage may be limited. Also, the analysis focused only on the first half of each year, so the impact on regions where fires happen more frequently in the latter half of the year, such as the western US, may not have been fully captured.
Wang explained that this quasi-experimental design provides strong associational evidence but is not a controlled experiment.
Understanding the human Impact
Wang emphasized that the study is not an evaluation of fire policies. The analysis does, however, suggest that there’s no single ideal policy response. Where fires decreased, human ignition seems to dominate. In those areas, reducing accidental ignitions through public education and maintaining beneficial prescribed burning can be important. On the other hand, areas where fires increased might need to address reduced monitoring and suppression. Maintaining firefighting and patrol capacity during disruptions can be important there.
Wang added, “Overall, a uniform policy is unlikely to work, and strategies should be tailored to local human-fire relationships.” Fire-risk projections might benefit from accounting for human behavior. That way, more accurate fire projections can be made even as weather and society change.
Cell Reports Sustainability, 2026. DOI: 10.1016/j.crsus.2026.100860
