Hello,
This month I thought people might be interested in a short overview I pulled together about some of the fires in recent years and the impact they've had (instead of only detailed summaries of each paper). Let me know what you think! I do have normal summaries of four papers on fire (two mentioned in the overview) as well.
If you know someone who wants to sign up to receive these summaries, they can do so at http://bit.ly/sciencejon (no need to email me).
FIRE OVERVIEW:
Earlier this year in and around one of the largest cities in the US, almost 50,000 acres burned (https://www.fire.ca.gov/incidents/2025), destroying >16,000 buildings, displacing tens of thousands of people, and causing an estimated damage of >$250 billion dollars (https://www.nbcnews.com/news/us-news/california-wildfires-what-we-know-palisades-eaton-los-angeles-rcna188239). This follows an exceptional fire season across North and South America in 2024 (https://earth.org/north-and-south-america-endured-exceptional-wildfire-season-in-2024/).
Experts estimate that there has been a “ten‑fold increase in the frequency of fire regime change during the last 250 years,” (Sayedi et al. 2024) and wildland fuels have almost universally been getting dryer over the last 40 years (Ellis et al. 2022). While fire is normal in many ecosystems (and essential in some), we also have many recent examples of fires which devastated nature due to unusual severity, scale, speed, and return intervals. For example, in 2019-20, after severe drought in Australia a fire burned over 25 million acres (>100,000 km2) and “killed or displaced an estimated 3 billion mammals, birds, frogs, and reptiles” (Legge et al. 2023). The Pantanal has had increasingly common severe fires, e.g., in 2020 almost half of the ~10 million acres that burned hadn’t burned before in the last 20 years (Garcua et al. 2021), killing roughly 17 million vertebrates (Tomas et al. 2021).
In some cases severe fire can also lead to high greenhouse gas emissions, especially for peatlands. For example, in 1997-8 Indonesian peat fires emitted a gigaton of carbon (~15% of global fossil fuel emissions, Turetsky et al. 2015).
There is hope: our ability to remotely detect forest fires early is improving (Barmpoutis et al. 2020), and Indigenous fire brigades have shown promise as a low-cost way to dramatically reduce harmful wildfire (Ribeiro et al. 2023).
SUMMARIES OF SPECIFIC FIRE PAPERS:
GLOBAL FIRE:
Ellis et al. 2022 is a global analysis of fire risk over the past 41 years, using estimated moisture trends in fuel (surface litter and dead plant debris) as the key metric. Fig 2a shows the % of days during the fire season where fuel moisture is expected to be below 10% (and thus at high fire risk), while 2b shows the total # of fire season days at high fire risk and Fig 4 shows the trend in high fire risk over time (36% of ecoregions are drying vs. only 4% getting wetter). They note that days w/ dry fuel isn't the only key driver of risk; consistent dry conditions limit fuel accumulation and thus the risk of severe fire. So surprisingly historically wet forests which accumulate lots of plant matter in wet years between fires may be the most at risk (as other research has shown).
FIRE IN SOUTH AMERICA:
Feron et al. 2024 analyzes how fire risk in South America has increased in the last 52 years (especially in the North Amazon). They estimate fire risk by combining the increasing number of warm days, dry days, and flammable days (combined in Fig 3). El Niño worsens risk in the Nothern Amazon, but lessens it in the Gran Chaco (where La Niña worsens the risk). The northeast part of the Gran Chaco has seen the most increase in fire risk (Fig 1a). The authors note that where humans set fires is also a key driver of wildfires spreading. In the Amazon severe fire has caused local warming (from black carbon) and decreasing rainfall.
Barros-Rosa et al. 2025 is a complex analysis of water and fire in the Pantanal and Planalto in Brazil. They looked at changes in land use and water and fire from 1985 to 2022. They found 1) open water in the Pantanal dropped from 20% to 5% (this analysis has a very high rate of error and variance so the precise numbers are likely wrong but the overall drying trend is valid), 2) forest and savanna were cleared for cattle (replacing them with exotic grass - doubling in the Planalto and tripling in the Pantanal), although 3) native grasslands also doubled in the Pantanal. They also find areas that have dried out are the most affected by wildfires. The authors also highlight existing policies allowing massive conversion of habitat to exotic grass, and allowing artificial drainage in wetlands outside the Pantanal.
Oliveira et al. 2025 argues that rigid "burn windows" when prescribed fire should be done works poorly in wetlands like the Pantanal (where the government limits prescribed fire to the beginning of the dry season (BDS), a ~5 month period as shown in Fig. 2). Burn windows remain important: prescribed fire requires considering both fuel loads and how wet or dry it is to ensure fire can burn but remains contained, as well as things like wind direction that could affect human health. But flooding combines w/ rainfall to determine actual fuel loads, limiting the utility of prescribed fire when rain is low but flooding remains. Considering river height as a proxy for flooding they find the end of the BDS is typically ideal for prescribed fire (although varying year to year, Fig. 6) even though rainfall is much lower than the beginning of BDS when flooding limits the use of prescribed fire (Fig. 4b and 4c). But they note that in the Northern Pantanal where rain and flood are more aligned than the Southern Pantanal the burn window is longer and more predictable (Fig. 5). The conclude that in wetlands like the Pantanal burn windows should be dynamic year to year and consider flooding as well as rainfall. One key point: prescribed burning is more important in high flood years, b/c while the window is shorter, flooding allows more vegetation to accumulate which raises the risk of fire once floods recede (we've often see severe fires in the Pantanal the year after a very wet year).
REFERENCES FOR PAPERS SUMMARIZED INDIVIDUALLY:
Ellis, T. M., Bowman, D. M. J. S., Jain, P., Flannigan, M. D., & Williamson, G. J. (2022). Global increase in wildfire risk due to climate‐driven declines in fuel moisture. Global Change Biology, 28(4), 1544–1559. https://doi.org/10.1111/gcb.16006
Feron, S., Cordero, R. R., Damiani, A., MacDonell, S., Pizarro, J., Goubanova, K., Valenzuela, R., Wang, C., Rester, L., & Beaulieu, A. (2024). South America is becoming warmer, drier, and more flammable. Communications Earth & Environment, 5(1), 501. https://doi.org/10.1038/s43247-024-01654-7
Barros-Rosa, L., Moura Peluso, L., Lemes, P., Johnson, M. S., Dalmagro, H. J., Nunes da Cunha, C., Zanella de Arruda, P. H., Mateus, L., & Penha, J. (2025). The ineffectiveness of current environmental and fire policies in the world’s largest wetland. Environmental Research Letters, 20(3), 034039. https://doi.org/10.1088/1748-9326/adb7f5
Oliveira, M. da R., Pereira, A. de M. M., Bao, F., Ferreira, B. H. dos S., Fernando, A. E., Roque, F. de O., Pott, A., Damasceno-Junior, G. A., & Neves, D. R. M. (2025). Designing Burn Windows for Integrated Fire Management in Wetlands: Why Should Flooding Not Be Overlooked? Wetlands, 45(4), 35. https://doi.org/10.1007/s13157-025-01919-7
REFERENCES FOR OTHER PAPERS IN OVERVIEW:
Barmpoutis, P., Papaioannou, P., Dimitropoulos, K., & Grammalidis, N. (2020). A Review on Early Forest Fire Detection Systems Using Optical Remote Sensing. Sensors, 20(22), 6442. https://doi.org/10.3390/s20226442
Garcia, L. C., Szabo, J. K., de Oliveira Roque, F., de Matos Martins Pereira, A., Nunes da Cunha, C., Damasceno-Júnior, G. A., Morato, R. G., Tomas, W. M., Libonati, R., & Ribeiro, D. B. (2021). Record-breaking wildfires in the world’s largest continuous tropical wetland: Integrative fire management is urgently needed for both biodiversity and humans. Journal of Environmental Management, 293(April), 112870. https://doi.org/10.1016/j.jenvman.2021.112870
Legge, S., Rumpff, L., Garnett, S. T., & Woinarski, J. C. Z. (2023). Loss of terrestrial biodiversity in Australia: Magnitude, causation, and response. Science, 381(6658), 622–631. https://doi.org/10.1126/science.adg7870
Ribeiro, D. B., & Pereira, A. M. M. (2023). Solving the problem of wildfires in the Pantanal Wetlands. Perspectives in Ecology and Conservation, 21(4), 271–273. https://doi.org/10.1016/j.pecon.2023.10.004
Sayedi, S. S., Abbott, B. W., Vannière, B., Leys, B., Colombaroli, D., Romera, G. G., Słowiński, M., Aleman, J. C., Blarquez, O., Feurdean, A., Brown, K., Aakala, T., Alenius, T., Allen, K., Andric, M., Bergeron, Y., Biagioni, S., Bradshaw, R., Bremond, L., … Daniau, A.-L. (2024). Assessing changes in global fire regimes. Fire Ecology, 20(1), 18. https://doi.org/10.1186/s42408-023-00237-9
Tomas, W. M., Berlinck, C. N., Chiaravalloti, R. M., Faggioni, G. P., Strüssmann, C., Libonati, R., Abrahão, C. R., do Valle Alvarenga, G., de Faria Bacellar, A. E., de Queiroz Batista, F. R., Bornato, T. S., Camilo, A. R., Castedo, J., Fernando, A. M. E., de Freitas, G. O., Garcia, C. M., Gonçalves, H. S., de Freitas Guilherme, M. B., Layme, V. M. G., … Morato, R. (2021). Distance sampling surveys reveal 17 million vertebrates directly killed by the 2020’s wildfires in the Pantanal, Brazil. Scientific Reports, 11(1), 23547. https://doi.org/10.1038/s41598-021-02844-5
Turetsky, M. R., Benscoter, B., Page, S., Rein, G., Van Der Werf, G. R., & Watts, A. (2015). Global vulnerability of peatlands to fire and carbon loss. Nature Geoscience, 8(1), 11–14. https://doi.org/10.1038/ngeo2325
Sincerely,
Jon
p.s. The picture is of the first drum circle I ever attended, which was at work during a "learning week" event for my department!
p.p.s. Nothing in this post is an April Fool's joke or untrue in any way as far as I know :)
