Assessing changes in global fire regimes
Authors: Sayedi Sayedeh Sara , Abbott Benjamin W. , Vannière Boris , Leys Bérangère , Colombaroli Daniele , Romera Graciela Gil , Słowiński Michał , Aleman Julie C. , Blarquez Olivier , Feurdean Angelica , Brown Kendrick , Aakala Tuomas , Alenius Teija , Allen Kathryn , Andric Maja , Bergeron Yves , Biagioni Siria , Bradshaw Richard , Bremond Laurent , Brisset Elodie , Brooks Joseph , Brugger Sandra O. , Brussel Thomas , Cadd Haidee , Cagliero Eleonora , Carcaillet Christopher , Carter Vachel , Catry Filipe X. , Champreux Antoine , Chaste Emeline , Chavardès Raphaël Daniel , Chipman Melissa , Conedera Marco , Connor Simon , Constantine Mark , Courtney Mustaphi Colin , Dabengwa Abraham N. , Daniels William , De Boer Erik , Dietze Elisabeth , Estrany Joan , Fernandes Paulo , Finsinger Walter , Flantua Suzette G. A. , Fox-Hughes Paul , Gaboriau Dorian M. , M.Gayo Eugenia , Girardin Martin. P. , Glenn Jeffrey , Glückler Ramesh , González-Arango Catalina , Groves Mariangelica , Hamilton Douglas S. , Hamilton Rebecca Jenner , Hantson Stijn , Hapsari K. Anggi , Hardiman Mark , Hawthorne Donna , Hoffman Kira , Inoue Jun , Karp Allison T. , Krebs Patrik , Kulkarni Charuta , Kuosmanen Niina , Lacourse Terri , Ledru Marie-Pierre , Lestienne Marion , Long Colin , López-Sáez José Antonio , Loughlin Nicholas , Niklasson Mats , Madrigal Javier , Maezumi S. Yoshi , Marcisz Katarzyna , Mariani Michela , McWethy David , Meyer Grant , Molinari Chiara , Montoya Encarni , Mooney Scott , Morales-Molino Cesar , Morris Jesse , Moss Patrick , Oliveras Imma , Pereira José Miguel , Pezzatti Gianni Boris , Pickarski Nadine , Pini Roberta , Rehn Emma , Remy Cécile C. , Revelles Jordi , Rius Damien , Robin Vincent , Ruan Yanming , Rudaya Natalia , Russell-Smith Jeremy , Seppä Heikki , Shumilovskikh Lyudmila , T.Sommers William , Tavşanoğlu Çağatay , Umbanhowar Charles , Urquiaga Erickson , Urrego Dunia , Vachula Richard S. , Wallenius Tuomo , You Chao , Daniau Anne-Laure 
Published: February 2024

Abstract
Background
The global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300.

Results
Respondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios.

Conclusion
The influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.