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What do you mean, 'megafire'?


Linley, GD and Jolly, CJ and Doherty, TS and Geary, WL and Armenteras, D and Belcher, CM and Bird, RB and Duane, A and Fletcher, MS and Giorgis, MA and Haslem, A and Jones, GM and Kelly, LT and Lee, CKF and Nolan, RH and Parr, CL and Pausas, JG and Price, JN and Regos, A and Ritchie, EG and Ruffault, J and Williamson, GJ and Wu, Q and Nimmo, DG, What do you mean, 'megafire'?, Global Ecology and Biogeography pp. 1-17. ISSN 1466-8238 (2022) [Refereed Article]

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DOI: doi:10.1111/geb.13499


Background: ‘Megafire’ is an emerging concept commonly used to describe fires that are extreme in terms of size, behaviour, and/or impacts, but the term’s meaning remains ambiguous.

Approach: We sought to resolve ambiguity surrounding the meaning of ‘megafire’ by conducting a structured review of the use and definition of the term in several languages in the peer-reviewed scientific literature. We collated definitions and descriptions of megafire and identified criteria frequently invoked to define megafire. We recorded the size and location of megafires and mapped them to reveal global variation in the size of fires described as megafires.

Results: We identified 109 studies that define the term ‘megafire’ or identify a megafire, with the term first appearing in the peer-reviewed literature in 2005. Seventy-one (~65%) of these studies attempted to describe or define the term. There was considerable variability in the criteria used to define megafire, although definitions of megafire based on fire size were most common. Megafire size thresholds varied geographically from > 100–100,000 ha, with fires > 10,000 ha the most common size threshold (41%, 18/44 studies). Definitions of megafire were most common from studies led by authors from North America (52%, 37/71). We recorded 137 instances from 84 studies where fires were reported as megafires, the vast majority (94%, 129/137) of which exceed 10,000 ha in size. Megafires occurred in a range of biomes, but were most frequently described in forested biomes (112/137, 82%), and usually described single ignition fires (59% 81/137).

Conclusion: As Earth’s climate and ecosystems change, it is important that scientists can communicate trends in the occurrence of larger and more extreme fires with clarity. To overcome ambiguity, we suggest a definition of megafire as fires > 10,000 ha arising from single or multiple related ignition events. We introduce two additional terms – gigafire (> 100,000 ha) and terafire (> 1,000,000 ha) – for fires of an even larger scale than megafires.

Item Details

Item Type:Refereed Article
Keywords:anthropocene, catastrophic fire, climate change, extreme wildfire event, mega-fire, Pyrocene, wildfire disaster
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Forestry sciences
Research Field:Forestry fire management
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Natural hazards
Objective Field:Climatological hazards (e.g. extreme temperatures, drought and wildfires)
UTAS Author:Williamson, GJ (Dr Grant Williamson)
ID Code:149986
Year Published:2022
Web of Science® Times Cited:2
Deposited By:Plant Science
Deposited On:2022-05-06
Last Modified:2022-07-25

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