Abstract
Forest fires are usually viewed within the context of a single fire season, in which weather conditions and fuel supply can combine to create conditions favourable for fire ignition—usually by lightning or human activity—and spread1–3. But some fires exhibit ‘overwintering’ behaviour, in which they smoulder through the non-fire season and flare up in the subsequent spring4,5. In boreal (northern) forests, deep organic soils favourable for smouldering6, along with accelerated climate warming7, may present unusually favourable conditions for overwintering. However, the extent of overwintering in boreal forests and the underlying factors influencing this behaviour remain unclear. Here we show that overwintering fires in boreal forests are associated with hot summers generating large fire years and deep burning into organic soils, conditions that have become more frequent in our study areas in recent decades. Our results are based on an algorithm with which we detect overwintering fires in Alaska, USA, and the Northwest Territories, Canada, using field and remote sensing datasets. Between 2002 and 2018, overwintering fires were responsible for 0.8 per cent of the total burned area; however, in one year this amounted to 38 per cent. The spatiotemporal predictability of overwintering fires could be used by fire management agencies to facilitate early detection, which may result in reduced carbon emissions and firefighting costs.
| Original language | English |
|---|---|
| Pages (from-to) | 399-404 |
| Number of pages | 6 |
| Journal | Nature |
| Volume | 593 |
| Issue number | 7859 |
| Early online date | 19 May 2021 |
| DOIs | |
| Publication status | Published - 20 May 2021 |
Bibliographical note
Funding Information:Acknowledgements We would like to thank C. Van Der Horn and G. Branson (Alaska Interagency Coordination Center), and M. Coyle (Forest Management Division, Department of Environment and Natural Resources, Government of the Northwest Territories), for providing ground truth data on overwintering fires. We wish to thank Environment and Climate Change Canada for their generous permission to use Canadian Lightning Detection Network data, and the Bureau of Land Management, Alaska Fire Service, for providing cost information. We thank NASA JPL’s Snow Data Center for making their MODSCAG data available. This work was funded by the Netherlands Organization for Scientific Research (NWO) through a Vidi grant (Fires Pushing Trees North) awarded to S.V. B.M.R. acknowledges support from the National Aeronautics and Space Administration (NASA) Arctic-Boreal Vulnerability Experiment (ABoVE; NNX15AU56A).
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature Limited.
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
Funding
Acknowledgements We would like to thank C. Van Der Horn and G. Branson (Alaska Interagency Coordination Center), and M. Coyle (Forest Management Division, Department of Environment and Natural Resources, Government of the Northwest Territories), for providing ground truth data on overwintering fires. We wish to thank Environment and Climate Change Canada for their generous permission to use Canadian Lightning Detection Network data, and the Bureau of Land Management, Alaska Fire Service, for providing cost information. We thank NASA JPL’s Snow Data Center for making their MODSCAG data available. This work was funded by the Netherlands Organization for Scientific Research (NWO) through a Vidi grant (Fires Pushing Trees North) awarded to S.V. B.M.R. acknowledges support from the National Aeronautics and Space Administration (NASA) Arctic-Boreal Vulnerability Experiment (ABoVE; NNX15AU56A).
| Funders | Funder number |
|---|---|
| Fires Pushing Trees North | |
| National Science Foundation | 1757348 |
| National Aeronautics and Space Administration | NNX15AU56A |
| Nederlandse Organisatie voor Wetenschappelijk Onderzoek |
