The response of wildfire regimes to Last Glacial Maximum carbon dioxide and climate
<p>Climate and fuel availability jointly control the incidence of wildfires. The effects of atmospheric CO<span class="inline-formula"><sub>2</sub></span> on plant growth influence fuel availability independently of climate, but the relative importance of each...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-09-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/3981/2023/bg-20-3981-2023.pdf |
| Summary: | <p>Climate and fuel availability jointly control the incidence of wildfires.
The effects of atmospheric CO<span class="inline-formula"><sub>2</sub></span> on plant growth influence fuel
availability independently of climate, but the relative importance of each
in driving large-scale changes in wildfire regimes cannot easily be
quantified from observations alone. Here, we use previously developed
empirical models to simulate the global spatial pattern of burnt area, fire
size, and fire intensity for modern and Last Glacial Maximum (LGM;
<span class="inline-formula">∼</span> 21 000 ka) conditions using both realistic changes in
climate and CO<span class="inline-formula"><sub>2</sub></span> and sensitivity experiments to separate their
effects. Three different LGM scenarios are used to represent the range of
modelled LGM climates. We show large, modelled reductions in burnt area at
the LGM compared to the recent period, consistent with the sedimentary
charcoal record. This reduction was predominantly driven by the effect of
low CO<span class="inline-formula"><sub>2</sub></span> on vegetation productivity. The amplitude of the reduction
under low-CO<span class="inline-formula"><sub>2</sub></span> conditions was similar regardless of the LGM climate
scenario and was not observed in any LGM scenario when only climate effects
were considered, with one LGM climate scenario showing increased burning
under these conditions. Fire intensity showed a similar sensitivity to
CO<span class="inline-formula"><sub>2</sub></span> across different climates but was also sensitive to changes in
vapour pressure deficit (VPD). Modelled fire size was reduced under LGM
CO<span class="inline-formula"><sub>2</sub></span> in many regions but increased under LGM climates because of changes
in wind strength, dry days (DDs), and diurnal temperature range (DTR). This
increase was offset under the coldest LGM climate in the northern latitudes
because of a large reduction in VPD. These results emphasize the fact that
the relative magnitudes of changes in different climate variables influence
the wildfire regime and that different aspects of climate change can have
opposing effects. The importance of CO<span class="inline-formula"><sub>2</sub></span> effects imply that future
projections of wildfire must take rising CO<span class="inline-formula"><sub>2</sub></span> into account.</p> |
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| ISSN: | 1726-4170 1726-4189 |