Wildfire responses to abrupt climate change in North America

Abstract

It is widely accepted, based on data from the last few decades and on model simulations, that anthropogenic climate change will cause increased fire activity. However, less attention has been paid to the relationship between abrupt climate changes and heightened fire activity in the paleorecord. We use 35 charcoal and pollen records to assess how fire regimes in North America changed during the last glacial-interglacial transition (15 to 10 ka), a time of large and rapid climate changes. We also test the hypothesis that a comet impact initiated continental-scale wildfires at 12.9 ka; the data do not support this idea, nor are continent-wide fires indicated at any time during deglaciation. There are, however, clear links between large climate changes and fire activity. Biomass burning gradually increased from the glacial period to the beginning of the Younger Dryas. Although there are changes in biomass burning during the Younger Dryas, there is no systematic trend. There is a further increase in biomass burning after the Younger Dryas. Intervals of rapid climate change at 13.9, 13.2, and 11.7 ka are marked by large increases in fire activity. The timing of changes in fire is not coincident with changes in human population density or the timing of the extinction of the megafauna. Although these factors could have contributed to fire-regime changes at individual sites or at specific times, the charcoal data indicate an important role for climate, and particularly rapid climate change, in determining broad-scale levels of fire activity.biomass burning ͉ charcoal ͉ comet ͉ Younger Dryas

Predictability of biomass burning in response to climate changes

“…Fire tracks the climate changes in a predictable way that is consistent with known climatic controls on biomass burning (see also [Arneth et al, 2010;Daniau et al, 2010b;Marlon et al, 2009]). The major component of variability in biomass burning over the past 21 kyr reflects the shift from globally cold/glacial to warm/interglacial conditions.…”

Fluctuating fire regimes and their historical effects on genetic variation in an endangered shrubland specialist

“…2008; Marlon et al. 2009). The charcoal deposits increased between 12,000 and 9000 ybp after the cooling of Younger Dryas period (Fig.…”

“…2008; Marlon et al. 2009; Bryant 2012). Pollen records show that juniper–oak savannas in Texas also expanded after the LGM, becoming the dominant vegetation on Edwards' Plateau and contacting prairie grasslands from the American Midwest (Bryant 2012).…”

“…These changes in the fire regime have been tied to events of rapid climate change between 15,000 and 10,000 ybp (Marlon et al. 2009) during the last glacial–interglacial transition in North America stemming from abrupt temperature changes, in particular the cooling at the Younger Dryas (~12,900–11,700 ybp, Steffensen et al. 2008).…”

Smoke consequences of new wildfire regimes driven by climate change

“…They also vary in the degree to which fire-regime properties are emergent [McKenzie and Kennedy, 2011], i.e., arising directly from drivers such as climate or fuels simulated within the DGVM, or prescribed, e.g., by specifying fire-return intervals or fire cycles a priori. The latter type draws on historical fire regimes dating back to the middle Holocene, providing an implicit calibration to centuries of fire-climate observations [Marlon et al, 2009[Marlon et al, , 2012Hessl, 2011]. The former type eschews that calibration, thereby avoiding the no analog problem: projected climate, even in the near term (decades), is outside of the Holocene range [Williams and Jackson, 2007].…”