Wildfire responses to abrupt climate change in North America

Marlon, J.R., Bartlein, P.J., Walsh, M.K., Harrison, S.P., Brown, K.J., Edwards, M.E., Higuera, P.E., Power, M.J., Anderson, R.S., Briles, C., Brunelle, A., Carcaillet, C., Daniels, M., Hu, F.S., Lavoie, M., Long, C., Minckley, T., Richard, P.J.H., Scott, A.C., Shafer, D.S., Tinner, W., Umbanhowar, C.E. and Whitlock, C. (2009) Wildfire responses to abrupt climate change in North America. Proceedings of the National Academy of Sciences of the United States of America, 106 (8), 2519-2525. (doi:10.1073/pnas.0808212106).

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.

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Contributors

Author: M.E. Edwards

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