Learn how plants respond to higher atmospheric CO2 concentrations

How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

A Multi-Century History of Forest Fires in Central Siberia
Wallenius, T., Larjavaara, M., Heikkinen, J. and Shibistova, O. 2011. Declining fires in Larix-dominated forests in northern Irkutsk district. International Journal of Wildland Fire 20: 248-254.

The authors write that "the effect of ongoing climate change on forest fires is a hotly debated topic," with many "experts" arguing that "the climatic warming in the 20th and 21st century has resulted and will result in an increase in forest fires."

What was done
In a study that addresses this issue, Wallenius et al. strove to "add information about forest fire history of the as-yet poorly studied Larix-dominated forests of central Siberia by means of high-precision dendrochronological dating of past fires." Working in the northern part of the Irkutsk district of central Siberia (centered at approximately 60.75°N, 107.75°E), in areas "untouched by modern forestry and agriculture," where "population density is low, with less than 0.1 inhabitant per square kilometer," they studied four individual landscapes "at 25-40 km (one day by boat) distances from each other in the forests along the Nizhnyaya Tunguska, and 6-10 km (one day on foot) inland from the river bank," reconstructing their fire histories from fire-scarred Larix and Pinus trees located in 46 different plots.

What was learned
The Finnish, Panamanian and Russian researchers determined that "in the 18th century, on average, 1.9% of the forests burned annually, but in the 20th century, this figure was only 0.6%," while "the fire cycles for these periods were 52 and 164 years, respectively." And they say that "a further analysis of the period before the enhanced fire control program in the 1950s revealed a significant lengthening in the fire cycle between the periods 1650-1799 and 1800-1949, from 61 to 152 years, respectively." And they report that "a similar phenomenon has been observed in Fennoscandia, southern Canada and the western United States, where the annually burned proportions have decreased since the 19th century (Niklasson and Granstrom, 2000; Weir et al., 2000; Heyerdahl et al., 2001; Bergeron et al., 2004)." And they note that "in these regions, the decrease has been mostly much steeper, and the current fire cycles are several hundreds or thousands of years."

What it means
Contrary to the contentions of many "experts," the real-world results of Wallenius et al., plus those of the other researchers they mention, suggest just the opposite of what the world's climate alarmists would have one believe about climate change and wildfires, as fires appear to have declined in this part of the planet as the earth emerged from the global chill of the Little Ice Age. For more on the subject, including a few contrary findings from other locations, as well as studies that consider additional factors, see Fire (Relationship to Global Warming) in our Subject Index).

Bergeron, Y., Gauthier, S., Flannigan, M. and Kafka, V. 2004. Fire regimes at the transition between mixedwood and coniferous boreal forest in northwestern Quebec. Ecology 85: 1916-1932.

Hyerdahl, E.K., Brubaker, L.B. and Agee, J.K. 2001. Spatial controls of historical fire regimes: a multiscale example from the interior west, USA. Ecology 82: 660-678.

Niklasson, M. and Granstrom, A. 2000. Numbers and sizes of fires: long-term spatially explicit fire history in a Swedish boreal landscape. Ecology 81: 1484-1499.

Weir, J.M.H., Johnson, E.A. and Miyanishi, K. 2000. Fire frequency and the spatial age mosaic of the mixed-wood boreal forest in western Canada. Ecological Applications 10: 1162-1177.

Reviewed 27 July 2011