Arctic forest fires add to climate chaos

Montana State University released details of an interesting four year study on the effects of global warming on the world’s Arctic tundra, summarised by lead author, post-doctoral researcher Philip Higuera.

The study found that arctic tundra are far more susceptible to fires than previously thought, an important finding, given the potential for tundra fires to release organic carbon – which could add significantly to the amount of greenhouse gases already blamed for global warming.

The ancient sediment cores taken in the study, showed the shrub tundra burned as frequently as modern boreal forests in Alaska – every 140 years on average, but with some fires spaced only 30 years apart.

Higuera’s research is important because other evidence indicates that as the climate has warmed in the past 50 to 100 years, shrubs have expanded across the world’s tundra regions.

“There is evidence of increasing shrub biomass in modern tundra ecosystems, and we expect temperatures to continue to increase and overall moisture levels to decrease. Combine these two factors and it suggests a greater potential for fires,” Higuera said. “The sediment cores indicate that it’s happened before.”

These findings are significant because the world’s high latitude tundra and boreal forest ecosystems contain roughly 30 percent of the planet’s total soil carbon, the report said. Currently, much of the carbon is locked in permafrost. But a warming climate could cause the permafrost to melt and release its carbon stores into the atmosphere where it would contribute to the greenhouse effect.

“Vegetation change through an increase in shrub biomass and more frequent burning will change a great deal of the carbon cycle in these high latitudes,” Higuera said. “We don’t fully understand the implications, except that it’s reasonable to expect that carbon that was previously locked up could enter the atmosphere.”

The importance of this study and further research that it will encourage is summed up in the introduction:

“Tundra and boreal ecosystems store one third of the world’s soil carbon . The fate of this vast carbon stock has become a major concern to global-change scientists because its release to the atmosphere could exacerbate CO2–related climate change . “

The approach taken by the researchers, using the paleoecological approach circumvented the limiting factor of lack of fire history studies and short observational records. It offers the only way to obtain long-term empirical records of fire and vegetation change relevant for understanding tundra fire regimes under future climate and vegetation scenarios.

As the Arctic warms and the tundra biomass expands perhaps allowing new vegetation, the risk to the world of fires in this region will become more important and critical to global climate change.

As Higuera’s paper: “Fires in Ancient Shrub Tundra: Implications of Paleorecords for Arctic Environmental Change” is available online at the following link, it makes interesting reading. in the open-access journal PLoS One

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