'Understanding how wildfires impact ecosystems could improve predictions of future climate changes'

Posted by ap507 at Aug 26, 2016 10:19 AM |
Dr Kirsten Barrett discusses the impact of wildfires on society and climate in southern Siberia

Think: Leicester does not necessarily reflect the views of the University of Leicester - it expresses the independent views and opinions of the academic who has authored the piece. If you do not agree with the opinions expressed, and you are a doctoral student/academic at the University of Leicester, you may write a counter opinion for Think: Leicester and send to ap507@le.ac.uk

Boreal wildfires have been in the news quite a bit lately, with major fires in Alaska last summer, the evacuation of Ft McMurray earlier this year, and widespread burning across Siberia this summer.

Boreal forests constitute the largest forested ecosystem on earth, and although they are generally located in colder regions, they are prone to burning, particularly during hot and dry summers.

I’ve recently been granted some funding by the Natural Environmental Research Council (NERC) to look at the impact of wildfires in southern Siberia, an area subject to frequent and widespread fire disturbance. Such fires can threaten or destroy human settlements, and impact the climate through changes in carbon emissions and albedo (or how much solar radiation is absorbed by the planet's surface). The immediate costs to human society are easier to quantify than the more dispersed costs of future climate changes, but both impacts can have potentially serious consequences.

We generally prioritise boreal fire research more because of the feedbacks to climate than the direct impact on human society, in part because of the relatively low population density found in high latitude regions. Climate feedbacks from fire are poorly understood at present, and often omitted from models of climate change. Fires alter forests by changing the amount of carbon stored in vegetation and soils, thereby affecting the amount of carbon in the atmosphere and the risk of additional fire. The change in surface reflectance properties, by char and ash over the short term, and by sustained changes in vegetation type over the long term, also impacts climate. And fire leads to the thawing of permanently frozen ground (permafrost) that currently stores more carbon than is in the atmosphere, exposing that carbon to decomposition and oxidation which increases atmospheric carbon levels.

The net effect of these feedbacks, in addition to the “unknown unknowns” involved, requires creative and intensive research approaches to determine how such disturbances can exacerbate or even mitigate climate change.

One familiar aspect of climate change is the expansion of the range of trees in northern latitudes, possibly enlarging the forested area and increasing the amount of carbon stored in vegetation. Increases in vegetation carbon storage might also come from increased forest productivity due to higher temperatures and longer growing seasons. But boreal fires complicate these dynamics substantially, through the periodic removal of forest carbon, and even the persistent loss of forests where the climate becomes too warm and too dry to support forest re-growth post-fire.

To improve our understanding and predictions of future climate changes, we need better information about how wildfires impact boreal ecosystems, and how these effects in turn cause changes in climate.

When boreal wildfires are receiving more media attention, I'm frequently asked what we can do to prevent them, and the unfortunate answer is often not very much. Sometimes targeted fire risk management efforts such as fire breaks or controlled burns can be employed around cities or villages, but it's impossible to control fires over such a large area.

Probably the biggest hurdle to preventing fires is knowing where to direct our efforts. It is often difficult to know where fires are likely to ignite, particularly when they are caused by lightning strikes. And many boreal fires occur in regions that are very sparsely populated, so they may never encroach on human settlements. In regions where wildfires have been suppressed, such as the western US, those unburned fuels have subsequently built up to critical points where it is no longer possible to prevent periodically massive fire outbreaks. Therefore rather than focusing on how to stop boreal wildfire disturbances, we need to concentrate our research efforts on understanding how fires respond to and impact climate, and building this knowledge into projections of future change.

Share this page: