Forest Fires, Climate and Air Quality

Sarah Monks, Steve Arnold, Martyn Chipperfield

Forest Fires

Forest fires occur throughout the world, emitting large quantities of trace gases and aerosols into the atmosphere. These emissions increase concentrations of gases and aerosols which affect air quality in many regions and can alter the concentrations of greenhouse gases such as carbon dioxide (CO₂) and ozone (O₃).

Forest fires are largely driven by atmospheric conditions such as temperature and precipitation, which affect plant growth and drying of fuel. Global climate models predict future changes in these climate fire-drivers due to human emissions of greenhouse gases. This is expected to influence fire frequency and severity and therefore emissions in many regions.

Fire emissions in the boreal regions of Canada, Alaska (ALCA) and Siberia (NESI) show connections with precipitation and the El Nino-Southern Oscillation.

Interactions between Forest Fires and the Arctic

Fires in the boreal forests of Canada, North America and Siberia are ideally located to affect Arctic trace gas and aerosol burdens and it is in this region where future temperature increases are expected to be the greatest. Due to the high reflectivity of land and sea-ice in the Arctic, changes in local concentrations of greenhouse gases could have an even larger impact on the climate. At Leeds we use TOMCAT, a global chemical transport model (CTM), to study how current forest fire emissions affect Arctic burdens of trace gases. A recent study by Monks et al., (2012) found that forest fire emissions are the dominant driver of observed inter-annual variability of Arctic carbon monoxide (CO) and highlighted the boreal regions of Canada and Siberia as the dominant source regions of Arctic fire CO. Investigation of the fire-drivers in these regions showed that the springtime precipitation modulated fires in these regions and that this could be influenced by the El Nino-Southern Oscillation, a well-known atmospheric and ocean phenomenon which affects global temperature and precipitation.

Modelling carbon monoxide from different fire regions highlights the high inter-annual and inter-seasonal variability in the impact of fire emissions on the Arctic. It also helps to identify where the fire CO is coming from, e.g., Alaska and Canada and North-east Siberia are shown here to be important source regions.

Relevant Publications

Monks, S. A., S. R. Arnold, and M. P. Chipperfield (2012), Evidence for El Niño–Southern Oscillation (ENSO) influence on Arctic CO interannual variability through biomass burning emissions, Geophys. Res. Lett., 39, L14804, doi:10.1029/2012GL052512.