The purpose of this project is to forecast the effects of climate change on wildfire activity and impacts on its impacts on forest resources in British Columbia, which was identified as a key uncertainty in a review of climate change impacts on forest management (BCMOFR 2006). Through their impact on forest age structure and species composition, forest fires can impact the sustainability of timber supply and other resource values (Armstrong 2004). Average global temperature increases are expected to increase between 1.3 and 1.7 degree by 2050 over 1980-1999 levels (Field et al 2007), although there will be regional variation in temperature and precipitation changes, with higher temperature increases in northern regions. Flannigan et al (2002) predicted an increase in the seasonal fire danger severity rating and an increase in fire season length of 2-3 weeks in BC by the year 2085. Recent work by Flannigan et al (2005) suggested a 74-118% increase in average area burned in Canada by the end of this century (3xCO2 scenario) without taking into account changes in vegetation, insect outbreaks, ignitions, fire season length and human activity. However, results for BC were less conclusive. Further work is needed to improve predictions of impacts in BC to guide mitigation strategies. Furthermore, while weather is a strong driver of fire activity, as area burned increases, there may be negative feedback due to an increasing proportion of less flammable vegetation in the landscape that is not included in most climate change projections. Little work has been done to examine changes in potential fire severity measures, such as the number of days with crown fire vs surface fire activity, and forest floor depth of burn, which will have important ecological consequences.
Between 1919-2007 approximately 20 million ha were burned in BC (Fig 1). However, the annual area burned in BC, as elsewhere, is highly variable, and follows a negative exponential distribution (Fig 2). This variation, which is mainly due to weather, has a great influence on timber supply and other resource values. For example, the amount of winter precipitation determines whether forest fuels are saturated at the beginning of the fire season, while the amount of snow and timing of the spring melt influences the length of the fire season. Westerlink et al (2006) found correlations between forest fires and spring snowmelt timing, which they also linked to summer drought conditions at mid-elevation locations in the western USA. During the fire season, the flammability of forest fuels depends on the frequency, duration and intensity of drying periods and precipitation events; large forest fires are associated with atmospheric circulation patterns characterized by a prominent ridge with a strong meridional flow (Skinner et al. 2002).
Stahl et al (2006) classified synoptic circulation patterns over BC into 13 types (Fig 3) and examined their frequency in relation to the El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). Positive PDO was associated with warm dry winters in mainland BC. Preliminary analyses suggest that forest fires are mostly associated with synoptic Types 1 and 2 (the dominant types in summer) and that there is a higher frequency of fires in Type 7 than there are Type 7 days (Fig 4). More work is needed to examine the relationship between large scale circulation types (ENSO, PDO), synoptic circulation patterns, fire weather and fire activity. An understanding of the effects of the various modes of variability on local climate is also important to effective downscaling of GCMs (Stahl et al 2006).
This project will address three key research questions:
1.How may predicted changes in temperature and other weather variables due to global climate change and large scale circulation patters affect future fire weather?
2. How will changes in fire weather influence changes in fire risk, and fire severity? Are there potential fe ...
Meyn, Andrea, Taylor, Steve W.; Flannagan, Mike D.; Thonicke, Kirsten; Cramer, Wolfgang; Regniere, Jacques; St. Amant, Remi; Van der Kamp, Derek W.; Moore, R. Dan. 2009. Wildfire Risk in a Changing Climate. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR047
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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