Future Impacts of Climate Change on Forest Fire Danger in Northeastern China

As a result of global climate change, many areas around the world will be more prone to increased wildfire activity. Wildfires will become more frequent, burn more intensely, and will burn larger areas; additionally, fire seasons (time periods during which fire is most active) will in many cases be observed for longer durations annually. In a study by Xiao-rui et al. (2011), projections of climate change effects on wildfire danger in the boreal forests of northeastern China were made for the remainder of the century. These future effects were weighed against and validated by historical regional climate data for the baseline period of 1961–1990. The purpose of the study was to prove that fire danger, fire activity, area burned, and fire season duration would all increase significantly over the next century. Xiao-rui et al. concluded that the above phenomena would in fact occur under two of four climate change scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC) covering the period from 1991–2100.

–Lindon Pronto

Xiao-rui, T., Li-fu, S., Feng-jun, Z., Ming-yu, W., McRae, Douglas J., 2011. Future impacts of climate change on forest fire danger in northeastern Chin. Journal of Forestry Research 22, 437–446.

          The area chosen for this study encompassed three general areas of boreal forest in northeastern China, accounting for about 37% of the total forested area in the country. These areas were the Daxing’an Mountains, the Xiaoxing’an Mountains, and the Changbai Mountain forest region. The overall terrain consists of plains in the central area and mountains in the east and west. The study used a validation period of 30 years based on data available from the China Meteorological Data and Sharing Network, where 107 weather stations were located within the study area. Xiao-rui et al. chose to use the Canadian Forest Fire Weather Index (FWI) System to analyze changes to fire danger and the fire season for future periods under IPCC Special Report on Emission Scenarios (SRES) models A2 and B2. The FWI is calculated on the basis of six factors that shape the effect of fuel moisture and wind on fire behavior. The two models used from the IPCC Special Report on Emission Scenarios demonstrate an estimated global average surface temperature warming of 1.4–5.4°C between now and 2100. Both A2 and B2 fall under the “regionalization” scenario (heterogeneous world) where A2 is global temperature increase under a projected approach of regionally orientated economic development, while B2 is a projected approach of localized efforts of environmental sustainability (IPCC, 2007). Additionally projections were made for the overall time periods of a) 2020s, b) 2050s, and c) 2080s; sub-periods examined changes by individual decade. Data sets were illustrated under both A2 and B2 scenarios.

          For the study area, two peak times took place during each fire season. First, an approximately three-quarter percent of annual fires occurred during the spring season from March to May, while in the fall period in October, fewer than 10% occurred but accounted for nearly one-quarter of the annual area burned.  As a result of these findings, the study was adjusted to account for the two separate fire season peaks under both the A2 and B2 IPCC scenarios. The overall historical trend of the Fire Weather Index (FWI) was high in the spring, and relatively low in autumn; this correlates to future FWI projections, with a notable spike in the 2080s. Geographically, heightened FWI and fire activity were predicted for most of the region especially in the southeast, while few and temporary decreases in high risk fire days were observed. The east-central region exhibited the overall highest FWI values under both models by 2080. Also by 2080, the potential burned areas under scenario A2 are expected to increase by 10% in the spring peak and by 23% in autumn, while under B2 an increase of 18% and 35% respectively, was predicted. One of the more critical effects of global warming is the number of days of fire seasons. This study suggests that for northeastern China, the number of days that exhibit high or extreme fire danger may by 2080 increase by more than 20 days in the Daxing'an Mountains and Xiaoxing’an Mountains, and 41−60 days in the Changbai Mountain region. This trend is expected to be most obvious in the southeast and northwest regions.

The three most important factors that drive fire behavior are fuel, weather, and topography. An important element that was not accounted for in this study is the potential impact of 100 years of climate change on fuel type. The authors of this study suggest that in order to gain a clearer understanding for developing a fire management strategy, it is important that future research focus on incorporating additional effects of long-term climate change on successional vegetation changes in burned areas or areas of temperature induced plant regime shifts. In conclusion, Xiao-rui et al. contend that under the temperature increases outlined by the IPCC models, the threat of wildfires will increase, a greater area will be burned, and certain geographic areas will exhibit significantly lengthened annual periods of high FWI values during the peak spring and autumn fire season. The authors hope that this study can aide in shaping future fire management strategy and practice through knowledge of these future climate scenarios, such as through improving elements like prescribed burning and initial attack-phase fire suppression responses.

Other sources:

IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning,Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.