Grantee Research Project Results
Final Report: Investigation of the Effects of Changing Climate on Fires and the Consequences for U.S. Air Quality, Phase 2.
EPA Grant Number: R834282Title: Investigation of the Effects of Changing Climate on Fires and the Consequences for U.S. Air Quality, Phase 2.
Investigators: Logan, Jennifer A. , Mickley, Loretta J. , Rind, David
Institution: Harvard University , NASA Goddard Institute for Space Studies
EPA Project Officer: Chung, Serena
Project Period: November 1, 2009 through October 31, 2012 (Extended to October 31, 2013)
Project Amount: $599,366
RFA: Adaptation for Future Air Quality Analysis and Decision Support Tools in Light of Global Change Impacts and Mitigation (2008) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Climate Change , Air
Objective:
North American wildfires are important sources of the ozone precursors carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOCs). Their emissions have been shown to influence air quality on both local and downwind regions. There has been an increasing trend of wildfire activity over North America in recent decades caused by the changing climate. With a possible warmer future climate, wildfire activity may be more frequent over the western U.S. As a result, we may expect more serious problems in air quality from wildfire emissions by the midcentury.
This project continued our investigation of the impact of changing climate on wildfires, and the consequences for air quality over the U.S, funded under EPA 2004-STAR-L1. We improved the prediction tools of wildfire activity over the western United States, Alaska, and Canada by taking into account new and critical factors. To reduce uncertainties in our predictions, we performed ensemble projections for future wildfire activity with new fire models driven by data from multiple climate models. We then applied the calculated fire emissions to the chemistry-aerosol transport model GEOS-Chem to estimate the fire-induced changes in carbonaceous (black carbon and organic carbon) aerosol concentrations. For these simulations we drove GEOS-Chem with meteorological fields archived from the Goddard Institute of Space Studies (GISS) climate model.
Summary/Accomplishments (Outputs/Outcomes):
1. Ensemble projections of wildfire activity and carbonaceous aerosol concentrations over the western United States in the mid-21st century. (Yue et al., 2013)
We developed both regression models and a parameterization model for fire prediction over the western U.S. The regression models build relationships between area burned and meteorological factors with stepwise regression based on ecoregions; they explain 25%-60% of the variance in area burned in the six ecoregions. The parameterization model determines daily area burned for each grid point using an empirical function composed of temperature, relative humidity, and precipitation. We used simulated present-day and future daily meteorological variables under the A1B scenario from 14 IPCC models and the NASA/GISS GCM3 to drive both fire models. The regression models project that the annual area burned will increase by 25%-125% and the parameterization by 35%-169% in the six ecoregions; both fire models predict a significant increase in area burned for forest ecoregions. The fire season is projected to be three weeks longer in the warmer and drier climate. With the GEOS-Chem model, we estimate that the average surface concentrations of organic carbon aerosol in summer over the western United States will increase by 46%-70% and black carbon will increase by 20-27% at midcentury, due to the increased wildfire emission.
2. Projection of wildfire activity in Southern California at the mid-21st century. (Yue et al., 2014).
In Yue et al. (2013), California was treated as one region, and our approaches for predicting wildfires were least successful there. In Year 2, we focused on improving the predictions for California. We compiled new area burned data on a grid of 0.5°×0.5° for southern California during 1980-2009 based on over 55000 fire reports from the Fire and Aviation Management Web Applications (FAMWEB). With the new area burned data, we developed and evaluated both the regression and parameterization models for three sub-regions in southern California. The regression fits, which use site-based meteorological variables from the FAMWEB, explain 40-46% of the variance in area burned in the sub-regions, a large improvement over our previous result, 25%. The parameterization is driven with the North American Regional Reanalysis (NARR) on a 0.5°×0.5° grid. We improved the parameterization approach over southern California by taking into account local geographic factors (e.g. topography, population, and fuel load) and Santa Ana wind events. It is most successful in southwest California, explaining 64% of the variance in area burned. In addition, the model captures well the seasonality of wildfires in the three regions. Projections with the parameterization show that 7 out of 14 GCMs successfully capture the maximum area burned in October induced by Santa Ana events in southwest California during 1981-2000. With these 7 GCMs, the regression models projected median increases of 100% in southwest California, 35% in the Sierra Nevada, and 10% in central western California by mid-century, compared to 40% and 50% respectively in the first two of these regions with the parameterization. The seasonality of area burned also shows some changes, with possible increases of the area burned in September and October and more large fires in November by midcentury.
3. Impact of 2050 climate change on North American wildfire: consequences for ozone air quality. (Yue et al., draft ms.)
We extended our fire projections to Alaska and Canada in Year 3. We divided the North American boreal forests into 12 ecoregions. In each ecoregion, we used the same regression method as in Yue et al. (2013) to build relationships between area burned and meteorological variables. We aggregated area burned from the interagency fire reports from FAMWEB for Alaska and fire point data from the Canadian National Fire Database (CNFDB). The regressions explain 34-75% of the variance in area burned except for Eastern Taiga Shield. We applied these regressions with simulated climate from multiple GCMs and project that the median area burned increases by 150-390% in Alaska and western Canada at midcentury, due to the higher temperature and geopotential height relative to present day. We predicted median increases of 20-90% for central and southern Canadian ecoregions but a decrease up to 50% in northern Canada due to the increase in GCM precipitation. Using the GEOS-Chem model driven by GISS GCM meteorology, we find that changes in wildfire emissions alone lead to increases in summer surface ozone level by 4 ppbv for Alaska, 2 ppbv for Canada, and 1 ppbv for the western U.S. by midcentury. For northwestern U.S. states, the increase of local wildfire emissions enhances surface ozone by an average of 1 ppbv and the transport of pollutants from boreal fires worsens it by an additional 0.5 ppbv. The projected changes in wildfire increase the surface ozone above the 95th percentile by 1 ppbv in northwestern U.S., 5 ppbv in high latitudes of Canada, and 15 ppbv in Alaska, suggesting a greater frequency of pollution episodes in the future atmosphere. We expect to submit this paper for publication in early 2014.
Conclusions:
Yue et al. (2013) showed that wildfire activity will likely increase in the western U.S. in the warmer climate at mid-century, with as much as a doubling of area burned in some forested regions. These increases in area burned together with the longer fire season calculated in our study could significantly limit visibility in parks and wilderness areas and worsen regional air quality. In Yue et al. (2014), we again found increases of 20-100% in area burned and a longer fire season by the 2050s in the populous region of southern California. Such a change in fire activity would threaten the safety of California residents and increase the expense of fire suppression. An expansion of fire area would increase biomass burning emissions, seriously degrading both air quality and visibility locally and downwind. For Alaska and northern Canada, Yue et al. (draft ms.) found that the competition between increased temperature and greater precipitation results in some uncertainty in the projections for area burned at the mid-century. Nonetheless, this study also found an enhancement in area burned over much of this region by the 2050s, especially in Alaska and western Canada, where area burned increases by factors of 2-4.
By relying on an ensemble of models for climate projections, our work provides greater confidence in predictions of fire activity in the future, and quantifies the impact for air quality. Our results also underscore the importance of careful forest management and land use practices in a changing climate regime.
Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 6 publications | 3 publications in selected types | All 3 journal articles |
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Yue X, Mickley LJ, Logan JA, Kaplan JO. Ensemble projections of wildfire activity and carbonaceous aerosol concentrations over the western United States in the mid-21st century. Atmospheric Environment 2013;77:767-780. |
R834282 (Final) |
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Yue X, Mickley LJ, Logan JA. Projection of wildfire activity in southern California in the mid-21st century. Climate Dynamics 2014;43(7-8):1973-1991. |
R834282 (Final) |
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Yue X, Mickley LJ, Logan JA, Hudman RC, Martin MV, Yantosca RM. Impact of 2050 climate change on North American wildfire: consequences for ozone air quality. Atmospheric Chemistry and Physics 2015;15(17):10033-10055. |
R834282 (Final) |
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Supplemental Keywords:
boreal forests, fire emissions, tropospheric ozone, scenario, ensemble projection, pollution episodes, chemical transport model, climate change
, RFA, Scientific Discipline, Air, climate change, Air Pollution Effects, Environmental Monitoring
Relevant Websites:
Jennifer A. Logan Exit
Loretta J. Mickley Exit
Effects of climate change on wildfires and future air quality in the western US. Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.