Grantee Research Project Results
2007 Progress Report: Investigation of the Effects of Changing Climate on Fires and the Consequences for U.S. Air Quality, Using a Hierarchy of Chemistry and Climate Models
EPA Grant Number: R832275Title: Investigation of the Effects of Changing Climate on Fires and the Consequences for U.S. Air Quality, Using a Hierarchy of Chemistry and Climate Models
Investigators: Logan, Jennifer A. , Jacob, Daniel J. , Mickley, Loretta J. , Mazzoni, Dominic M. , Byun, Daewon , Diner, David , Li, Qinbin
Institution: Harvard University , Jet Propulsion Laboratory - Pasadena , University of Houston
EPA Project Officer: Chung, Serena
Project Period: April 1, 2005 through March 31, 2008 (Extended to March 31, 2010)
Project Period Covered by this Report: April 1, 2005 through December 31,2008
Project Amount: $750,000
RFA: Fire, Climate, and Air Quality (2004) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Climate Change , Air
Objective:
This project is an assessment of the impacts of climate change on forest fires and ozone and particulate matter air quality in the United States from the present day till 2050. The project will explore the relationships between climate and frequency and intensity of forest fires in North America. Future climate predicted using a general circulation model (GCM) and relationships between fire and climate that we have developed will be used to predict future fires in the United States. The height of forest fire plumes over North America will be investigated using the MISR satellite data. Using global and regional scale chemistry-aerosol transport models we will investigate the role of future fires on air quality.
Progress Summary:
1 Fire prediction model for the western United States.
The first part of this project focused on developing a fire prediction scheme to predict the effect of future climate change on fire activity in the western United States. Stepwise linear regression was used to determine the best relationships between observed area burned and variables chosen from temperature, relative humidity, wind speed, 24 hour rainfall, and from three fuel moisture codes and four fire weather indices from the FWI model, following the approach of Flannigan et al. [2005]. We used observed area burned from the 1ºx1º database of Westerling et al. [2003] for 1980-2004. Area burned was binned according to the ecological stratification of Bailey et al. [1994] which defines 18 ecosystem classes in the western United States. These ecosystems were further aggregated to produce 6 ecoregions with similar vegetation and climate, as we found that we could better fit area burned for the larger ecoregions.
Our results showed that May-October mean temperature and fuel moisture explain 24-57% of the observed variance in annual area burned in the Western United States. Explained variance is generally greater in forest dominated ecosystems (48-52%) than in shrub and grass dominated ecosystems (24-49%) [Spracklen et al., 2009]. The lower explained variance in the latter ecosystems is likely due to the importance of the previous year's weather for fire activity in these areas [Westerling et al., 2003; Westerling and Bryant, 2008; Littell et al., 2008], which we did not take into account.
2 Simulation of future area burned.
We used the GISS GCM III to generate meteorological boundary conditions from the present-day to 2050. Greenhouse gas concentrations in the model were updated yearly following the A1B scenario, which describes a homogeneous future world with rapid economic growth, introduction of new technologies, and balanced energy generation from fossil and alternative fuels. We used the GISS predicted meteorology as input to the FWI model to calculate daily moisture and temperature parameters for May to October of 2000-2050. We then calculated future area burned by applying our regression analysis to the model meteorology and drought and fire indices for these years. Results showed that the A1B climate leads to a 54% increase in area burned in the Western United States by 2050, relative to the present-day. Changes in area burned are ecosystem dependent, with the forests of the Pacific Northwest and Rocky Mountains experiencing the greatest increases of 78% and 175%, respectively [Spracklen et al., 2009].
3 Effect of future fires on present-day and future air quality.
We used GEOS-Chem to examine the impact of wildfires on organic carbon (OC) aerosol concentrations in the western United States. We derived OC emissions from wildfires using data for area burned for 1980–2004 and ecosystem specific fuel loadings. Our results showed conclusively that wildfires drive the interannual variability of observed OC concentrations in the West [Spracklen et al., 2007]. We estimated that the observed increase in wildfire activity after the mid 1980s has increased mean summertime OC concentrations by 30% relative to 1970–1984 for this region [Spracklen et al., 2007].
To calculate the effect of future wildfires on air quality, we used the GEOS-Chem global 3-D model, forced by the GISS calculated meteorology for the present-day and future. To compute wildfire emissions, we located each predicted fire randomly within a given ecosystem and distributed the area burned according to observed wildfire behavior. We then used the resulting area burned maps together with ecosystem specific fuel loadings derived from the Fuel Characteristic Classification System (FCCS) of the USDA Forest Service [McKenzie et al., 2007] and emission factors from Andreae and Merlet [2001]. Our results from GEOS-Chem showed for the first time that changing wildfires could have a large impact on OC emissions and thus on U.S. air quality (Figure 1). We found that the increased area burned in the future climate leads to a near doubling of wildfire carbonaceous aerosol emissions by mid-century. We calculated that climate change will increase summertime OC aerosol concentrations over the western United States by 40% and elemental carbon (EC) concentrations by 20% from 2000 to 2050. Most of this increase (75% for OC, 95% for EC) is caused by larger wildfire emissions in a warming climate, with the rest caused by direct effect of changing climate on air quality.
We have also considered the effect of changing wildfires on ozone air quality. Preliminary results show that future wildfires in the Northwest will increase summertime surface ozone by a few ppb over much of that region.
4 Analysis of forest fire plume heights from MISR.
We collaborated with the David Diner of the Jet Propulsion Laboratory, P.I. of the Multi-angle Imaging SpectroRadiometer (MISR) instrument, to develop a data-base of fire plume heights for five years over North America. JPL first tested an automated data mining algorithm to search through the MISR data for plumes that were connected to MODIS fire pixels. This approach identified 77 plumes over Alaska/Yukon in 2004, and showed that the median plume height was 2.2 km [Mazzoni et al., 2007]. The automated approach missed many plumes, however, and the MISRtool was then developed. This tool also uses MODIS fire pixels to find candidate plumes, but relies on a person to digitize each plume shape; the subsequent extraction of MISR data is automated. With this tool, 664 plumes were identified in Alaska/Yukon in 2004, and ~10% were above the boundary layer at the local time of the MISR overpass, ~11:00-12:00 [Kahn et al., 2008]. We have now produced height data for almost 3000 plumes in 2002-2007 (except for 2003), and the MISR plume database is now available on the web [http://www-misr2.jpl.nasa.gov/EPA-Plumes/]. We next used the MODIS Land Cover Map to relate the fire plumes to underlying vegetation. We found that the percentage of smoke plumes that rose more than 0.5 km above the boundary layer varied depending on vegetation type and year, for example 1-10% for cropland fires, 7-19% for forest fires, and 12-25% for shrub fires. Plumes located above the boundary layer tended to be trapped in a stable layer.
5 CMAQ regional model simulation.
For a more accurate picture of the impact of future wildfires on air quality, we collaborated with Daewon Byun of University of Houston to perform simulations with the regional chemical model CMAQ. Harvard supplied U. Houston with calculated area burned statistics and GEOS-Chem chemical output to use as boundary conditions for CMAQ. Meteorological fields for CMAQ were calculated by MM5, using boundary conditions from the GISS model. In order to investigate the impact of downscaling methods from GISS GCM to the regional MM5 model, we tested two downscaling methods: (1) direct downscaling from GISS (5° x 4°) to 36-km MM5, and (2) using 108-km MM5 simulation as an intermediate step in the downscaling scheme. We expect to complete the CMAQ simulations by summer 2009.
Future Activities:
Our main findings are as follows:
- Wildfires drive the interannual variability of observed OC concentrations in the West. The observed increase in wildfire activity after the mid 1980s has increased mean summertime OC concentrations by 30% relative to 1970–1984 for this region.
- The A1B climate leads to a 54% increase in area burned in the Western United States by 2050, relative to the present-day. Changes in area burned are ecosystem dependent, with the forests of the Pacific Northwest and Rocky Mountains experiencing the greatest increases of 78% and 175%, respectively.
- Climate change will increase summertime OC aerosol concentrations over the western United States by 40% and elemental carbon (EC) concentrations by 20% from 2000 to 2050. Most of this increase (75% for OC, 95% for EC) is caused by larger wildfire emissions in a warming climate, with the rest caused by direct effect of changing climate on air quality.
In summary, our research has made important contributions toward the EPA’s overarching goals of safeguarding human health and the environment. In particular, our work has enhanced the ability of policymakers to gauge the coming “climate penalty” on ongoing efforts to reduce air pollution across the United States. (Here climate penalty is defined as the additional emission controls necessary to meet a given air quality target [EPA, 2007].) We quantified the impact of climate change on area burned for the western United States, in contrast to previous studies that either estimated changes in a fire index or focused on a small geographic area. We showed that wildfires in the western United States have a significant effect on air quality in the United States in the present-day, and that this effect will likely increase by 2050. Our work represents the first-ever assessment of the effects of fires in a future climate on air quality in the United States. In addition, our analysis of the height of plumes from forest fires has led to more realistic simulations of the effects of fires on present day and future air quality.
References:
Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 14 publications | 5 publications in selected types | All 5 journal articles |
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Kahn RA, Chen Y, Nelson DL, Leung F-Y, Li Q, Diner DJ, Logan JA. Wildfire smoke injection heights: two perspectives from space. Geophysical Research Letters 2008;35:L04809, doi:10.1029/2007GL032165. |
R832275 (2007) R832275 (2008) R832275 (Final) |
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Mazzoni D, Logan JA, Diner D, Kahn R, Tong L, Li Q. A data-mining approach to associating MISR smoke plume heights with MODIS fire measurements. Remote Sensing of Environment 2007;107(1-2):138-148. |
R832275 (2006) R832275 (2007) R832275 (2008) R832275 (Final) |
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Spracklen D, Logan JA, Mickley LJ, Park RJ, Yevich R, Westerling AL, Jaffe DA. Wildfires drive interannual variability of organic carbon aerosol in the western U.S. in summer. Geophysical Research Letters 2007;34:L16816, doi:10.0129/2007GL030037. |
R832275 (2006) R832275 (2007) R832275 (2008) R832275 (Final) |
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Supplemental Keywords:
forest fires, wildfires, biomass burning, air quality, tropospheric ozone, tropospheric aerosol, PM, visibility, climate models, air pollution, climate change, health effects, pollution prevention, public policy, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Environmental Chemistry, climate change, Air Pollution Effects, Monitoring/Modeling, Aquatic Ecosystem, Environmental Monitoring, Ecological Risk Assessment, Atmosphere, anthropogenic stress, environmental measurement, meteorology, climatic influence, global ciruclation model, tidal marsh, ozone depletion, socioeconomics, climate models, ecosystem indicators, aquatic ecosystems, environmental stress, coastal ecosystems, global climate models, ecological models, climate model, ecosystem stress, sea level rise, forest resources, Global Climate Change, atmospheric chemistry, climate variabilityRelevant Websites:
http://www.people.fas.harvard.edu/~logan/research2.html Exit
www.imaqs.uh.edu 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.