2014 Progress Report: Source Attribution of Radiative Forcing in Chemical Transport Models

EPA Grant Number: R835211
Title: Source Attribution of Radiative Forcing in Chemical Transport Models
Investigators: Henze, Daven K
Institution: University of Colorado at Boulder
EPA Project Officer: Callan, Richard
Project Period: June 1, 2012 through May 31, 2014 (Extended to May 31, 2016)
Project Period Covered by this Report: June 1, 2014 through May 31,2015
Project Amount: $244,446
RFA: Source Attribution of Radiative Forcing in Chemical Transport (2011) RFA Text |  Recipients Lists
Research Category: Global Climate Change , Air Quality and Air Toxics , Climate Change , Air


The project objective is to account for the radiative forcing impacts of aerosols and tropospheric ozone (O3) from changes to their precursor emissions owing to air quality and greenhouse gas policies. This will be accomplished through the following research tasks: 
  1. Quantify the impacts of emissions from each sector, in each model grid cell, on the global and regional radiative forcing of tropospheric O3 and aerosols.
  2. Assess the radiative forcing consequences of emissions scenarios designed to target combinations of aerosol and greenhouse gas reductions. 

Progress Summary:

The third year of this project has focused on advancing our estimates of aerosol radiative source attribution in two major ways. Our initial work (Henze et al., 2012) included the direct aerosol radiative forcing. This last year, we have included indirect and semi-direct e ffects, as well as contributions from the albedo feedback of black carbon deposited on snow and ice. This is achieved through the application of scaling factors to account for indirect and semi-direct forcing. These scaling factors draw from multi-model comparisons such as ACCMIP and the 5th IPCC report. To account for the contribution of BC emissions to the radiative forcing of BC deposition on snow and ice, we first perform an additional adjoint model calculation to estimate the contribution of emissions of BC in each grid cell to BC deposited on snow and ice. These results are then used to spatially distribute the global mean estimated snow/ice albedo radiative forcing of 0.15 Wm-2. In addition, while our first study focused on the impact of global radiative forcing, now we have considered regional radiative forcing, and combined these with absolute regional temperature potentials (ARTPs) derived from climate model simulations by Shindell (2012) to estimate the changes in temperature across four latitudinal bands with associated aerosol precursor emissions. 
These updates to our attribution method have been applied in a case study estimating the climate impacts of carbonaceous aerosol from cookstoves (Lacey and Henze, submitted). Cookstove use is globally one of the largest unregulated anthropogenic sources of primary carbonaceous aerosol. While reducing cookstove emissions through national-scale mitigation e fforts has clear benefi ts for improving indoor and ambient air quality, and signi cant climate benefi ts from reduced green-house gas emissions, climate impacts associated with reductions to co-emitted black (BC) and organic carbonaceous (OC) aerosol are not well characterized. Here we attribute direct, indirect, semi-direct, and snow/ice albedo radiative forcing and associated zonal surface temperature changes to national-scale carbonaceous aerosol cookstove emissions using a new combination of adjoint sensitivity modeling and climate-model parameterizations. Bounds are placed on these estimates, drawing from current literature ranges for aerosol radiative forcing along with a range of solid fuel emissions characterizations. We estimate a range of 0.16 K warming to 0.28 K cooling with a central estimate of 0.06 K cooling from the global removal of cookstove aerosol emissions. At the national scale, countries' climate impacts range from net warming (e.g., Mexico and Brazil) to net cooling, although the range of estimated impacts for all countries span zero given uncertainties in radiative forcing estimates and fuel characterization. We identify similarities and di fferences in the sets of countries with the highest emissions and largest cookstove temperature impacts (China, India, Nigeria, Pakistan, Bangladesh and Nepal), those with the largest temperature impact per carbon emitted (Kazakhstan, Estonia, and Mongolia), and those that would provide the most efficient cooling from a switch to fuel with a lower BC emission factor (Kazakhstan, Estonia, and Latvia). The results presented here thus provide valuable information for climate impact assessments across a wide range of cookstove initiatives. 


Future Activities:

The remaining efforts will focus on combining our source attribution of aerosol impacts with: (1) source attribution of climate impacts from both long-lived greenhouse gases as well as tropospheric O3 from Bowman and Henze (2012), and (2) source attribution of PM2.5 health impacts, from Lee et al. (2015). This will allow us to most completely evaluate the climate and health impacts of air quality initiatives, such as those focused on reducing emissions from cookstoves or sources of CH4


Bowman K, Henze DK. Attribution of direct ozone radiative forcing to spatially resolved emissions. Geophysical Research Letters. 2012 Nov 28;39(22).

Henze, D.K., D.T. Shindell, F. Akhtar, R.D.J. Spurr, R.W. Pinder, D. Loughlin, M. Kopacz, K. Singh, and C. Shim, 2012: Spatially refined aerosol direct radiative forcing efficiencies. Environ. Sci. Technol.46, 9511-9518, doi:10.1021/es301993

Lee CJ, Martin RV, Henze DK, Brauer M, Cohen A, Donkelaar AV. Response of global particulate-matter-related mortality to changes in local precursor emissions. Environmental Sci. Technol. 2015 Mar 24;49(7):4335-44.

Shindell, D., J.C.I. Kuylenstierna, E. Vignati, R. van Dingenen, M. Amann, Z. Klimont, S.C. Anenberg, N. Muller, G. Janssens-Maenhout, F. Raes, J. Schwartz, G. Faluvegi, L. Pozzoli, K. Kupiainen, L. Höglund-Isaksson, L. Emberson, D. Streets, V. Ramanathan, K. Hicks, N.T.K. Oanh, G. Milly, M. Williams, V. Demkine, and D. Fowler, 2012: Simultaneously mitigating near-term climate change and improving human health and food security. Science, 335, 183-189, doi:10.1126/science.1210026

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other project views: All 15 publications 3 publications in selected types All 3 journal articles
Type Citation Project Document Sources
Journal Article Akhtar FH, Pinder RW, Loughlin DH, Henze DK. GLIMPSE:a rapid decision framework for energy and environmental policy. Environmental Science & Technology 2013;47(21):12011-12019. R835211 (2012)
R835211 (2013)
R835211 (2014)
R835211 (Final)
  • Abstract from PubMed
  • Full-text: Harvard University-Full Text PDF
  • Abstract: ES&T-Abstract
  • Other: ES&T-Full Text PDF
  • Journal Article Lacey F, Henze D. Global climate impacts of country-level primary carbonaceous aerosol from solid-fuel cookstove emissions. Environmental Research Letters 2015;10(11):114003 (10 pp.) R835211 (2013)
    R835211 (2014)
    R835211 (Final)
  • Full-text: Environmental Research Letters-Full Text HTML
  • Abstract: Environmental Research Letters-Abstract
  • Other: Environmental Research Letters-Full Text PDF
  • Supplemental Keywords:

    Adjoint sensitivity, environmental policy, air quality regulations, fine particulate matter, climate change, remote sensing 

    Progress and Final Reports:

    Original Abstract
    2012 Progress Report
    2013 Progress Report
    Final Report