Impact of preindustrial to present‐day changes in short‐lived pollutant emissions on atmospheric composition and climate forcing

Abstract

[1] We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL AM3) and apply it to investigate the net impact of preindustrial (PI) to present (PD) changes in short-lived pollutant emissions (ozone precursors, sulfur dioxide, and carbonaceous aerosols) and methane concentration on atmospheric composition and climate forcing. The inclusion of online troposphere-stratosphere interactions, gas-aerosol chemistry, and aerosol-cloud interactions (including direct and indirect aerosol radiative effects) in AM3 enables a more complete representation of interactions among short-lived species, and thus their net climate impact, than was considered in previous climate assessments. The base AM3 simulation, driven with observed sea surface temperature (SST) and sea ice cover (SIC) over the period , generally reproduces the observed mean magnitude, spatial distribution, and seasonal cycle of tropospheric ozone and carbon monoxide. The global mean aerosol optical depth in our base simulation is within 5% of satellite measurements over the 1982-2006 time period. We conduct a pair of simulations in which only the short-lived pollutant emissions and methane concentrations are changed from PI (1860) to PD (2000) levels (i.e., SST, SIC, greenhouse gases, and ozone-depleting substances are held at PD levels). From the PI to PD, we find that changes in short-lived pollutant emissions and methane have caused the tropospheric ozone burden to increase by 39% and the global burdens of sulfate, black carbon, and organic carbon to increase by factors of 3, 2.4, and 1.4, respectively. Tropospheric hydroxyl concentration decreases by 7%, showing that increases in OH sinks (methane, carbon monoxide, nonmethane volatile organic compounds, and sulfur dioxide) dominate over sources (ozone and nitrogen oxides) in the model. Combined changes in tropospheric ozone and aerosols cause a net negative top-of-the-atmosphere radiative forcing perturbation (À1.05 W m À2 ) indicating that the negative forcing (direct plus indirect) from aerosol changes dominates over the positive forcing due to ozone increases, thus masking nearly half of the PI to PD positive forcing from long-lived greenhouse gases globally, consistent with other current generation chemistry-climate models.Citation: Naik, V., L. W. Horowitz, A. M. Fiore, P. Ginoux, J. Mao, A. M. Aghedo, and H. Levy II (2013), Impact of preindustrial to present-day changes in short-lived pollutant emissions on atmospheric composition and climate forcing,

Review of the global models used within phase 1 of the Chemistry–Climate Model Initiative (CCMI)

“…AM3 is the atmospheric component of the Geophysical Fluid Dynamic Laboratory (GFDL) global coupled atmosphereocean-land-sea ice model (CM3), which includes interactive stratosphere-troposphere chemistry and aerosols at C48 cubed-sphere horizontal resolution (approximately 2 • × 2 • ) Austin et al, 2013;Naik et al, 2013). In support of CCMI-1, we conduct a suite of multi-decadal hindcast simulations designed to isolate the response of atmospheric constituents to historical changes in human-induced emissions, methane, wildfires, and meteorology.…”

Exploring the relationship between surface PM<sub>2.5</sub> and meteorology in Northern India

“…5d, e) allows for accumulation of aerosols as air masses flow to the southeast across the high-emission IGP region (e.g., Nair et al, 2007;Kumar et al, 2015;Sen et al, 2017). Nair et al (2007) highlights the role of this transport mechanism by showing PM 2.5 levels in the IGP increased with the distance the air mass had traveled from the west. Nair et al (2007) note that this also applies to the transport of weather phenomena conducive to aerosol buildup such as a cold air mass.…”

“…The task is especially challenging for simulating the distribution of PM 2.5 over Northern India due to its extreme physical (i.e., complex topography), chemical (concentrated and abundant primary and precursor emissions), as well as dynamical meteorological (i.e., shallow boundary layer heights with frequent inversions during winter) conditions. While summer months are characterized by the southwest monsoon and relatively low pollution levels, the region's wintertime meteorology greatly favors PM 2.5 buildup; i.e., low wind speeds, shallow boundary layer heights, and high relative humidity (e.g., Nair et al, 2007). Additionally, multiple feedback mechanisms between meteorology and surface PM 2.5 exist such that, if they are not adequately represented, can amplify problems with a given model.…”

“…While the sources of these emissions are relatively well-known, there are large uncertainties in emission estimates across inventories (e.g., Jena et al, 2015;Zhong et al, 2016). Indeed, correctly simulating the extremely high PM 2.5 abundances in the IGP has proved troublesome for current global chemistry models (Reddy et al, 2004;Mian Chin et al, 2009;Ganguly et al, 2009;Menon et al, 2010;Henriksson et al, 2011;Goto et al, 2011;Nair et al, 2012;Cherian et al, 2013;Moorthy et al, 2013;Sanap et al, 2014;Pan et al, 2015). A multi-model evaluation by Pan et al (2015) concluded that an underestimation of wintertime biofuel emissions was the dominant cause of the models' low biases.…”

Summertime cyclones over the Great Lakes Storm Track from 1860–2100: variability, trends, and association with ozone pollution

“…We use a set of simulations conducted with the GFDL CM3 GCM Naik et al, 2012;Griffies et al, 2011;Shevliakova et al, 2009). Most pertinent to our application are the fully coupled stratospheric and tropospheric chemistry based on the models of MOZART-2 and AMTRAC (Austin and Wilson, 2003), respectively, and aerosol-cloud interactions in liquid clouds (Ming and Ramaswamy, 2009; Lamarque et al (2010), and (3) future: 2006-2100 for three scenarios: Representative Concentration Pathway (RCP) 8.5 (Riahi et al, 2007, RCP 4.5 (Clarke et al, 2007;Thomson et al, 2011), and a variation of RCP 4.5 in which only well-mixed green house gases evolve in RCP 4.5 (RCP 4.5 * ; see also John et al, 2012) and short-lived climate forcers (O 3 precursors such as NO x , CO, NMVOC, as well as aerosols and stratospheric ozone depleting substances) are held at 2005 levels.…”