Sensitivity of Aerosol Distribution and Climate Response to Stratospheric SO2 Injection Locations. Issue 23 (7th December 2017)

• Record Type: Journal Article
• Authors: Tilmes, Simone; Richter, Jadwiga H.; Mills, Michael J.; Kravitz, Ben; MacMartin, Douglas G.; Vitt, Francis; Tribbia, Joseph J.; Lamarque, Jean‐Francois
• Is Part Of: Journal of geophysical research. Volume 122:Issue 23(2017)
• Page Start: 12, 591
• Page End: 12, 615
• Publication Date: 2017-12-07
• Subjects: climate engineering -- geoengineering -- solar radiation management -- stratospheric aerosol modification -- stratospheric sulfur injections -- climate impacts; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2017JD026888
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Injection of SO2 into the stratosphere has been proposed as a method to, in part, counteract anthropogenic climate change. So far, most studies investigated injections at the equator or in a region in the tropics. Here we use Community Earth System Model version 1 Whole Atmosphere Community Climate Model (CESM1(WACCM)) to explore the impact of continuous single grid point SO2 injections at seven different latitudes and two altitudes in the stratosphere on aerosol distribution and climate. For each of the 14 locations, 3 different constant SO2 emission rates were tested to identify linearity in aerosol burden, aerosol optical depth, and climate effects. We found that injections at 15°N and 15°S and at 25 km altitude have equal or greater effect on radiation and surface temperature than injections at the equator. Nonequatorial injections transport SO2 and sulfate aerosols more efficiently into middle and high latitudes and result in particles of smaller effective radius and larger aerosol burden in middle and high latitudes. Injections at 15°S produce the largest increase in global average aerosol optical depth and increase the change in radiative forcing per Tg SO2 /yr by about 15% compared to equatorial injections. High‐altitude injections at 15°N produce the largest reduction in global average temperature of 0.2° per Tg S/yr for the last 7 years of a 10 year experiment. Injections at higher altitude are generally more efficient at reducing surface temperature, with the exception of large equatorial injections of at least 12 Tg SO2 /yr. These findings have important implications for designing a strategy to counteract global climate change. Key Points: Stratospheric SO2 injections outside the equator at 25 km are more efficient in reducing global temperatures than at the equator Nonequatorial injections transport SO2 more efficiently into middle and high latitudes and providing a larger region for aerosol formation Sufficiently large injections at the equator at different altitudes lead to similar climate impacts