A model image of simulated sea ice loss
September Arctic sea ice projection for the year 2095 with climate change (left) and with stratospheric aerosol geoengineering (right) based on simulations using WACCM. Red and green lines represent an Arctic sea ice fraction of 50% and 15%, respectively, for the year 2020. Sea surface temperatures are illustrated in colors from blueish (below 3°C) over greenish (3°C–10°C) toward red (above 10°C). Changes in Greenland ice sheets have not been included in these simulations. Sea ice extent is one of the many possible Earth system features that could be evaluated under a holistic assessment of the effects of geoengineering. Credit: Matt Rehme and Tim Scheitlin (NCAR/CISL)
Source: Journal of Geophysical Research: Atmospheres

Solar geoengineering involves deliberately modifying the amount of solar radiation that reaches Earth’s surface, and it has been proposed as a means of counteracting some of the negative impacts of climate change. Because large-scale geoengineering experiments, such as deploying giant mirrors to reflect sunlight away from Earth’s surface, are not generally practical, global climate models are the best available tools for assessing the potential consequences of such actions.

Of the many solar geoengineering methods that have been proposed, one considered the most feasible is the injection of sulfur dioxide into the stratosphere. This process mimics the cooling effects of volcanic eruptions by adding a substantial amount of reflective particulates to this atmospheric layer. But because the effects of these injections are not always clear, previous models have been unable to paint a complete picture of their potential consequences.

To address this challenge, Kravitz et al. have introduced the state-of-the-art Community Earth System Model (CESM1), which utilizes the Whole Atmosphere Community Climate Model (WACCM) to perform global chemistry modeling. Unlike other climate models, CESM1 includes some of the most important processes associated with stratospheric sulfur injections, including stratospheric chemical reactions.

This special issue includes a series of studies that explore how variations in altitude, latitude, and the size of the injections can alter the simulation results and improve our understanding of the resulting changes to the surface climate and the stratosphere. Collectively, these articles represent an important first attempt to evaluate whether stratospheric sulfur dioxide injections can be designed to meet precise climate objectives. By better elucidating what these injections and potentially other climate interventions can—and cannot—accomplish, this issue offers a new road map for assessing the effects of solar geoengineering. (Journal of Geophysical Research: Atmospheres, https://doi.org/10.1029/2018JD029293, 2019)

—Terri Cook, Freelance Writer


Cook, T. (2019), A new road map for assessing the effects of solar geoengineering, Eos, 100, https://doi.org/10.1029/2019EO122073. Published on 01 May 2019.

Text © 2019. The authors. CC BY-NC-ND 3.0
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