| SOLAR GEOENGINEERING WEEKLY SUMMARY (02 DECEMBER - 08 DECEMBER 2024) Subscribe to our newsletter to receive monthly updates on Solar Geoengineering:
RESEARCH PAPERSCheng, Y., & McColl, K. A. (2024). Unexpected warming from land radiative management. Geophysical Research Letters, 51(22), e2024GL112433. Abstract “Land radiative management” (LRM)—deliberately increasing surface albedo to decrease temperatures—has been proposed as a form of geoengineering to mitigate the effects of regional warming. Here, we show that, contrary to expectations, LRM causes temperatures to increase in surrounding regions. The basic reason for the increase is unintended impacts on precipitation. Precipitation is suppressed over the LRM region, but this effect also extends to nearby areas unprotected by LRM. The reduction in precipitation and soil moisture in these regions leads to higher temperatures than would be expected in the absence of LRM. The resulting warming outside the LRM region is comparable to the cooling achieved inside it. This implies that, if wealthy regions unilaterally adopt LRM to cool, their neighbors may experience warming, worsening heat inequality.
Henry, M., Bednarz, E. M., & Haywood, J. (2024). How does the latitude of stratospheric aerosol injection affect the climate in UKESM1?. Atmospheric Chemistry and Physics, 24(23), 13253-13268. Abstract Stratospheric aerosol injection (SAI) refers to a climate intervention method by which aerosols are intentionally added to the lower stratosphere to enhance sunlight reflection and offset some of the adverse effects of global warming. The climate outcomes of SAI depend on the location, amount, and timing of injection, as well as the material used. Here, we isolate the role of the latitude of SO2 injection by comparing different scenarios that have the same global-mean temperature target, altitude of injection, and hemispherically symmetric injection rates. These are as follows: injection at the Equator (EQ) and injection at 15° N and S (15N+15S), 30° N and S (30N+30S), or 60° N and S (60N+60S). We show that injection at the Equator leads to a substantial undercooling of the Arctic, a significant reduction in tropical precipitation, reductions in high-latitude ozone, heating in the tropical lower-stratosphere, and strengthening of the stratospheric jets in both hemispheres. Additionally, we find that the most efficient injection locations are the subtropics (15 and 30° N and S), although the 60N+60S strategy only requires around 30 % more SO2 injection for the same amount of cooling; the latter also leads to much less stratospheric warming but only marginally increases high-latitude surface cooling. Finally, while all the SAI strategies come with trade-offs, our work shows that the 30N+30S strategy is a good candidate strategy for an intermodel comparison and is easier to implement than a multi-latitude controller algorithm.
Quaglia, I., & Visioni, D. (2024). Modeling 2020 regulatory changes in international shipping emissions helps explain 2023 anomalous warming. EGUsphere, 2024, 1-19. Abstract The summer of 2023 saw an anomalous increase in temperatures even when considering the ongoing greenhouse-gas-driven warming trend. Here we demonstrate that regulatory changes to sulfate emissions from international shipping routes, which resulted in a significant reduction in sulfate particulate released during international shipping starting on 1 January 2020, have been a major contributing factor to the monthly surface temperature anomalies during the last year. We do this by including the appropriate changes to emission databases developed for the Climate Model Intercomparison Project version 6 (CMIP6) in Community Earth System Model (CESM2) simulations. The aerosol termination effect simulated by the updated CESM2 simulations of W m−2 and 0.08 K±0.03 K is consistent with observations of both radiative forcing and surface temperature, manifesting a similar delay as the one observed in observational datasets between the implementation of the emission changes and the anomalous increase in warming. Our findings highlight the importance of considering realistic near-future changes in short-lived climate forcers for future climate projections, such as for CMIP7, for an improved understanding and communication of short-term climatic changes.
Tilmes, S., Bednarz, E. M., Jörimann, A., Visioni, D., Kinnison, D. E., Chiodo, G., & Plummer, D. (2024). Stratospheric Aerosol Intervention Experiment for the Chemistry-Climate Model Intercomparison Project. EGUsphere, 2024, 1-32. Abstract A new Stratospheric Aerosol Intervention (SAI) experiment has been designed for the Chemistry- Climate Modeling Initiative (CCMI-2022) to assess the impacts of SAI on stratospheric chemistry and dynamical responses and inter-model differences using a constrained setup with a prescribed stratospheric aerosol distribution and fixed sea-surface temperatures (SSTs) and sea-ice. This paper describes the details of the experimental setup and the prescribed aerosol distribution. Furthermore, we discuss differences in the Whole Atmosphere Community Climate Model (WACCM6) results between the interactive stratospheric aerosol configuration with coupling to land, ocean, and sea ice that was used to produce the stratospheric aerosol distribution and the results of the constrained SAI experiment. With this, we identify and isolate the stratosphere-controlled SAI-induced impacts from those influenced by the coupling with the ocean. We confirm earlier suggestions that the SAI-induced positive phase of the Northern Atlantic Oscillation in winter, with the corresponding winter warming over Eurasia, is directly driven by the effect of SAI on the stratosphere-troposphere coupling. We further show that the resulting stratospheric responses are largely similar between the fully coupled and constrained experiments, demonstrating the suitability of the simplified setup to study impacts in the stratosphere in a multi-model framework. Only small differences arise in the stratospheric ozone and dynamical SAI responses between the two experiments due to minor differences in the aerosol distributions and their coupling with local changes in temperatures, upwelling, and chemistry, alongside interactive coupling with the ocean and sea ice.
WEB POSTSThe Solar Geoengineering Monthly Updates Newsletter (November'2024) Solar Geoengineering UpdatesIf you find this work valuable, consider supporting us with a paid subscription. We put a lot of time and effort into compiling this resource for you… 5 days ago · 3 likes · Andrew Lockley Rescuing climate repair from the Sci-Fi trope (One Percent Brighter) One Percent BrighterWhen —rarely— mainstream publications do condescend to talk about climate repair, one trope is always trotted out: Sci-Fi. Schemes to cool the world that leverage a well-understood geophysical variable like albedo are the stuff of fantastical literature… 9 hours ago · 10 likes · 2 comments · Quico Toro
REPORTS
JOB OPPORTUNITY“Dr. Pete Irvine at the University of Chicago is seeking a highly motivated postdoctoral scholar to join an interdisciplinary research team in a position supported by the University of Chicago’s Climate Systems Engineering initiative (Director: David Keith). The aim of this position will be to conduct a comprehensive evaluation of how effective Stratospheric Aerosol Injection (SAI) would be at offsetting the climate effects of global warming.”
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