Award Announcement: Impacts and Tradeoffs of Simulated High-Latitude/Low-Altitude SAI Deployment
Reflective is excited to announce the grantees for the Impacts and Tradeoffs of Simulated High-Latitude/Low-Altitude SAI Deployment funding opportunity.
We have selected eight grantee teams to research a wide-ranging set of areas related to high-latitude deployment of SAI. We were also able to fund specific variable outputs from global climate models requested by our grantees. These data will be made publicly available on the Reflective cloud hub.
We’d like to acknowledge all the incredible proposals we received, and thank all applicants for taking the time to submit one. Additionally, we’d also like to thank our amazing team of reviewers for providing peer reviews for all proposals — an essential step in our evaluation process.
About the Grant
Currently, most SAI modeling assumes deployment at altitudes above 20 km—for instance, the ARISE-SAI scenario involves injections at ~22km. However, a fleet of aircraft capable of reaching these altitudes does not currently exist. The tropopause is lower at the poles, which means that deployment at high latitudes is hypothetically feasible with existing aircraft – but there are minimal studies about the impacts of this strategy.
This grant was designed to answer four critical questions to guide where the field focuses energy next:
- Benefits of 15km vs. 13 km: Are there significant benefits (health, environmental, technical, economic) to aircraft that can reach altitudes of 15 km instead of 13 km in the context of high-latitude/low-altitude deployment?
- Showstoppers: Are there technical or scientific “showstoppers” or dealbreakers for high-latitude/low-altitude SAI that have not yet been considered?
- Scaling: How do the potential negative impacts of high-latitude/low-altitude deployment scale? Is there a threshold—during a gradual ramp-up (not exceeding current warming rates)—at which negative impacts necessitate higher-altitude, lower-latitude deployment via specialized aircraft? When might this occur?
- Surface Impacts: Are there specific surface impacts (e.g., air quality, atmospheric chemistry, water availability/quality, permafrost thaw, temperature extremes, ecosystem changes, food security, etc.) that would need to be monitored, or researched more in depth, as they represent a significant source of uncertainties for high-latitude/low-altitude deployments?
About the Grantees
The grantees and their teams, listed below, represent four continents, with over 30% coming from the Global South.
Assessing the impacts of high-latitude low-altitude polar SAI on the Southern Ocean carbon cycle
Dr. Abhijith Ulayottil Venugopal & Dr. Laura Revell, University of Canterbury
The project aims to deliver a comprehensive understanding of the dynamic feedbacks triggered by high-latitude, low-altitude Stratospheric Aerosol Injection in the Southern Ocean carbon cycle. The team will study this by assessing four different metrics. First, changes in stratospheric ozone and associated potential increases in meridional temperature gradients in the Southern Hemisphere (SH). Second, hypothesized increases in SH westerly wind strength and poleward shift. Third, the potential acceleration of the Antarctic Circumpolar Current (ACC). Lastly, how these all come together to impact air-sea CO2 fluxes in the Southern Ocean.
Balancing Benefits and Risks: Polar Stratospheric Aerosol Injection and Antarctica’s Tipping Points
Dr. Paul Goddard & Dr. Ben Kravitz, Indiana University
Antarctic ice melt is the largest potential contributor to sea level rise and the greatest source of uncertainty in future projections. Limiting temperature rise is critical to preventing potentially catastrophic sea level rise from melting ice sheets. Global SAI strategies stabilize temperatures in both the West (WAIS) and East (EAIS) Antarctic Ice Sheets. However, polar SAI only does this for WAIS and not EAIS. This study aims to determine why this is the case, with Dr. Goddard and Dr. Kravitz hypothesizing that different processes govern the changes for each ice sheet. Additionally, the study will investigate whether 13km injection will amplify ice loss risk compared to 15km, along with comparing how the results from the two questions above depend on model structure by comparing CESM, UKESM, and E3SM data.
Climate Intervention or Regional Risk? Exploring High Latitude Low Altitude Stratospheric Aerosol Injection (SAI) Impacts on West African Monsoon and Climate Extremes
Dr. Nana Ama Browne Klutse, Ghana Environmental Protection Authority & Dr. Kwesi Akumenyi Quagraine, National Center for Atmospheric Research
The project primarily seeks to investigate whether there are concrete differences in the impacts of high-latitude SAI deployment when injecting at 13km vs. 15km. Dr. Klutse, Dr. Quagraine and the project team plan on evaluating this question through two pathways. First, through researching the impacts of the different injection altitudes on West African Monsoon variability and dynamics. This includes analyses of differences in monsoon onset, peak, and retreat dates, intraseasonal oscillations, and evolution of the ITCZ, among other factors. Second, the comparison of injection altitude will be looked at through the lens of climate extremes — heatwaves and precipitation — and compound events — co-occurrence of droughts & dry heatwaves and extreme precipitation & moist heatwaves.
Global Drought and Extreme Precipitation Responses to SAI Strategies
Dr. Samantha Stevenson & Dr. Se-Yong Song, University of California, Santa Barbara
This research investigates the impact of high-latitude, low-altitude SAI on precipitation extremes, particularly compared to ARISE-SAI scenarios. The project also seeks to evaluate the underlying physical drivers causing these changes. More specifically, Dr. Stevenson and Dr. Song propose to contrast global patterns of precipitation extremes, soil moisture, SST and its teleconnections between ARISE-SAI and high-latitude/low-altitude simulations to identify the role of SAI injection pattern. This will be compared with the magnitude of inter-model differences, which will be assessed through intercomparisons of the CESM2/UKESM/E3SMv2 ensembles for both ARISE-SAI and high-latitude deployments.
Impact of Stratospheric Aerosol Injection on Agroclimatic Extremes and Crop suitability in West Africa
Dr. Vincent Olarenwaju Ajayi, Federal University of Technology, Akure & Dr. Temitope Samuel Egbebiyi, University of Cape Town
The project seeks to investigate the impact of ARISE-SAI and high-latitude, low-altitude deployment scenarios on agroclimate extremes and crop suitability in West Africa. More specifically, indices such as consecutive wet days, consecutive dry days, warm spell duration index, and growing season length, among others, will be used to measure the agroclimate extremes. For the crop suitability piece, the Ecocrop suitability model will be used to evaluate the impacts of SAI on maize, cassava, and cowpea. Overall, this research aims to provide a detailed look at how different SAI scenarios will impact agriculture in West Africa
Impacts of High-Latitude/Low-Altitude Stratospheric Aerosol Injection on Surface Temperature and Precipitation in Mainland Southeast Asia
Dr. Pornampai “Ping-Ping” Narenpitak, National Electronics and Computer Technology Center
This research aims to determine the impacts of high-latitude, low-altitude SAI on the surface climate in Mainland Southeast Asia (M-SEA). Dr. Narenpitak aims to investigate whether this deployment scenario can not only offset warming, but do so without suppressing regional precipitation like equatorial injection scenarios do. Additionally, the project seeks to explore how high-latitude, low-altitude deployment impacts the Hadley Circulation, monsoon variability in M-SEA and near-surface air quality. These changes associated with this SAI scenario will also be compared with other climate change and SRM scenarios.
Polar Bear Fasting Season Length as an Ecologically Relevant Metric for Evaluating High-Latitude/Low-Altitude SAI Deployment Outcomes
Dr. Michael Diamond, Florida State University
This project seeks to use polar bear cub recruitment success as a proxy to measure the success of performing high-latitude SAI injection at 15km vs 13km. Dr. Diamond will use a recently established relationship between ice free days, fasting duration, and energy requirements for lactation to determine the cub recruitment success metric above. The project team seeks to determine whether this provides a meaningfully different sense of whether SAI is “successful” based on this metric. The team hypothesizes that temporal and regional variability could matter greatly for biological processes with threshold behaviors in ways that would be poorly captured by analyzing temperature or sea ice concentration alone.
Projecting human mortality impacts of lower-altitude versus higher-altitude stratospheric aerosol injection
Dr. Brooke Anderson, Colorado State University
This project not only aims to determine the health impacts of different SAI scenarios, but also make it easier to couple climate and epidemiological research going forwards. This research will investigate the health burdens and mortality impacts of different altitude SAI injection scenarios, specifically G6-1.5K-SAI and 15km and 13km high-altitude injection. However, to do so the different metrics, temporal scale, and geographic scale between climate models and health exposure-response functions need to be aligned. The project team will start with available climate model simulation outputs to develop open-source global datasets of tropospheric ozone, PM2.5, and temperature that are ready to integrate into health impact assessments. They will then use this to analyze the human health impacts of the SAI strategies above, including mortality, as well as providing tutorial examples for how to do this with other climate simulations.