Changes in global teleconnection patterns under global warming and stratospheric aerosol intervention scenarios

Abstract

Abstract. We investigate the potential impact of Stratospheric Aerosol Intervention (SAI) on the spatiotemporal behavior of large-scale climate teleconnection patterns represented by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), El Niño/Southern Oscillation (ENSO) and Atlantic Multidecadal Oscillation (AMO) indices using simulations from the Community Earth System Models (CESM1 and CESM2). The leading Empirical Orthogonal Function of sea surface temperature (SST) anomalies indicates that greenhouse gas forcing is accompanied by increases in variance across both the North Atlantic (i.e., AMO) and North Pacific (i.e., PDO) and a decrease over the tropical Pacific (i.e., ENSO); however, SAI effectively reverses these global warming-imposed changes. The projected spatial patterns of SST anomaly related to ENSO show no significant change under either global warming or SAI. In contrast, the spatial anomaly patterns pertaining to AMO (i.e., in the North Atlantic) and PDO (i.e., in the North Pacific) changes under global warming are effectively suppressed by SAI. For AMO, the low contrast between the cold-tongue pattern and its surroundings in the North Atlantic, predicted under global warming, is restored under SAI scenarios to similar patterns as in the historical period. The frequencies of El Niño and La Niña episodes increase with greenhouse gas emissions in the models, while SAI tends to compensate for them. All climate indices’ dominant modes of inter-annual variability are projected to be preserved in both warming and SAI scenarios. However, the dominant decadal and interdecadal variability mode changes induced by global warming are exacerbated by SAI, particularly in the Atlantic-based AMO.

The Indonesian Throughflow Circulation Under Solar Geoengineering

“…There is an observed relationship between ITF transport and the El Niño-Southern Oscillation (ENSO), with stronger transport during La Niña and weaker transport during El Niña, with ITF variability lagging ENSO variability by 8-9 months (England and Huang, 2005;Meyers, 1996). No effects of ENSO on ITF transport are obvious in our results as the models ENSO variability is not synchronized or tuned to the real world but exists as an emergent property of each ESM (Rezaei et al, 2022).…”

Multi‐Model Simulation of Solar Geoengineering Indicates Avoidable Destabilization of the West Antarctic Ice Sheet

“…The driver for the changing surface winds is ultimately the globally applied SAI which overcools the tropical regions relative to the poles and strengthens polar vortex (Figure 6). The resulting reduction in the pole‐equator temperature gradient should preferentially reduce the wind variability near the continental shelf break in the Amundsen Sea, but may also affect for example, teleconnection patterns (Rezaei et al., 2023). Low‐latitude injections of sulfate in the CESM model (Visioni et al., 2020) change the thermal wind balance due to localized heating, increasing the equator‐to‐pole horizontal temperature gradient in the stratosphere and strengthening the polar vortex in both hemispheres.…”

The Holton–Tan mechanism under stratospheric aerosol intervention

“…SAI is thought to be effective at moderating key climate hazards (Irvine et al, 2019) but does so imperfectly and presents its own risks including changes in the global teleconnection patterns (Rezaei et al, 2022), storm tracks (Karami et al, 2020), ocean acidification (Lauvset et al, 2017), ozone losses from sulfur injections (Tilmes et al, 2008), and unequal and nonuniform regional compensation in temperature and precipitation distributions (Robock, 2008;Kravitz et al, 2014;Mousavi et al, 2022). Thus, it remains unclear whether the risks of SAI exceed or fall short of the risks of breaking the 2 • C target (Parker and Irvine, 2018;Rahman et al, 2018), and such risks and benefits need to be evaluated for all parts of the Earth system.…”