Effects of Warming and Stratospheric Aerosol Injection on Tropical Cyclone Distribution and Frequency: Results from a High-Resolution Global Circulation Model

As global circulation models (GCMs) have increased in spatial resolution, more realistic tropical cyclones (TCs) and TC distributions have been simulated. Whereas prior research on TC climatologies has relied on proxies like Potential Intensity and synthetic storm models, the cyclones simulated by newer “storm-resolving” GCMs can now be analyzed directly. This is particularly useful for studying projected global storm distributions under radically altered future climates, including high-emissions warming scenarios, and those shaped by climate interventions. Such interventions include various directed changes in global albedo, such as Stratospheric Aerosol Injection (SAI). In this paper, we utilize a new high-resolution model configuration to conduct experiments examining the effects of SAI on tropical cyclones. These experiments are constructed based on prior work on SAI, using the GLENS ensemble. Our analysis focuses on three 10-year simulations conducted using 30-km grid spacing. The first is a recent-past calibration run. The second uses the Intergovernmental Panel on Climate Change climate pathway SSP 8.5, for the years 2090-2099, with no SAI. The third simulation also uses SSP 8.5 for the years 2090-2099, but with SAI beginning in 2020 to maintain a global temperature rise of no more than 1.5 K. We use a novel TC-tracking algorithm to analyze resulting changes in storm tracks and properties. Our results show that while SAI may return global storm counts back to late 20th-century levels, there are large basin-by-basin changes in storm number and intensity. These are strongly driven by increases in mean ENSO indices with warming and especially with intervention.