Assessing Outcomes in Stratospheric Aerosol Injection Scenarios Shortly
After Deployment
Abstract
Current global actions to reduce greenhouse gas emissions are very
likely to be insufficient to meet the climate targets outlined under the
Paris Agreement. This motivates research on possible methods for
intervening in the Earth system to minimize climate risk while
decarbonization efforts continue. One such hypothetical climate
intervention is stratospheric aerosol injection (SAI), where reflective
particles would be released into the stratosphere to cool the planet by
reducing solar insolation. The climate response to SAI is not well
understood, particularly on short-term time horizons frequently used by
decision makers and planning practitioners to assess climate
information. This knowledge gap limits informed discussion of SAI
outside the scientific community. We demonstrate two framings to explore
the climate response in the decade after SAI deployment in modeling
experiments with parallel SAI and no-SAI simulations. The first framing,
which we call a snapshot around deployment, displays change over time
within the SAI scenarios and applies to the question “What happens
before and after SAI is deployed in the model?” The second framing, the
intervention impact, displays the difference between the SAI and no-SAI
simulations, corresponding to the question “What is the impact of a
given intervention relative to climate change with no intervention?” We
apply these framings to annual mean 2-meter temperature, precipitation,
and a precipitation extreme in the first two experiments to use large
ensembles of Earth system models that comprehensively represent both the
SAI injection process and climate response, and connect these results to
implications for other climate variables.