The Risk of Termination Shock From Solar Geoengineering

Abstract

If solar geoengineering were to be deployed so as to mask a high level of global warming, and then stopped suddenly, there would be a rapid and damaging rise in temperatures. This effect is often referred to as termination shock, and it is an influential concept. Based on studies of its potential impacts, commentators often cite termination shock as one of the greatest risks of solar geoengineering. However, there has been little consideration of the likelihood of termination shock, so that conclusions about its risk are premature. This paper explores the physical characteristics of termination shock, then uses simple scenario analysis to plot out the pathways by which different driver events (such as terrorist attacks, natural disasters, or political action) could lead to termination. It then considers where timely policies could intervene to avert termination shock. We conclude that some relatively simple policies could protect a solar geoengineering system against most of the plausible drivers. If backup deployment hardware were maintained and if solar geoengineering were implemented by agreement among just a few powerful countries, then the system should be resilient against all but the most extreme catastrophes. If this analysis is correct, then termination shock should be much less likely, and therefore much less of a risk, than has previously been assumed. Much more sophisticated scenario analysis—going beyond simulations purely of worst‐case scenarios—will be needed to allow for more insightful policy conclusions.

The Response of Permafrost and High‐Latitude Ecosystems Under Large‐Scale Stratospheric Aerosol Injection and Its Termination

“…The speed of permafrost degradation upon SAI termination is approximately 4× faster than the maximum degradation rate found during the 21st century in RCP8.5. This rate, however, is highly dependent on the choice of scenario, and recent studies point out that termination shock should be much less likely, and therefore much less of a risk, than has previously been assumed (Parker & Irvine, 2018). However, the difference in permafrost extent and temperature even after several decades of SAI termination can lead to some differences in permafrost degradation and permafrost carbon release.…”

Uncertainty and the basis for confidence in solar geoengineering research

“…Termination effect Low; termination is a well-established risk 31 High; impacts of sudden termination of SAG are likely to be severe 32,169 Medium Impacts Ecosystem response High; limited studies 27,170 High; ecosystem services constitute the entire food chain and a sizable portion of the world's economy 171…”

“…A wide range of modelled tropical precipitation) 22 . SAG could also pose additional physical climate risks, such as depletion of stratospheric ozone and subsequent ultraviolet radiation changes 23,24 , interactions with cirrus clouds and possible effects on the radiative balance 25 , increased acid rain 26 , changes to ecosystems 27 , effects on the ocean 28 , agricultural impacts 29,30 and the potential for climate rebound from the sudden termination of SAG 31,32 . figure 1 summarizes some of the conclusions and risks involved in SAG, which have also been previously reviewed 4,5,[33][34][35][36][37][38][39] .…”

Solar geoengineering to reduce climate change: a review of governance proposals

“…Although many writers have noted that solar geoengineering would need to be maintained in order to prevent a 'termination shock', only a handful have described how this could be prevented [205]. Andy Parker and Peter Irvine conclude that geographically distributed, well protected and redundant implementation hardware among multiple relatively powerful countries coupled with sharing of the requisite knowledge should be able to prevent sudden and sustained cessation [207].…”