Wake Smith

and 3 more

AbstractTipping elements are features of the climate system which can display self-reinforcing and non-linear responses if pushed beyond a certain threshold (the “tipping point”). Models suggest that we may surpass several of these tipping points in the next few decades, irrespective of which emissions pathway humanity follows. Some tipping elements reside in the Arctic and Antarctic and could potentially be avoided or arrested via a solar geoengineering program only at the poles. This paper considers the utility of proactively developing the capacity to respond to emergent tipping element threats at the poles as a matter of risk management. It then examines both the air and ground infrastructure that would be required to operationalize such capability by 2040 and finds that this would require a funded launch decision by a financially credible actor by roughly 2030.1. IntroductionDespite the rapid growth of solar and wind power along with advancements in battery technology capabilities to store such energy, demand for fossil fuels remains undiminished1 and greenhouse gas emissions continue to increase2. Without rapid and dramatic changes in our emissions trajectory, humanity may surpass a 1.5°C global average surface temperature anomaly by 2030 and 2°C by mid-century3. Such a temperature trajectory would not only be damaging in its own right, but would risk triggering self-reinforcing transitions in various tipping elements of the climate system4–9, which in turn could dramatically accelerate climate damages.The potential urgency of devising responses to tipping elements is illustrated in Table 1, which is derived from Armstrong McKay et al. (2022). The minimum estimates of the global mean surface temperatures that would trigger many of these tipping elements are in many cases well below 2ºC, and expected tipping temperature values for key tipping elements such as abrupt permafrost thaw and subpolar gyre (SPG) collapse are also below 2ºC5. These tipping temperature thresholds will be surpassed irrespective of which Representative Concentration Pathway (RCP) the world ultimately selects. Even diverting to a radical emissions reduction scenario such as RCP2.6 would not prevent us from crossing before 2050 the minimum temperature threshold that might trigger a tip of the Atlantic Meridional Overturning Circulation (AMOC)5. It is possible that we have already crossed the thresholds that might lead to an irrecoverable loss of the West Antarctic or Greenland ice sheets5. Or, those thresholds may lie just ahead..