Earth’s climate is vulnerable to potential climate catastrophes that could threaten the longevity of civilization. Continued increases in greenhouse gas forcing could lead to the collapse of major ice sheets, which would cause catastrophic sea level rise and could cause the oceanic thermohaline circulation to halt. Further warming could cause the heat stress index to exceed survival limits, inducing hyperthermia in humans and other mammals. Even more extreme warming could shift Earth into a runaway greenhouse regime that would lead to the loss of all oceans, and the end of all life.
Geoengineering refers to the large-scale use of technology to alter Earth’s global climate, and geoengineering has been suggested as a way to ameliorate contemporary climate change. Addressing these immediate climate challenges through a combined strategy of adaptation, mitigation, and (if needed) geoengineering is a critical issue facing us today. Whether or not we decide to engage in geoengineering today, we must still devise a long-term strategy to address our changing climate.
But in the longer-term, could we also use geoengineering techniques to increase the size of the polar ice caps? This paper raises the question, “Should we geoengineer larger ice caps?” By doing so, the global average temperature of Earth could be lowered from its current state to a new stable regime with much larger ice caps. Earth has experienced shifts in ice coverage in its past, and a prolonged program of geoengineering–say, lasting a thousand years or more–could allow us to permanently shift the energy balance of Earth. More ice at the poles increases the amount of sunlight reflected back to space, leading to cooler temperatures.
Of course, the unfortunate side effects of this idea would be mass migration of populations near the poles, shifts in global agricultural zones, and a required commitment of millenia in order to avoid undesired side-effects. Human civilization today probably lacks the fortitude to embark on such a long-term goal. Nevertheless, thinking about the long-term management of our planetary system helps us realize that we have already entered the epoch of the Anthropocene. Our civilization itself is fundamentally intertwined with our global climate, and we should allow humility, rather than hubris, guide decisions to control our environment.