Refreezing the poles by reducing incoming sunlight would be feasible and surprisingly cheap, according to a new study.
The Earth’s poles are warming several times faster than the world average. In fact, record heatwaves were reported earlier this year in both the Arctic and Antarctic. The melting of ice and the destruction of glaciers at high latitudes will accelerate the rise in sea levels across the planet. Fortunately, it would be feasible and very cheap to re-freeze the poles, reducing the amount of sunlight that gets in. This is stated in a new study published September 15, 2022 in IOP Publishing. Environmental Research Communications.
The scientists outlined a possible future geoengineering program in which high-flying jets would spray microscopic aerosol particles into the atmosphere at 60 degrees north and south latitude – roughly in Anchorage and at the southern tip of Patagonia. When injected at 43,000 feet / 13,000 meters (above the cruising altitude of an airliner), these aerosols will slowly drift poleward, slightly obscuring the surface below them.
“There is widespread and reasonable concern about using aerosols to cool the planet,” notes lead author Wake Smith, “but if the risk/benefit ratio paid off somewhere, it would be at the poles.” Smith teaches at[{” attribute=””>Yale University and a Senior Fellow at the Mossavar-Rahmani Center for Business and Government at Harvard Kennedy School.
Particle injections would be performed seasonally in the long days of the local spring and early summer. Both hemispheres could be serviced by the same fleet of jets, ferrying to the opposite pole with the change of seasons.
A tabular iceberg floating within Paradise Harbour, Antarctica. Credit: IOP Publishing
Pre-existing military air-to-air refueling tankers such as the aged KC-135 and the A330 MMRT don’t have enough payload at the required altitudes. However, newly designed high-altitude tankers would prove much more efficient. A fleet of roughly 125 such tankers could loft a payload sufficient to cool the regions poleward of 60°N/S by 2°C per year. This would be enough to return them close to their pre-industrial average temper atures. Annual costs are estimated at $11 billion. This is less than one-third the cost of cooling the entire planet by the same 2°C magnitude and just a tiny fraction of the cost of reaching net zero emissions.
“Game-changing though this could be in a rapidly warming world, stratospheric aerosol injections merely treat a symptom of climate change but not the underlying disease. It’s aspirin, not penicillin. It’s not a substitute for decarbonization,” says Smith.
Cooling at the poles would provide direct protection for only a small portion of the planet. However, the mid-latitudes should also experience some temperature reduction. Since less than 1% of the global human population lives in the target deployment zones, a polar deployment would entail much less direct risk to most of humanity than a global program.
“Nonetheless, any intentional turning of the global thermostat would be of common interest to all of humanity and not merely the province of Arctic and Patagonian nations,” adds Smith.
In summary, the current study is just a small and preliminary step towards understanding the costs, benefits, and risks of undertaking climate intervention at high latitudes. It provides further reason to believe that such tools could prove useful both in preserving the cryosphere near the poles and slowing global sea level rise.
Reference: “A subpolar-focused stratospheric aerosol injection deployment scenario” by Wake Smith, Umang Bhattarai, Douglas G MacMartin, Walker Raymond Lee, Daniele Visioni, Ben Kravitz and Christian V Rice, 15 September 2022, Environmental Research Communications.DOI: 10.1088/2515-7620/ac8cd3
