Cientistas dizem que recongelar os pólos da Terra é possível e extremamente barato

Os pólos da Terra estão aquecendo várias vezes mais rápido do que a média global. De fato, ondas de calor recordes foram relatadas no início deste ano no Ártico e na Antártida. O derretimento do gelo e o colapso das geleiras em altas latitudes acelerariam o aumento do nível do mar ao redor do planeta. Felizmente, seria extremamente viável e barato recongelar os pólos reduzindo a luz solar recebida. Isso está de acordo com uma nova pesquisa publicada em 15 de setembro de 2022 no IOP Publishing’s Comunicações de Pesquisa Ambiental.

Os cientistas criaram um potencial programa futuro de geoengenharia no qual jatos de alta altitude pulverizam partículas microscópicas de aerossol na atmosfera em latitudes de 60 graus norte e sul – aproximadamente Anchorage e a ponta sul da Patagônia. Se injetados a 43.000 pés/13.000 metros (acima das altitudes de navegação da aeronave), esses aerossóis vagarão lentamente em direção ao polo, sombreando a superfície um pouco abaixo.

O autor principal, Wake Smith, observa: “Existem preocupações generalizadas e razoáveis ​​sobre as implantações de aerossóis para resfriar o planeta, mas se a equação risco/benefício valer a pena em qualquer lugar, é nos pólos”. Professor Smith em[{” 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 temperatures. 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