Global warming could be reversed by refreezing the poles, according to a new study published in the journal Communication of environmental research. The restoration of the Earth’s ice “caps” at its north and south poles would result from blocking out the sun, which would maintain weather patterns.
The ambitious idea sounds like a crazy plot from a sci-fi blockbuster – but it’s “both doable and remarkably cheap”, say the researchers. Planes would fly over the Arctic and Antarctic spraying particles – known as stratospheric aerosol injection (SAI). They fight greenhouse gases by dimming starlight – cooling the whole planet, the US team explains.
First author Professor Wake Smith, from Yale University, said: ‘It would seek to mitigate climate change by reflecting a small fraction of incoming solar radiation back into space.’
The study found that this should only be done in subpolar regions. Previous proposals have suggested using the technique across the planet. It would rapidly envelop the poles and could halt or reverse the melting of ice and permafrost at high latitudes, halting sea level rise.
Effective deployment at much lower altitudes than would be necessary in the tropics also presents fewer aeronautical challenges.
“Our model estimates the cost of implementing the SAI subpolar program at $11 billion per year in 2022,” Smith said.
“That’s less than a third of the $36 billion estimated to cool the entire globe’s surface temperatures by 2°C. [35.6 degrees Fahrenheit (F)].”
Most of the savings are due to the much smaller area and fewer aircraft carrying five times the payload given much lower altitudes than covering the tropics, for example. Operating costs also included crew, insurance, maintenance, ground, navigation and landing fees.
Smith said: “The Arctic faces a particularly severe threat from climate change, warming at around twice the global average.”
The annual average surface temperature has increased by more than 3 degrees Celsius (37.4 degrees F) between 1971 and 2019. The extent of sea ice in September from 2010 to 2019 was 40% lower than from 1979 to 1988.
“By mid-century, if not sooner, summer Arctic sea ice will likely effectively be gone, with potentially catastrophic climate consequences for the planet as a whole,” Smith said.
Antarctica is also warming faster than the planetary average – with melting ice a potential “tipping point” for climate change.
Smith said, “Stratospheric aerosol injection is a prospective intervention that would seek to reduce global warming by slightly increasing the reflectivity of Earth’s upper atmosphere.”
It does not replace other strategies, including mitigation, adaptation and carbon dioxide removal, he stressed. “The vast majority of simulations involve the deployment of aerosols on a global scale in order to bring down temperatures around the world,” he said.
“This paper considers an alternative scenario in which SAI could be deployed only in subpolar regions.”
The IPCC (Intergovernmental Panel on Climate Change) presented a “sobering picture”, he added.
The global average surface temperature in 2011-2020 was 1.09°C (33.962 degrees F) higher than in 1850-1900. In 2018, global average sea level had already risen 8 inches since 1901.
Smith said: “Across all of the shared socio-economic pathways that form the basis of climate projections assessed by the IPCC, global surface temperatures continue to rise until at least mid-century.
“Perhaps most worryingly, many changes caused by past and future greenhouse gas emissions are irreversible for centuries or even millennia.”
Record heat waves were reported earlier this year in the Arctic and Antarctica. Melting ice and collapsing glaciers at high latitudes would accelerate sea level rise around the planet.