Once seen as spooky sci-fi and conspiracy theories, geoengineering to halt runaway climate change is now being looked at with growing urgency. A range of dire scientific warnings that the world community can no longer delay major cuts in carbon emissions, coupled with a recent surge in atmospheric concentrations of CO2, has left a growing number of scientists saying that it’s time to give the controversial technologies a serious look.
“What we do over the next 10 years will determine the future of humanity for the next 10,000 years.”
“Time is no longer on our side,” one geoengineering advocate, former British government chief scientist David King, told a conference last fall. King helped secure the Paris Climate Agreement in 2015, but he no longer believes cutting planet-warming emissions is enough to stave off disaster.
Technologies earmarked for the Cambridge center’s attention include a range of efforts to restrict solar radiation from reaching the lower atmosphere, including spraying aerosols of sulphate particles into the stratosphere, and refreezing rapidly warming parts of the polar regions by deploying tall ships to pump salt particles from the ocean into polar clouds to make them brighter.
United States scientists are on the case, too. The National Academies last October launched a study into sunlight reflection technologies, including their feasibility, impacts and risks, and governance requirements. China too has an active government-funded research program. It insists it has no current plans for deployment, but is looking, among other things, at how solar shading might slow the rapid melting of Himalayan glaciers.
Some experts contend we may be approaching a moment when nothing other than geoengineering can meet the international community’s promise to prevent “dangerous anthropogenic interference with the climate system.”
In 15 years’ time, as the impacts of warming worsen, planes loaded with sulphate particles start taking off from airfields around the world. They fly to 65,000 feet, well above existing air lanes, and spray their loads into the stratosphere: 4,000 flights in the first year, 8,000 in the second, 12,000 in the third, and so on until, after another 15 years, fleets of purpose-built, high-altitude tankers are making 60,000 flights annually.