We’re running out of time—geoengineering needed now

[Fred Pearce, 5-29-19, "Geoengineer the Planet? More Scientists Now Say It Must Be an Option," Yale E360, ] WL

Once seen as spooky sci-fi, geoengineering to halt runaway climate change is now being looked at with growing urgency. A spate 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. “Time is no longer on our side,” one geoengineering advocate, former British government chief scientist David King, told a conference last fall. “What we do over the next 10 years will determine the future of humanity for the next 10,000 years.” King helped secure the Paris Climate Agreement in 2015, but he no longer believes cutting planet-warming emissions is enough to stave off disaster. He is in the process of establishing a Center for Climate Repair at Cambridge University. It would be the world’s first major research center dedicated to a task that, he says, “is going to be necessary.” 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. “We are running out of time to mitigate catastrophic climate change,” says one scientist. 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. Marcia McNutt, president of the National Academy of Sciences, said: “We are running out of time to mitigate catastrophic climate change. Some of these interventions… may need to be considered in future.” The study’s prospective authors held their first meeting in Washington, D.C., at the end of April. Speakers included David Keith, a Harvard University physicist who has developed his own patented technology for using chemistry to remove CO2 directly from the atmosphere, and Kelly Wanser of the Marine Cloud Brightening Project, which is studying the efficacy of seeding clouds with sea salt and other materials to reflect more sunlight back into space. The project is preparing for future field trials. 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. Geoengineering the climate to halt global warming has been discussed almost as long as the threat of warming itself. American researchers back in the 1960s suggested floating billions of white objects such as golf balls on the oceans to reflect sunlight. In 1977, Cesare Marchetti of the Austria-based International Institute for Applied Systems Analysis discussed ways of catching all of Europe’s CO2 emissions and injecting them into sinking Atlantic Ocean currents. Various geoengineering methods could help lower global temperatures. In 1982, Soviet scientist Mikhail Budyko proposed filling the stratosphere with sulphate particles to reflect sunlight back into space. The first experiments to test the idea of fertilizing the oceans with iron to stimulate the growth of CO2-absorbing algae were carried out by British researchers in 1995. Two years later, Edward Teller, inventor of the hydrogen bomb, proposed putting giant mirrors into space. Still, many climate scientists until recently regarded such proposals as fringe, if not heretical, arguing that they undermine the case for urgent reductions in greenhouse gas emissions. A group of scientists writing in Nature as recently as April last year, called solar geoengineering “outlandish and unsettling… redolent of science fiction.” But the mood is shifting. There is broad, international scientific agreement that the window of opportunity to avoid breaching the Paris climate target of staying “well below” 2 degrees Celsius (3.6 degrees Fahrenheit), is narrowing sharply. A pause in the rise in CO2 emissions that brought hope in 2015 and 2016 has ended; the increase has resumed at a time when we should be making progress toward a goal of halving emissions by 2030, says Johan Rockstrom, science director of the Potsdam Institute for Climate Impacts Research. CO2 concentrations in the atmosphere — the planetary thermostat — are now at 415 parts per million (ppm) and rising by almost 3 ppm each year, reaching levels that have not been seen in 3 million years. “We have two years left to bend the curve” downward, says Rockstrom. A plume of exhaust extends from the Mitchell Power Station, a coal-fired power plant built along the Monongahela River, 20 miles southwest of Pittsburgh, in New Eagle, Pennsylvania. How far can technology go to stave off climate change? Read more. Some experts contend we may be approaching a moment when nothing other than geoengineering can meet the international community’s promise — made when signing the UN Climate Change Convention at the Earth Summit in 1992 — to prevent “dangerous anthropogenic interference with the climate system.” Myles Allen of Oxford University’s Environmental Change Institute says: “Every year we are not even trying to reduce emissions is another 40 billion tons of CO2 dumped into the atmosphere that we are blithely committing future generations to scrub out again.” One researcher says that geo-engineering’s potential to promote conflict “is likely to be substantial.” Possible geoengineering schemes and schedules are now being discussed. Take this plan published last fall by Gernot Wagner, executive director of Harvard University’s Solar Geoengineering Research Program: 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. The thickening shroud of particles would fight climate change by mimicking the output of volcanic eruptions that deflect solar radiation streaming into the atmosphere. Famously, the eruption of sulphate particles from Mount Pinatubo in the Philippines in 1991 caused a global cooling of up to 0.6 degrees C for the following two years. The planned 15-year human-made “eruption” would shave 0.3 degrees off warming, halving the likely increase during that time.