Tuesday, April 18, 2017

The Growing Case for Geoengineering

[ed. See also: NASA Designs Suit Capable Of Protecting Humans Hoping To One Day Live On Earth]

David Mitchell pulls into the parking lot of the Desert Research Institute, an environmental science outpost of the University of Nevada, perched in the dry red hills above Reno. The campus stares over the tops of the downtown casinos into the snow-buried Pine Nut Mountains. On this morning, wispy cirrus clouds draw long lines above the range.

Mitchell, a lanky, soft-spoken atmospheric physicist, believes these frigid clouds in the upper troposphere may offer one of our best fallback plans for combating climate change. The tiny ice crystals in cirrus clouds cast thermal radiation back against the surface of the earth, trapping heat like a blanket—or, more to the point, like carbon dioxide. But Mitchell, an associate research professor at the institute, thinks there might be a way to counteract the effects of these clouds.

It would work like this: Fleets of large drones would crisscross the upper latitudes of the globe during winter months, sprinkling the skies with tons of extremely fine dust-like materials every year. If Mitchell is right, this would produce larger ice crystals than normal, creating thinner cirrus clouds that dissipate faster. “That would allow more radiation into space, cooling the earth,” Mitchell says. Done on a large enough scale, this “cloud seeding” could ease global temperatures by as much as 1.4 °C, more than the planet has warmed since the Industrial Revolution, according to a separate Yale study.

Big questions remain about whether it would really work, what damaging side effects might arise, and whether the world should risk deploying a tool that could alter the entire climate. Indeed, the suggestion that we should entrust the global thermostat to an armada of flying robots will strike many as preposterous. But the real question is: preposterous compared to what?

Without some kind of drastic action, climate change could be killing an estimated half-million people annually by the middle of this century, through famine, flooding, heat stress, and human conflict. Preventing temperatures from rising 2 °C above preindustrial levels, long considered the danger zone that should be avoided at all cost, now looks nearly impossible. It would mean cutting greenhouse-­gas emissions by as much as 70 percent by 2050, and it may well require developing technologies that could suck megatons of carbon dioxide out of the atmosphere, according to the U.N.’s Intergovernmental Panel on Climate Change. But a growing body of research suggests that we probably will not have the time or technology to pull this off. Notably, even if every nation sticks to the commitments it’s made under the politically ambitious Paris climate accords, global temperatures could still soar more than 5 °C by 2100.

“Everyone is looking at two degrees, but to me it’s a pipe dream,” says Daniel Schrag, director of the Harvard University Center for the Environment, who was one of President Obama’s top advisors on climate change. “I fear we’ll be lucky to escape four, and I want to make sure nobody ever sees six.”

The difference between two and four degrees is another quarter-billion people without reliable access to water, more than a hundred million more exposed to flooding, and massive declines in worldwide crop yields, according to a study by the Committee on Climate Change, a London-­based scientific group established to advise the U.K. government (see below).

The idea that we could counteract these dangers by reĆ«engineering the climate itself, techniques collectively known as geoengineering, began to emerge from the scientific fringes about a decade ago (see “The Geoengineering Gambit”). Now momentum behind the idea is building: increasingly grim climate projections have convinced a growing number of scientists it’s time to start conducting experiments to find out what might work. In addition, an impressive list of institutions including Harvard University, the Carnegie Council, and the University of California, Los Angeles, have recently established research initiatives.

Few serious scientists would argue that we should begin deploying geoengineering anytime soon. But with time running out, it’s imperative to explore any option that could pull the world back from the brink of catastrophe, says Jane Long, a former associate director at Lawrence Livermore National Laboratory. “I don’t really know what the answer is,” she says. “But I do believe we need to keep saying what the truth is, and the truth is, we might need it.”

by James Temple, MIT Technology Review | Read more:
Image: Tatsuro Kiuchi