Forbes/24 September 2017
Scholars of geoengineering have reported increasing interest in their work this month as humans seem increasingly unlikely to avert catastrophic global warming.
Governments, universities, think tanks and international bodies are turning to the idea of tinkering with the earth by making it absorb more carbon dioxide or reflect more sunlight into space, the scholars said.
“Even a decade ago this was largely in the realm of fantasy for many, but now there’s a lot of discussion of this in the Intergovernmental Panel on Climate Change reports, in various government research programs, et cetera,” said Wil Burns, the co-executive director of the Forum for Climate Engineering Assessment.
Harvard researcher David Keith said in an appearance at Carnegie-Mellon University this month that Janos Pasztor’s interest in geoengineering “has really changed things.” Pasztor was the chief advisor on climate to former UN Secretary General Ban Ki-Moon. He has entered the once-marginalized discussion of geoengineering—which Keith said “is in some ways like the adult as entered the room.” Last year Pasztor became the founding director of the Carnegie Climate Geoengineering Governance Project.
“This is getting talked about at quite high levels of the UN Framework Convention,” Keith said. “This weekend we’ll get to be face to face with Al Gore debating this. I mean, it really is happening in a way that it wasn’t happening before.”
Gore has described geoengineering as “insane, utterly mad and delusional in the extreme.” But it’s starting to look delusional to think humans will be able to curtail carbon emissions quickly enough to keep the average global surface temperature from rising more than 2ºC, the level at which scientists anticipate catastrophic impacts.
“We already see widespread impacts, consequential impacts on every continent,” said Katherine Mach, a senior research scientist at Stanford University and director of Stanford’s Environmental Assessment Facility. “We can even look at extreme events, like a drought, a flood, and see the ways that we’re driving up the risks.”
Mach said the world has made substantial progress since the Paris Agreement. “The planet as a whole is making a lot of progress in responding to climate change. Our emissions of heat-trapping gasses globally have slowed down. We’re also seeing vast acceleration in terms of our deployment of clean energy solutions,” she said.
But the carbon dioxide already in the atmosphere will have “near-permanent effects.” To keep warming below 2ºC, the human contribution of CO2 has to remain below three trillion tons. It’s already reached two trillion tons, and the next trillion is expected to enter the atmosphere over the next 20 years, Mach said.
That’s about how much time researchers need to better understand the climate impacts of geoengineering, saidDoug MacMartin, a senior research associate at Cornell University.
“We’re now at a point where while mitigation is necessary, it’s not necessarily sufficient,” MacMartin said. “What we know how to do in terms of cutting our carbon emissions is just not going to be fast enough.”
Nonetheless, MacMartin said it would “terrify me enormously” if someone proposed geoengineering today, before the climate impacts are better understood. He estimates it will take 20 years to achieve that understanding. He’s also terrified that once geoengineering is deployed, people will think it’s safe again to pollute. “People say, ‘Oh great, now that we have a solution we can keep emitting CO2.’ That’s probably the thing that keeps me up at night.”
Keith, Mach and MacMartin all emphasized that geoengineering alone cannot solve the problem of anthropogenic climate change. Combined with mitigation, however, it could shave off a temperature peak or slow warming enough to buy humans some time.
“If solar geoengineering makes sense at all, it makes sense as a supplement to cutting emissions, not as a substitute for cutting emissions,” Keith said.
Solar geoengineering is the half of the field that considers making the earth more reflective, either by putting reflective particles in the atmosphere or in space or by encouraging cloud formation. The other half of the field considers ways to absorb atmospheric carbon dioxide and sequester it.
“There are a lot of different types of geoengineering,” Mach said. “They range from planting a tree to putting mirrors into space.”
In the best understood and most discussed method, aircraft would disperse sulfates into the stratosphere, which would reflect some incoming solar energy.
“If we wanted to put sulfates in the stratosphere, which is the thing we know best, then there’s a whole bunch of specific risks with doing that,” Keith said: “Stratospheric ozone loss, warming of the lower stratosphere, impacts on the troposphere—anything you put up in the stratosphere will eventually make it back to the surface—what does it do to human health?”
So far, it appears the risks are much smaller than the risk of allowing anthropogenic climate change to continue unabated, he argued.
“The question is, which is more risky?” Keith asked. “A world with 450 or 550 parts per million of CO2 in the atmosphere, or that same world plus a little bit of solar geoengineering?”
The scientists worry less about risks from geoengineering than about human responses to geoengineering, including conflicts between countries that take differing views of it, a relaxation of attitudes toward carbon pollution, or the possibility that polluters will exploit the technology.
“I want to say up front that I get it—that people will use the work that I and others are doing to try to argue that we don’t need to try to work as hard to cut emissions. So Exxon or the petro-states probably already have to some extent and will likely use that,” Keith said. “I still think it makes sense for us to know a lot about this.”
News Source: Forbes