In this article from American Scholar—though beginning from the possibly incorrect assumption that global warming is human caused and can be human corrected—the information about the various forms of geoengineering that are being discussed is very interesting, and very alarming.
“In the past four years, planetary climate modification, or geoengineering, has become the subject of intense inquiry. What exactly is geoengineering? First, consider the distinction between weather and climate. Weather is what’s happening more or less right now. Climate is the accumulation of weather over a standard average of 30 years. What geoengineering proposes to do is to modify climate, to deliberately intervene in natural processes, lowering global average temperatures and thus ameliorating the human effects that are warming the climate. There are two broad ways to do this: carbon dioxide removal (CDR) and solar radiation management (SRM). Carbon dioxide removal would use various methods to reduce anthropogenic CO2 levels in the air. Solar radiation management would send more sunlight back into space, reducing the input of what scientists call radiative forcing and what laypeople call heat. The former method works slowly, while the latter method can work within months. The authors of a 2009 Royal Society report said that geoengineering “is very likely to be technically feasible,” although it is not a substitute for reducing emissions in the first place. But the lack of political will to reduce emissions, the increasing levels of greenhouse gases in the atmosphere, the present and future effects of climate change, and the need to act fast to counter these trends have led a number of scientists and policymakers to give geoengineering serious consideration as a research endeavor and as a potential partial solution to near-term climate change.
“The questions this endeavor raises are foundational, even though the parts per million of atmospheric carbon dioxide seem so minuscule and the predicted temperature increases don’t seem, in a daily context, to be so daunting. And yet. Just what is the sweet spot for the Earth’s global average temperature—or, rather, the temperature we want the Earth to have? Keep the warming to about a 2°C rise? Should the parts per million (ppm) of atmospheric CO2 be 350? 450? We’re already pushing 400 ppm. At 450 we might avoid warming the planet above the 2°C mark. But that’s a 50-50 proposition if we rely solely on reducing emissions, according to Tom Wigley of the National Center for Atmospheric Research, and, he says, “any pathway to 450 looks rather optimistic.” The Royal Society says that “it seems increasingly likely that concentrations will exceed 500 ppm by mid-century and may approach 1000 ppm by 2100.” Such levels could lead to civilization-ending global warming.
“What should trigger our use of geoengineering? Five hundred ppm? A series of sudden and strange weather events? Rapid release of ocean methane, which is frozen now but if thawed would dump massive amounts of this greenhouse gas in the air? No one knows and no one yet agrees. Should geoengineering proceed as one in a suite of options while we wrangle with cutting emissions? Or is it a last resort when Iceland no longer lives up to its name? Here, too, disagreement reigns.
“In its largest sense, geoengineering is not just an attempt to cool the planet’s atmosphere or to make our agitated climate happier. It’s an attempt to extend the lifespan of the Holocene, our current geologic epoch—which began about 12,000 years ago—so that humans and other creatures might last a bit longer than otherwise. Of course, some scientists call the current geologic period the Anthropocene—the era of global, human-induced changes to the atmosphere and biosphere. If that’s the case, then geoengineering is the ironic pursuit of vast technological means to return us to the Holocene. It’s a form of technological nostalgia.
“Scientist Paul Crutzen, who invented the term Anthropocene, blew the lid off what had been a fringe science in a 2006 letter published in the journal Climatic Change. Crutzen, a Nobel laureate and a soft-spoken lover of opera records, argued that our collective failure to reduce emissions now required scientists to take geoengineering seriously, especially the most exotic SRM idea of all: injecting sulfur in the stratosphere to reflect sunlight. Conveniently, sulfur injection is relatively cheap—no more than $50 billion a year, Crutzen suggested—and it works quickly. We know this because when volcanoes spew sulfur the planet cools.
“Scientists have begun researching CDR and SRM techniques. Congress and the House of Commons have both held hearings. And John Holdren, President Obama’s science adviser, won’t rule out geoengineering “if we get desperate enough.” Later he backpedaled from this sentiment, but the word is out.”