What has the atomic number of 16, and is liable, in the form of a compound, to be spritzed into the stratosphere by the mega-ton? You'd be right if you said sulfur. That's one of the interventions suggested by geo-engineers to reduce global warming, along with such initiatives as making biochar, "sequestering" CO2 under the earth, brightening clouds by spraying water upwards, and dumping iron powder in the sea. A sulfur compound injected into the middle atmosphere would mimic a massive volcanic eruption, which is known to reduce the mean surface temperature.
Geo-engineering is what humans could do after they've been unable to reduce emissions of greenhouse gases adequately or are afraid to try or feel that a reduction is not "cost-effective." Some advocates say we should keep geo-engineering in reserve in case of an emergency; while others urge us to do it pre-emptively, as an alternative to reducing the carbon emitted by tailpipes, smokestacks, and other industrial and vehicular sources.
A few years ago science writer Eli Kintisch produced Hack the Planet, a critique of geo-engineering, and now Clive Hamilton, in Earthmasters, brings the story up to date, with a special focus on ethics. In Australia, where he lives, Hamilton is branded as a public intellectual, which means he shares his extensive knowledge not only with his colleagues but with the educated public. A skeptic about humans, Hamilton called his prior book, Requiem for a Species, which devoted part of chapter 6 to geo-engineering, the subject of the entire new book.
Global warming has been on the agenda at least since 1988 when climate scientist James Hansen testified to a Congressional committee, and the next year when Bill McKibben gave us The End of Nature. That was about a quarter century ago. Most climate scientists prefer reducing the emission of greenhouse gases to any form of geo-engineering, but this isn't happening (except as a result of economic recession). Fossil fuel firms warn that reducing emissions might wreck the economy, depressing the standard of living. So the carbon builds up, and geo-engineering waits as the potential savior.
Why not just do it? Let's run through several difficulties.
First, by definition we don't know what unintended consequences would emerge if, for example, humans were to spray tons of a sulfur compound into the stratosphere. In medical terms, the cure might be disastrously worse than the disease. Serious engineers and financiers judged the chances were vanishingly low for an explosion of the Challenger, the near-collapse of the U.S. financial system, or the multiple problems at Fukushima Daiichi.
Second, stopping some of the sun's radiation from reaching the earth would do nothing to reduce the acidification of the oceans, which like warming, is a product of carbon emissions.
Third, once this sulfur shield were created, it would have to be renewed: while CO2 persists for centuries, the sulfur lasts only a few years. If after a while the spraying stopped for any reason, the global temperature would quickly rise, perhaps too quickly for the survival of some plants and animals.
Fourth, we have no international protocol specifying who can decide to spray the sulfur. If such a momentous decision could be negotiated, why not negotiate a reduction of emissions?
Fifth, to whom would nations complain if they felt disadvantaged by the results of sulfur spraying, who would judge their cases, what standards would apply, and who would pay damages? For example, what if there were a failure of monsoons and other rainfall needed for crops?
Sixth, and perhaps most seductive, if geo-engineering were done pre-emptively, a bridge to the development and introduction of sustainable energy as cheap as natural gas or coal, would it not simply replace what it was meant to introduce? Even if methods of cheap low-carbon energy were invented, they would still have to be built as the new infrastructure.
Seventh, is geo-engineering not just the latest Promethean project, when what we need is systems that Hamilton calls "Soterian"? This is his verbal coinage from the name of Sotera, the Greek god of "safety, preservation, and deliverance from harm." President Nixon said the solution to any failures of technology is more technology. Hamilton argues that is the wrong path.
True, the fossil fuel companies did not say, "we'll push these substances on unsuspecting users who will crave them for immediate benefit, not looking to the future." Arguably they felt they were profiting by helping to build a civilization, by supplying coal, oil, and natural gas used in the steam engine, electric power plants, vehicles, furnaces, stoves, various industrial processes. The problem was, the vast immediate benefits brought a vast eventual flaw. It's hard to demonize the fuel suppliers without recognizing that all of us are their customers. They will defend their interests, fiercely. We need to recognize that our interests are now diverging sharply from those of the merchants of carbon.
This recognition comes at an awkward time. What's at risk is not only our customary sources of energy, but also our civic religion. Whatever spiritual beliefs some of us hold, almost everyone worships at the altar of "progress." (The motto of the state where I grew up is "Excelsior," or in the English, "ever upward.") We expect that we will be able to buy more tomorrow than today, that our descendents will be better off, in perpetuity.
It is as if we've made a decision, by default, to risk that the findings of climate science are just a bad dream, or that a cheap form of sustainable energy will be developed, or that we'll find a way to defeat the economic interests of the fossil fuel industries, or that geo-engineering will save us and not have unintended consequences worse than global warming. As a friend is fond of asking, what can possibly go wrong?
Note: After writing the prior draft of this article, then meant to be the final draft, I experienced the entire text disappearing in an instant during the upload, with no remaining version available. This unprecedented event astonished and angered me, until I paused to realize that the subject of the article involves a vastly worse loss, for many, than what had just occurred in my computer. The accidental disappearance of the familiar had, in a tiny way, a repairable way, reinforced the gravity of our situation.