Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

The very idea of climate engineering sounds like the crazed scheme of a mad scientist, and it once was close to taboo. Critics see it as a Promethean folly that could have unintended consequences such as disrupting rainfall patterns and damaging the ozone layer. Since the effects of any measure applied to the entire planet are uneven from place to place, climate engineering raises the question of whose hand should be on the world’s thermostat: as with a bickering couple, if one country lowered the temperature at the expense of another, it could set off a war. Once the world depended on climate engineering, then if for any reason it slacked off, temperatures in the carbon-soaked atmosphere would soar far more quickly than people could adapt. The mere mention of an escape hatch for the climate crisis creates a moral hazard, tempting countries to shirk their duty to reduce greenhouse gas emissions. And the accumulated CO2 in the atmosphere would continue to dissolve in seawater, slowly turning the oceans into carbonic acid.

For all these reasons, no responsible person could maintain that we can just keep pumping carbon into the air and slather sunscreen onto the stratosphere to compensate. But in a 2013 book the physicist David Keith makes a case for a form of climate engineering that is moderate, responsive, and temporary. “Moderate” means that the amounts of sulfate or calcite would be just enough to reduce the rate of warming, not cancel it altogether; moderation is a virtue because small manipulations are less likely to bring unwelcome surprises. “Responsive” means that any manipulation would be careful, gradual, closely monitored, constantly adjusted, and, if indicated, halted altogether. And “temporary” means that the program would be designed only to give humanity breathing space until it eliminates greenhouse gas emissions and brings the CO2 in the atmosphere back to preindustrial levels. In response to the fear that the world would become addicted to climate engineering forever, Keith remarks, “Is it plausible that we will not figure out how to pull, say, five gigatons of carbon per year out of the air by 2075? I don’t buy it.”¹⁰⁶

Though Keith is among the world’s foremost climate engineers, he cannot be accused of being carried away by innovation thrill. A similarly thoughtful case may be found in the journalist Oliver Morton’s 2015 book The Planet Remade, which presents the historical, political, and moral dimensions of climate engineering alongside the technical state of the art. Morton shows that humanity has been disrupting global cycles of water, nitrogen, and carbon for more than a century, so it’s too late to preserve a primeval Earth system. And given the enormity of the climate change problem, it’s unwise to assume we will solve it quickly or easily. Research into how we might minimize the harm to millions of people before the solutions are completely in place only seems prudent, and Morton lays out scenarios of how a program of moderate and temporary climate engineering might be implemented even in a world that falls short of ideal global governance. The legal scholar Dan Kahan has shown that far from creating a moral hazard, providing information about climate engineering makes people more concerned about climate change and less biased by their political ideology.¹⁰⁷

Despite a half-century of panic, humanity is not on an irrevocable path to ecological suicide. The fear of resource shortages is misconceived. So is the misanthropic environmentalism that sees modern humans as vile despoilers of a pristine planet. An enlightened environmentalism recognizes that humans need to use energy to lift themselves out of the poverty to which entropy and evolution consign them. It seeks the means to do so with the least harm to the planet and the living world. History suggests that this modern, pragmatic, and humanistic environmentalism can work. As the world gets richer and more tech-savvy, it dematerializes, decarbonizes, and densifies, sparing land and species. As people get richer and better educated, they care more about the environment, figure out ways to protect it, and are better able to pay the costs. Many parts of the environment are rebounding, emboldening us to deal with the admittedly severe problems that remain.