How serious is the threat of global warming? One way to figure out is to take your cues from some leading climate scientists: They have moved on. That doesn't mean they've abandoned the issue, but they are looking beyond what all agree is the most obvious solution -- decreasing the amount of carbon we spew into the atmosphere in the first place.
These scientists are beginning to look for a Plan B. There are two distinct approaches under consideration -- sucking carbon out of the atmosphere, or creating an artificial sun shield for the planet. The former, which involves reversing some of the very processes that are leading to the climate problem, is expensive. The latter just sounds scary. David Keith, a leading thinker on geoengineering, calls it "chemotherapy" for the planet. "You are repulsed?" he says. "Good. No one should like it. It's a terrible option."
Repugnant or not, with the globe failing to develop other ways to halt climate change, geoengineering is increasingly becoming an option. The science and engineering are relentlessly marching on: Most research so far has focused on computer modeling, but some has started to move beyond -- trying to test, for example, how to deliver particles into the upper reaches of the atmosphere. This summer, an entrepreneur conducted a rogue experiment, dumping 100 tons of iron into the Pacific in an attempt to "seed" the ocean and spur the removal of carbon dioxide from the atmosphere. This episode represents a particularly apt example of science -- in this case, self-experimentation -- speeding far ahead of public opinion and oversight.
The high costs of doing nothing
If the world can't get its act together to limit carbon emissions, geoengineering may be the only option we have. Distill the climate problem down to the essentials, and it becomes obvious that global warming is fundamentally a market failure: All seven billion of us human beings are "free riders" on a planet that is heating up. We put billions of tons of carbon dioxide into the atmosphere every year, and largely aren't required to pay for the privilege. There's too little incentive to stop polluting.
Americans are some of the world's worst offenders. Every U.S. citizen, on average, emits around 20 tons of carbon dioxide a year -- twice that of the average European. All kinds of things contribute to that number. Driving the average U.S. vehicle in an average year accounts for more than 5 tons. The full carbon footprint of the average thrice-weekly cheeseburger: half a ton a year. One roundtrip cross-country flight: one ton.
Each of these tons of carbon dioxide causes at least $20 worth of damage in adverse health effects, flooded coastlines, and other effects of climate change. By mid-century, that figure will rise to at least $50. And a truly catastrophic event caused by a warmer climate, like Antarctic ice sheets collapsing long ahead of schedule or Arctic methane bubbling up at precipitous rates, resulting in runaway global warming, could increase those costs by a factor of 10 or more. How do you put a price tag on even a 1 percent risk of altering the climate so much that it could destroy civilization as we know it?
Few of us are paying our fair share for the damage that we're doing to the planet. For example, airlines don't add $20 to ticket prices in order to pay for the damage caused per passenger by flying back and forth across the country. That decreases costs up front, but it also comes at enormous cost to society down the road. The world's population -- led by the one billion or so global high emitters -- are doing many hundreds of billions of dollars of damage to the planet, and in the near future the costs will skyrocket into the trillions.
"Free riding" also plagues relations between countries. Some, like the European Union have a cap or tax on carbon pollution. Most are still waiting on the sidelines. Why should any single country cut its carbon emissions when it knows that its reductions will only be a drop in the bucket toward solving climate change -- and other nations aren't asking their citizens to pay their fair share? Blame it on short election cycles, partisanship, or fossil energy interests, the political will often doesn't exist -- whether in Washington or the latest global environment gathering in Rio de Janeiro.