Superfreakonomics_ global cooling, patri - Steven D. Levitt [83]
Caldeira’s study showed that doubling the amount of carbon dioxide while holding steady all other inputs—water, nutrients, and so forth—yields a 70 percent increase in plant growth, an obvious boon to agricultural productivity.
“That’s why most commercial hydroponic greenhouses have supplemental carbon dioxide,” Myhrvold says. “And they typically run at 1,400 parts per million.”
“Twenty thousand years ago,” Caldeira says, “carbon-dioxide levels were lower, sea level was lower—and trees were in a near state of asphyxiation for lack of carbon dioxide. There’s nothing special about today’s carbon-dioxide level, or today’s sea level, or today’s temperature. What damages us are rapid rates of change. Overall, more carbon dioxide is probably a good thing for the biosphere—it’s just that it’s increasing too fast.”
The gentlemen of IV abound with further examples of global warming memes that are all wrong.
Rising sea levels, for instance, “aren’t being driven primarily by glaciers melting,” Wood says, no matter how useful that image may be for environmental activists. The truth is far less sexy. “It is driven mostly by water-warming—literally, the thermal expansion of ocean water as it warms up.”
Sea levels are rising, Wood says—and have been for roughly twelve thousand years, since the end of the last ice age. The oceans are about 425 feet higher today, but the bulk of that rise occurred in the first thousand years. In the past century, the seas have risen less than eight inches.
As to the future: rather than the catastrophic thirty-foot rise some people have predicted over the next century—good-bye, Florida!—Wood notes that the most authoritative literature on the subject suggests a rise of about one and a half feet by 2100. That’s much less than the twice-daily tidal variation in most coastal locations. “So it’s a little bit difficult,” he says, “to understand what the purported crisis is about.”
Caldeira, with something of a pained look on his face, mentions a most surprising environmental scourge: trees. Yes, trees. As much as Caldeira personally lives the green life—his Stanford office is cooled by a misting water chamber rather than air-conditioning—his research has found that planting trees in certain locations actually exacerbates warming because comparatively dark leaves absorb more incoming sunlight than, say, grassy plains, sandy deserts, or snow-covered expanses.
Then there’s this little-discussed fact about global warming: while the drumbeat of doom has grown louder over the past several years, the average global temperature during that time has in fact decreased.
In the darkened conference room, Myhrvold cues up an overhead slide that summarizes IV’s views of the current slate of proposed global-warming solutions. The slide says:
Too littleToo lateToo optimistic
Too little means that typical conservation efforts simply won’t make much of a difference. “If you believe there’s a problem worth solving,” Myhrvold says, “then these solutions won’t be enough to solve it. Wind power and most other alternative energy things are cute, but they don’t scale to a sufficient degree. At this point, wind farms are a government subsidy scheme, fundamentally.” What about the beloved Prius and other low-emission vehicles? “They’re great,” he says, “except that transportation is just not that big of a sector.”
Also, coal is so cheap that trying to generate electricity without it would be economic suicide, especially for developing countries. Myhrvold argues that cap-and-trade agreements, whereby coal emissions are limited by quota and cost, can’t help much, in part because it is already…
Too late. The half-life of atmospheric carbon dioxide is roughly one hundred years, and some of it remains in the atmosphere for thousands of years. So even if humankind immediately stopped burning all fossil fuel, the existing carbon dioxide would remain in the atmosphere for several generations. Pretend the United States (and perhaps Europe) miraculously converted overnight and became zero-carbon societies. Then pretend