The climate change debate isn’t going to be settled by rhetoric, but the next few elections probably will be. That said, President Obama, administratively imposing limits on carbon dioxide emissions by US power plants, declared last week, “We don’t have time for a meeting of the flat earth society.”
The editorial page of The Wall Street Journal dug in its heels. The early stages of an economic recovery were no time to be taking measures to slow global warming, the editors wrote: “He wants to reduce greenhouse s emissions by 17 percent by 2020, but over his 6,500 word address he articulated no such goal for the unemployment rate or GDP.”
Besides, they continued, “[H]e never explained how his plan will reduce warming, or why climate models have failed to predict the warming slowdown of the last dozen years even as more CO2 is pumped into the atmosphere.”
And in any event, the president’s administrative measures were “profoundly undemocratic,” because “Congress has never legislated that there are social costs to carbon emissions, much less how to measure them.”
Let’s see how that plays after the coming summer weather. For what will add credibility to one side or the other in the climate science debate is a few more years or decades of experience. Instrumentation is rapidly improving: new satellite data show that glaciers around the world are melting, but not quite as fast as glaciologists returning from fieldwork had feared. Still, sea levels are rising and water-supply problems are getting worse. Sensible persons will continue to look to the evidence.
Because of Obama’s speech, I spent part of last week reading Public Policy in an Uncertain World: Analysis and Decisions by Charles Manski, of Northwestern University. It is a heroic effort by a distinguished economist and statistician to put into words the consequences of the fact that we live in a world of partial knowledge.
Manski has nothing to say about climate change. His expertise is in the realm of social policy – for a time he was director of the government-supported Institute for Research on Poverty. But he does offer a field guide to varieties of overreach that anyone who thinks for a living will recognize.
Among them: “conventional certitude,” stemming from strong assumptions; “dueling certitudes,” most likely when matters are most contentious; “conflating science and advocacy,” a tendency subject to changing standards of evidence over time; “wishful extrapolation;” “illogical certitude;” and “media overreach,” which Manski illustrates with the study which purported to show that a standout kindergarten teacher should be paid $320,000 a year, equal to the present value of the enhanced lifetime earnings of a schoolroomful of five-year-olds, which wound up on page one of The New York Times while it was still nothing more than a set of PowerPoint slides.
Manski’s book boils down to a sustained argument that predictions should be expressed probabilistically, as a range of possibilities (an interval or a bound, in jargon) that are best expressed graphically as a fan chart, rather than as a single number or “point.” (The cost of pending legislation is routinely “scored,” or estimated by the Congressional Budget Office with an exact prediction.) He wrote, he says, for undergraduates and masters students in public policy and social science programs; for civil servants and others who make policy decisions; and for the journalists who cover their decisions. Perhaps it will eventually do for literary policy analysis what Edward Tufte’s classic The Visual Display of Quantitative Information did thirty years ago for graphical design. Meanwhile, I nostalgically thought back to the days when reporters were similarly tutored with simpler dicta: “If your mother says she loves you, check it out!” and “Nothing between human beings is more than one-to-three,” which turns out, alas, in the words of the immortal Damon Runyon, to really be “All life is six-to-five against.”
What those odds actually are in the matter of climate change is still a matter of very great uncertainty. The main event here, in terms of economics, will be the appearance this autumn of The Climate Casino: Risk, Uncertainty, and Economics for a Warmer World, by William Nordhaus, of Yale University, a singularly well-informed expert on the topic – more informed, say, than, the editorial board of the WSJ. We have entered a casino of sorts, Nordhaus warns, and are gambling with the future of the planet, though there is still time to back out by adopting a global system of carbon taxes. Nordhaus is the president-elect of the American Economic Association; you can look forward to hearing plenty more.
In the meantime, enjoy the summer weather….
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