For the last 40 years the American scholar and war critic Noam Chomsky has argued that there is a question missing in the perennial debates about whether the US should go to war against its apparently innumerable mortal adversaries. Hawks present claims about the threat of communism and terrorism that must be stopped, militarily, in far-flung lands, while the doves, who go along or not with a given war action in the beginning, ultimately argue on cost-benefit grounds that the (inevitable) escalation is too expensive fiscally or politically to continue. Few ask at the outset, as Chomsky observes, by what moral or legal right does the US bomb, invade or occupy another country, and so many.

In a similar way there is a missing question in the global discussion about human-induced climate change, and Bjørn Lomborg is in the vanguard of ensuring that this key question stays where it belongs – out of sight.

The background: beginning about a decade ago in his first book, The Skeptical Environmentalist: Measuring the Real State of the World, Lomborg challenged "widely held beliefs that the environmental situation is getting worse and worse" and mocked the "dire" assessments by scientists and environmentalists that global warming was a serious threat. In a more recent book, Cool It: The Skeptical Environmentalist's Guide to Global Warming, he again mocked climate-change "hysteria", advising the world to "chill out" about man-made warming.

While in both books Lomborg conceded (in a few sentences) the fact of human-induced warming, he argued (in hundreds of pages) that it was "no catastrophe" by issuing grotesquely misleading claims – one after the other – in seeking to discredit the scientific basis of current and projected climate impacts. His reasoning was that if global warming isn't so bad, there is no need to reduce CO 2 emissions to any significant extent.

Now that the ongoing published science on global warming has veered sharply toward worst-case scenarios across a range of climate impacts, in Smart Solutions to Climate Change, a new volume edited by Lomborg, he writes: "The risks of unchecked global warming are now widely acknowledged" and "we have long moved on from any mainstream disagreements about the science of climate change". This is the lipstick, but the pig is still a pig. This is because Lomborg still argues in this book, as he did in the others, that cost-benefit economics analysis shows that it is prohibitively expensive for the world to sharply reduce CO 2 emissions to the extent required by the scientific evidence: "Drastic carbon cuts would be the poorest way to respond to global warming."

Here's where the missing question comes into play, since Lomborg does not seriously address the fundamental problem of rising atmospheric CO 2 concentrations in the absence of global greenhouse reductions: what will happen to the earth and human civilisation when atmospheric CO 2 concentrations rise – essentially unchecked, if we followed Lomborg's recommendations – to 450 parts per million, 550ppm, 700ppm, 800ppm; and when the average global temperature rises by 2C, 3C, and 4C to 7C?

Climate scientists have set 350ppm and a 2C average temperature rise (from 1750 to 2100) as the upper range targets to prevent a global climate disaster. Since we are already at 390ppm and since a 2C plus rise is a near certainty, how does Lomborg's appeal to forgo sharp reductions in CO 2 emissions reflect climate science? He argues that there are "smarter solutions to climate change" than a focus on reducing CO 2 . This is hardly smart: it's insanity.

If Lomborg were really looking for smart solutions, he would push for an end to perpetual and brutal war, which diverts scarce resources and public focus from what Lomborg accurately says needs more money, including some of the research and policy projects recommended by the contributors to this volume. There might even be a few hundred billion dollars left to invest annually in new energy and mass transit economies, and science-mandated CO 2 reductions. We're only two questions short of achieving those goals. Sounds pretty economical to me.

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