Debunking Bj¸rn Lomborg — Part II, Misrepresenting Sea Level Rise

Lomborg is a champion cherry-picker when he isn’t just getting his facts wrong, as I argued in Part I. He has a deceptively misleading — and outright erroneous — discussion of sea level rise projections in Cool It. Let’s start with a few all-too-typical howlers:

Antarctica is generally soaking up more water than Greenland is shedding, as the IPCC predicts. The IPCC estimates that the very worst additional increase to be expected from Greenland could be 8 inches over the century, but this is possible only in a model where CO2 levels rise two to four times more than expected by 2100 (p. 64).

No, no, and no. First, as was widely reported back in 2006 — and thus well known to Lomborg while writing Cool It — the first-ever gravity survey of the entire Antarctic ice sheet by NASA and German scientists using a satellite launched in 2002 found “Antarctica’s ice sheet decreased by 152 (plus or minus 80) cubic kilometers of ice annually between April 2002 and August 2005.” That’s as much water as the U.S. consumes in three months.

Second, the IPCC clearly states “models [of sea level rise] used to date do not include uncertainties in climate-carbon cycle feedbacks nor do they include the full effect of changes in ice sheet flow.” Indeed, the IPCC goes out of its way to make clear that its projections exclude “future rapid dynamical changes in ice flow” — changes we are already seeing in both Greenland and Antarctica (subs. req’d). So the “very worst additional increase” possible from Greenland is much more than 8 inches. The IPCC explicitly says “larger values cannot be excluded.”

And this “very worst additional increase” does not require “CO2 levels rise two to four times more than expected by 2100.” It applies to the standard range of IPCC scenarios — and as I have written, since 2000, carbon dioxide emissions have grown faster than any IPCC model had projected.

This all goes beyond cherry-picking and sloppiness — it is outright deception. And Cool It has much more intellectually dishonesty.

For instance, Lomborg can’t get enough of the IPCC for sea level rise:

In its 2007 report, the UN estimates that sea levels will rise about a foot over the rest of the century…. sea-level increase by 2050 will be about 5 inches (pp. 60–61).

Thanks to this modest sea-level rise, and the possibility that developing countries will have the money in the future to protect their land with levees, he concludes, “a rich Bangladesh will lose only 0.000034 percent of its present dry-land area” (p. 48). No worries, mate!

Most of the time, however, Lomborg doesn’t buy the U.N. consensus at all. For instance, one of his central arguments is that global warming will save millions of lives: “heat deaths will not outweigh avoided cold deaths, not in 2050, 2100, or even 2200” (p. 39). Yet after reviewing all of the literature, not just the handful of studies that Lomborg cherry-picks, the IPCC states with “high confidence”:

Studies in temperate areas [“mainly in industrialized countries”] have shown that climate change is projected to bring some benefits, such as fewer deaths from cold exposure. Overall it is expected that these benefits will be outweighed by the negative health effects of rising temperatures worldwide, especially in developing countries.

Snap! It is intellectually dishonest to devote several pages to cherry-picking studies that disagree with the IPCC consensus on net health effects because you don’t like its scientific conclusion, while then devoting several pages to hiding behind [a misstatement of] the U.N. consensus on sea level rise because you know a lot reasonable people think the U.N. wildly underestimated the upper end of the range and you want to attack Al Gore for worrying about 20-foot sea level rise.On this blog, I have tried to be clear what I believe with my earlier three-part series: Since sea level, arctic ice, and most other climate change indicators have been changing faster than most IPCC models projected and since the IPCC neglects key amplifying carbon cycle feedbacks, the IPCC reports almost certainly underestimate future climate impacts. This is similar to a point just made in Science.

Lomborg, however, doesn’t just cherry pick — he misrepresents what the IPCC said and he misstates the facts about the ice sheets and his (or at least Denmark’s) beloved Greenland. One sentence is especially garbled:

Even with the most extreme estimates of Greenland melting over a couple of years (sic!), a sea-level rise would take one thousand years.

I cannot figure out what Lomborg was trying to say. Is he saying it would take 1000 years for Greenland to melt and raise sea levels 7 meters? That is an estimate based on models that don’t include the kind of rapid ice sheet dynamics that are already occurring.

While I don’t consider it an extreme estimate based on my interviews with leading climate scientists, NASA’s James Hansen has repeatedly pointed out that in past times of rapid warming, sea levels have risen one meter ever 20 years, and could rise several meters within a century — the same prediction Gore makes, which Lomborg ridicules. Of course, Lomborg has not a single reference to the work of America’s top climate scientist.

I would also note that if we are considering adaptation, the rate sea levels are changing is as important as the absolute jump in sea levels by 2100. An important Science article from early this year used empirical data from last century to project that sea levels could be up to 5 feet higher in 2100 and rising 6 inches a decade! The author notes “all that such a rise would require is that the linear relation of the rate of sea-level rise and temperature, which was found to be valid in the 20th century, remains valid in the 21st century.”

But how do you adapt to seas rising 6 inches a decade? Even if you are a hypothetical rich Bangladesh rather than an actually poor Bangladesh? The first meter of sea level rise would flood 17% of Bangladesh, displacing tens of millions of people, and reducing its rice-farming land by 50 percent. It would inundate over 13,000 square miles of this country.

Even if the chances of this catastrophic outcome were 5% — rather than, say, 50%, as suggested by the work of Hansen and others — it would be enough to warrant strong action today. But Lomborg simply refuses to consider plausible worst-case scenarios, even probable bad-case scenarios, which is his biggest flaw, as we will see in Part III.

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