Lindzen in Newsweek

Gavin Schmidt and Michael Mann

As part of a much larger discussion on Learning to live with Global Warming in Newsweek recently, the editors gave some space for Richard Lindzen to give his standard ‘it’s no big deal’ opinion. While we disagree, we have no beef with serious discussions of the costs and benefits of various courses of action and on the need for adaption to the climate change that is already locked in.

However, Lindzen’s piece is not a serious discussion.

Instead, it is a series of strawman arguments, red-herrings and out and out errors.

Lindzen claims that because we don’t know what the ideal temperature of the planet should be, we shouldn’t be concerned about global warming. But concern about human-driven climate change is not because this is the most perfect of possible worlds – it is because, whatever it’s imperfections, it is the world that society is imperfectly adapted to. Lindzen is well aware that predictions of weather are different from climate predictions (the statistics of weather), yet cheerfully uses popular conflation of the two issues to confuse his readers.

Lindzen claims that the known amount of ‘forcing’ on the system proves that CO2 will only have a small effect, yet makes plain in the subsequent paragraph that the total forcing (and hence what the planet should be reacting to) is quite uncertain (particularly before the satellite era). If the total forcing is uncertain, how can he say that he knows that the sensitivity is small? This issue has been dealt with much more seriously than Lindzen alludes to (as he well knows) and it’s clear that this calculation is simply too uncertain to constrain sensitivity on it’s own.

Among the more egregious of Lindzen’s assertions is this one:

Ten years ago climate modelers also couldn’t account for the warming that occurred from about 1050 to 1300. They tried to expunge the medieval warm period from the observational record—an effort that is now generally discredited.

It’s remarkable that Lindzen is able to pack so many errors into two short sentences. First of all, doubts about the global scale of warmth associated with the “Medieval Climate Anomaly” date back well over a decade and certainly precede any known attempts to use climate models to simulate Medieval temperatures [e.g. Hughes and Diaz (1994), Was there a ‘medieval warm period’, and if so, where and when?; there are even earlier conference proceedings that were published coming to similar conclusions]. To the best of our knowledge, the first published attempt to use a climate model and estimated forcing histories to simulate the climate of the past millennium was described less than 7 years ago in this Science article by Tom Crowley, not 10 years ago– (a 43% error ;) ). Crowley’s original study and the other similar studies published since, established that the model simulations are in fact in close agreement with the reconstructions, all of which indicate that at the scale of the Northern Hemisphere, peak Medieval warmth was perhaps comparable to early/mid 20th century warmth, but that it fell well short of the warmth of the most recent decades. Not only has the most recent IPCC report confirmed this assessment, it has in fact extended it further back, concluding that the large-scale warmth of recent decades is likely anomalous in at least the past 1300 years. So we’re puzzled as to precisely what Lindzen would like to have us believe was “expunged” or “discredited”, and by whom?

Finally, we find it curious that Lindzen chose to include this very lawyerly disclaimer at the end of the piece:

[Lindzen’s] research has always been funded exclusively by the U.S. government. He receives no funding from any energy companies.

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