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Tuesday 24 Jul 2018 | 00:05 | SYDNEY

Reader riposte: Why Cato is wrong on climate change


Sam Roggeveen


14 August 2008 13:55

Dominic Meagher (who blogs at East Asia Forum) writes in response to my post highlighting a Cato Institute article by Jim Manzi, which endorses a 'do very little' approach to climate change (UPDATE: There's also a response to Manzi on the Cato website):

My experience with Cato is that you need to parse everything they say, line by line, word by word, looking for misdirections, untruths, partial truths, bait-and-switch tactics, straw-man arguments, proof-by-assertion and other logical fallacies and debating tricks. And sure enough, in this piece Manzi employs several of these techniques.

Note Jim Manzi begins by pointing out some uncontested facts: CO2 is a greenhouse gas. He goes on to explain the thermal dynamics of the greenhouse effect. This is well known; he isn't writing this to inform anyone. He's writing it to establish his credentials as someone who listens to scientific evidence. Next, Manzi pumps up the credentials of the IPCC (the bait):

The United Nations Intergovernmental Panel on Climate Change (IPCC) represents the largest existing global effort to answer such technical questions.

Again, common knowledge. But this establishes him as someone doesn't deny the credibility of the IPCC (the sad state of climate change 'skeptics' is that acknowledging the IPCC makes Manzi seem reasonable by comparison). He then reports:

The current IPCC consensus forecast is that, under fairly reasonable assumptions for world population and economic growth, global temperatures will rise by about 3 °C by the year 2100.

That was the switch: a clever use of false attribution. Manzi already used appeal to authority and now he attributes a position which sounds like something the IPCC might have said. But he doesn't link to any IPCC endorsed statement suggesting consensus on a 3 degree 'global temperature rise by 2100'. The concepts of 'global temperatures', 'IPCC consensus', and 'fairly reasonable assumptions' are all highly misleading and the IPCC has gone to great pains to point this out. Now comes another false attribution:

Also according to the IPCC, a 4 °C increase in temperatures would cause total estimated economic losses of 1–5 percent of global GDP.

No reference, no link. I'm not aware that the IPCC has gone too far into estimating economic consequences. My understanding is that they focus on the science, being mostly scientists.

Now comes an unfounded conclusion resting on a misdirection implying another appeal to authority:

By implication, if we were at 3 °C of warming at the end of this century, we would be well into the 22nd century before we reached a 4 °C rise, with this associated level of cost.

This is presented as though the IPCC drew the implication, but actually it is Manzi who is drawing this implication, and it doesn't follow from the (false) premise he started with. Climate models are highly non-linear. This is widely known, even amongst lay people. Yet he applies a linear transition path to draw the 'implication'. By now we're up to the fourth paragraph of a 24 paragraph op-ed and are yet to discover a shred of honest writing. I don't hold high hopes for the rest of Manzi's piece, but the burden of proof by now is squarely in the court of anyone who wants to defend Manzi's thesis.