Cherry Picking Climate Catastrophes: Response to Conor Clarke, Part II
Conor Clarke at The Atlantic blog, raised several issues with my study, “What to Do About Climate Change,” which Cato published last year.
One of Conor Clarke’s comments was that my analysis did not extend beyond the 21st century. He found this problematic because, as Conor put it, climate change would extend beyond 2100, and even if GDP is higher in 2100 with unfettered global warming than without, it’s not obvious that this GDP would continue to be higher “in the year 2200 or 2300 or 3758”. I addressed this portion of his argument in Part I of my response. Here I will address the second part of this argument, that “the possibility of ‘catastrophic’ climate change events — those with low probability but extremely high cost — becomes real after 2100.”
The examples of potentially catastrophic events that could be caused by anthropogenic greenhouse gas induced global warming (AGW) that have been offered to date (e.g., melting of the Greenland or West Antarctic Ice Sheets, or the shutdown of the thermohaline circulation) contain a few drops of plausibility submerged in oceans of speculation. There are no scientifically justified estimates of the probability of their occurrence by any given date. Nor are there scientifically justified estimates of the magnitude of damages such events might cause, not just in biophysical terms but also in socioeconomic terms. Therefore, to call these events “low probability” — as Mr. Clarke does — is a misnomer. They are more appropriately termed as plausible but highly speculative events.
Consider, for example, the potential collapse of the Greenland Ice Sheet (GIS). According to the IPCC’s WG I Summary for Policy Makers (p. 17), “If a negative surface mass balance were sustained for millennia, that would lead to virtually complete elimination of the Greenland Ice Sheet and a resulting contribution to sea level rise of about 7 m” (emphasis added). Presumably the same applies to the West Antarctic Ice Sheet.
But what is the probability that a negative surface mass balance can, in fact, be sustained for millennia, particularly after considering the amount of fossil fuels that can be economically extracted and the likelihood that other energy sources will not displace fossil fuels in the interim? [Remember we are told that peak oil is nigh, that renewables are almost competitive with fossil fuels, and that wind, solar and biofuels will soon pay for themselves.]
Second, for an event to be classified as a catastrophe, it should occur relatively quickly precluding efforts by man or nature to adapt or otherwise deal with it. But if it occurs over millennia, as the IPCC says, or even centuries, that gives humanity ample time to adjust, albeit at a socioeconomic cost. But it need not be prohibitively dangerous to life, limb or property if: (1) the total amount of sea level rise (SLR) and, perhaps more importantly, the rate of SLR can be predicted with some confidence, as seems likely in the next few decades considering the resources being expended on such research; (2) the rate of SLR is slow relative to how fast populations can strengthen coastal defenses and/or relocate; and (3) there are no insurmountable barriers to migration.
This would be true even had the so-called “tipping point” already been passed and ultimate disintegration of the ice sheet was inevitable, so long as it takes millennia for the disintegration to be realized. In other words, the issue isn’t just whether the tipping point is reached, rather it is how long does it actually take to tip over. Take, for example, if a hand grenade is tossed into a crowded room. Whether this results in tragedy — and the magnitude of that tragedy — depends upon how much time it takes for the grenade to go off, the reaction time of the occupants, and their ability to respond.
Filed under: Energy and Environment; International Economics and Development
Comments on Criticism of Cato Ad
Our friends at www.realclimate.org and www.ryanavent.com have been taking shots at the statements in our ad, so I’d like to offer a little commentary.
We make three factual assertions.
First, we say that “surface temperature changes over the past century have been episodic and modest”. We cite Brohan et al., Journal of Geophysical Research (2006 and updates) and Swanson and Tsonis, Geophysical Research Letters, 2009. The first is the latest update of the East Anglia temperature history, which long has been the IPCC staple. It is the one most cited over the years by the IPCC because it was the first long history that contained much more than simply World Weather Records data updated with local records at the end of a month. At any rate, both it and other global histories indeed show modest warming, about 0.8degC from 1900-2000, and indeed it is episodic. Everyone (well probably almost everyone…there are some real people who don’t believe it is right) pretty much agrees that there are two periods of warming, 1910-45 and 1977-98, with a slight cooling in between and no trend after. If that’s not “episodic”, I don’t know what is. The Swanson paper in fact specifically quantifies these episodes. The paragaph near the end of it that says this may mean that warming will be faster than we thought was pure speculation. It could just have easily been argued (as I do) that the lack of recent warming more likely indicates that 21st century warming will be lower than forecast by oceanic feedback because lack of warming simply delays any water vapor amplification. Pure and simple.
The second assertion is that, “after controlling for population growth and property values, there has been no increase in damages from severe weather events”. The citation is short — a note in the Bulletin of the American Meteorological Society, by Pielke Jr. et al, 2005. The et al. numbers over ten other large-name scientists/analysts, and the reference list is the important part. There are a large number of citations on climate-related damages for various places and/or periods. We couldn’t list them all in this format, so we chose a single citation that could be consulted and an interested reader would find all the subsidiary supporting material.
Finally we state that “the computer models forecasting rapid temperature change abjectly fail to explain recent climate behavior”, citing Douglas et al., International Journal of Climatology, 2007, which showed the major disparity between forecasts of the upper tropospheric tropical “warm spot”, a hallmark of greenhouse projections, and observations in the radiosonde record. Yes it is true that Santer et al. have published a lengthy rebuttal, but it is extremely dense and marks just another go-round-and-round over this issue. Douglas et al. have a response but it hasn’t been published yet. The debate will go on and on. Further, it is quite apparent from comparing midrange multimodel estimates from the IPCC to observed temperatures, and those indeed projected for coming years, that there is a signficant disconnect developing between the models and surface temperature. They simply don’t anticipate multidecadal periods without warming. Oh yes, since this has happened, all of the sudden models can be forced to “explain” it, but that’s not prospective. Instead, it is retrospective adjustment. Such work wouldn’t be performed if there weren’t something wrong.
That’s more than enough to negate President-elect Obama’s statement that “The science is beyond dispute and the facts are clear”!
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