Getting Our Due

In the Diary feature of this week’s The Spectator, rational optimist Matt Ridley has a collection of rather random observations from his daily life that have him thinking about (or maybe wishing for since Old Man Winter has been slow to loose his grip in the U.K. and Western Europe, much like he has across the Eastern U.S.) anthropogenic global warming.

What has his attention is that global warming just doesn’t seem to be going according to plan. And for those who have bought into that plan, their plan-driven actions are starting to make them look foolish.

But it’s not as if we haven’t “told you so”—a fact that Ridley draws attention to in the closing segment of his article.

David Rose of the Mail on Sunday was vilified for saying that there’s been no global warming for about 16 years, but even the head of the Intergovernmental Panel on Climate Change [IPCC] now admits he’s right. Rose is also excoriated for drawing attention to papers which find that climate sensitivity to carbon dioxide is much lower than thought — as was I when I made the same point in the Wall Street Journal. Yet even the Economist has now conceded this. Tip your hat to Patrick Michaels, then of the University of Virginia, who together with three colleagues published a carefully argued estimate of climate sensitivity in 2002. For having the temerity to say they thought ‘21st-century warming will be modest’, Michaels was ostracised. A campaign began behind the scenes to fire the editor of the journal that published the paper, Chris de Freitas. Yet Michaels’s central estimate of climate sensitivity agrees well with recent studies. Scientists can behave remarkably like priests at times.

What we determined in our 2002 study was that the amount of global warming projected by the end of this century was most likely being overestimated.  When we adjusted the climate model projections to take into account and better match the actual observations, our best estimate of the amount of warming we expected from 1990 to 2100 was about 1.8°C (3.2°F), which was in the lower end of the IPCC projected range, and which Ridley correctly noted, we termed as “modest.”

Further, we anticipated the slowdown in the warming rate. Quoting from our 2002 paper titled “Revised 21st century temperature projections” (Michaels et al., 2002):

The ‘worst case’ warming now appears to be merely linear, subject to the modifications described in this paper. Furthermore, both Table 1 and Fig. 3 indicate that any exponential rise in atmospheric CO2 concentrations is weak at best. Consequently, the current linear warming may in fact be the adjustment to the exponential growth in CO2 that took place prior to 1975. Levitus et al. (2000) documented a warming of 0.06°C in the top 3 km of a large-area ocean sample over the course of 40 yr. A lag correlation between that deep-water record and the sea-surface temperature record from Quayle et al. (1999) is very suggestive that oceanic thermal lag maximizes around 35 yr (Michaels et al. 2001). Thus, the truly exponential phase of concentration growth in the atmosphere, which ended about 25 yr ago, should induce a linear warming for the next decade or two before it could actually begin to damp.

Now, more than 10 years later, more and more evidence is piling in that we were right, including several recent papers that apply a technique not all that dissimilar in theory than our own (e.g. Gillett et al., 2012; Stott et al., 2013).

So even though we still are largely ostracized, at least we rest assured that we were pretty much on target—and some people are starting to take notice.

References:

Gillett N. P., V. K. Arora, G. M. Flato, J. F.  Scinocca, and K. von Salzen, 2012. Improved constraints on 21st-century warming derived using 160 years of temperature observations. Geophysical Research Letters, 39, L01704.

Michaels, P. J., P. C. Knappenberger, O. W. Frauenfeld, and R. E. Davis, 2002. Revised 21st century temperature projections. Climate Research, 23, 1-9.

Stott, P., P. Good, G. Jones, N. Gillett, and E. Hawkins, 2013. The upper end of climate model temperature projections is inconsistent with past warming. Environmental Research Letters, 8, 014024, doi:10.1088/1748-9326/8/1/014024.