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Fri Dec 28, 2012, 03:25 PM

Skeptical Science: IPCC Temperature Projections Have Been Exceptionally Accurate.

I found this article on S & S and I thought I might post it:


Contrary to Contrarian Claims, IPCC Temperature Projections Have Been Exceptionally Accurate
Posted on 27 December 2012 by dana1981

There is a new myth circulating in the climate contrarian blogosphere and mainstream media that a figure presented in the "leaked" draft Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report shows that the planet has warmed less than previous IPCC report climate model simulations predicted. Tamino at the Open Mind blog and Skeptical Science's own Alex C have done a nice job refuting this myth. We prefer not to post material from the draft unpublished IPCC report, so refer to those links if you would like to see the figure in question.

In this post we will evaluate this contrarian claim by comparing the global surface temperature projections from each of the first four IPCC reports to the subsequent observed temperature changes. We will see what the peer-reviewed scientific literature has to say on the subject, and show that not only have the IPCC surface temperature projections been remarkably accurate, but they have also performed much better than predictions made by climate contrarians (Figure 1).........

Long story short.......the charts were right.

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Reply Skeptical Science: IPCC Temperature Projections Have Been Exceptionally Accurate. (Original post)
AverageJoe90 Dec 2012 OP
NoOneMan Dec 2012 #1
AverageJoe90 Dec 2012 #2

Response to AverageJoe90 (Original post)

Fri Dec 28, 2012, 04:03 PM

1. The charts were right, so far


Things might get unpredictable (non-linear due to feedback). But what is a more interesting point is that we have seemed to underestimate the secondary effects of temperature rise:

Conservative IPCC Errs on the Side of Least Drama

Although the IPCC climate models have performed remarkably well in projecting average global surface temperature warming thus far, Rahmstorf et al. (2012) found that the IPCC underestimated global average sea level rise since 1993 by 60%. Brysse et al. (2012) also found that the IPCC has tended to underestimate or failed to account for CO2 emissions, increased rainfall in already rainy areas, continental ice sheet melting, Arctic sea ice decline, and permafrost melting. Brysse et al. concludes that the on the whole the IPCC has been too conservative in its projections, "erring on the side of least drama" in effect preferring to be wrong on the conservative side in order to avoid criticism.

I think in the Anderson lecture where he noted something to the effect that we have overestimated the "safety" of such minimal rises (and we will likely exceed these arbitrary targets anyway). Our ecosystems may prove to be more sensitive to temperature changes than originally predicted.

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Response to NoOneMan (Reply #1)

Fri Dec 28, 2012, 04:41 PM

2. Well, that may indeed be true to an extent.

However, though, it's important to note that the latest IPCC graphs go out to 2300, and the trend does become less linear around 2150 or so, but not in the way some might think; the average RCP 8.5 scenario levels out at about, (well, whaddaya know?) 8.5*C. by 2300. (I'd have posted it already, but the forum software doesn't allow you to post directly from your computer archives, so I'll have to see if I can find a copy on the 'Net somewhere.)

As for the ecosystem comment, that may be true in some ways, but I'd also like to refer back to the end of the Ice Age as well, when temperatures rose by as much as 7*C in just half a century or so..... as far as we know at this time, no significant extinction regimes occurred during that time(or at least not thanks to the warming alone). Now, granted, today's circumstances are obviously somewhat different, especially when you take ground pollution, deforestation and other things into account, but even with that in mind, there does appear to be some hope.

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