By Bob Tisdale
The obvious intent of my recent post “17-Year And 30-Year Trends In Sea Surface Temperature Anomalies: The Differences Between Observed And IPCC AR4 Climate Models” was to illustrate the divergence between the IPCC AR4 projected Sea Surface Temperature trends and the trends of the observations as presented by the Hadley Centre’s HADISST Sea Surface Temperature dataset. Tamino has written a response with his post “Tisdale Fumbles, Pielke Cheers.” Obviously he missed the point of the post. Since he does not address this divergence, his post is simply a distraction. That fact is blatantly obvious. Everyone reading his post will realize this, though it is doubtful his faithful followers will call his attention to it. Tamino resorts to smoke and mirrors once again. But let’s look at a few of the points he tries to make.
Tamino objects to this statement that is included on all of the graphs in the “17-year and 30-year trends post”:
The Models Do Not Produce Multidecadal Variations In Sea Surface Temperature Anomalies Comparable To Those Observed, Because They Are Not Initialized To Do So. This, As It Should Be, Is Also Evident In Trends.
The reason I included that statement was because I have illustrated and discussed the lack of multidecadal variability in the IPCC AR4 models in earlier posts and I wanted to draw the readers’ attention to the difference between the trends of the model mean and the observed trends. It’s really that simple.
Tamino makes the following statement toward the end of the post:
“There are definitely problems with the models. For one thing, they don’t reproduce the rapid warming of sea surface temperature from 1915 to 1945 as strongly as the observed data indicate. But overall they’re not bad, and the amount of natural variability they show is realistic.”
But the fact that “For one thing, they don’t reproduce the rapid warming of sea surface temperature from 1915 to 1945 as strongly as the observed data indicate” means the Sea Surface Temperatures of the models also don’t flatten from 1945 to 1975 as the observations do, and it’s those two portions of the multidecadal variations in sea surface temperatures that are known to be missing in the models. That’s what’s being referred to on each of the graphs in red. The models capture the rise in temperature from 1975 to 2000, but they do not capture the rise and flattening from 1910 to 1975.
Tamino presents a comparison of 30-year trends for HADISST, the model mean, and the 9 runs of the GISS Model ER, which I’ve reproduced here as Figure 1. He then writes:
Note that the individual model runs show much more variability than the multi-model mean. In fact they show variability comparable to that shown by the observed data.
I’ve highlighted a portion of his graph in Figure 1 that he obviously overlooked. Look closely at the significant rise in trends of the HADISST data in the early 20th century, and then the equally impressive decline in trends. Do any of the GISS model runs produce the “Multidecadal Variations In Sea Surface Temperature Anomalies Comparable To Those Observed” during the early part of the 20thcentury? No. So thank you for confirming one of my points, Tamino. It also contradicts your nonsensical statement, “In fact they show variability comparable to that shown by the observed data.”
Tamino also goes into a detailed discussion of how the model mean can obscure any multidecadal variations in the individual model runs. But note that he doesn’t use the actual model runs. He uses “Artificial Models”. Refer to Figure 2. Artificial models?
Why doesn’t Tamino use the real models instead of artificial ones? Because then Tamino would have to show you that the majority of the models do not have multidecadal variations in trend that are similar in timing, frequency, and magnitude of the observation-based SST data. Refer to Animation 1.
I could have provided that animation in my post, but I elected not to present it because it added no value to the post.
As I noted earlier, Tamino’s post is simply a distraction from my post “17-Year And 30-Year Trends In Sea Surface Temperature Anomalies: The Differences Between Observed And IPCC AR4 Climate Models”, which showed the divergence between the trends of the IPCC AR4 model mean for global Sea Surface Temperatures and the observed Sea Surface Temperature trends.
Tamino makes a few statements in his post that I will be happy to agree with:
There are definitely problems with the models.
Certainly the models need more work.
Thanks for the opportunity to call attention to my post once again, Tamino.