Canada is simply warming at half the velocity of local weather mannequin simulations – watts that?
Reposted by Dr. Roy Spencer’s blog
January 21, 2021 by Roy W. Spencer, Ph. D.
As part of my presentation to the Friends of Science on January 19 about the absence of a climate emergency, I also examined the surface temperature in Canada to see how much the warming had compared to climate models there.
Canada has a huge temperature variation from year to year due to its strong continental climate. To study how observed surface temperature trends compare to climate model simulations, you need many of these simulations, each with its own large variability.
I examined the last 30 year period (1991-2020) with a total of 108 CMIP5 simulations from about 20 different climate models and calculated land surface trends over the latitudes from 51 N to 70 N and longitudes from 60 W to 130 W., which is approximately Canada covers. For observations, I used the same Lat / Lon limits and CRUTem5 dataset that the United Nations IPCC and world governments rely heavily on. All data was downloaded from the KNMI Climate Explorer.
First, let’s examine the annual mean temperature deviations from the 1981-2010 mean for the mean of the 108 model simulations compared to the observations. We see that Canada only warmed by 50% from the average for the CMIP5 models;; The linear trends are +0.23 C / decade and +0.49 C / decade. Note that for 7 of the last 8 years, the observations were below the average of the models.
Fig. 1. Annual temperature deviations 1991-2020 from the mean value 1981-2010 in Canada in observations (blue) compared to the mean of 108 CMIP5 climate model simulations (red). The +/- 1 standard deviation bars indicate the variability between the 108 individual model simulations.
Next, I show the trends of each model versus the observed trends with a histogram of the rankings from least to most warming (1991-2020).
Fig. 2. Ranking of surface temperature trends in Canada (1991-2020) for the 108 model simulations and the observations.
Note that 93.5% of the model simulations show warmer temperature trends than the observations.
These results from Canada generally agree with the results I found in the American Midwest over the summer, where the CMIP5 models heat up, on average, four times faster than the observations (since 1970) and, in a limited number, six times faster newer CMIP6 model simulations.
Implications
The Paris Agreement, along with other national and international efforts to reduce greenhouse gas emissions, is based on warming estimates that are roughly the average of the various climate models. Thus, these results have a direct impact on the proposed energy policy decisions.
As you may know, proponents of these climate models often emphasize the general agreement between the models and observations over a long period of time, for example since 1900.
But that is misleading.
We would expect that the noise of natural climate variability would produce only a small anthropogenic signal about global warming until (approximately) the 1980s. There are two reasons for this: Little CO2 was emitted in the 1970s, and even as emissions increased after the 1940s, the cooling effect of anthropogenic SO2 emissions offset much of this warming. This is also widely accepted by climate modelers.
Therefore, to really get a good signal for global warming – both in observations and in models – we should study temperature trends since about the 1980s. That is, only in the decades since the 1980s should we see a robust signal of anthropogenic warming against the backdrop of natural variability and without the confusion (and uncertainty) of large SO2 emissions in the mid-20th century.
And every year the warming signal should get a little stronger.
I continue to claim that climate models are now generating at least twice as much warming as they should, probably due to an equilibrium climate sensitivity that is about twice as high in the climate models. Given that the average CMIP6 climate sensitivity is even greater than that of CMIP5 – close to 4 degrees. C – It will be interesting to see if the divergence between models and observations (which started around the turn of the century) will persist in the future.
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