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Friday, February 12, 2021

The Canadian ESM5 climate model ... "simulates the greatest warming in the troposphere, roughly 7 times larger than the observed trends."


" ... our latest installment of stuff that actual scientists actually say, as opposed to stuff journalists make up then adorn with the phrase “scientists say” to make it sound legit. 


This item comes from a recent paper by Mitchell et al. in which they compared observed warming rates in the lower atmosphere over the tropics after 1979 (when satellites used for temperature monitoring were launched) to the trends simulated in climate models. 


... “Focusing on the
(new) CMIP6 models, we have confirmed the original findings of Mitchell et al (2013): first, the modeled tropospheric trends are biased warm throughout the troposphere (and notably in the upper troposphere, around 200 hPa) and, second, that these biases can be linked to biases in surface warming. 


As such, we see no improvement between the CMIP5 and the CMIP6 models.” 


The tropical region matters because that’s where key atmospheric processes operate that determine how much greenhouse gases will warm the whole planet. 


... Unfortunately the newest models are still as biased as the old ones.


The warm trends bias in the models is seen throughout the entire troposphere, but is greatest in the upper troposphere (peaking around 200 hPa), where the modeled trends are—on average – 4 to 5 times greater than the observations. 


We draw attention to the CanESM5 model: it simulates the greatest warming in the troposphere, roughly 7 times larger than the observed trends."