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Interview with climatologist Bjorn Stevens

02 Nov 2022 | Science Notes

Over at Judith Curry’s website Nic Lewis has posted an English translation of an interview with prominent German climatologist Bjorn Stevens and we encourage you to read the whole thing. Stevens is a leader in his field who pulls no punches when it comes to criticizing the alarmist bias of so many of his colleagues (“If you look closely, the most alarming stories often don’t stand up to scientific scrutiny... According to the simulations, the higher temperatures are mainly caused by a change in the clouds. We consider this effect to be overestimated today.”) We especially draw attention to his opening description of why climate models get clouds wrong, and indeed why climatologists themselves misunderstand clouds. It is that “In my field, most people think of a cloud as these compact white objects in the blue sky.” But they are no such thing.

Lewis introduces Stevens as “Director at the Max Planck Institute for Meteorology, the principal German climate science research and modeling centre” and “joint lead co-ordinator of the World Climate Research Programme’s Grand Challenge on Clouds, Circulation and Climate Sensitivity.” So let’s not hear anyone attempt to dismiss him as “not a climate scientist” even after he remarks “Clouds are tricksters. Even if the contours are sharp, the cloud structure is more like that of puff pastry. Nevertheless, many scientists use the children’s book clouds as a guide because they are easier to simulate. This makes the climate models less accurate.”

We could go further. To use modeling techniques you know are inaccurate, or should know are inaccurate, because they make modeling easier really is the joke about the guy who dropped his key by the door but is looking for it under the lamppost because the light is better. Except he didn’t then say “Ha, found it” then claim to have opened the lamppost and gone in.

The interview contains a lot of other valuable material including surprises like a cloud the size of a building only holds a litre of water and that in consequence “If you distributed all the condensed water in the atmosphere evenly around the globe, you would get a water film that is only two tenths of a millimeter thick.” And some pointed observations about the unsettled nature of climate science. So again we recommend that you check it out.

2 comments on “Interview with climatologist Bjorn Stevens”

  1. Unfortunately, in an otherwise very good interview, Mr. Stevens made an error….the total precipitable water in the atmosphere is 25 to 30 mm., not 0.2 mm……

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