Dr Jeffrey Kiehl is speaking about the dilemma of how to model warm poles during green house world conditions. He did this for the PT Extintion, Cretaceous, and the PETM. He's been working with Christine Shields. Karen Weiss (sp) also worked on the Eocene and Cretaceous.
The computer models do a good job now in tropical temps and matching irl. They're really bad for polar temps: even in greenhouse forcing, etc, keep ending up with polar ice in the model. Not good. 100 million years ago 10x CO2. 0-8 deg in Cret when it should be 20-25 deg. suggested heat transport and polar clouds. None work out.
(Lee and Dave Pollard (lastnames?? will find) had a paper in Science. New model in science with stratified ocean, assumption added aerosols and clouds much better. Cloud field back is supposed to be the mechanism. The atmosphere seems to need to be less dusty than now. This causes more sun light being absorbed. 50 cloud droplets, 17 microns per cubic centimeter. Natural sources for aerosols: microorganisms, dust, smoke, sea salt, isoprene? from vegetation all nucleate clouds.
They tried this with a change in PETM simulation: 8x CO2. The change to the model caused a big amplification temperature wise. This makes it much warmer. Polar temperature goes from near 0 deg to 15-20 deg. Problem is world warmer. Much warmer. All of temperatures, not flat across the world. Real life was rather flat temperature gradient.
PT boundary ought to have few sources of nucleating clouds. Put in the model and they get 4-5 deg higher now. Works better here. Causes terrible feedback to even more stratification of the ocean. Really bad feedback. 40 deg C in tropics, btw.
Cloud model change doesn't solve problem. Really does help though. Really needs to happen during stressed ecologies. To verify we need data on the paleo aerosols. Any paleo volunteers?
I'll clean this up a bit later I am running behind. That was dense. oy.
The computer models do a good job now in tropical temps and matching irl. They're really bad for polar temps: even in greenhouse forcing, etc, keep ending up with polar ice in the model. Not good. 100 million years ago 10x CO2. 0-8 deg in Cret when it should be 20-25 deg. suggested heat transport and polar clouds. None work out.
(Lee and Dave Pollard (lastnames?? will find) had a paper in Science. New model in science with stratified ocean, assumption added aerosols and clouds much better. Cloud field back is supposed to be the mechanism. The atmosphere seems to need to be less dusty than now. This causes more sun light being absorbed. 50 cloud droplets, 17 microns per cubic centimeter. Natural sources for aerosols: microorganisms, dust, smoke, sea salt, isoprene? from vegetation all nucleate clouds.
They tried this with a change in PETM simulation: 8x CO2. The change to the model caused a big amplification temperature wise. This makes it much warmer. Polar temperature goes from near 0 deg to 15-20 deg. Problem is world warmer. Much warmer. All of temperatures, not flat across the world. Real life was rather flat temperature gradient.
PT boundary ought to have few sources of nucleating clouds. Put in the model and they get 4-5 deg higher now. Works better here. Causes terrible feedback to even more stratification of the ocean. Really bad feedback. 40 deg C in tropics, btw.
Cloud model change doesn't solve problem. Really does help though. Really needs to happen during stressed ecologies. To verify we need data on the paleo aerosols. Any paleo volunteers?
I'll clean this up a bit later I am running behind. That was dense. oy.
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