Negative Greenhouse Effect on the Antarctic Plateau

[blizzard1024]

I have always wondered about the greenhouse effect on the Antarctic plateau since there is a strong troposphere temperature inversion near the surface. Hence the thermal profile looks like

the stratosphere which we know GHGs like CO2 lead to cooling.  I found PEER reviewed papers on this that there indeed is a negative greenhouse effect on the Antarctic plateau. 

This was in Nature    https://www.nature.com/articles/s41612-018-0031-y   

 

So based on this, what happened during the last glacial maximum?  Much of the land masses in the NH were covered by similar ice sheets and likely had a negative greenhouse effect. Hence the argument that warming from orbital parameters warmed the planet and increased CO2 which then increased temperatures will not work over the ice sheets!   this argument always didn't sit well with me. If CO2 is the control knob for the climate, then why does it not kick off the climate changes?   If it is a feedback, it would cool the ice sheets! This paper also shows that the greenhouse effect is weakest in the polar regions (negative over Antarctic Plateau) and is strongest over the tropics which makes sense since water vapor IS the primary greenhouse gas.  CO2 is a weak GHG that somehow becomes stronger during times when ice sheets melt supposedly.  What changes in the quantam mechanics???  Anyway, I think this study changes how we see CO2 and its role in glacial and interglacial cycles. Water vapor is the primary GHG. That's my scientific opinion. 

 

[TheClimateChanger]

40 minutes ago, blizzard1024 said:

I have always wondered about the greenhouse effect on the Antarctic plateau since there is a strong troposphere temperature inversion near the surface. Hence the thermal profile looks like

the stratosphere which we know GHGs like CO2 lead to cooling.  I found PEER reviewed papers on this that there indeed is a negative greenhouse effect on the Antarctic plateau. 

This was in Nature    https://www.nature.com/articles/s41612-018-0031-y   

 

So based on this, what happened during the last glacial maximum?  Much of the land masses in the NH were covered by similar ice sheets and likely had a negative greenhouse effect. Hence the argument that warming from orbital parameters warmed the planet and increased CO2 which then increased temperatures will not work over the ice sheets!   this argument always didn't sit well with me. If CO2 is the control knob for the climate, then why does it not kick off the climate changes?   If it is a feedback, it would cool the ice sheets! This paper also shows that the greenhouse effect is weakest in the polar regions (negative over Antarctic Plateau) and is strongest over the tropics which makes sense since water vapor IS the primary greenhouse gas.  CO2 is a weak GHG that somehow becomes stronger during times when ice sheets melt supposedly.  What changes in the quantam mechanics???  Anyway, I think this study changes how we see CO2 and its role in glacial and interglacial cycles. Water vapor is the primary GHG. That's my scientific opinion. 

 

It looks like your analysis suffers from some unfounded assumptions. I don't see any evidence that "the land masses in the NH ... likely had a negative greenhouse effect" during the LGM. Looks like this phenomenon is quite rare - limited to the Antarctic Plateau - and seasonal (no negative GHE in austral summer). Much of Antarctica does not have a Negative GHE, as per Figure 1 in the paper cited. And that appears to be the case for Greenland as well. They do surmise that perhaps such conditions occurred in past ice ages, but only specifically identify Greenland as a possibility. I think it's unlikely the continental ice sheets (e.g., Laurentide) would have been sufficiently devoid of water vapor and subject to the same intensity of inversion as the Antarctica Plateau.

But even if they did, I don't see how this calls into question the role of CO2? CO2 would only be a negative feedback if a true negative GHE existed; even with a weaker positive GHE, it would still be a positive feedback. Moreover, it would be a positive feedback everywhere not covered by ice even assuming a negative effect over ice. As you, yourself, have previously pointed out, warming in one location does not exist in a vacuum. Ocean and atmospheric currents would eventually move warmer air across the globe. Over time, warming of the unglaciated regions would increase water vapor and erode the surface temperature inversions over the glaciated regions, shifting any negative GHE to a positive one.

The cited paper suggests the same could occur over Antarctica:

[blizzard1024]

Agree.  This to me means water vapor in the main driver of these changes. Not CO2.  And the glacial topography during the last Glacial Maximum was massive and larger than Antarctica so one could easily surmise a similar temperature profile with ice highly reflective and a sharp low level temperature inversion.  The ice sheets were 1-2 miles high similar to Antarctica.  So once water vapor increases from warming oceans it then drove the greenhouse effect to positive which then kicked off a chain of positive feedbacks to wipe the ice out quickly in geologic times. Once a glacier melts, its gets dirty and dusty decreasing albedo, plus it melts to a lower elevation which is warmer. So, its water vapor that responds to the changes from the orbital parameters. CO2 is leading to a negative temperature tendency in a lot of the NH when the ice sheets are large and just begin to melt. So increasing CO2 probably doesn't do much since it is a weak GHG relative to H20.  Here's another point: nobody has studied this.  This NEEDs to be studied.