This was my comment:

    Mike Maguire

        November 30, 2021 8:02 am

What’s most interesting is that the effect they describe from global warming is the 100% “polar” opposite of the effect taking place on the other side of the planet…….the Arctic.

In the Northern Hemisphere, we know with certainty that the warming has been magnified as you go poleward. The Arctic has warmed the most. This has been accurately measured.

This has DECREASED the meridional temperature gradient and weakened jet streams in the Northern Hemisphere. This, the result of an assumption that the heat from global warming is collecting faster at the higher latitudes……which actually is verified with observations. 

This current study, assumes something different. The heat from global warming is collecting at  LOWER latitudes in the oceans and causing an INCREASE in the meridional temperature gradient because the higher latitudes are not cooling as much in the Southern Hemisphere, like they are in the Northern Hemisphere.
This leads to the complete opposite effect in the Southern Hemisphere by tightening the temperature gradient there which increases wind. 

So the question really is: Why does each end of the planet have completely different temperature gradient dynamics with changing latitude?
Maybe they address that somewhere in the paper that I can’t read?
Could be related to the differences in ocean/land, with the Antarctic being a massive land mass, surrounded by much more ocean compared to the Arctic. 

If they don’t address and explain that, then their assumptions and reasoning here are very speculative and overlooking something(s), possibly more powerful than the causes they assign to the effect.