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We know the Global Mean Temperature is increasing due to climate change. But for the Global Mean Atmosphere Pressure, can we see an obvious trend?

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  • $\begingroup$ A very interesting question, would think by Ideal Gas Law it should be, going up by about 3 or 4 mb (for a degree Celsius warming), or in some combination with a similar scale density decrease (unless extra mass is lost to space). I expect the discrepancy in such may lie with the connected cooling of the stratosphere too? But I'm no expect on the topic, so hopefully others have more thorough answers they know rather than guesses. $\endgroup$ Dec 14, 2021 at 13:39
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    $\begingroup$ As there is increasing the global total water vapour content....... $\endgroup$
    – Poutnik
    Dec 15, 2021 at 10:49
  • $\begingroup$ @Poutnik was going to say that vapor pressure is relatively quite small... but it actually goes up about a mb (= 0.1 kPa) per °C increase in dew point in the region of average temperatures... so that'd be a decent contribution. Some may say "it's lighter than air"... but unless it's removing air somehow from the atmosphere, it's still increasing pressure overall? $\endgroup$ Dec 16, 2021 at 7:47
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    $\begingroup$ @JeopardyTempest If we neglect light decreasing of gravity with altitude, the pressure would be numerically equal the weight of the thought air column ( well, conus ) mass above the unit surface area. And if we increase the mean mass...... $\endgroup$
    – Poutnik
    Dec 16, 2021 at 7:56

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Climate change will increase the size of stalled high-pressure weather systems called "blocking events" that have already produced some of the 21st century's deadliest heat waves, according to a Rice University study.

https://www.sciencedaily.com/releases/2019/11/191113075107.htm

Atmospheric blocking events are middle-latitude, high-pressure systems that stay in place for days or even weeks. Depending upon when and where they develop, blocking events can cause droughts or downpours and heat waves or cold spells.

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  • $\begingroup$ But the global mean pressure depends on the atmosphere mass, different synoptic pressure distribution alone has negligible effect, connected to slight change of gravity with altitude. $\endgroup$
    – Poutnik
    Jan 29, 2022 at 16:46
  • $\begingroup$ this does not realy answer the question will the air pressure change as a result of the expanding warmer air,i think the pressure will stay the same as warmer air is lighter and there is(no phun intended)a lot of space for expansion. $\endgroup$ Jan 30, 2022 at 6:04
  • $\begingroup$ The question was: can we see an obvious trend? --- We observe the trend of increased size of stalled high-pressure systems. We can also observe increased cloud hight and lapse rate. We know that the top of the troposphere(-60°C) is ~16km at the equator and only ~ 7km at the poles and tends to be higher in summer. The expansion is thus confined to the troposphere and the volume of the atmosphere as a whole remains the same. The earth gets rid of the increased temperatures and energy solely through long-wave radiation and not through expansion into space or constantly increasing air pressure. $\endgroup$
    – Rammstein
    Jan 31, 2022 at 2:21

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