It has been clear to me for ten years now that the jetstreams had begun reversing the poleward drift that went on during the late 20th century warming spell.
AGW (Anthropogenic Global Warming) theory having invested so much in the assertion that a warming world produced more zonal/poleward jets the reversal of trend has led to increasing panic and thrashing about in confusion as the reversal became more pronounced over the past ten years and especially since 2005.
Then the extended very low solar minimum has ‘coincided’ with a very negative AO (Arctic Oscillation) with much more equatorward jets.
We can also see from the records that the more positive (poleward jets) era of AO was roughly in tune with the high solar cycles 21, 22 and 23 and that AO was generally more negative (equatorward jets) during slightly weaker cycle 20.
The exceptions to the solar fit would be occasions when opposing oceanic cycles such as ENSO (El Nino/La Nina)affected the width of the tropical air masses from below sometimes opposing and sometimes supplementing the top down solar influence.
The jets just get bounced around between the polar and tropical air masses as the polar(solar) and oceanic influences interact.
The trend in ocean heat content will be found to be closely linked to the degree of cloudiness and global albedo and they will be found to be dictated by the behaviour of the jets at any given time.
Thus around 2003 the jets became sufficiently meridional (equatorward) for ocean heat content to begin to fall.
Needless to say AGW had nothing to do with those poleward shifts and had nothing significant to contribute to the present situation either.
Similarly the evidence is becoming overwhelming that there is some sort of top down effect on the vertical temperature profile of the atmosphere which appears to correspond to changes in the mix of wavelengths and particles as the level of solar activity varies.
In a sense it is primarily a matter of internal system variability BUT such internal variability is provoked by small external changes. An internal amplifier no less.
The amplification arises from albedo changes as the jets switch between poleward/zonal and equatorward/meridional behaviour. The former produces significantly less global cloud cover than the latter as evidenced by the Earthshine project which reveals a change in trend for both albedo and cloudiness in the late 90s which is around the same time that the poleward shift of the jets went into reverse.
I don’t think that this is good news for Svensmark either. On that basis the cosmic ray variations would just be a proxy for solar variability with no necessary climate effect although there may be some.
Me. A change of 1.8 ± 1.0% in the UV-A (320–400 nm) spectrum and 2.4 ± 1.9% in the visible (400–600 nm) spectrum over the course of a solar cycle was observed at the South Pole Amundsen-Scott Station (See this paper - Solar irradiance at Earth surface varies up to 24 times more than expected). If the same is true for the Arctic then this is a major top down influence. Throw in the variability due to UV B and C that regulates and is regulated by ozone and oxygen reinforcing and moderating the influence of the other wavelength variations and the funeral for the AGW by CO2 hypothesis can be carried out without further procrastination.
Further amplifiers cascade. The influence of lower stratospheric air currents (dictated by the temperature difference between the equatorial and polar temperatures) on the trade winds that strongly influence the ENSO oscillation mood and strength is enhanced and moderated by the jet stream strength and position.
I've looked hard for the main cause of the slow recovery of lower stratospheric temperatures following major eruptions. My tentative suggestion for this lies in the concentration of water vapour and its phase change to ice crystals. As vapor H2O is a strong absorber of IR both from the atmosphere below and incoming from the Sun, hence a warming influence that I suggest is amplified temporarily by the injection of significant volumes of WV and dark aerosols due to penetrating eruptions. Dispersal by air currents and rapid formation of ice crystals due to the volume of aerosols on which the WV can condense and accumulate not only removes dark particles from the action but also reverses the warming influence of the WV phase to cooling due to high albedo. Due to their mass ice crystals precipitate out of the stratosphere, removing a cooling influence and allowing temperatures to slowly rise to the level dictated by ozone volume and UV emissions as well as NOx influence.
Erl Happ has written extensively about the stratosphere - troposphere relationship, his blog writings are here and guest posts at WUWT:
Earth’s changing atmosphere