The basic problem in climate science, and its indeed a very basic problem, is an inability to differentiate between cause and effect. Its the old problem of the chicken and the egg.
Letting the mathematicians into the act is the source of the difficulty. They see their responsibility as bringing their equations to bear. Cause and effect is ignored. Correlation is sufficient. Attribution is someone else’s problem. The guys who were concerned with attribution were pensioned off long ago. Now we have robots looking after the show. Using models. Recipe for disaster.
In determining cause and effect one needs to have a focus on observation first and foremost.
The modes of change are discernable in reanalysis data. It takes effort to examine what has happened at fifteen pressure levels in the atmosphere in all eighteen 10° latitude bands from pole to pole.
We now have 74 years of reliable data. Its necessarily based on interpolation from sparse sampling but simple physical principles that are well understood govern the behaviour of gases. See the data source here.
The answers are in the data. It’s not rocket science.
First, discard the notion that CO2 might be relevant. The Southern Hemisphere has not warmed for three decades in December and January.
Second, discard the notion that weather and climate, the winds and the currents are driven by the energy that is acquired in the tropics.
Throw out fluid dynamics.
The climate system is energized by what is described as ‘extratropical cyclones’. The name in itself is discouragement, because it leads people to believe that the tropical cyclone is the more important phenomenon. Better to call it a ‘polar cyclone’. Wind intensity is the same as for a tropical cyclone but the area affected is 100 times as large. It’s genesis is not at the surface but at jet stream levels. If he were alive today, Bjerknes would improve his analysis of polar front phenomena because he would have access to Reanalysis data. He would also improve his understanding of ENSO. Tragically, we are still stuck with Brjerknes idea of what ENSO is, that is not much of an advance of Walker.
These polar lows tend to aggregate and become more severe at solar minimum. The most severe solar minimum is possibly seen on 200 year time scales.
Observe that the atmosphere moves in the same direction as the Earth, but faster, and fastest at the winter pole. The solar wind is least disturbed and most consistent in its magnetic signature at solar minimum. It’s impact on the atmosphere depends on electromagnetic phenomena. The atmosphere will be more reactive when it is most ionized, more particles orienting themselves according to the magnetic field because and behaving like little magnets zipping along the lines of magnetic force and bumping the neutrals along with them. The atmosphere is most ionized at solar minimum because cosmic rays impacting the atmosphere are most intense when sunspot activity is least. So there are more particles acting as little magnets. Doing the shoving. Add to that the fact that UVB and UVC is least intense at solar minimum, the atmosphere is least inflated, more dense in neutrals where it is most ionized. Ozone is not neutral and it is least affected by short wave radiation at solar minimum. It is a superb absorber of the Earths long wave radiation that is available 24/7/365 and its partial pressure is greatest in the winter hemisphere. The ability of ozone to impart kinetic energy to nitrogen and oxygen is a function of the density of the atmosphere. At least two thirds of the depth of the atmospheric column at 50-70° of latitude, the most elevated two thirds of the column, has sufficient ozone to dramatically affect its temperature and density in winter. So, in these high latitudes a map of total column ozone is also a map of surface pressure.
The polar cyclone originates where the air density gradient is steepest. That’s where subtropical air is confronted by very cold air descending over the Antarctic continent to jet stream altitudes and below, according to the flux in surface pressure over the continent that hits its maximum in winter. The evolution of surface pressure over the Antarctic continent, very important to the temperature of the air that sweeps up in a south westerly flow after the passage of a low pressure system because surface pressure is higher over the Antarctic Continent than anywhere else on the globe, has been a one way affair over the last 74 years, down, down down. Snow in Brazil. A wet Australia in 2021. Very cold winter. Windy all the time. Roofs coming off. Water in the streets. People driven inside and infecting each other with Covid. Get some Ivermectin now. See here. In the absence of the tablets usually prescribed for humans get Cattlemax.
Polar cyclones involve the entirely of the atmospheric column. There is no troposphere in high latitudes in winter. The elevation of ozone in little spirals of disturbed air is observable at 10 hPa over the Arctic even in the height of summer. See nullschool here. What goes up must come down. When it descends into the upper half of the troposphere in the mid latitudes it drives the comings and goings of ice cloud, the stuff that is ‘stratified’, indicating the direction of flow of the upper air.
As polar cyclones intensify in high latitudes atmospheric mass is shifted from their zone of activity to essentially reactive centers of descending air (non initiating) that develop over the oceans where the cold surface favours descent. As surface pressure is driven down in the latitudes where polar cyclones originate they tend to aggregate into bigger systems that necessarily spread into the mid latitudes invading the latitudes normally occupied by high pressure cells of descending air. In these latitudes, in winter, in the southern hemisphere, like right now there is a succession of intense lows and highs and the winter gets very cold, like now, and the higher the latitude, the relatively the colder it gets because the ratio of cold to warm increases. Currently the sea to the south west of W. Australia is up to 2.5° cooler than normal. Observe the air flow from Antarctica here.
The Aleutian Low doesn’t develop particularly low surface pressures but it exhibits the widest fluctuation in surface pressure. It shifts to the stratosphere in summer and there is little to show for its activity in surface pressure data until conditions favour its genesis, like now for instance, August 2021. It fluctuates so much that it impacts the pressure regime in the Antarctic trough and over the Antarctic continent. Its evolution governs the pressure differential across the Pacific Ocean, the trade winds and upwelling phenomena that are the essence of ENSO. It does that by shifting atmospheric mass towards the southern hemisphere in a heroic fashion between September and March directly impacting the difference in surface pressure between the Chilean high in the east and the Maritime continent to the north of Australia in the east…..ie the trade winds and the upwelling phenomenon that brings cold water to the surface not only in the Galapagos islands but globally, wherever there is a difference in the density of water and wind stress.
The upshot is that surface temperature very much depends on surface pressure dynamics that is driven by the polar lows.