I write these things 'live', with only a general thought as where I am going. But it's time to sum up. We are back to my original graphic.
This is Dr. Roy Spencer's graph of background microwave measured by satellites. It's really the old space man's attempt at warming his hands, or a measure of how much heat the Earth is putting out. Dr. Spencer thinks it is a direct measure of the Earth's temperature, but it isn't really, because of the extreme insulation of those wet clouds.
The neat thing about clouds are that they are a 'one-way' insulator, like a heat pump. The sun warms the top of the clouds, and that heat is carried by the rain drops down to the earth. But the big volcanoes put out ash which has a two-way effect. It stops heat from coming and going out by killing clear air convection. CO2 does neither, and clear air convection kills any effect it might theoretically have.
El Nino disrupts the fairly static cloud distribution over the equator. It warms the poles and causes a huge amount of heat to be radiated out to space. We pay for it with a cold 'hangover'.
Now for the reason of 'hot and cold Earth' over millions of years. It's ocean currents which we know, from our water-cooler cpu coolers are a most efficient heat pump. With large expanses of ocean during the 'crunch' phase, we just get equatorial currents, with very little North-South. Of course, there is the matter that the grouped continents are a giant insulator, and they start to bake the deep subducted oceanic slabs. This produces a huge amount of water vapour, and, yes, CO2. No ocean currents, and tons of water vapour make for a hot time.
During 'Snowball Earth', of which we are now entering, we get efficient heat pumping from ocean currents going to the poles. These currents are directed by the continents themselves, since ocean currents would be happy just staying at the equator.
The above graph shows a general decrease in Earth radiator efficiency in the early 2000's. That's what started the whole 'hockey stick, we're going to die' thing. Recently, the earth is picking up radiating, which explains our level temperatures. After El Nino, I'm sure we're going back to the 70's freeze. The warmists can retire with all their money. :)