A. Jacksonian left an interesting comment on my piece "Clouds" posted at Classical Values. It is a fascinating look at magnetism, war, global climate, and impending doom from natural causes. I'm posting it here in full. And, thanks A.J. for your always interesting posts and comments.

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Actually, there have been numerous magnetic field reversals in Earth's history. The fact that this was so was discovered due to WWII subsurface magnetic readings taken to try and find U-Boats. Once all the data got put together, identical stripes of different magnetic polarity could be seen on either side of the mid-Atlantic. This was one of the great insights that led to the first International Geophysical Year and the culmination of data from core samples on magnetism and radioactivity that led to the discovery that these stripes were coincident at the same time in history indicating they were placed at the same time. The mid-Atlantic ridge was analyzed and folks realized that new material was being forced out there and it contained the same magnetic orientation and strength as the surroundings as the rock cooled. The very first tape recorder had been discovered, save the 'tape' was oceanic basalt. Global studies of similar rocks pointed to the exact same magnetic orientation at the same time and the same changes over time. This has proven to be a long term key for analyzing rock strata, and measuring the orientation and radioactivity not only places it in time but in position.

From all of that continents now were seen as in motion... well, all geological plates were seen as in relative motion to each other based on sub-plate movement. All from trying to find U-Boats in WWII. That information required that we change how we look at the planet and ask it different questions and we found different answers, and so our view of the planet changed and changed again so we could understand what the rock
was telling us.

Some magnetic flip-flops have been coincident with extinctions (large and small) but not all of them. Changes in background cosmic ray incidents is an indicator from the solar system's relative position within the galaxy and who its neighbors have been. That has also varied over time some changes, up and down, coincident with extinctions, some not. Continents coming together to form supercontinents and their break-ups have been a high, nearly 1:1 indicator of extinction events as habitats suddenly disappear or appear both having long-term impacts on life in those ecozones.

Volcanic activity can play a part, especially those large caldera events at Yellowstone, Toba and elsewhere, as they release large amounts of particulates into the upper atmosphere. The idea for for the amounts was put forward in a good way by a movie on the History Channel. Consider the ejecta to Mt. St. Helens to be a sugar cube. Tambora was a box of sugar cubes (the volcano responsible for the 'year without a summer'). Yellowstone is a 1m x 1m x 1m packing crate of sugar cubes. That gets pretty close to the scale differences involved for relative particulate output, save the actual crate is a bit bigger than the 1 meter cube. Yellowstone, itself, goes through different cyclic events, where it will rest for hundreds of thousands of years and then erupt and continue with smaller-scale, continuous eruptions for a long period and then go quiet. Considering that this same hotspot laid down the meters thick basaltic rock seen in Oregon and Washington States, that is nothing to be sneezed at.

We haven't even started in on the real disasters that can hit North America and will, sooner or later. Cyclicity and periodicity tell us that these things will return, sooner or later, as the geophysics behind them has not changed for them. Global Warming? Heh. Yellowstone! Because once it hits, it continues on for thousands if not tens of thousands of years... did it before and will do it again. And that will assuredly change climates on the planet... I wouldn't suggest trying to 'laser lance' it either. That would be like taking a can of soda, putting it in a paint shaking machine for half an hour, heating it up to couple of hundred degrees and *then* trying to put a small hole in the container. Not a good idea, at all, really. Just like trying to build flood protection on land that is sinking...

Cross Posted at Power and Control