co2 and Plate Tectonics

2 Jan 2018

At ... Cosmos is an Australian mainstream science magazine which often has interesting articles on a variety of subjects. In this one it provides an overview of the Plate Tectonics theory - which is worth digesting. It begins with a quote from Carl Sagan, well known to people of a certain generation (the 1960s). Earth lies in the Goldilocks zone - that allows water to exist in a liquid form and the supposition form this is that water allows life to thrive. We are then told the Earth is the only rocky planet that we know of that constantly renovates its surface as a result of tectonic plates driving into the Mantle in some places and re-emerging as molten lava via volcanoes. One might allow oneself to ponder at this moment and reflect. They are saying the Earth is the only planet yet discovered so far that has evidence of Plate Tectonics - and therefore life. This statement shows how deeply ingrained the hypothesis of Plate Tectonics is embedded in mainstream science - a largely theoretical rather than an observable process (although no doubt some geologists would disagree).

Plate Tectonics is a geological phenomenon that came into form in the 1950s and 1960s as it could be combined with Milankovitch orbital dynamics and the Ice Ages as perceived by uniformitarians. It is used to explain the movement of the continents around the globe and its acceptance came about after the discovery of magnetic stripes on the Atlantic sea floor. However, Plate Tectonics is also popular with astro-biologists it would seem as we learn it has developed into an explanation for the carbon cycle. This theory visualises a recycling of co2 from the atmosphere into the planet's interior via mineral sequestration - and then out again via volcanoes. This, they say, has kept the climate of the earth temperate. It is assumed the Sun's heat has increased in intensity since the birth of the Earth and the thinking is that Earth would have succumbed to overheating as the oceans hold on, or sequester vast quantities of co2. This is of course the missing heat conumdrum. Where does all the heat go that co2 is assumed to produce - and the finger was pointed at the oceans. They tell us water has saved us from a fate like Venus - another reference to Carl Sagan and his idea of a runaway greenhouse effect on Venus.

There follo9ws a history of Plate Tectonics theory - going back to a Flemish map maker who noticed the coast of S America could fit snugly into that of Africa. Alfred Wegener is then mentioned, and the discovery of magnetic stripes etc. It seems some geologists have moved on - and embraced climate science. It is said that co2 washed out of the atmosphere is distributed in rainwater to form carbonic acid and this breaks down minerals in rocks and these leach into the oceans etc. Marine organisms take up the carbon to build their shells and skeletons which ultimately settle on the sea floor and become limestone (including chalk). It sounds so trite - and such a simple explanation. Why is it made? Have some geologists, and in this case an astrobiologist, discovered the rich seam of research grants whenever co2 is mentioned (funded by you know who)? co2 is the very stuff of life - and yes, this is what they are saying - quite unlike the Amrican EPA ruling that sought to reclassify co2 as a pollutant. 

However, when we get to the nitty gritty of the article we discover scientists do not know what caused Plate Tectonics to occur in the first place and admit it can hardly be as old as the planet. We are then transported to the Jack Hills in western Australia, some of the worlds oldest rocks (which include crystals known as zircons). These hills were once molten magma that upwelled on to the surface - crystalising as they hit fresh air. However, they did not at the time cause Plate Tectonics as they appear to be a localised phenomenon. There is no evidence of the globe reforming at this time - although other localised upwellings of a similar age are known. Geologists, we are informed, think Plate Tectonics began around 2.7 billion years ago - and there have been four supercontinents, the last of which was known as Pangea (335 million years ago). Relics of the first supercontinent are said to be scattered across western Australia, Greenland, N America, and Scandinavia. What kick started the process of Plate Tectonics? An asteroid strike has been suggested, whilst others have theorise a dramatic event below affected the crust above. Magma welled up beneath the supercontinent and split it asunder.  What comes across is that Plate Tectonics is not as robust as popular science allows - but in spite of that this article is useful as it allows us to peer inside the heads of the scientists who drive the consensus view.