images courtesy of robertscribbler.com and johnenglander.net
If we look at the Earth geologic record, one thing is extremely obvious. There have been numerous Extinction Level Events and they have occurred with frightening regularity. The top graph is a plot of time versus % of known species extinctions. What is shockingly evident, is the regularity at which extinctions have occurred.
The large extinctions are most evident, but if you look a little closer you will note there has been an extinction level event approximately every 25-30 million years. This frightening regularity for extinction level events suggests there is a single cause for this 25-30 million year cycle.
While some extinctions have been explained, the cause for most of them is still unknown. For example, the extinction of the dinosaurs 65 million years ago (End of the Cretaceous) has been shown to be the result of an asteroid impact in the Yucatan Peninsula. The extinction at the End of the Permian (largest extinction level event) was known to be numerous volcanic eruptions followed by runaway greenhouse effect and sulphur dioxide levels in the oceans to build to toxic levels. These are only 2 events out of the numerous events shown in the graph.
Some scientists now suggest that the 25-30 million year extinction cycle is caused by a rogue gas giant planet that follows an enormous elliptical orbit around our Sun whose orbit is approximately 25-30 million years to complete. Whenever it comes close to the Sun, its gravity can disrupt neighbouring asteroids and draw them towards our Solar System. However, this rogue Planet X has yet to be discovered.
Some scientists argue that it is the path of the our solar system through the Milky Way Galaxy that causes these 25-30 million year extinctions cycles because each time it passes through the north end of the galaxy our Solar System gets hit with a significant increase in cosmic rays that can cause massive weather changes on Earth.
Still some other scientists argue that Dark Matter is the culprit, because our Solar System’s path goes through areas of space containing large amounts of Dark Matter that can change the paths of asteroids and comets hurling them at Earth.
However, we only know of 1 asteroid impact proven to cause an extinction and the most massive extinction was likely caused by massive volcanic eruptions. There is no evidence that all the other smaller extinctions were caused by asteroid impacts. For example, the second graph shows huge amounts of CO2 were present during many of the extinction level events. Asteroids would not normally be the cause of the release of massive amounts of CO2 in the atmosphere.
While the debate of the regular 25-30 million year extinction cycle will continue for many years, further space telescope data (from GAIA-European Space Agency) combined with continued geological work should prove very interesting in the coming years.
Maddalena Environmental Inc.