CLIMATE CHANGE PART III
The current ice age, the Pliocene-Quaternary glaciation, started about 2.58 million years ago during the late Pliocene, when the spread of ice sheets in the Northern Hemisphere began. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000- and 100,000-year time scales called glacial periods, glacials or glacial advances, and inter-glacial periods, inter-glacials or glacial retreats. The earth is currently in an inter-glacial, and the last glacial period ended about 10,000 years ago, although technically we are still in the ice age because there are still ice packs or sheets in some parts of the world. All that remains of the continental ice sheets are the Greenland and Antarctic ice sheets and smaller glaciers such as on Baffin Island.
Another meteor impact that was unnoticed and given little notice for a long time was the Eltanin meteor that slammed-dunked into deep ocean water in the south Pacific.
A team of Australian researchers says that because the Eltanin meteor—which was up to two kilometers across—crashed into deep water, most scientists have not adequately considered either its potential for immediate catastrophic impacts on coastlines around the Pacific rim or its capacity to destabilize the entire planet’s climate system.
“This is the only known deep-ocean impact event on the planet and it’s largely been forgotten because there’s no obvious giant crater to investigate, as there would have been if it had hit a landmass,” says Professor James Goff, lead author of a forthcoming paper in the Journal of Quaternary Science. Goff is co-director of UNSW’s Australia-Pacific Tsunami Research Centre and Natural Hazards Research Laboratory.
“But consider that we’re talking about something the size of a small mountain crashing at very high speed into very deep ocean, between Chile and Antarctica. Unlike a land impact, where the energy of the collision is largely absorbed locally, this would have generated an incredible splash with waves literally hundreds of meters high near the impact site.
“Some modeling suggests that the ensuing mega-tsunami could have been unimaginably large—sweeping across vast areas of the Pacific and engulfing coastlines far inland. But it also would have ejected massive amounts of water vapor, sulphur and dust up into the stratosphere. “The tsunami alone would have been devastating enough in the short term, but all that material shot so high into the atmosphere could have been enough to dim the sun and dramatically reduce surface temperatures. Earth was already in a gradual cooling phase, so this might have been enough to rapidly accelerate and accentuate the process and kick start the Ice Ages.”
In the paper, Goff and colleagues from UNSW and the Australian Nuclear Science and Technology Organisation, note that geologists and climatologists have interpreted geological deposits in Chile, Antarctica, Australia, and elsewhere as evidence of climatic change, marking the start of the Quaternary period. An alternative interpretation is that some or all of these deposits may be the result of mega-tsunami inundation, the study suggests.
“There’s no doubt the world was already cooling through the mid and late Pliocene,” says co-author Professor Mike Archer. “What we’re suggesting is that the Eltanin impact may have rammed this slow-moving change forward in an instant—hurtling the world into the cycle of glaciations that characterized the next 2.5 million years and triggered our own evolution as a species.
The effects of these meteor impacts are real and devastating beyond imagination with their effects lasting for thousands of years. It is quite natural for us to think that it will not happen to us but miniature collisions are happening so an earth-shattering collision could be on the way at any time.
Part four of this series will look at an element of our climate that doesn’t seem to rate any mention even though it has effects that we witness every day.