Antarctic Circle has been for years the most debatable and unresolved mysteries in science. Scientists over the years have taken great pains to research and prove their theories about it but with very less success. Recently though, a team of scientists may have solved the long-debated riddle of Antarctica and what they have found out may not be very pleasant.
A team of researchers from Ohio State University in 1984 had reported of a surprising fossil find. This fossil was found more than a mile above sea level, in Antarctica’s freezing and far inland Trans-antarctic mountain range. These fossils were deposits of tiny marine organisms called diatoms that were found in layers of rock that dated to the Pliocene era, millions and millions of years ago. Diatoms are ubiquitous marine microorganisms whose tiny shells coat the ocean floor when they die. So the question is how did they reach high up there in the mountains?
A debate rolled on this and it was called ‘Sirius Group’ after Mount Sirius, one of the range’s many peaks. The group divided into two camps- the ‘dynamicists’ and ‘stabilists’. The dynamicists claimed that the enormous ice sheet of East Antarctica had dramatically collapsed in the Pliocene, bringing the ocean far closer in to the Trans-antarctic range, and that successive upthrusts of the Earth and re-advances of glaciers had then delivered the diatoms from the seafloor to great heights. Whereas, the stabilists argued that the ice sheet had stayed intact, but powerful winds had swept the diatoms all the way from the distant sea surface into the mountains. These two camps got very nasty with their arguments and some of the researchers even tried to resolve matters by suggesting that a meteorite, and subsequent cataclysms, could account for the odd fossil locations.
But decades later now, with the development of research tools and methods, Reed Scherer, an Antarctic researcher form North Illinois University, has paired up with two other researchers to analyze further into the Antarctic matter, i.e., on the newest computer simulation of how Antarctica’s ice behaves, by revisiting the tales of those pesky diatoms. They have a found a solution and it suggests that large parts of East Antarctica can indeed collapse in conditions not too dissimilar from those we’re creating today with all of our greenhouse gas emissions. This new study is co-authored by Rob DeConto of the University of Massachusetts, and David Pollard of Penn State University, who recently published a new ice sheet model of Antarctica that predicts the ice continent can raise sea levels by nearly a meter on its own during this century. They reached this result by adding several new dynamic ice collapse processes to glacial models that had been slow to melt East Antarctica even in quite warm conditions also simultaneously lending weight to the views of the stabilists in the debate over the Sirius fossils, while also seeming to suggest that the people needn’t worry about truly radical sea-level rise from Antarctica.
The result is that in the Pliocene,especially the mid-Pliocene warm period, when atmospheric carbon dioxide was at about the level as it is now, 400 parts per million, but global temperatures were 1-2 degrees warmer than at present, shows the oceans eating substantially into key parts of East Antarctica. In particular, the multi-kilometer thick ice that currently fills the extremely deep Aurora and Wilkes basins of the eastern ice sheet retreats inland for hundreds of miles. The West Antarctic collapse alone will drive the global seas to a much higher level than caused by any other collapse.
According to their study, the collapse could set apace the global warming and thrust us forth in a world where the diatoms will be thrown up to the Trans-antarctic mountains. If the ice retreats from the Aurora and Wilkes basin then all that will be left behind in the ocean bays will be a large number of diatoms. The winds cannot simply scoop them out of the water and hurl them on the mountains as they would be too heavy to travel, because of being wet. So further study postulates another development, that after a few thousand years of seas filled with happy diatoms, dying and lining the ocean floor in front of the remnant glaciers of the Wilkes and Aurora basins, the once submerged Earth would slowly rebound in some spots. This would create an archipelago of islands, new landmasses free to rise to the surface now that so much ice has sloughed off their backs. Scherer notes that his new scenario doesn’t really proclaim either of the dynamicists or the stabilists as the victors. His view is clearly reliant on a substantial amount of dynamics, but it also doesn’t show the East Antarctica ice retreated nearly as far back as earlier proposals. Nor does it use glacial processes to move the deposited diatoms. Rather, it borrows the stabilist idea of wind-blown transport, albeit only after ice has retreated and land has risen in its wake.
The Scherer led research earned much praise from David Harwood, one of the original ‘dynamicists’ currently a professor at the University of Nebraska-Lincoln. Harwood stated that this paper’s integration of climate, ice sheet, and atmospheric models provided interesting new perspective on potential source regions for the Antarctic, marine Pliocene diatoms present in glacial sediments of the Transantarctic Mountains, from interior basins of East Antarctica.
But beyond solving the riddle of the Sirius deposits in the Trans-antarctic Mountains, the new study speaks to the present moment. After all, the warm Pliocene, with its much higher seas, is one of the key past eras that scientists regularly look to for an analogue for where we are currently driving the planet with our greenhouse gases. Therefore, the new work suggests that if we keep pushing the system, we’ll not only have to worry about the loss of Greenland’s and West Antarctica’s ice, but also major losses from the biggest ice sheet of them all, East Antarctica.
Solving this key scientific problem from Antarctica’s past turns out to immediately raise major concerns about its future. Granted, on a scientific and individual level, there’s also the satisfaction of finally being able to unify quite a lot of information into an explanation that fits the data and also matches our growing present day understanding of Antarctic vulnerability.
This is another piece of a jigsaw puzzle that the community is rapidly putting together, and which appears to show that the ice sheets are more sensitive to warming than we had hoped. If humans continue to warm the climate, we are likely to commit to large and perhaps rapid sea-level rise that could be very costly. No one piece of the puzzle shows this, but as they fit together, the picture is becoming clearer.
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