A melting that could dramatically accelerate the climate catastrophe – The Thwaites Glacier is dissolving in Antarctica
Again and again there are climate effect surprises that shock even experienced climate researchers. These are often new findings that heighten the drama of climate developments even further. Recently (researched since 2014; first published in 2019, and now as a larger publication in September 2022), for example, a completely new risk was concretely recorded in research on Antarctica: The so-called Thwaites Glacier, an ice sheet, i.e. lying on the mainland of Antarctica, could retreat rapidly in the near future, with its ice flowing into the sea. The reason that this glacier is also called the „doomsday glacier“ or the „weak underbelly of Antarctica“ is that it is extremely susceptible to such a significant retreat, which, due to its incredible ice masses, could in turn cause a striking rise in global sea levels worldwide, more than half a meter. This, in turn, would mean that numerous sea cities such as Los Angeles, New York, London, Venice, Lisbon or Tokyo, as well as entire countries such as Bangladesh, would find themselves below the sea surface.
The Thwaites Glacier is not yet a part of the climate models, which are being discussed once again at the COP27 conference (from 6-18 November 2022), where the international political community meets to discuss the climate crisis for the 27th time; this time in Cairo. And again the same statements are made: „Damage from higher temperatures, droughts, floods, landslides and much more are growing rapidly“, „We must do something“, „Affected developing countries must be helped“, etc., only to be forgotten again after the end of the conference until the next one, the COP28 conference in 2023 in Dubai. Will we hear in Cairo about such dramatic climate consequences as the fall of Thwaite’s ice mass at the South Pole? Probably not (no contribution from the COP27 conference on the Thwaites glacier can be found).
As early as the late 1960s, John Mercer, a geographer from England, warned that large parts of the ice in the west of the South Pole could melt very soon, causing a rise in global sea levels of up to six meters. Ten years later, in 1978, Mercer pointed out in the scientific journal Nature that such a massive effect is caused by the burning of fossil fuels and the warming it causes. Again, he faced strong opposition with his statement. Today we know that he was right. It could even be that this single (very large) glacier in Antarctica will determine – and dramatize – sea level rise in the coming decades.
Let us take a closer look at West Antarctica (the details were not published in detail until 2022). Alpine glaciers, as we can directly observe, are melting from the surface. The glaciers in West Antarctica, on the other hand, are not melting from above, because icy minus temperatures prevail there, but from below. They are undercut by „warm“ water (just above freezing). Thus the ice melts from below and then slides into the sea. For thousands of years, the amount of ice lost in Antarctica in this way corresponded to the amount of ice gained through snowfall, so that the size of the ice sheet has hardly changed since the last ice age. This is no longer the case today due to climate change. Now there are some special structures in West Antarctica that exacerbate this: The most important is that the mainland is „retrogradely“ inclined, meaning that the bedrock on which the glacier lies slopes inland, with about 1500 meters below sea level at its lowest point. Thus, the ice layer inland becomes thicker and thicker. The ice above the sinking mainland is now more and more easily undermined by warmer water (caused by climate change) – it simply seeps into the lower-lying mainland structures, causing the ice to lose its grip on the ground, become unstable and finally break into the sea.
This makes the ice sheet that shapes West Antarctica, the Thwaites Glacier, a prominent weak spot in Antarctica that soon threatens to flow into the sea. And it is huge, almost as big as Great Britain, and several kilometers thick. It is only held in place by an ice cork in the form of a single (very large) glacier, the Thwaites Ice Shelf, which prevents it from flowing into the sea. In other words, the ice shelf floating off the mainland coast of Antarctica acts like a brake block, preventing the mainland ice from flowing into the sea in its enormous volume. Recent studies show that firstly, the ice shelf is losing its hold on a submarine shoal that acts as a singular pinning point, and secondly, that the shear margin separating the eastern Thwaites Ice Shelf from the tongue of the Thwaites Glacier has expanded, further weakening the ice shelf’s connection to the pinning point. Satellite data, ground penetrating radar and not least GPS measurements of the intersection of the cracks with hidden basal crevasse zones indicate that the collapse of the ice shelf could be initiated within as little as 5-10 years(!). While the giant glacier could still take several centuries to completely collapse even after the loss of the ice shelf, its steady flow and thus its contribution to sea level rise would nevertheless accelerate considerably.
Once again, what is happening in concrete terms: „Warmer“ water generated by climate effects penetrates to the West Antarctic mainland and undermines the ice sheet. The ice melting from below loses its grip on the ground and slides into the sea. The warmer water can eat its way deeper and deeper under the glacier due to the retrograde tilt, causing the ice to become liquefied from the interior, so that the glacier becomes increasingly unstable on the ice and continues to slide. The front wall of the glacier eventually collapses and more and more ice falls into the sea. The looming collapse of the glacier over the mainland can already be seen in a sequence of radar images, which reveal that massive cracks have recently formed in the central part of the ice shelf, spreading at rates of up to 2 km per year.
So far, sea levels have been rising because of the melting of Greenland ice and mountain glaciers, as well as because the water in the sea expands when it warms. In the future, Antarctica will be the biggest driver of this. Ninety per cent of the world’s ice volume is located here. If the Antarctic ice completely dissolves, the sea will rise 300 times more than by the 19cm in the 20th century. The sea will thus rise by an unimaginable 60 meters! It will probably start with the melting of the Thwaites Glacier. This alone will cause the sea to rise by 0.6 meters and will already have a massive impact on our life on this planet.