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The Doomsday Glacier (aka. Thwaites Glacier) has garnered a lot of media attention in recent years due to the threat it poses to rising global sea levels. Scientific research has revealed that the glacier is one of the fastest receding glaciers and also has one of the least stable ice shelves in all of West Antarctica. Not only this, but the collapse of the Doomsday Glacier risks creating a knock-on effect and brings into question the stability of surrounding glaciers too.
👉 In this article we'll explore what the Doomsday Glacier actually is, why it's got scientists so worried, and what we can do to prevent its collapse.
Thwaites Glacier is huge, measuring in at around 120 km wide and covering an area of 192,000 square kilometres. To put its size into perspective, the glacier is larger than England, Wales, and Northern Ireland put together - or larger than the state of Florida for our American readers! And like many glaciers across the world, the Doomsday Glacier is on the retreat, losing around 50 billion tons more ice than is replaced by fresh snowfall every year.
Even more worrying is the fact that the amount of ice loss suffered by the glacier has doubled over the last thirty years alone which means that the rate of ice loss is increasing.
As with many glaciers, melted water from Thwaites Glacier runs off directly from the glacier, into the ocean. This means that the more the glacier melts, the bigger the threat to rising sea levels it represents.
As it currently stands, the global sea level rises by about 3.4 millimetres every year, and experts believe that Thwaites Glacier supplies as much as 4% of this annual sea level rise. If the Doomsday Glacier were to suddenly collapse, global sea levels would rise by as much as 65cm - which would result in disastrous consequences.
Not only would the melting ice result in a significant sea level rise across the globe, but the collapse of the glacier also has the potential to set off a chain reaction, resulting in the breakdown of surrounding glaciers too. If the Thwaites Glacier's neighbours - such as Pine Island Glacier - were to also collapse, sea levels could rise by as much as an additional 1.5 metres.
Worryingly, Thwaites Glacier is undergoing the largest changes of any ice-ocean system in Antarctica: it's one of the fastest receding glaciers and also has one of the least stable ice shelves. This is why the glacier has attracted so much media attention in recent years.
Thwaites Glacier is partly supported by an ice shelf (ie. the Thwaites ice Shelf) that extends out into the Amundsen Sea. This ice shelf acts as a sort of plug, supporting the land-bound glacier and protecting it from the warmer ocean waters. However, this important ice shelf is under threat from rising temperatures and scientists are concerned that the ice shelf could collapse within the next decade, causing the glaciers' contribution to global sea level rises to increase from 4% to 5% in the short term, and accelerating even further over the next few centuries.
Scientists have been studying Thwaites Glacier for several decades and have measured an increase in both the glacier's flow and a retreat of its grounding line. So what exactly does this mean?
Glacial flow refers to the movement of the glacier. This movement is caused by gravity and means that glaciers will always flow downstream. Thwaites Glacier is what’s referred to as an outlet glacier, which is to say that it flows towards the ocean.
This movement of ice flow is what causes floating ice shelves to form - in the case of the Thwaites Glacier these dazzling-white ice, cliffs are vast, stretching out for 120km, standing 40 metres above sea level, and reaching a depth of 200 metres below the ocean's surface.
The problem with an increasing glacial flow is that it causes the ice shelf to break up more quickly than new ice can be created, thereby destabilising the ice shelf. This is highly problematic since the ice shelf provides stability to the glacier and prevents the rapid acceleration in its collapse.
The retreat of Thwaites Glacier's grounding line is another observation of the glacier's increasing instability. The grounding line is a term that describes the boundary between the floating ice and the ice that sits on top of actual land. A retreating grounding line isn't good news. As the grounding line retreats back inland, a cavity is created underneath the now floating ice shelf; the larger this is the more unstable the ice sheet becomes and the more prone to collapse and breaking off it is.
Thwaites Glacier's receding grounding line has led to the creation of a gigantic cavern at the bottom of the glacier. The retreat of this line allows for relatively warm ocean water to find new gaps between the bedrock and the ice above it, which means that the water is able to flow in, melting the glacier from below.
❗️ In 2021, a NASA-led study discovered the scale of the Thwaites Glacier’s cavity. Standing at nearly 300 metres in height and two-thirds the size of the area of Manhattan, the cavity is thought to have once contained around 14 billion tons of ice.
What was most shocking about the discovery, however, was the speed at which the cavity was formed. It only took 3 years for the ice to melt and for the cavernous space to take its place. This heightens the risk of Thwaites Glacier becoming dislodged from the rock bed below, and since the bedrock helps to keep the glacier in place and to maintain its stability, this is very concerning.
Recent research has shed new light on the dynamics at play within Thwaites Glacier, revealing a more complex picture than previously understood. While the glacier is indeed receding, studies have shown that the rate of ice melt at its base is not as rapid as expected - a piece of relatively good news that suggests some resilience in the glacier's response to warming.
However, this optimistic view is tempered by other findings that raise significant concerns. The underwater topography near Thwaites Glacier features a series of staircase-like structures known as terraces, as well as numerous cracks and crevasses. These formations are particularly susceptible to melting. The high rate of melt observed in these areas is alarming because it facilitates the intrusion of warm ocean waters into the glacier. This not only accelerates the melting process but also contributes to structural instability throughout the glacier system.
This complex interaction between the glacier's slower base melting rate and the accelerated melting in structurally vulnerable areas underscores the nuanced nature of the threat. Scientists have expressed concerns that these conditions, especially the extensive crevassing and the warm water infiltration enabled by the terraces, could potentially lead to the collapse of the ice shelf within the next decade. This scenario would have dramatic consequences for the glacier's overall stability and global sea levels. Therefore, while there are elements of good news in the recent findings, the overarching implications remain worrisome.
Thwaites Glacier is undergoing rapid deterioration primarily due to human-induced climate changes.
The Industrial Revolution initiated an era of heavy reliance on fossil fuels, such as coal, petroleum, and natural gas. This shift led to a significant increase in the levels of carbon dioxide and other greenhouse gas emissions. These gases trap heat, leading to an overall warming of the planet. A key outcome of this warming is the increase in both air and water temperatures worldwide, with the ocean absorbing about 90% of this excess heat.
The impact of global warming is particularly acute in the polar regions. The poles are experiencing warming at a rate more than twice the global average due to phenomena like polar amplification. This process occurs because melting ice reduces the Earth's albedo (reflectivity), leading to more absorption of solar radiation and further warming. Additionally, warmer air temperatures and ocean waters exacerbate the melting of glaciers. Warm water, especially, undermines glaciers by eroding the ice shelves that buttress them from below. This is particularly relevant for Thwaites Glacier, where the warming Southern Ocean is accelerating its melting and contributing to its instability.
Moreover, changes in wind patterns associated with global warming are driving warmer waters towards the West Antarctic Ice Sheet, further increasing the heat flux at the glacier base. This not only hastens the glacier's retreat but also weakens surrounding ice structures, increasing the risk of a larger collapse.
👉 The melting and retreat of Thwaites Glacier are reflective of broader climatic changes affecting the Earth's atmosphere, driven by sustained global warming and amplified by feedback loops in polar regions. This situation underscores the urgency of addressing global climate change to mitigate further destabilisation of critical ice masses like Thwaites Glacier.
Accelerated global sea level rise
Thwaites Glacier is one of the largest and most rapidly changing glaciers in Antarctica. Its sheer size and the rate at which it is melting mean it has a significant impact on global sea levels. The projected 65-centimetre sea level rise would be catastrophic for coastal communities worldwide. This drastic rise would exacerbate flooding, lead to the loss of habitat, and increase the frequency and severity of storm surges.
The melting of Thwaites Glacier not only has direct consequences for global sea levels and ecosystems but also poses a significant threat to the stability of nearby glaciers in the West Antarctic Ice Sheet. Thwaites acts as a keystone, holding back other glaciers and ice masses; its rapid disintegration could trigger a cascading effect, leading to accelerated mass loss in glaciers such as the neighbouring Pine Island Glacier. This phenomenon is often referred to as marine ice sheet instability.
Essentially, as Thwaites retreats, it reduces the buttressing effect on these adjacent glaciers, leading to their faster flow into the ocean. The loss of such large volumes of ice further exacerbates global sea level rise and increases the potential for significant reshaping of Antarctica's ice landscape. This destabilisation could follow a feedback loop, where the more glaciers melt, the more susceptible the region becomes to further ice loss, amplifying the impacts on global sea levels and climate systems.
The Antarctic glaciers, including the West Antarctic Ice Sheet, play a crucial role in the circulation of the Southern Ocean. As sea ice melts and fresh meltwater flows into the sea, it can disrupt the density-driven layering of the ocean waters. Normally, colder, saltier water sinks below the warmer, fresher water, a process essential for the proper functioning of global ocean currents. An influx of freshwater from melting glaciers can disrupt this process, potentially altering the global conveyor belt of ocean currents that regulates weather patterns and temperatures across the Earth.
The ecosystems around Antarctica are uniquely adapted to cold, stable conditions. The rapid influx of freshwater and the resulting decrease in salinity can disrupt the local marine environments. Species that depend on saline conditions, such as certain types of krill which are a key part of the Antarctic food web, may find survival challenging. This change could have cascading effects up the food chain, affecting predators like seals, penguins, and whales.
The changes in oceanic currents around Antarctica could modify weather patterns far beyond the polar regions. For example, warmer waters and disrupted currents might influence phenomena like El Niño events, which have global impacts on weather patterns, including droughts in Southeast Asia, wildfires in Australia, and reduced hurricane activity in the Pacific. These changes are complex and could destabilise established weather patterns that billions of people depend on for agriculture and water resources.
The Antarctic region, particularly the permafrost and ice traps, contains significant amounts of methane and carbon dioxide. As Thwaites Glacier melts, these gases could be released into the atmosphere, accelerating the rate of global warming. This release not only contributes directly to the greenhouse effect but also indirectly affects the reflective capability of ice, a phenomenon known as albedo. Melting ice reduces the Earth’s albedo, absorbing more solar energy and further warming the planet.
While less populated than other parts of the world, the Antarctic region holds significant scientific interest and is considered an important barometer for the health of the global environment. The loss of glaciers like Thwaites compromises our ability to conduct crucial climate research and monitor environmental changes that are pivotal in the global fight against climate change.
❗️ The Doomsday Glacier is called this for a reason, and scientists are highly concerned by the glacier's rapid rate of retreat. Their research has revealed that the Thwaites ice shelf is at risk of collapse as soon as the next decade, which will ultimately accelerate the rate at which the glacier itself declines.
However, even if the ice shelf collapses, the effects will be progressive and it will take several centuries for the glacier to completely melt. So what can we do in the meantime to prevent the melting of glaciers?
The most important thing that we can do to try and slow down the rate of glacier melt is to eliminate the emission of greenhouse gases. As long as we're releasing these gases into the air, global temperatures will continue to rise, which means that glaciers will continue to suffer from accelerated melting. This is why it's so important that we take steps to decarbonise our societies and reduce our dependence on fossil fuels.
❗️Even if we manage to reach net zero emissions, a lot of damage has already been done, and the Earth's glaciers will continue to melt for decades to come. This is why scientific research into the melting of glaciers such as the Doomsday Glacier is so important - it allows scientists to create models that predict the impacts of the melting ice, which will help us to better prepare for and adapt to the effects of climate change.
👉 Scientists from the British Antarctic Survey (BAS) and other research institutions are set to investigate the potential collapse of Thwaites Glacier in the coming decades or centuries. The UK-US-led International Thwaites Glacier Collaboration, a partnership between the US National Science Foundation (NSF) and the UK Natural Environment Research Council (NERC), hopes to provide new insights, allowing scientists to make better predictions on how the glacier will respond to our rapidly warming environment. These models will allow us to better prepare for the impacts of melting glaciers and their effects.
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