Millions of cracks are cracking and melting in Greenland

As I turned a corner, I was struck by a completely surreal scene: A large rift opened in the bottom of the river and swallows the water, creating a great whirlpool.. In doing so, large jets of moisture are released into the air. This may all sound like a CGI scene from an action movie, but it’s totally real.

A make cry (or glacier in Spanish, a big hole in the ice) is forming on the Greenland ice sheet right in front of me.. But that really shouldn’t be here: what we’re seeing doesn’t match what science is telling us right now.

As a glaciologist, I have spent 35 years researching how meltwater affects the flow and stability of glaciers and ice sheets.

This huge hole in the surface is just the beginning of the meltwater’s journey through the bowels of the ice sheet. While channeling towards Moulins, The liquid opens up an intricate network of tunnels through the ice sheet. This web extends for hundreds of meters to the bottom of the ice cap.

When it reaches the bottom, the melt water settles in the subglacial drainage system of the frozen layer; This web carries water to the edges of the ice and eventually ends up in the ocean, with important consequences for the thermodynamics and flow of the overlying ice sheet.

Scenes like this one, and new research into ice sheet mechanics, are challenging conventional notion of what happens inside and below icy layers, where observations are extremely complex but have far-reaching implications.

Studies show that The frozen layers of Greenland and Antarctica are much more vulnerable to global warming than computer models predict.and that these layers can be destabilizing from the inside.

This is an unfolding tragedy for the 500 million people living in the most vulnerable coastal areas., because the Greenland and Antarctic ice sheets are actually giant frozen freshwater reservoirs that have accumulated more than 65 meters of equivalent global sea level rise. Since the 1990s, mass loss has accelerated, making it both the main contributor and wild card to future sea level rise.

Narrow cracks that hide large gaps

This Moulins They are nearly vertical channels that capture and channel the flow of meltwater from the frozen surface each summer. There are thousands of such holes in Greenland, and they can reach impressive sizes., due to the thickness of the ice and extremely high surface melting rates. These ditches may be as large as tennis courts on the surface, but under the ice they form secret chambers that could swallow an entire cathedral.

But this is new make cry What I witnessed was really removed from any rift area or melting lake that science dictated they should form.

In a recent article, Dave Chandler and I show that:The ice sheets are riddled with millions of tiny cracks opened by meltwater overflowing into rivers and streams.

Because glacial ice is so fragile on the surface, such cracks are ubiquitous in the melting zones of all glaciers, ice sheets, and ice shelves. But because they are so small they cannot be detected by satellite remote sensing.

In many cases, we find that a current-fed hydrofracture like this allows water to penetrate hundreds of feet deep without the crack needing to penetrate the bed and form a bed. make cry complete. However, even these partial deep hydrofractures have a significant effect on the stability of the ice sheet.

As water enters, it damages the structure of the ice sheet and releases its latent heat. The ice mass warms and softens and therefore flows and melts faster, like the candle of a heated candle.

Current-driven hydrofractures mechanically damage the ice and destabilize it from the inside by transferring heat deep into the ice sheet. As a result, the inner fabric and structural integrity of ice sheets are becoming more vulnerable to climate warming.

Evolving processes that accelerate ice loss

Over the past two decades, melting events have become more common and intense as global temperatures have risen, exacerbated by the warming of the Arctic to about four times the global average.

The ice sheet is also flowing faster than ever before, forming icebergs. It has lost about 270 billion metric tons of ice a year since 2002: that’s more than an inch and a half rise in global sea level. Currently, Greenland contributes to an average of 1 millimeter of sea level rise per year.

A study conducted in 2022 concluded that: Even if global warming stops now, sea level rise of at least 27 centimeters will be inevitable.Due to the instability that Greenland has experienced over the past two decades due to climate change.

Understanding the risks ahead is crucial. However, current ice sheet computer models used to assess how Greenland and Antarctica will respond to future warming do not take into account the augmentation processes being discovered. This means The estimates of sea level rise provided by these models (used for reports by the Intergovernmental Panel on Climate Change (IPCC) and policymakers around the world) are conservative. and reduce global sea level rise rates.

But our research is the latest of many. Recent research has shown that:

Warmer ocean currents enter the coasts of Antarctica and Greenland, flowing under ice shelves to undermine outlet glaciers and destabilize their fronts.

Increased precipitation in the Greenland ice sheet not only depletes the snow cover, but also accelerates surface melting and ice flow.

Algae and microbes darken the surface of the ice sheet as the surface snow cover melts, thus absorbing more solar radiation, which accelerates the melting of the ice.

Overlapping ice sheets form in the snowpack throughout the accretion zone, thus creating an impermeable barrier that reduces meltwater retention and creates extraordinary runoff.

The water at the bottom of the ice sheet melts and softens the frozen bed, thus causing base slippage and accelerating the flow of the inner ice sheet towards the edges.

In recent months, Other papers have also described previously unknown feedback processes occurring beneath ice sheets, which computer models do not currently include.. Often these processes occur on a scale too fine for models to capture.

Two of these studies independently detect increased submarine melting at the land contact line in Greenland and Antarctica, where large outlet glaciers and ice streams flow into the sea and begin to rise from their beds as floating ice shelves. These processes greatly accelerate the effects of climate change on the ice sheet, and in the Greenland case, they could double their contribution to future mass loss and sea level rise.

Current climate models minimize risks

Along with other glaciologists and other experts, I declare that the current ice sheet computer modeling used to inform the IPCC does not take into account the sudden changes seen in Greenland and Antarctica.nor the risks they entail.

Current ice sheet models do not include these emerging feedbacks, leading to estimates of slow sea level rise. policy makers fall into a false sense of security. We have come a long way since the first IPCC reports in the early 1990s to treat polar ice caps as purely static entities, but we do not yet understand the truth.

As a dedicated field scientist, I am well aware of how privileged I am to work in these sublime environments inspired and humiliated by what I observe. But it also fills me with bad feelings about our lower coastal areas and What awaits 10% of the world’s population living in them?.

Alun Hubbard is Professor of Glaciology at the University of Tromsø (Norway) and Chair of the Arctic Five.

Original article: https://theconversation.com/meltwater-is-hydro-fracking-greenlands-ice-sheet-through-millions-of-hairline-cracks-destabilizing-its-internal-structure-207468

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Contact details of the environment department: crisisclimatica@prensaiberica.es