A skyscraper-sized tsunami rippled across the planet, and no one saw it.

Seismologists have detected an unusual signal at monitoring stations recording seismic activity during September 2023. We’re monitoring it on sensors all over the world, from the Arctic to Antarctica.

We were puzzled: the signal was unlike any other we had ever recorded before. Instead of the roaring, full of frequencies typical of earthquakes, it was a monotonous hum containing a single vibration frequency. And even more alarming, the signal persisted for nine days.

The Dixon Strait is surrounded by rugged mountains.

Initially classified as a USO (unidentified seismic object), the source of the signal was eventually located in a massive landslide in Greenland’s remote Dixon Fjord. A massive amount of rock and ice, enough to fill 10,000 Olympic-sized swimming pools, rushed into the fjord, creating a 200-meter-high tsunami and a phenomenon known as a “seiche”: a wave in the frozen fjord that continued to flutter back and forth, some 10,000 times over nine days.

To put the tsunami in context, the 200-metre wave was twice the height of the tower housing Big Ben in London, and several times higher than any earthquake recorded since the massive underwater quakes in Indonesia in 2004 (the Boxing Day tsunami) or Japan in 2011 (the tsunami that hit the Fukushima nuclear power plant). It was probably the highest wave anywhere on Earth. Since 1980.

Our discovery, recently published in the journal sciencesin collaboration with 66 other scientists from 40 institutions in 15 countries. As in the case of an airplane crash investigation, to solve this mystery it was necessary to gather a wide range of evidence, from large amounts of seismic data to satellite images, measurements of water levels in fjords and detailed simulations of the evolution of living organisms. tsunami wave.

All of this revealed a series of catastrophic events, from decades to seconds before the collapse. The landslide descended a steep glacier into a narrow valley before plunging into a narrow, confined fjord. But ultimately, it was decades of global warming that shrank the glacier by dozens of meters, bringing the towering mountain above it to a halt.

Unknown waters

But beyond the rarity of this scientific marvel, this event highlights a deeper and more disturbing truth: that climate change is reshaping our planet and our scientific methods in ways we are only beginning to understand.

It’s a stark reminder that we’re navigating uncharted waters. Just a year ago, the idea of ​​nine days of isolation would have been dismissed as absurd. Likewise, a century ago, the idea that global warming could destabilize the slopes of the Arctic, causing massive landslides and tsunamis almost every year, would have been considered far-fetched. Yet these once unimaginable events are now our lives. new reality.

As we move into this new era, we can expect to see more phenomena that defy our previous understanding, simply because our experience does not include the extreme conditions we are now facing. We have discovered a nine-day wave that was previously unimaginable.

Traditionally, discussions of climate change have focused on looking at the atmosphere and oceans, with changes in weather patterns and rising sea levels. But Dixon Strait forces us to look at the crust beneath our feet.

For perhaps the first time, climate change has caused a seismic event with global implications. The Greenland landslide caused the ground to shake, shaking the planet and generating seismic waves that rippled across the globe within an hour of the event. No patch of land beneath our feet was immune to these vibrations, metaphorically opening cracks in our understanding of these events.

It will happen again

Although tsunami-related landslides have been recorded before, the September 2023 collapse was the first ever in East Greenland, a region that had seemed immune to such catastrophic climate-change-driven events.

It certainly won’t be the last megatsunami of its kind. As permafrost on steep slopes continues to warm and glaciers continue to shrink, we can expect such events to occur. more often and more widely In all polar and mountainous regions of the world. Unstable slopes have recently been identified in western greenland And in Alaska They are clear examples of impending disasters.

As we face these extreme and unpredictable events, it is becoming clear that our current scientific methods and tools may need to be further developed to deal with them. We do not have a standard workflow for analyzing the Greenland event in 2023. We also need to adopt a new mindset, because our current understanding is shaped by a stable climate that is now almost extinct.

As we continue to change our planet’s climate, we must be prepared for unexpected phenomena that challenge our current understanding and require new ways of thinking. The ground beneath our feet is shaking, literally and figuratively. While the scientific community must adapt and pave the way for informed decision-making, it is up to policymakers to act.

Stephen HicksResearch Fellow in Computational Seismology, UCL and Christian SvenvigSenior Researcher, Department of Maps and Mineral Resources, Geological Survey of Denmark and Greenland

This article was originally published on ConversationRead. creative.