The rapid melting of the Greenland Ice Sheet is likely to trigger catastrophic earthquakes and tsunamis powerful enough to impact the North American and European coastlines.
The weight of the ice sheet is reduced from the loss of ice from melting and the calving of tidal glaciers, which impacts the earth's crust, unleashing intense seismic activity.
Calving glaciers is already causing tsunamis in Greenland. But, they are localized and not a regional threat.
So warns Bill McQuire, currently a Professor of Geophysical & Climate Hazards at the University College of London.
A possible precedent was the “great Storegga tsunami” that devastated the coasts of Scandinavia and the British Isles 8,200 years ago. An offshore earthquake, triggered by the release of pressure after northern Europe’s ice sheets had melted, set off a vast landslide of submarine sediments under the Norwegian Sea. Geological evidence shows the resulting tsunami wave reached 15 to 20 metres high in the Shetland islands and 3 to 6 metres high further down the North Sea.
“As the Greenland ice cap melts, the uplift in the crust is going to trigger earthquakes,” said McGuire. “We don’t know enough about the sediments off the Greenland coast to predict confidently what might happen there, but it is certainly possible that within decades there could be a tsunami right across the north Atlantic.”
The loss of ice from Greenland and to a lesser extent Iceland and Svalbard is lifting up the earth’s crust around the north Atlantic, McGuire said. Sensitive GPS instruments on coasts around the ocean are beginning to detect this uplift, which is taking place at a rate ranging from a few millimetres to 2.5cm a year.“The whole central part of Greenland is below sea level, forced down by the weight of the 3km thick ice cover, so the crust has a long way to bounce back,” he said.
McGuire notes that Alaska is already showing increasing seismic activity as arctic amplification. He notes that Alaska is the climate change canary in the coal mine for this phenomenon. SW Alaska recently experienced a magnitude 8.2 earthquake. The strongest in over fifty years.
He denied being alarmist. “When global temperatures may be rising at the fastest rate in the history of our planet, I’m proud to be raising the alarm,” he said. “Almost every forecast so far about climate change has been an underestimate.”
The calving of icebergs currently generates local tsunamis, but it is the subsea landslides we will need to worry about that will reach heavily populated areas.
The writers in Climate Brief work to keep the Daily Kos community informed and engaged with breaking news about the climate crisis worldwide while providing inspiring stories of environmental heroes, opportunities for direct engagement, and perspectives on the intersection of climate activism with spirituality politics, and the arts.
Climate Brief posts every evening, 5 pm est