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Greenland earthquake and tsunami – hazards of melting ice?

Is gradual CO2 increase speeding up Greenland ice sheet melt?  (Pic: I.Quaile)

Following the news over the weekend with a trip to Greenland this summer at the back of my mind, my attention was immediately caught by reports of a tsunami and earthquake in Greenland. Four people were reported missing. Buildings had been swept away, including the power station on the island of Nuugaatsiaq. Greenland is not the first place that comes to mind in connection with earthquakes and tsunamis. But in fact they are not as rare as you might think.

The cause of the weekend’s event is still unclear. But a tweet from the Greenland Climate Research Centre links to an article in the Washington Post from June 25 2015:

“Glacial earthquakes”

“Giant earthquakes are shaking Greenland – and scientists just figured out the disturbing reason why.”

The article reports on a paper published in the journal Science at that time by researchers from Swansea University in the UK, the Lamont-Doherty Earth Observatory at Columbia University and several other institutions. It says the loss of Greenland’s ice can generate “glacial earthquakes”.

“When vast icebergs break off at the end of tidal glaciers, they tumble in the water and jam the glaciers themselves backwards. The result is a seismic event detectable across the Earth”.

Worrying reading indeed, as GCRC wrote in their tweet.

The Washington Post article quoted Meredith Nettles from Columbia, one of the co-authors.

She specifically mentions the tsunami effect:

“The tsunami is caused because the iceberg has to move a lot of water out of the way as it tips over”.

Arctic icebergs can displace a lot of water (Pic: I.Quaile, Greenland)

Too early to say

I have been trying to find more information on what the experts think caused this weekend’s particular event. So far, there is no clarity. But the GCRC tweet with link to the Washington Post article seems to indicate they think it could be ice-related.

Another theory is that the quake and tsunami were caused by a landslide. The news agency DPA says the Geological Survey of Denmark and Greenland are still trying to determine the cause of the tsunami.

“Initially, geologists believed it was triggered by an earthquake, but another theory blamed a large landslide from one of the mountains on the fjord system”.

It seems the Danish Arctic Commando published images showing signs of an extensive landslide.

“Tsunamis and large waves at times affect Greenland’s coasts, but, according to the Geological Survey, they are usually caused by landslides and the breaking off of ice from melting glaciers”, the agency writes.

DPA earlier noted that the Danish earthquake authority GEUS had recorded a 4.0 quake.

Warning from Greenland ice cores

One way or other, the weekend tsunami is unlikely to allay anxiety about the effects of rapidly melting substantial quantities of ice.

And a study just published by Germany’s Alfred-Wegener-Institute (AWI) provides more food for thought about human-induced changes to our climate. It indicates that the gradual nature of the changes we are making to the CO2 concentration in the atmosphere is no guarantee that the resulting climate change will also be gradual. On the contrary. Computer models based on information from ice cores from Greenland show that in high latitudes of the northern hemisphere, there were abrupt changes in climate, which the scientists attribute to a gradual increase in CO2.

Measuring CO2 in Ny Alesund, Svalbard, Spitzbergen

Rising CO2 emissions – no part of the world is spared (Measuring station on Svalbard, Pic. Quaile)

During the last ice age, they say that the influence of atmospheric CO2 on the North Atlantic Current within a few decades led to an increase in temperature of up to 10 degrees Celsius in Greenland. The study, published in the journal Nature Geoscience, by scientists from AWI and the University of Cardiff shows that in recent earth history, there have been situations when gradual increases in CO2 concentrations at what are known as “tipping points” led to abrupt changes in ocean circulation and climate.

Sudden warm age on the horizon?

Lead author Xu Zhang says the study is the first to prove that a gradual increase in CO2 can set off very rapid warming, based on interactions between ocean currents and the atmosphere.

The authors also show that the rise in CO2 is the main cause of chances in ocean currents during the transition from an ice age to a warm period.

Of course, they add, the framework conditions today are different from those during an ice age, so it is not possible to say the rise in CO2 will have similar effects in future.

But they say they can definitely show that there were abrupt climate changes in Earth’s history, which can be traced back to continual rises in CO2 concentrations.

Reason enough for concern to people living on the coast of Greenland – not to mention the rest of us, given the key role the world’s biggest island, with the biggest freshwater mass in the northern hemisphere sitting on top of it in the form a giant ice sheet,  plays in influencing climate and sea levels around the globe?

 

 

 

Date

June 19, 2017 | 3:12 pm

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