Climate chaos from melting ice – history shows what we could be facing
The chaos caused by melting ice at the end of the last glaciation, 10,000 years ago, shows what may be in store for us as Greenland and Antarctic ice faces a similar collapse.
By James Ayre
The collapse and melting of the Eurasian ice sheet at the end of the last ice age led to chaos all across the European continent, according to a new study published in the journal Quaternary Science Reviews.
To put it bluntly, the collapse of the ice sheet led to dramatic and extreme flooding events, sea level rise, and, perhaps more interestingly, the formation of “mega-rivers” that swept some of the continent nearly clean at various points. These events of course led to serious changes to ecological systems and environments, and to the human habitability of the region.
“Our model experiments show that from 15,000 to 13,000 years ago, the Eurasian ice sheet lost 750 cubic kilometres of ice a year. For short periods, it peaked at ice loss rates of over 3,000 cubic kilometres per year,” commented first author Henry Patton, a researcher at CAGE Centre for Arctic Gas Hydrate, Environment and Climate at UiT The Arctic University of Norway.
To better explain what those figures mean, so that can understand the implications … one cubic kilometer of ice is the equivalent of a cube of ice 1 kilometer long on each side. Roughly, that’s equivalent to around 1,000,000,000 x 3,000 tonnes of water.
“There is an event in this deglaciation story called Meltwater Pulse 1A. This was a period of very rapid sea level rise that lasted some 400–500 years when global temperatures were rising very quickly. During this period, we estimate that the Eurasian Ice Sheet contributed around 2.5 metres to global sea level rise” continued Patton.
“To place it in context,” explained professor Alun Hubbard, the study’s second author, “this is almost ten times the current rates of ice being lost from Greenland and Antarctica today. What’s fascinating is that not all Eurasian ice retreat was from surface melting alone. Its northern and western sectors across the Barents Sea, Norway and Britain terminated directly into the sea. They underwent rapid collapse through calving of vast armadas of icebergs and undercutting of the ice margin by warm ocean currents.”
That sounds familiar, right?
Hubbard noted: “This is a harbinger of what’s starting to happen to the Greenland ice sheet.”
And also a harbinger of what’s beginning to happen to the West Antarctic ice sheet.
The new study noted that, “One of the most dramatic impacts was the formation of the enormous Fleuve Manche. This was a mega-river network that drained the present-day Vistula, Elbe, Rhine and Thames rivers, and the meltwater from the ice sheet itself, through the Seine Estuary and into the North Atlantic.”
Patton continued: “Some speculate that at some points during the European deglaciation this river system had a discharge twice that of the Amazon today. Based on our latest reconstruction of this system, we have calculated that its catchment area was similar to that of the Mississippi. It was certainly the largest river system to have ever drained the Eurasian continent.”
A university press release continues: “The vast reach of this catchment meant that this mega-river had the capacity to contribute enormous volumes of cold freshwater directly into the North Atlantic, enough to have severely modified the Gulf Stream — a major climate influencer.
“Also, the sea level rise and the colossal amounts of meltwater discharged from the collapsing ice sheet meant that areas that previously were land eventually became seabed.”
“Britain and Ireland, which had been joined to Europe throughout the last ice age, finally separated with the flooding of the English Channel around 10,000 years ago. It was the original Brexit, so to speak,” Alun Hubbard continued.
Overall, the situation is likely one that can be taken as somewhat analogous to the one that people will be facing over the coming decades and centuries as the ice sheets of Greenlandand West Antarctica continue collapsing.