A Heinrich event

“I have about a decade of experience with the Ice Patrol, and in my time here, and talking with people who have been here longer, I’ve never seen anything like this or heard of anything like this before,” — Gabrielle McGrath Coast Guard Commander of the US Ice Patrol.

“A Heinrich event is a phenomenon in which large armadas of icebergs break off from glaciers and traverse the North Atlantic.” — Commons

“Consider the situation during past ice sheet disintegrations. In melt-water pulse 1A, about 14,000 years ago, sea level rose about 20 meters in approximately 400 years (Kienast et al., 2003). That is an average of 1 meter of sea level rise every 20 years.” — Dr. James Hansen

*****

This week an unprecedented 481 icebergs swarmed into the shipping lanes of a storm-tossed North Atlantic. Strong hurricane force winds had ripped these bergs from their sea ice moored haven of Baffin Bay and thrust them into the ocean waters off Newfoundland. The week before, there were only 37 such icebergs in the Atlantic’s far northern waters. And the new number this week is nearly 6 times the annual average for this time of year at 83. To be very clear, there is no record, at present, of such a large surge of icebergs entering these waters in so short a period at any time in the modern reckoning.


(Many glaciers along the periphery of Greenland have passed the point of no return. In other words, at present temperatures, these glaciers will completely melt. In the past, such major melting events have released ‘armadas of icebergs’ into the North Atlantic in instances called Heinrich Events. Video source: Chasing Ice.)

Likely Precursor to a Heinrich Event

During recent years, rates of iceberg discharge from Greenland have been increasing. More icebergs are calving from great masses of ice like the Jackobshavn Glacier along the west-central coast of Greenland. Speed of ice discharge from Jackobshavn has about doubled during recent years. And new studies indicate that ice mass loss all around coastal Greenland is accelerating even as many glaciers have now reached a point of no return and will inevitably melt into the North Atlantic due to the human-forced warming of our world. As a result, Greenland is producing more icebergs. And this year, it appears that this glacial melt acceleration combined with a very powerful storm to flood the North Atlantic with the bergs at a hither-to unprecedented rate.

(This week, a massive swarm of icebergs that calved from Greenland and entered Baffin Bay have been kicked into the North Atlantic by a powerful storm system. To be clear, this is the kind of thing you’d expect at the start of a Heinrich Event. Image source: U.S. Coastguard.)

Right now, no one wants to make the conclusion that we are starting to enter a Heinrich Event. Or worse — that the present rate of warming at 30 times faster than at the end of the last ice age is rapidly putting us in peril. But the geological evidence for just such an event was a proliferation of ice-rafted boulders from swarms of icebergs that subsequently melted and dropped their rock loads onto the sea floor of the North Atlantic. Heinrich Events are triggered by rapid glacial melt and destabilization of Greenland and Antarctic glaciers as warming airs and waters force the great ice masses past key tipping points.


https://robertscribbler.com/2017/04/...ntic/#comments