New Study, Good News Greenland’s Ice Loss Likely Won’t Disrupt Atlantic Current

“Will dissuade people from climate doomism,” researcher hopes.  Ice sheet runoff at the coast has much less impact on the AMOC than melting ice bergs ou to sea do. 

We hear it again and again: the melting ice in Greenland due to global warming will soon lead to a collapse of the Gulf Stream system, with the result that it would be difficult to restart. Then we would see great disasters like those depicted in Roland Emmerich’s dramatic climate movie  “Day after Tomorrow”.

Hat-tip: EIKE

The seawater salinity in the north is critical because the salt-rich tropical water cools and sinks due to the higher salt content. This acts as the pump that makes circulation possible in the first place. This serves to transport very large amounts of heat into the North Atlantic, keeping Europe on the mild side in the wintertime. Scenarios have been published recently that calculate a drastic cooling of the large area (especially Europe) around it if the Gulf Stream system got “switched off”.  But those scenarios are proving to be over-dramatic and alarmist.

Yuxin Zhou, a postdoctoral researcher in UC Santa Barbara’s Department of Earth Science, recently went back in history to study when the AMOC was severely weakened, from 68,000 to 16,000 years ago, when the Laurentide Ice Sheet existed and thick ice covered northern North America and even New York City. Today that massive ice shelf of course no longer exists and thus there is no longer the potential of an ice melt and ice berg release of that scale.

Very different, less dramatic circumstances today

By analyzing sea sediment deposited by floating ice bergs out to sea in the North Atlantic, Zhou found that AMOC heat transferring oceanic current had been already moderately weakened back then before all the icebergs floated over the North Atlantic. Comparing the situation to today: “In contrast, the circulation is very vigorous right now, which suggests the melting of Greenland is not likely to plunge the North Atlantic into another deep freeze of the sort the alarmists fret about all the time.

Moreover, Technology Networks here adds (emphasis added):

Not all melting has the same effect on the Atlantic circulation. Freshwater released as icebergs has a much larger impact on the AMOC than runoff, which is released after melting on land. Icebergs can cool the surrounding seawater, causing it to freeze into sea ice. Ironically, this ice layer acts as a blanket, keeping the ocean surface warm and preventing it from plunging down to the depths and driving the Atlantic circulation. What’s more, icebergs travel much farther out to sea than runoff, delivering freshwater to the regions where this deepwater formation occurs.”

Stop the doomism

Zhou summarizes: ““We have a lot of anxiety about how fast climate change is happening and how dramatic the changes could be. But this is a piece of good climate news that hopefully will dissuade people from climate doomism, and give people hope, because we do need hope to fight the climate crisis.”

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