Atlantic Ocean Current Might Not Shut Down So Soon

Greenland’s ice loss, measured from the Grace and Grace-FO satellites. NASA. Several recent studies have raised real-world alarms that a crucial ocean current that circulates heat to northern countries might shut down this century, with potentially disastrous consequences. That scenario has happened in the past, most recently more than 16,000 years ago. However, it relies on Greenland shedding a lot of ice into the ocean.

Yuxin Zhou at The Conversation: While Greenland is losing huge volumes of ice right now – worryingly comparable to a midrange Heinrich event – the ice loss will likely not continue for long enough to shut down the current on its own.

Icebergs are much more effective at disrupting the current than meltwater from land, in part because icebergs can carry fresh water directly out to the locations where the current sinks. Future warming, however, will force the Greenland ice sheet to recede away from the coast too soon to deliver enough fresh water by iceberg.

The strength of the Atlantic Meridional Overturning Circulation, or AMOC, is projected to decline 24% to 39% by 2100. By then, Greenland’s iceberg formation will be closer to the weakest Heinrich events of the past. Heinrich events, in contrast, lasted 200 years or so.

Instead of icebergs, meltwater pouring into the Atlantic at the island’s edge is projected to become the leading cause of Greenland’s thinning. Meltwater still sends fresh water into the ocean, but it mixes with seawater and tends to move along the coast rather than directly freshening the open ocean as drifting icebergs do.

More here.

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