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.
…The same fresh water and iceberg release that increases regional and hemispheric storm potential also harms ocean health. For when downwelling of cooler, northern currents cease and fail to provide oxygen to the deep ocean — the ocean stratifies, loses a portion of its life-giving oxygen, and starts to produce more and more anoxic dead zones. Ocean circulation interruptions due to Heinrich Events can be relatively brief (on geological time scales) — as has likely been the case at the end of the last ice age during the melt toward the present interglacial — or long-lasting. In the long lasting instance of ocean stratification, bottom water formation is thought to shift to the Equator. In the Earth’s deep past, such events are identified as a primary trigger for ocean mass extinction events or even transition points for a deadly Canfield Ocean state. But you have to shift to an ice-free world at about 6 + degrees Celsius warmer than present to get to the start of that state — a proposition that is now entirely within reach if we continue on the present and ill-fated expedition of continued fossil fuel burning.
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