Deep Ocean Changes

Imagine this: In the near future, climate change has melted the polar ice caps to a critical point, interrupting ocean currents and sparking, ironically, a new ice age. That’s the premise of apocalyptic movie The Day After Tomorrow, and while an instantaneous global ice age is fantastical, the disruption of marine currents is still a serious concern of climate scientists.

Interestingly, continued global warming and rapid melting of ice sheets could lead to a drop in temperatures of five to ten degrees Celsius in western Europe. This paradox is due to the regular pattern of ocean currents, called the Global Ocean Conveyor, that carries warm Gulf Coast water into the northeastern Atlantic. Without warm seawater, Europe would cool significantly. Changes elsewhere around the world are likely to be as confounding and severe.

In the past 50 years, scientists have seen strong evidence of changing ocean currents associated with the rapid melting of glaciers in the Antarctic. This is important because surface water that typically sinks to deep levels of the sea, enriching the nutrient-deficient depths with oxygen and helping to control global climate and patterns of marine motion, is no longer cycling the way it should. The melting of the Antarctic ice sheet is likely to blame, yet another ominous omen of climate change and its global effects. However, a recent study found that, in 2018, the downward trend of “dense water” sinkage in the Antarctic mysteriously reversed—water cycling rates suddenly increased.

So, this is great news; we don’t have to worry about an overnight ice age, right? Right, but it’s not a permanent fix. Scientists speculate that this is a temporary change instigated by two factors: “An extreme El Niño event occurring at the same time as stronger and southward-shifted westerly winds.” This unique combination of meteorological phenomena affected the ocean currents enough to restore the usual patterns. However, scientists warn that this is a temporary pattern and cannot be relied upon as a long-term solution.

The Antarctic’s temporary reversion to regular currents reflects two things: that there is still much to be learned about the dynamics of our planet, and that small sample sizes are not representative of the larger concept of climate change. Both issues can be remedied by long-term, in-depth studies to gain a better understanding of the history of our planet. There is much work to be done, but hopefully discoveries like this one can help illuminate a murky future.

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