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International

Antarctica is Losing Its Edge

A study published earlier this week in the journal The Cryosphere found that the largest ice shelf on the Antarctic Peninsula is at imminent risk of collapse. RMI senior fellow Robert “Hutch” Hutchinson recently returned from a trip to the Antarctic, where he saw that continent’s rapidly changing environment up close. He brings back sobering words of caution—and added urgency to act boldly against global warming.

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The biting, sharp-edged cold I’d expected on my recent three-week ship and kayak trip in Antarctica was not there. I was seldom cold, and often overheated. The Antarctic Peninsula in summer is now significantly warmer than Colorado in winter. For a human it seems darn nice, even when it’s raining on you. But maybe it’s not so good for penguins. Or ice. Or, in the end, us.

I visited the Antarctic Peninsula and the Southern Ocean to better understand what is going on, from a practical and big-picture perspective, and of course to see some of the amazing White Continent and its occupants for myself. I came back with three observations:

  • Really important pieces of Antarctica are melting
  • The changes are affecting all life systems and this may have implications for the global ocean ecosystem
  • Many of these changes appear to be irreversible

Antarctica really is melting

Like the recent bad news from Greenland, scientists are basically finding out new and uncomfortably rapid ways that marine ice shelves are melting. Although predicted by famed glaciologist J.H. Mercer of Ohio State University in 1978, few took notice, and now there is little chance anything can be done to stop it.

The gigantic marine ice sheets and glaciers in West Antarctica are roughly the size of Texas. As they thin, they break off at the edges and permit the vast accumulations of glacial ice behind them to melt back and move faster toward the ocean. The largest West Antarctica ice shelf—the Ross—is currently losing about 300 cubic kilometers per year. The total effect from losing West Antarctica ice could be a sea level rise of up to four meters.

The Southern Ocean, at least in key areas and at key depths, is much warmer than it used to be, melting the ice from underneath. Even half a degree Fahrenheit is a big deal, and the change may already be more than that on average. In addition, stronger circumpolar winds appear to be driving currents, which enable deep, warm (over 32 degrees F) water to more rapidly eat away at the ice from underneath. It’s all the more scary because much of the area we are talking about is actually below sea level, and as the warm sea works at the “pinned” ice sitting on the land, it will be undermined and move faster toward the ocean.

In East Antarctica, once considered stable if not growing its ice mass a little, the Totten Glacier is thinning by about two meters per year. An Australian study recently revealed how this is happening by measuring a channel that enabled warmer waters to eat away at the underside of the shelf. That’s right—for those who love to argue about iffy climate models—these are measurements. In other words, facts. Not opinions to be debated. It would be like arguing with your thermometer every morning—pointless. Since the capture area for the Totten alone is almost half the size of West Australia this could mean up to another three meters of sea level rise. Recent studies indicate there are at least five other Eastern ice shelves at glacier outlets where high melt may also be occurring.

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These changes can affect the entire ocean ecosystem

As the Antarctic Peninsula changes, it disrupts and threatens the life within it. First, like other parts of West Antarctica, the air temperature in both summer and winter has gone up. Hence the multiple days of rain and fog I enjoyed—a far wetter climate than only a few decades ago. The winter version has more snow than before— warmer air carries more moisture—but much less sea ice, forming later.

The story of the once-booming Adélie penguin colony near the U.S. Palmer Station shows what happens next: The extra winter snow takes longer to recede (despite the warmer summer), delaying the start of penguin nesting and mating. The limited winter ice means less food, as the penguins’ key food, krill, loses its primary food source—algae growing on the underside of ice. Adélie penguins are now threatened—at least 70 percent are at risk . Another species, Chinstrap penguins, which prefer open water but also eat mostly krill and need bare rock for nesting, are also on the decline for similar reasons.

Most life in Antarctica is actually in the oceans. And it is especially adapted to near-zero or below-zero water temperatures. These special conditions and adaptations mean that even a small temperature change can be a huge deal. Such changes, some of them potentially disastrous, are already in evidence. The most important appear to be those affecting krill—small shrimplike crustaceans that form the basis for almost all of the Southern Ocean food chain. Not only are the ice-growing algae that feed krill disappearing, but diatoms, a major krill food that floats free, are also at risk from acidification. Krill themselves are affected by acidification—it makes them develop too slowly to be able to survive in the larval stages.

While we contemplate a krill-short world, which could readily be the end of most animal life near Antarctica (with global repercussions as whales and other migrating animals also disappear) we must also recognize the risks to the rich plant life on the continental shelf. As rich in species as coral reefs, these organisms have few predators. King crabs, whose “skeleton-breaking” ways have decimated virgin areas in the Arctic when they were introduced, are present in large numbers in deep, slightly warmer waters near the Antarctic Peninsula and elsewhere. They are already within 200 meters of the rich but fragile undersea communities. It is hard to imagine, as the ocean warms, that the crabs will not move up and start munching.

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Do irreversible changes justify inaction?

The changes and ice losses discussed above appear to be irreversible. Their global effects will be hard and very expensive to handle. Life will not be the same. And some penguin populations will shrink, if not disappear. No matter what. It would be easy to say, therefore, that important changes to human habits are not needed (since it may be too late for Antarctica). Our only continent without permanent human inhabitants will simply have to cope—and it will be a great science experiment to see what happens.

This is wrong for three reasons that go even beyond sea level and penguins:

  • Other Antarctic systems are changing and can have dire consequences. Phytoplankton in the ocean produce most (perhaps 70–80 percent) of the oxygen in the atmosphere and take up most of the carbon dioxide that the oceans store. A key area for seasonal phytoplankton growth is around Antarctica—but like the algae, phytoplankton (which are also krill food) are decreasing. If this continues it could be fatal. We need oxygen.
     
  • Global current systems will change. We have seen, for instance, how delicately balanced the Antarctic systems are; fractions of a degree of ocean temperature make a huge difference. But there are even bigger changes that could happen. The Southern Ocean’s cold, salty Antarctic bottom water system helps drive the mixing and the ocean nutrition system for the entire planet. And the currents also serve as a thermal control (e.g., the Gulf Stream that keeps Europe warm). In addition, much of our seafood comes from places where the cold, nutrient- and oxygen-rich Antarctic water, now thousands of miles north, is forced to the surface. Continued heating of the Southern Ocean will certainly change these patterns, and such changes may be very challenging.
     
  • Even more tipping points are out there. Key glacial systems like West Antarctica are already past their tipping points. But there are likely other systems in motion that have never been measured—additional East Antarctica glacier systems, for instance—in the mysterious White Continent and globally. The smart guess is there are more tipping points and the surprises they bring will not generally be good ones for anyone.

So why make a crazy bet to say, “Let’s not bother?” It might cost us a few percent of GDP? If we do, Antarctica will likely lose more than its edge. It will lose its oceans, its middle, and its life—and so may we. But if we act quickly, we may be able to stop more systems from reaching their tipping point. While it may be too late for some of the Antarctic ice shelves and the Adélie penguins, it is not too late for the rest of us. But we must act now.

Images courtesy of Robert “Hutch” Hutchinson. Used with permission.