Jumping from floe to conclusion

April 6, 2009

The epic survival tale of Ernest Shackleton’s Imperial Transantarctic Expedition is justifiably the one that grabs everyone’s attention. But anyone who felt a thrill at the unlikely escape from the jaws of the frozen south should also consider reading “Farthest South”, the account of his previous attempt at the South Pole. In many ways this 1908 trek, which put Shackleton and three men just 97 miles from their goal after a 1,700 mile sledge haul, is a more thrilling tale. It is a rare account of people travelling into the unknown, cheating death (by cold, starvation or crevasse), and yet never forgetting that a large part of their mandate was to add to humanity’s scientific knowledge. In so doing they learned, often the hard way, that Antarctic is a land in flux. It changes constantly, and any visitor is forced to adapt. Fortunately, we no longer have suffer like Shackleton to learn about Antarctica. The wealth of data we collected from the safety of polar bases and satellites is unprecedented, and has allowed agencies such as the U.S. Geological to track the disappearance of some large swaths of ice shelf, a semi-permanent ice formation created during colder times. The USGS’ most recent report, however, has left me nonplussed. Perhaps because springtime shows some signs of arrival and I’m glad for a little solar energy. Or maybe I’ve been converted by a “heretic”.

No, I think what put me off about an otherwise informative update on the disintegration of several ice shelves on the Antarctic peninsula was what I perceived to be a bit of false logic in the general press release:

“USGS scientists report that these floating ice shelves are especially sensitive to climate change, so their rapid retreat may be a forecast for losses of the land-based ice sheet on the Antarctic continent if warming continues. This could result in sea-level rise, threatening low-lying coastal communities and islands.”

Feel free to consult the full report for a more balanced view of the situation, but I’m a little put off by the suggested “forecast”. How can we possibly divine the fate of the inland ice sheets based on the collapse of relatively small ice shelves on the Antarctic Peninsula? Given the amount of data at hand—which still isn’t a lot in the grand scheme of things—it’s a little like predicting a monstrous Pacific Rim earthquake based on Mt. Redoubt’s recent eruptions. Could minor volcanic activity be the straw that breaks 1,000 years of developing tectonic strain? A strong maybe: we have a lot to learn still about the real-time dynamics of plate movements. In fact, predicting earthquakes and violent eruptions will likely be easier, in the long run, than attempting to understand how human activity affects the temperature trends of our atmosphere and oceans. The carbon cycle itself is extraordinarily complex and only recently have we gained the ability to identify carbon sources remotely on a continuous, or have the use of satellite-enabled synthetic aperature radar to accurately gauge glacier flow rates over time.

No question, the Antarctic Peninsula has experienced short-term warming on a significant scale—average temperatures there have risen by 3.8°F over the past half century, which is higher than the global rise. But recent ice shelf activity can’t be tied to the collapse of the inland ice sheet. The loss of the Wordie Ice Shelf and the Jones Ice Shelf are inconsequential. The shrinkage of the Larsen Ice Shelf is significant, but has a lot to do with its latitude, and the collapse of the ice bridge on the Wilkins Ice Shelf makes a lot of sense to anyone who studies a map of the area. All of these put together don’t add up to even to a small portion of the Ross or Ronne Ice Shelves. And those are themselves a small percentage of the ice contained on the continent—91% of the global total. I live about 10 feet above sea level, and I don’t yet fear drowning.

What I do fear, however, are policy decisions based on conclusions backed up by data that can best be described as incomplete. Will we have enough results by 2012 to usher in a fair follow-up to the Kyoto Protocol? Even if we all go out and study Antarctica on foot, I doubt it.