How sea levels could rise dramatically

“How climate hysterics hurt their own cause.” — September 2014 headline from The Atlantic magazine I get side-tracked easily. I read The Atlantic article and was going to do a column on coal versus oil in the CO2 emissions debate (the author, Charles C. Mann, stated that coal was a much bigger worry).

“How climate hysterics hurt their own cause.”

— September 2014 headline from The Atlantic magazine

I get side-tracked easily. I read The Atlantic article and was going to do a column on coal versus oil in the CO2 emissions debate (the author, Charles C. Mann, stated that coal was a much bigger worry).

But then I noticed a tidbit that puzzled me. Mann, after reading a study from the prestigious journal Science, wrote that current melting from the West Antarctic ice sheet is only raising ocean levels by about 0.25 mm per year. That’s nothing. At that rate, Florida will drown at about the same time as Kim Kardashian writes a book about the Soviet penal system.

So I had a closer look. And I found that even the notoriously anti-alarmist wattsupwiththat.com was careful to note that “This study specifically cautions that the simulations used were not coupled to global climate models and as such these simulation results do not constitute a projection of future sea level rise impacts.” In other words, that very tiny rate of sea level rise doesn’t take into account the accelerating growth rates of not only our CO2 output, but also warming via the much more alarming liberation of CO2 and methane from the warming tundra in Canada and Russia.

And neither does that very small number begin to take into account the mechanism by which an Antarctic ice sheet lives and dies. The much bigger threat to sea levels is that caused by retreating “grounding lines,” which is where the bottom of glaciers meet bedrock. The middle part of a glacier is like an ice cube on a sheet of sandpaper. Even though the bottom of the ice is very slippery, it is still somewhat stuck. But when the warming ocean gets in between the two, it lifts up the ice and allows it to advance over the sandpaper (or bedrock) much more rapidly. And when that advancing chunk of ice calves off into a bunch of little icebergs in the ocean, the whole lot melts a lot more quickly.

So how fast can a grounding line retreat? The Pine Island glacier on the West Antarctic ice sheet is a veritable Speedy Gonzales. In the last 20 years, its grounding line has retreated about 25 km toward the South Pole. In other words, that’s how far the ocean has forced its way between the glacier and the bedrock of the Antarctic continent.

Compare that to the Athabasca Glacier just west of here. In the last 115 years, it has only retreated about 1.5 km. So the grounding line for the Pine Island Glacier — the point at which the ice is liable to crack off and float away — has been moving about a hundred times as fast as the Athabasca Glacier has been retreating.

The other hidden bit in the puzzle relates to the bedrock topography of Antarctica as a whole. When we look at a map of the place, we just assume that underneath the ice is a massive rock, which would still look something like the shape of Antarctica. But that’s not the case. Just google “Antarctic bedrock map” to see how much the continent shrinks without its icy mantle. All of a sudden it is half of what is currently shown in an atlas.

Why is that important? Because with no bedrock above sea level, that “grounding line” can easily advance across the whole width of West Antarctica with nothing to slow it down. And once you get two million cubic km of ice floating around, breaking up into little pieces and melting, you have a big problem.

And that’s where the article in The Atlantic fell silent. For some reason, Mann didn’t bother to read the whole article from the journal Science. For if he did, he might have noted that the researchers warned that in a worst case scenario, the sea levels could rise (just from the West Antarctic ice alone) 3.6 metres in 200 years. That’s about 75 times faster than the rate noted above.

And of course, that doesn’t take into account the ice in East Antarctica (another 25 million cubic km) and Greenland (three million cubic km).

But maybe we should cut Mann some slack. After all, he’s not a scientist. And he did make the much more believable statement about coal emissions being a significantly larger threat than oil emissions.

So perhaps for next month — if I don’t get sidetracked again — I’ll look at how Alberta is doing with regard to emissions from coal versus conventional oil versus bitumen.

Evan Bedford is a local environmentalist. Direct comments, questions and suggestions to wyddfa23@telus.net. Visit the Energy and Ecology website at www.evanbedford.com.

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