Tuesday, July 07, 2009

Al Gore's Twenty Feet-In-Mouth Problem

Going shopping with Al.

Some things are so obvious they're hard to see.

For example, the most dramatic part of Al Gore's "An Inconvenient Truth" was the scenes of flooded city streets and the ominous prediction of a 20-foot rise in sea levels by 2100. According to Al, this was the most damaging aspect of global warming, and the reason that "Something must be done, and it must be done now!"

Al continues to beat the panic drum, now comparing inaction on stopping global warming to inaction on stopping Nazi Germany. And the reason we must do it now, of course, is that awful flooding is eminent.

What else could make us join his march to save the world at great expense and loss of economic progress? The threat that the growing season will be longer? That crops will grow better and make better use of water resources? That the thundering herds that voted for global warming with their feet by moving south won't have to move as far now? That the world may become as warm as during the Holocene Climate Optimum of 5,000 to 9,000 years ago, when civilization began and thrived?

Maybe Al intends to rally us to the cry, "Turn back the Industrial Revolution!" He wants us to repudiate the mastery of energy that enabled us to transition from man power, t0 animal power, then wind and water power, and now to the unlimited, inexhaustible power of the atom.

To do that, Al knows that he has only one threat capable of generating unthinking panic. Just as in the Bible God sent The Deluge, Al has invoked The Sea Rise. And just as God had to get the deed done quickly - make it rain for forty days and forty nights - so Al too must make the future bleak, if not for ourselves then for our grandchildren.

A twenty-foot rise in a hundred years should do the trick.

However, Al has a problem, the snowline altitude.

The snowline altitude is the altitude of the lowest elevation interval in which minimum annual snow cover exceeds 50%. This ranges from about 5,500 metres above sea-level at the equator down to sea level at about 70° N&S latitude, depending on regional temperature amelioration effects. Permafrost then appears at sea level and extends deeper below sea level polewards.

As most of the Greenland and Antarctic ice sheets lie above the snowline and/or base of the permafrost zone, they cannot melt in a timeframe much less than several millennia; therefore it is likely that they will not, through melting, contribute significantly to sea level rise in the coming century. They can, however, do so through acceleration in flow and enhanced iceberg calving.

The fact that the Antarctica and Greenland snowlines will prevent rapid ice cap melt for thousands of years is so obvious that it is easy to overlook. Right, Al?

Without the rapid and massive melting of these ice caps, sea level increases will largely be limited to the thermal expansion of the oceans. As any fool soon learns from comparing the volume of the oceans to the solar energy necessary to drive expansion, this too is a long, slow process.

This is not to deny that sea levels rise during warming, since it has been often mentioned in my previous blog posts that they have risen over 400 feet in the past 18,000 years since the end of the last Ice Age, an average of two feet per century. My point in constantly revisiting this is that previous greater warming of much greater ice sheets did not produce the sea level increases predicted by Apolcalyptic Al.

If not then, why now, Al?

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