Friday, June 26, 2009

Glaciers, moraines and global warming

Yesterday, on a hot, hot, humid, humid, heat stroke warnings on TV afternoon I walked down the steep slope of the Elver Park moraine to the algae covered kettle pond at the moraine's bottom. For once I had the park almost to myself. Normally the bike path and wooded trial that start at the back parking lot have their share--and more--of bikers and runners this late in the afternoon. But today--except for one hardcore and heat impervious biker--I saw no one. Global warming had engulfed Madison.

Nine to ten thousand years ago the scene would have been different. The moraine marks the farthest push of the last of the glaciers that have scraped the Midwest flat. From the bottom of the kettle pond--formed when a ten acre glacial ice cube melted and the ground level dropped--to the top of the moraine looked to be about 400 feet. There had been a lot of ice here when mammoths and mastodons and saber tooth cats roamed the frozen tundra to the south.

So what, you might ask. The ice ages are over. Except in cute animated movies.

But the ice ages are NOT over. We are in an interglacial period--a period of warmth when the glaciers retreat north. Once there they begin to recollect snow and ice so they can advance south again. Then they hang around for a couple hundred thousand years.

Happened four times in the last million years. The basic causes of the glaciers--the earth's tilt and orbit, the heat output of the sun, and the routes of the ocean's currents that move or don't move heat from the south to the north--have not changed. So there is no reason to think that it won't happen again.

Quess what. Interglacial periods last an average of ten thousand years. And since the ice was here nine to ten thousand years ago--so it's about time to think of selling your Canadian fishing lodge. We might be in for a long cold snap.

Far fetched. Not really. Starting around 1400 Europe--the only northern area where anyone wrote about the weather--had its Little Ice Age. Glaciers moved down the Alps. Bad weather lead to famine and peasant revolts. Even the Thames river at London froze over solid for several weeks in 1815. Something that hasn't happened since.

Why?

1815, the start of the Industrial Revolution. Ever since then we have been dumping more and more CO2 into the atmosphere, trapping more and more heat from the sun and melting arctic ice at a rate never measured before. The great and evil global warming.

But what would have happened without global warming. Would the Little Ice Age be still with us--long bitterly cold winters, short growing seasons and a frozen Thames almost every year.

A contrarian position, I know. Not at all. political correct. But something to ponder as I sort through the images of moraines and kettle ponds taken on a hot hot day along the Ice Age Trail

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