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Global Warming circa 10,000 BC

Pleistocene_north_ice_map With the advent of accurate mapping, high-resolution satellite imagery, and expensive beachfront property, we view the Earth's geography as static and unchanging.  Sure, the continents looked very different when the dinosaurs roamed, but that was 100 million years ago.

Today's landscape is a pre-printed game board.  The unchanging surface on which we, our children, and our children's children will live our lives.  When the size of a river delta grows or shrinks, people cry foul.  When a barrier island is ravaged by storm, people cry foul.  When a drought causes productive farmland to become arid, people cry foul.  Inevitably, the Army Corp of Engineers is brought in to make things right.

Driven mainly by human urban and industrial activity, our planet is undergoing a rapid climate change.  The Earth is in transition from a moderate inter-glacial period into something hotter.  Our use of fossil fuels and resultant greenhouse gases heat our planet.  Our cities create localized heat islands of concrete, pavement, and glass.  Even without our influence, climate and geography are never fixed.  A beneficial climate may last for generations, but our Earth never stands still.

Many of us have seen maps of Pangea, the global supercontinent during the dinosaur age.  Although our imaginations can wander it's unknowable surface, it is very abstract to us.  No humans explored its mountains or shores.  No intelligent beings made maps and wondered 'Why is this here?"

The Earth at the end of the last ice age is more real because our ancestors lived it.  Pre-historic humans lived on and around the glaciers.  And, this ice retreated, our ancestors moved in.  What had once been buried by 2 mile thick sheets of ice became fertile farmland and hunting grounds.  As the weight of the ice was lifted, the land underneath rebounded, gaining in altitude.  As the ice melted, the seas rose.  Countless numbers of our ancestors died in catastrophic floods as rising temperatures caused natural ice dams to fail and release massive lakes of meltwater onto the landscape.

If an altered climate changed the world so drastically during recent glacial periods, how will the Earth be changed 2000 years from now.  How long will it take Mother Nature to wash away the impact of our industrial lifestyle?

The real question about global climate change isn't whether our Earth will survive our insults, but whether or not we are capable of living in the world we create.

The last ice age, the Wisconsinan, reached it peak around 18,000 years ago.  By 12,000 years ago, glacial melting was in full effect.  To understand the last ice age relative to human activity, one remembers that modern humans had settled Europe by at least 35,000 years ago.  These were the kind of people that lived in small communities, had calendars, buried their dead, created artwork, cared for their sick, and would hunt in well-coordinated groups.  These people had language, not animal grunts and noises.  These ice age people were no different from us.

The links below offer a selection of ice age geologic features across North America and Europe.  Learn how quickly larger-than-life landscapes can change on the whim of Earth's climate.  Try to imagine trying to survive in a time of such catastrophic change.

Glacial Lake Missoula - The size of Lake Erie and Ontario combined, this glacial lake covered most of Montana's western edge.  It contained over 500 cubic miles of water.  When the dam of glacial ice failed, it released a catastrophic flood that released this entire quantity of water overnight across Idaho, Oregon, and Washington.  This massive torrent carved out Grand Canyon-sized features in the blink of an eye.

Long Island - Over 4 million people live on Long Island.  Did you know that it's geological origins are fairly recent?  In fact, the earliest humans to arrive would have found an uninterrupted plain leading from Connecticut out to the Atlantic where the shoreline was 50 to 70 miles south of its present location.  Long Island Sound didn't even exist.

Coastlines and Sea Levels Around the World - At the height of the last ice age, sea levels were 100 meters (109 yards) lower than they are today.  As the ice age came to a close, the sea began to rise.  Each year of glacial melting released vast quantities of water into the Earth's oceans.  For decades, the sea level rose at least one foot per year.  In areas with gentle sloping land, this meant the sea could move inland by a mile or more in a single year.  And, it would continue to grow, year after year.  Considering man's ties to the sea and his dependence on it for food, it is no surprise that we don't find evidence of pre-historic settlements along the Earth's seashores.  They have long since drowned under the ocean.

Black Sea Deluge - As the Earth's water increasingly became bound up as glacial ice, ocean levels dropped.  The Black Sea connects to the Mediterranean through the Bosporus, a thin silty channel.  With water levels low, the two bodies of water were separated and the Black Sea existed as a smaller, freshwater lake for thousands of years.  A new theory posits that around 7000 years ago, as the ice melted and the Mediterranean rose, it burst through the Bosporus in a sudden rush.  The volume of water at the break would have been greater than 200 times that of Niagara Falls.  Within a year's time over sixty thousand square miles of landscape were under water.

January 22, 2006 in History | Permalink

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Comments

A perspective on global warming - On the one hand, the Earth has undergone heating and CO2 levels much greater than what we have now or are expected to produce within the next 100 years. Perhaps the biggest problem related to the current global warming induced by industrial activity is that it is happening so rapidly that the Earth's natural processes cannot adjust. Since the industrial revolution began, CO2 levels have risen from 280 parts per million to 380 ppm today. Such an increase in just a couple of centuries has never, to my understanding, ever occurred before. Natural changes in the past occurred over thousands or millions of years.

Posted by: Stephen | Mar 1, 2008 9:34:50 PM

Gentlemen:

The earth has been warming since the retreat of the glaciers in a contant state. That you fail to understand that we human have little or no impactmve the Sun, Oceans and volcano is beyond 25,000 American
scientists who sign a document stating that fact.

Posted by: Robert Breen | Mar 2, 2010 7:37:36 PM