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Changing Arctic

Climate Change Gave Humans Opportunity to Enter, Travel South Through North America


Climate change and the settlement of the New World …

Long before climate change became politically-heated buzzwords, archeologists were using the term to describe conditions that often required early humans to adapt or migrate to a more hospitable place.

For example, climate change is thought to have enabled humans from Asia to cross over into North America some 13,000 years ago, and then, to have opened up a route to the south through ice sheets that covered most of the continent.

UAF archeology professor Ben Potter at the Mead Archeological Site in Alaska's Interior.

“We want to understand what enabled people to then actually make that leap,” says University of Alaska-Fairbanks archeology professor Ben Potter. “How were they able to adapt their technology, their social organization, their mobility in order to expand into the New World?”

North America's glacial extent varied over milennia in North America as the smaller Cordilleran ice sheet, which covered the Canadian Rockies near the west coast, and the much-larger Laurentide ice sheet that dominated northcentral and northeastern North America waxed and waned. The red dots show sites where archeologists have found evidence of habitation by the New World's first settlers.

Potter and five co-authors attempt to answer those questions and others in a new study published last month in the scholarly journal Quaternary International. They suggest the New World’s first settlers could’ve taken an inland or coastal route, or both, in their trek southward during the most recent ice age.

“The question, of course, is how did the Native American ancestors expand into North America south of the ice sheets?”

Scientists believe the ancestors  were able to cross over from Asia because the ice age had locked up so much of Earth’s water that the sea level was hundreds of feet lower than today, leaving the so-called “land bridge” between the two continents high and dry. Subsequent warming over the next few thousand years opened up passages in the ice sheets to enable the people to move southward.

“So there’s a lot of debate on when was that possible,” he said in a recent interview. “When did the ice recede enough that there would be openings in order to permit travel?”

Potter says the findings in his and other archeological studies should prove useful information to scientists who are analyzing changes caused by global warming now under way.

“What archeology can provide to this issue is time – time depth,” he said. “Big changes, changes that aren’t observable over a window of a season or 10 years or 20 years, but a millennia.”

But Potter says it’ll be a challenge to apply that knowledge to today’s climate change, because it’s being caused by humans – and it’s occurring much faster than any other known to science.