Columbus Blamed For Little Ice Age

In the October 22 Issue:

Columbus blamed for Little Ice Age

Depopulation of Americas may have cooled climate

By Devin Powell

Web edition : Thursday, October 13th, 2011

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MINNEAPOLIS — By sailing to the New World, Christopher Columbus and the other explorers who followed may have set off a chain of events that cooled Europe’s climate for centuries.

The European conquest of the Americas decimated the people living there, leaving large areas of cleared land untended. Trees that filled in this territory pulled billions of tons of carbon dioxide from the atmosphere, diminishing the heat-trapping capacity of the atmosphere and cooling climate, says Richard Nevle, a geochemist at Stanford University.

“We have a massive reforestation event that’s sequestering carbon … coincident with the European arrival,” says Nevle, who described the consequences of this change October 11 at the Geological Society of America annual meeting.

Tying together many different lines of evidence, Nevle estimated how much carbon all those new trees would have consumed. He says it was enough to account for most or all of the sudden drop in atmospheric carbon dioxide recorded in Antarctic ice during the 16th and 17th centuries. This depletion of a key greenhouse gas, in turn, may have kicked off Europe’s so-called Little Ice Age, centuries of cooler temperatures that followed the Middle Ages.

By the end of the 15th century, between 40 million and 80 million people are thought to have been living in the Americas. Many of them burned trees to make room for crops, leaving behind charcoal deposits that have been found in the soils of Mexico, Nicaragua and other countries.

About 500 years ago, this charcoal accumulation plummeted as the people themselves disappeared. Smallpox, diphtheria and other diseases from Europe ultimately wiped out as much as 90 percent of the indigenous population.

Trees returned, reforesting an area at least the size of California, Nevle estimated. This new growth could have soaked up between 2 billion and 17 billion tons of carbon dioxide from the air.

Ice cores from Antarctica contain air bubbles that show a drop in carbon dioxide around this time. These bubbles suggest that levels of the greenhouse gas decreased by 6 to 10 parts per million between 1525 and the early 1600s.

“There’s nothing else happening in the rest of the world at this time, in terms of human land use, that could explain this rapid carbon uptake,” says Jed Kaplan, an earth systems scientist at the Federal Polytechnic School of Lausanne in Switzerland.

Natural processes may have also played a role in cooling off Europe: a decrease in solar activity, an increase in volcanic activity or colder oceans capable of absorbing more carbon dioxide. These phenomena better explain regional climate patterns during the Little Ice Age, says Michael Mann, a climate researcher at Pennsylvania State University in State College.

But reforestation fits with another clue hidden in Antarctic ice, says Nevle. As the population declined in the Americas, carbon dioxide in the atmosphere got heavier. Increasingly, molecules of the gas tended to be made of carbon-13, a naturally occurring isotope with an extra neutron. That could be because tree leaves prefer to take in gas made of carbon-12, leaving the heavier version in the air.

Kaplan points out that there’s a lot of uncertainty in such isotope measurements, so this evidence isn’t conclusive. But he agrees that the New World pandemics were a major event that can’t be ignored — a tragedy that highlighted mankind’s ability to influence the climate long before the industrial revolution.

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Found in: Earth and Humans

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Comments 11

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This is the silliest article I've ever read.... my God the moonbat Warmers are a desperate lot!

Robert Mileti

Oct. 14, 2011 at 10:23am
Nevle, I hate to break the news to you but you Climate Change scientists have not proven CO2 has any affect on the climate other than the political climate. It seems your study is nothing more than political wishful thinking.

spawn44 babo

Oct. 14, 2011 at 10:23am
It's an interesting theory but atmospheric CO2 is a weak and trace greenhouse gas whose heat-trapping potential is several orders of magnitude smaller than water vapor.

It seems more likely that the oceans cooled due to well-documented diminished solar activity and the cooler oceans absorbed more CO2.

David Snyder

Oct. 14, 2011 at 10:23am
Richard Nevle, and Devin Powell by giving him any credibility, have caused me to lose respect for Stanford University (although they do have a good football team). Some of these academics are absolute quacks. This concept is absurd ... lets go back 1000, 2000, 5000, 10,000 years or whatever and discuss how the expansion of the human population has impacted the universe. Good Grief!

John Hayes

Oct. 14, 2011 at 10:23am
This article gives too much coverage to the 'Politically Correct' piece of crap by this clown,Richard Nevle.
The "Little Ice Age" began long BEFORE 1492. The Pope in Rome sent Columbus a letter (after 1492) asking for Columbus to investigate, "what had happened to the Bishop of Greenland,"
because Rome had not had any letters from Greenland for many years. N.B. -- There were so many Catholics living in Greenland, that the Pope appointed a Bishop to live there.
The Middle Ages Warm Period had ended decades before, and could no longer sustain the European-style agrarian life-style.
Also, bear in mind that post-1500, World exploration meant required an exponential increase in wooden ships, both in number and in size. As a result, not only did population increase, but so did de-forestation. Indeed, perhaps the main export of the American Colonies was LUMBER. Even the export of tobacco,and then cotton required de-forestation.
By 1608, the well-known, but un-mapped 'Northwest Passage'
had frozen over to such an extent that Henry Hudson was un-able to complete his mapping. Re-forestation must have been exceedingly rapid to effect the entire Earth in such a short time.
Richard Nevle is proof of the adage that, "If the only tool you have is a Grant to prove A.G.W.(tm), then everything in the result of A.G.W.(tm)"

Bo Higgs

Oct. 14, 2011 at 10:23am
In the article, Jed Kaplan stated “There’s nothing else happening in the rest of the world at this time, in terms of human land use, that could explain this rapid carbon uptake”.

The key phrase here is "in terms of human land use". I think the theory is interesting, but it appears he was specifically looking for a way to tie this to a man-made event.

An additional question would be whether there is any correlation between the climate and the progress of the black plague across Europe (given that northern forests do not recover as fast as those in the tropics.

JPC

Oct. 14, 2011 at 10:23am
Looks like the liberal progressive mindset will go to any lengths to validate their ridiculous claims and to defame Columbus and America. Sickening that an agenda is driving these folks to pursue lies and then create new ones.

sdeakins

Oct. 14, 2011 at 10:23am
This is stupid stuff. The Global Warming crowd is just grabbing at straws here. The forrests of North America and South America were routinely burned by the Native population for eons every year. With the arrival of the Europeans, the forests were left alone and grew without interruption due to the collapse of domestic populations due to smallpox, influenza etc. As a result massive "virgin forrests" erupted all over the place. If anything there was a massive CO2 uptake as a result of the Spanish arrival. European CO2 emissions and depletion of the forrests dates with the Industrial Revolution which is 1820 and after! Would the Global Warming Crowd just shut up until they actually can get their facts together! Please learn our history. The Europeans viewed North America as a land inhabited by Giants (The American Indians were often 1 foot or more taller than the Europeans) with Mountains too high to climb, rivers too big to cross and with trees to big to cut down. This was due to 150 years of wild forrest growth! Get real people!

Paul Noel

Oct. 14, 2011 at 10:23am
Please note that the Trees stopped uptaking in about 30 years and the rest is just plain static terminal growth

Paul Noel

Oct. 14, 2011 at 10:23am
The author might just want to recheck the dates in the article. Columbus discovered America a few centuries AFTER Atlantic pack ice and Greenland glaciers began their advance.

The author, given the dates, could suggest that Columbus had some responsibility for the Maunder Minimum (period of reduced sunspots believed to have affected climate). It would make as much sense.

Grace Hatton

Oct. 14, 2011 at 10:23am
The Little Ice Age started around 1250. Columbus sailed in 1492. There is no connection between Columbus and the Little Ice Age.

Good Lord! I thought I was reading science when I logged onto sciencenews.org.

Cruithni Johnson

Oct. 14, 2011 at 2:37pm

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