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The Woolly Mammoth  (Source: Corbis/Royal BC Museum, British Columbia)

Ancient humans hunted mammoths, which some think contributed to their extinction.  (Source: On Charcoal)

Researchers in a new study claim that the extinctions, possibly triggered by man, caused the birch trees to take over in regions of Siberia, causing a warming effect of as much as 1 degree Fahrenheit.  (Source: EW Birch Builders)
Mammoth extinction 10,000 years ago may have led to as much as a 1 degree Fahrenheit increase in temperatures

Christopher Doughty, a post-doctoral researcher at the Carnegie Institution for Science in Stanford, California, has led a team of researchers that has reached some controversial and unusual claims about mankind's role in changing the Earth's climate.

Doughty, in a paper published [PDF] in the journal 
Geophysical Research Letters, claims that the extinction of woolly mammoths may have triggered a cascade of effects warming Siberia and neighboring Beringia by at least 0.3 to 0.4 degrees Fahrenheit.  If these controversial claims prove true, it would likely be the first example of man influencing the world's climate in humanity's brief history as a species.

The report may change preconceptions about climate change, claims Doughty; "Some people say that people are unable to affect the climate, that it's just too big.  That's obviously not the case. People started to affect global climate much earlier than we thought."

Previous studies had indicated that mankind's development of agriculture 8,000 years ago could have changed the Earth's climate, but the effects of hunting in mankind's earlier days were not thought to have had significant impact.  The new study draws its basis from a previous study in the November 20, 2009 edition of the journal 
Science.  That study indicated that mammoths kept small trees in check, preserving grasslands.  With their extinction, the darker trees grew, increasing the overall darkness of the terrain, absorbing more solar radiation, and ultimately triggering a warming effect.

The issue with that study was that it posed a chicken-and-the-egg sort of conundrum; warming climates would encourage tree growth over tundra grasslands, but tree growth could also 
trigger warming.  Doughty claims in his new study that in the 850-year period where most of the mammoths disappeared from hunting, the levels of birch pollen increased by 26 percent.  Using modern elephant data, it was estimated that 23 percent of this increase came from the death of the mammoths, while the rest was caused by the heating trend itself.

The team then compiled vegetation loss findings and climate simulations to pinpoint how much of an impact the forestation increased had.  They found that it likely raised temperatures from 0.4 degrees F to the nearly 1 degree F.

Doughty admits in the study that it's not been conclusively shown that humans caused the extinction of mammoths in the first place (again, this is a chicken-egg riddle as warming climates could have pushed them to extinction, but their extinction could have warmed climates).  Man did hunt the beasts, and its the prevailing theory that we played at least a small role in their extinction.

The study was funded by NASA and the Carnegie Institution for Science.

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RE: Bull!
By Amiga500 on 7/5/2010 3:41:53 PM , Rating: 2
Deferring to someone else's judgment does not make you just relieves yourself of the responsibility of thinking for yourself in the first place.

Actually, deferring to someone else's judgment is almost always a sign of someone who is smart enough to know what they don't know...

Better to hand a task off to someone else that knows more about the subject than plough on with little more than arrogance and hot air to get the job done.

RE: Bull!
By SPOOFE on 7/5/2010 4:06:03 PM , Rating: 2
Actually, deferring to someone else's judgment is almost always a sign of someone who is smart enough to know what they don't know...

Your comment does not clash with Reclaimer's; he is correct that deferring to another does not make one intelligent. In that situation, a sign of intelligence would be WHO one defers to, and why.

Better to hand a task off to someone else that knows more about the subject than plough on with little more than arrogance and hot air to get the job done.

Better still to keep a critical eye on that someone else and scrap him, his work, and his opinion when it starts to look fishy. It's not like there's any shortage of smart dudes with opinions, and embracing a variety of opinions and having them compete helps ensure that the best idea wins out.

RE: Bull!
By arachnid on 7/5/2010 9:27:52 PM , Rating: 2
More trees means less CO2, which should result in cooling according to their peers, right?

RE: Bull!
By gamerk2 on 7/6/2010 8:26:30 AM , Rating: 2
Read up on Albedo. Darker surfaces absorb more solar radiation [Heat] then ligher ones. [Black absorbs, white reflects; basic science]. Therefore, more trees covering the ice would darken the planets surface, absorbing more heat in the process. The effects of Albedo have been extensivly studied, since modifiying a planets albedo has long been considered a key to any terraforming attempts [NASA did a LOT of studies in this area in regards to Mars in the late 70's...]

The theory itself is perfectly sound; whether its true is another matter. But you see how quickly climate science turns into a mess, with all the regional/global/solar factors to consider. Yes, more trees = more O2 = more cooling, but you also darken the planet which leads to more heat absorbtion.

RE: Bull!
By JediJeb on 7/6/2010 6:02:24 PM , Rating: 2
I had a funny thought that would go along with the article in a bad way. If the trees lead to warming, then we should cut down all the dark trees of the rain forests and replace them with light colored grasses or just soil to offset warming.

Just as the end of the article says, they don't know what caused what or to what extent. It is all just a guess, just as mine about cutting down all the trees. The only way to know for sure would be to cut them down, which would be a terrible idea.

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