Around about the time the last Ice Age was ending on Earth, a number of extinctions occurred. Most notably the Woolly Mammoth, which had been thriving for tens of thousands of years, met its end around 4 thousand years ago.
Traditional thinking has been that the great beasts died out as the planet's climate warmed dramatically with a long period of thawing that started around 20,000 years ago. Adapted to millennia of cold, the animals simply weren't able to handle the climate change, and so they died out.
But recently scientists have begun to suggest that humans, with their big brains and hunting spears may have collaborated with climate change to hunt the Mammoth into extinction.
So who is the greatest killer of all?
New evidence is adding to the pile that humans win the prize for worst killers, at least for the last 10,000 years. Sure climate change played a role in thinning out the mammoths, but researchers are now reporting that humans probably killed off the Giant Kangaroo, Marsupial Rhino, and a host of other big animals (aka 'megafauna') that had been happily living in Tasmania until we showed up.
There's plenty of other evidence that humans are efficient murderers, and some people have argued that the planet has been so altered by our presence that the last 200+ years constitutes a new geologic period called the Anthropocene. Even worse, there's debate over whether the extinctions that began with the end of the Ice Age ever ended, or whether humans just took over where climate change left off.
Call it one big, 10,000 year-long extinction that's still going on today.
OK, so humans appear to be the clear winners in this morbid contest, right? Not so fast. As I mentioned last year in an article for New Scientist, non-anthropogenic climate change is now thought to be the cause of perhaps *every* one of the so-called Big Five mass extinctions in Earth's past. Yes, including the one that killed the dinosaurs 65 million years ago.
We homo sapiens have already shown ourselves to be prolific killers using nothing more than sharpened stones. The fact that modern society has stumbled on the greatest destructive power the planet has ever known -- climate change -- should make us very worried indeed.
Image: NASA, via UC Irvine
Michael I found your blog while doing reserach about Dr Ping at UAF and his new carbon pool study in NAture GEosience you wrote about. and you talked to Dr Ted SChuur too in Florida about this stuff below, maybe 300-500 years in future.
I wonder if you could write a story one day SOON about my POLAR CITIES idea, and what it is I am doing with it and why. Like Ted, I believe that by year 2500 we will be in deep doo and will need these kind of adaptation strategies. NEW YORK TIMES dot Earth interviewed me last MArch for story on blog,. can you do follow up, i have more NEWS for you
email me here
danbloom@gmail.com
Tufts 1971
That's not enough to make much difference by the year 2100, but Ted Schuur of the University of Florida thinks we need to look further into the future.
In a paper to be published in the September issue of the journal Bioscience, he estimates that 1,672 billion tons of carbon are locked in Arctic permafrosts, much of it in Siberia. The carbon leak is slow -- he estimates it could only be as high as 1 billion tons each year worldwide, or about 10 percent of what is emitted today through human activity emissions. But over the next four centuries it could end up in the atmosphere, drastically altering Earth's climate.
"The Ping paper is great so far as it goes, but it's only dealing with this one zone: North America," Schuur said. "That's like describing what an elephant looks like by talking all about its foot. We're trying to describe the whole elephant."
If Schuur's estimate is right, Arctic soils harbor two to three times more carbon than is currently aloft in Earth's atmosphere. If it were to be released as greenhouse gases over the course of the next few centuries, the effect on the climate might not be noticeable by the year 2100. But by the year 2400 or 2500 it would be tremendous.
"Right now there's about 780 billion tons of carbon in the atmosphere. And now you say you're going to take and slowly put much of 1,600 billion tons from the soil up there. That's going to have a huge effect on the heat-trapping capacity of the Earth," Schuur said.
"Say you look at Earth in 500 years," he said. "It's probably going to be a very different place."
Posted by: danny bloom | August 26, 2008 at 09:41 AM