Man changed climate for 8,000 years?

[Shyriath]

http://www.cnn.com/2003/TECH/science/12/10/prehistoric.climate.ap/index.html

-- Measurements of ancient air bubbles trapped in Antarctic ice offered evidence that humans have been changing the global climate since thousands of years before the industrial revolution.

Beginning 8,000 years ago, atmospheric levels of carbon dioxide began to rise as humans started clearing forests, planting crops and raising livestock, a scientist said Tuesday. Methane levels started increasing 3,000 years later.

The combined increases of the two greenhouse gases implicated in global warming were slow but steady and staved off what should have been a period of significant natural cooling, said Bill Ruddiman, emeritus professor at the University of Virginia.

The changes also disrupted regular patterns that dominated the 400,000 years of atmospheric history that scientists have teased from samples of ancient ice.

[Dogmudgeon]

1. The Chicken, the Egg, or the Campfire?

I'm not so certain this was due to human activity; you could make a strong argument that Humanity's development of civilization was a result of the warming.

8000 year ago, the Younger-Dryas mini-ice-age had come to an end, and temperatures all over the globe increased by an average of ten degrees. This would have allowed more extensive travel by early humans of all "flavors" (Modern, Neanderthal, or other subspecies).

I'd also argue that the warming was part of a natural cycle. The Wisconsin/Würm glacial period lasted 110,000 years. It was certainly time for an "interstadial" period of about 10,000 years to start. This pattern has been going on, with great regularity, for more than 2 million years (20-25 cycles).

Actually, the Younger-Dryas period was the exception to the rule.

I don't think Humanity has as much impact on overall global heat as we currently think; but I do strongly believe that the changes we cause in heat-distribution flows in the ecosphere have very profound effects. Either way, I take strong issue with the "global warming debunkers" for their spun science.

I also think it's close-to-certain that we are "kindling" ourselves into a prematurely quick return to "stadial" (that is, galcial) conditions.

--bkl

[Stilgar]

2. Could not have put that better myself

I think we have areas of local warming that are man made (urban heat sink) but I think the overall climate is going to do what it wants.

We call large floods global warming and account damage in floods as rising costs. QUIT BUILDING ON FLOOD PLAINS. If you see a dike, dont be surprised when the flood comes.

[Boomer]

3. A UK report on this theory

http://www.guardian.co.uk/life/dispatch/story/0,12978,1108851,00.html

The idea is likely to spark debate among climate scientists, but at least one sceptic is changing his mind. "I hadn't fully appreciated the magnitude of the human disturbance," says Thomas Crowley, who works on global warming at Duke University in Durham, North Carolina. "I've been thinking more and more that Ruddiman is on to something."

[johnnybama]

4. global warming

I really don't think man has any affect on the global climate. Global warming and cooling have gone on since the beginning. It is a naturally occuring event. Just my opinion