Because most philosophies that frown on reproduction don't survive.

Tuesday, August 18, 2009

Blame the Neolithic

A brief article in The Economist relays some evidence a palaeoclimatologist has recently put forward that anthropogenic global warming began 5000-7000 years ago, as a result of slash-and-burn agriculture spreading throughout Europe and Asia. Or to be less exciting, ice core samples show that CO2 and methane levels started rising 5000-7000 years ago, and since it's known that agriculture was spreading widely at that time, Dr. William Ruddiman of UV Charlottesville (among others) argues that early agriculture may be to blame. Although the world population 5000 years ago was obviously much smaller, the efficiency of agriculture was so much lower (Ruddiman estimates per capita land use was 10x higher than in recent recorded history.

The idea of early societies causing heavy environmental tolls is not new. There's fairly wide support for the idea that deforestation and over-mining contributed to the collapse of the Bronze Age cultures in the Mediterranian. However, the idea that "global warming" started with the late neolithic is kind of charming. Please consider adopting a more hunter-gatherer lifestyle!

More practically, this strikes me as underlining that there is not some single, sacred, stability point which industrial civilization has destroyed. We humans and our planet have always had an effect on each other, and it's virtually impossible for us to avoid that. The course of wisdom lies in trying to avoid making more impact than necessary (while not setting unrealistic goals or stiffling development) and being prepared to deal with unwanted effects that may occur.


Anonymous said...

True. Zoologists long ago noted the striking coincidence that extinctions of large fauna seemed to quickly follow human settlement of a continent (mammoths and saber-toothed tigers in North America 13,000 years ago, for example). And the most interesting thing about Easter Island is not those big weird statue-heads - it's the blinding (to a naturalist) evidence that the island was once heavily forested, yet has not a single tree today. Environmental destruction appears to have been a human trait from the very beginning, not just something that came about with industrialization or western culture.

But one thing is different today: we can recognize the damage that we are doing before it becomes irreversible, and we have the ability to stop it.

Question: why did you put global warming in quotation marks?


Darwin said...

An attempt to distinguist "global warming" in the political/environmentalist sense of the-earth-is-getting-warmer-and-it's-our-fault from the simple fact of temperatures being warmer.

After all, it's been well known for some time that temperatures started increasing around 3000 BC -- it's just that it's never been suggested this was anthropogenic before. (And to be honest, this strikes me as at best a loose correlation, not clear causation.)

I'd agree with you that we have more ability to know about the effects of our actions than before and try to do something about it -- but at the same time I think it's important to be honest with ourselves about how much ability we actually have. Claims of "we're going to reduce our CO2 emmissions by 80% in 25 years" are, to our current knowledge, totally impossible, and it strikes me as irresponsible that such goals are talked about so often.

Darwin said...

distinguish, not distinguist

Big Tex said...

Well, if we are to reduce CO2 emissions, we really need to focus on the largest emitter of CO2... the oceans. But as I understand it, increased CO2 levels in the atmosphere are a result of warmer temperatures, not a cause. As the earth goes through a warming cycle, CO2 that was dissolved in the ocean is gradually released. Case in point, ever notice how warm sodas fizz more than cold ones when pouring it into a glass? Similarly, one manner in which to carbonate your kegs of homebrew is to place it under pressure and keep it cool... CO2 will gradually dissolve into the liquid. Cooler temperatures allow for greater amounts amounts of CO2 to dissolve into my beer. This is why increases in CO2 seem to lag the temperature increases by about 800 years.

Anonymous said...

Big Tex, cite a source for that, preferrably something peer-reviewed. Everything I have ever read says that the oceans are a carbon sink. (frex, algae consume CO2. Coral consumes CO2. Water dissolves some CO2.)


CMinor said...

I'd read mention of this hypothesis a few years ago--interesting that it's been followed up; I'll have to read up.

Please consider adopting a more hunter-gatherer lifestyle! Now there's a picture! We've had so much poke sprout up in our backyard this year that I reflected while weeding that we could hold out for quite a while on the stuff in the event of a food-supply- interrupting catastrophe. It makes me feel awfully hunter-gathery, but I suspect the kids would take death over poke salad every night.

Foxfier, formerly Sailorette said...

Heh, I'm just waiting for folks to calculate out the guessed mass-burning of the grassland in the middle of America and add that to calculations....

On the "Oceans/CO2" thing, if I remember right the living plants in the water of the ocean are a lovely CO2 sink-- but the volcanoes under the water are the primary CO2 source, as is the rotting plant matter.