Clark Spencer Larsen form the Department of Anthropology, The Ohio State University, has recenty published a paper in
Quaternary International outlining how agriculture was impacting on the environment, including climate, 10,000 years ago.
Titled, ‘The agricultural revolution as environmental catastrophe: Implications for health and lifestyle in the Holocene’ its conclusions include:
“Most of us are well aware of the dramatic changes in the Earth’s landscapes as forests give way to agricultural land, and the resulting environmental degradation, loss of species, and other disasters. A common misperception is that prior to modern times, humans were much more concerned about managing their environment so as to avoid the problems that have surfaced in such a dramatic fashion in the 20th century. However, study of ancient landscapes in Mesoamerica, North America, and the Middle East
shows evidence that earlier agriculturalists had profound impacts, highly negative in some areas, on the lands they exploited.In the Mediterranean basin, for example, nearly all landscapes were degraded or otherwise transformed in dramatic ways.
The analysis of the past reveals that the current threats to the landscape have their origins in the period of human history when plant domestication began 10,000 years (or so) ago.
Finally, once the effects on Earth’s climate by industrial-era human activities-the so-called greenhouse effect-were recognized, a number of workers assumed that it related to just the last couple of hundred years. However, new evidence of anamolous trends in CO2 and CH4 possibly owing to agricultural-related deforestation after about 8000 years ago, indicates that the negative impact involving greenhouse gases began soon after the start of agriculture.”
So organic farming is not necessarily the answer?
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Hey, slow down! Agriculture (human activity) producing anomolous greenhouse gasses since 8,000 years ago? Makes sense, though, since there have been plenty of climate change events recorded since agriculture began. Gosh, those naughty humans have been at it for quite a while.
But this knocks a few holes in the AGW fixation on blaming the last 200 years of industrial emissions for the current slight surface warming, doesnt it?
That’s the trouble with too much research. Can mess up nice handy theories.
This anthropologist takes a rather free-wheeling approach to the notion of “negative environmental impacts.” Negative impacts, according to whom? Well, according to humans, we must suppose. But then there are ventriloquists who claim to speak “for the environment,” so I guess he means, “negative according to the environment.”
The environment has lots of stuff in it, but it doesn’t have *attitudes*. So we could have some heavy-duty anthropomorphizing going on here.
Then there’s the basic question of what “negative” means. One man’s forest is another man’s pasture is another man’s field is another man’s housing development.
What *is* clear is the growing consensus: Any human-induced change in the environment is negative. That even includes a hunting-and-gathering lifestyle, which puts tasty weeds and slow-moving animals at a disadvantage, with downward pressure on their populations.
Maybe anthropologists should stick to anthropology.
Schiller.
Not a bad attempt at portraying humanity as original sin, farmer as vandal. 8000 years ago we were only recently out of an ice age. We modified our landscape to enable more of our children to survive to adulthood. This included improved nutrition, improved crop production and, so it is said, a warmer climate.
And the judgement of history will be that we continued to improve our lot, and warm our planet, until clear evidence indicated that the warming, if it exists, is both excessive and would produce more adverse impacts than beneficial outcomes.
The jury is still out.
Careful guys – sign off on this and you’re saying that greenhouse gases have actually had an effect. So a lot more will have a lot more of an effect. The difference between one teaspoon and six tea-spoons of sugar in your coffee. Better to argue that it’s all nonsense and stay philosophically safe.
And negative effects – perhaps no soil ? – lots of overgrazing in the Middle East and Mediterranean – time to get out the bible for a lesson in land degradation. “Early floggers” should have had their leases under review.
Tim Flannery writes about pre-industrial agriculture and its role in AGW in his book “The Weather Makers”.
Helen is only making herself look foolish by acting as if this is some kind of new revelation that damages the AGW hypothesis.
This item cites Ruddiman, who probably did most of the important agricultural investigation on which this item is based.
Bill Ruddiman’s book Plows, Plagues, and Petroleum has just arrived in my library and I’m eager to read it.
Unlike Jared Diamond and Tim Flannery, Ruddiman has a career behind him studying and teaching about farming.
see
http://www.powells.com/biblio?show=0691121648
Plows, Plagues, and Petroleum
How Humans Took Control of Climate
by William F. Ruddiman
ISBN: 0691121648
Publisher:Princeton University Press
Synopsis:
Tackling the belief that humankind’s active involvement in climate change really began with the industrial revolution, Ruddiman’s provocative new book argues that humans have actually been changing the climate for some 8,000 years as a result of the earlier discovery of agriculture.
Publisher Comments:
The impact on climate from 200 years of industrial development is an everyday fact of life, but did humankind’s active involvement in climate change really begin with the industrial revolution, as commonly believed? William Ruddiman’s provocative new book argues that humans have actually been changing the climate for some 8,000 years–as a result of the earlier discovery of agriculture. The Ruddiman Hypothesis will spark intense debate. We learn that the impact of farming on greenhouse-gas levels, thousands of years before the industrial revolution, kept our planet notably warmer than if natural climate cycles had prevailed–quite possibly forestalling a new ice age. Plows, Plagues, and Petroleum is the first book to trace the full historical sweep of human interaction with Earth’s climate. Ruddiman takes us through three broad stages of human history: when nature was in control; when humans began to take control, discovering agriculture and affecting climate through CO2 and methane emissions; and, finally, the more recent human impact on climate change. Along the way he raises the fascinating possibility that plagues, by depleting human populations, also affected reforestation and thus climate–as suggested by dips in greenhouse gases when major pandemics have occurred. The book concludes by looking to the future and critiquing the impact of special interest money on the global warming debate. Eminently readable and far-reaching in argument, Plows, Plagues, and Petroleum shows us that even as civilization developed, we were already changing the climate in which we lived.
detribe – for anyone whose local library gets Scientific American magazine (or you can buy on-line)
Did Humans Stop an Ice Age?
Comments on “How did humans first alter global climate?” by William F. Ruddiman, Scientific American, March 2005
Caveat – this work is not with some ongoing debate and you need to consider the implications carefully.
http://www.realclimate.org/index.php?p=118
and
http://www.realclimate.org/index.php?p=223
(Ruddiman at RC)
Ian, Contrary to your comment, the article actually argues that early agriculture has not been good for human nutrition etcetera, check the abstract:
“In addition to altering landscapes around the globe from the terminal Pleistocene and early Holocene, the shift from foraging to farming resulted in negative and multiple consequences for human health. Study of human skeletal remains from archaeological contexts shows that the introduction of grains and other cultigens and the increase in their dietary focus resulted in a decline in health and alterations in activity and lifestyle. Although agriculture provided the economic basis for the rise of states and development of civilizations, the change in diet and acquisition of food resulted in a decline in quality of life for most human populations in the last 10,000 years.”
in more detail: I recall the farming of cereals (esp. maize?) caused bone deficiencies & dental probs & a drop in lifespan
Yes Thinksy is correct IMHO (and Graeme O’Neill’s too- he first told me about it and it took a bit of digging to condirm it).
But there is another, bigger science story that;s just hit the news that’s highly relevant, (IMHO too).
Mankind has evolved since farming began (shock, horror, Genes frequencies change !).
see my Good News Bad News posting at GMO Pundit
http://gmopundit.blogspot.com/2006/03/good-news-and-bad-news-about-farming.html
Early farming coincided with a period of great natural climate change involving the transition from the preceeding glacial period. How much, if any, of the purported environmental impacts were anthropogenic is highly problematic. Certainly there is abundant and repeated evidence that CO2 and CH4 levels have followed temperature by about a millenium.
Although primitive farming did provide a less much less varied diet than hunter/gathering modern agriculture provides a much greater one.
Modtran is probably the most advanced radiation model for the earth’s atmosphere. http://geosci.uchicago.edu/~archer/cgimodels/radiation.html and it indicates very little change in IR backradiaton with either a doubling of CO2 or even a halving of it. In fact to begin to make a significance difference requires a reduction of an order of magnitude below pre-industrial CO2 levels. In short the GH effect of CO2 appears to be effectively saturated at levels far lower than the preindustrial one and lower than Earth has ever experienced.
Thanks for sending me the copy of Ruddiman, Phil. But I have to rain on your parade as this is purely speculative stuff that fails a test of significance. While Ruddiman makes the odd reference to population changes, he fails to point out that the estimated population of the planet 5000 years ago was only 50 million people.
According to Dr. Michael Pidwirny, Department of Geography, Okanagan University College at,
http://www.geog.ouc.bc.ca/conted/onlinecourses/geog_210/210_3_4.html
“Prior to the agricultural revolution, the size of the human population was probably only a few million individuals surviving primarily by hunting and gathering. With the domestication of plant and animal species about 10,000 years ago, the human population experienced an increase in growth. By about 5000 BC, food production gains caused by the agricultural revolution, enabled the planet to support about 50 million individuals. For the next several thousand years the human population continued to grow at a lower but steadily increasing rate of about 0.03 % per year. By the year 1 AD the human population numbered about 200 million”.
And these 50 million people were in family units of at least 5 people. And these family units were only able to cultivate an area of about 1 hectare. So this meant that the claimed global change was triggered by only 10 million hectares of cultivation.
More importantly, only about half of this was in Asia and not all of that population was concentrated on the chinese irrigated lands.
Furthermore, Ruddiman appears to be under the impression that rice paddies remain under water all year round. This is simply not true as the innundation is only maintained for the few months that it takes for the rice to grow. It must be drained to allow the grain to mature and dry out. After which it remains like any other dry paddock for at least 8 months of the year. Ergo, it seems that rice farming only produces methane while the field is under water.
So the claimed spike in methane from rice farming could only have come from about 4 million hectares for about a third of each year. And this, I am sure, would be only a very small portion of the total area of year round wetland in the world at that time.
So, again, good story, pity about the lack of a test of significance applied to the facts.
But the photo was good. Especially the large area of retained vegetation and the clearly visible regrowth to be seen on previously terraced land. And note the houses built on the steeper land so as not to waste good agricultural land.
And before we go blaming all the bare hills of the Greek Islands on anthropogenic deforestation, as appears to be the fashion, for those quoting Homer’s descriptions of forested islands, it is worth remembering that the forests of those regions were not fire tolerant and may be able to trace their absence to the little blast that took the top clean off Santorini. It was enough to wipe out the Minoans on Crete and the the much closer Cyclades islands would have suffered more and longer and hence failed to regenerate.
I wonder if Ruddiman overlayed volcanic activity over his CO2 data? How many hectares of early agriculture would be equivalent to Santorini & Pompei?
Ian – as I said above “Caveat – this work is not with some ongoing debate and you need to consider the implications carefully.”
My parade was already damp from recent philosophical precipitation on this hallowed blog.
On volcanoes – depends of how long the effect lasts.
Anyway back of Ruddiman – so if you have done the smart thing and don’t think it’s adds up – (safer contrarian ground) – so we’ve now got 270 ppm to 380 ppm now to contend with, and increasing.
But is interesting to ponder what emissions early agricultural land clearing and rice cultivation may have caused – where’s that envelope Ian? (And I’m not agriculture bashing here either – just interested).
Walter – I don’t buy the saturation argument. There’s plenty written on that issue.
http://www.aip.org/history/climate/Radmath.htmhttp://www.realclimate.org/wp-comments-popup.php?p=171&c=1 see comment 15
http://www.aip.org/history/climate/co2.htm
Also speaking of ModTRAN – this paper is an empirical measurement of the greenhouse flux in recent years using ModTRAN in part!
Radiative forcing – measured at Earth’s surface – corroborate the
increasing greenhouse effect
Rolf Philipona,1 Bruno Du¨rr,1 Christoph Marty,1 Atsumu Ohmura,2 and Martin Wild2
Received 3 October 2003; revised 3 December 2003; accepted 23 December 2003; published 6 February 2004.
[1] The Intergovernmental Panel of Climate Change
(IPCC) confirmed concentrations of atmospheric
greenhouse gases and radiative forcing to increase as a
result of human activities. Nevertheless, changes in
radiative forcing related to increasing greenhouse gas
concentrations could not be experimentally detected at
Earth’s surface so far. Here we show that atmospheric
longwave downward radiation significantly increased
(+5.2(2.2) Wm2) partly due to increased cloud amount
(+1.0(2.8) Wm2) over eight years of measurements at eight
radiation stations distributed over the central Alps. Model
calculations show the cloud-free longwave flux increase
(+4.2(1.9) Wm2) to be in due proportion with temperature
(+0.82(0.41) C) and absolute humidity (+0.21(0.10) g m3)
increases, but three times larger than expected from
anthropogenic greenhouse gases. However, after
subtracting for two thirds of temperature and humidity
rises, the increase of cloud-free longwave downward
radiation (+1.8(0.8) Wm2) remains statistically
significant and demonstrates radiative forcing due to an
enhanced greenhouse effect. INDEX TERMS: 0325
Atmospheric Composition and Structure: Evolution of the
atmosphere; 1610 Global Change: Atmosphere (0315, 0325);
1620 Global Change: Climate dynamics (3309); 1640 Global
Change: Remote sensing; 3359 Meteorology and Atmospheric
Dynamics: Radiative processes. Citation: Philipona, R., B. Du¨rr,
C. Marty, A. Ohmura, and M. Wild (2004), Radiative forcing –
measured at Earth’s surface – corroborate the increasing
greenhouse effect, Geophys. Res. Lett., 31, L03202, doi:10.1029/
2003GL018765.
I don’t accept the 270 ppm level as proven because all values over 290 ppm were “smoothed” or eliminated on the assumption that they were from biological contamination. This is clearly a prejudgement that will have an impact on the outcome. Especially as it appears that excessively low levels were left in.
And the critics of Jarowosky have still not refuted his claim that there are at least 20 types of contamination in ice core sampling which can all effect the recorded CO2 levels.
We have evidence of data records being eliminated entirely for having high reading contaminants. So there is clear recognition that contamination takes place but it is selective. All I have seen to date is criticism of him for failing to find a solution to those contamination problems but with no recognition that contamination could also decrease recorded readings. Most of the other criticisms of Jarowosky hinged on interpretation of his language to imply a fraudulent intent when, from my reading, it merely reflected usage that was quite consistent with language commonly employed by users of English as a second language. Not good enough.
1. the comment that rice fields are only flooded for a few months. Depends on how many crops of rice you produce in a year. some parts of Indonesia can manage 3, and 2 is also quite common in SE Asia.
2. The archaeological record is full human impacts on the environment. e.g. aboriginal use of fire as a hunting tool in Australia and sub-Sarahan Africa changed the vegetation, iron smelting in West Africa and Southern Africa cleared many forested areas. Nomadic cattle herders in the Sahel burning grasslands in the dry season…..all of these impacts have been there a long time and continue. I thought the debate is one about scale?
Geez…
Whilst you guys are arguing the toss about who is good: (me! me! me! link! link! link! and more link! link! ) the rest of the world has moved on.
Rog – true but .. ..
Those who cannot learn from history are doomed to repeat it.
George Santayana:
I must correct one possible misconception from my earlier post. Of the 50 million people in 10 million odd families it is wrong to assume that they were all static cultivators. 5000 years ago all of Australia, Nth America, Sth America, Southern Africa, most of Indonesia (less Java) and much of Europe were still hunter gatherers or shifting cultivators.
And this would account for about half the total population of the world at that time. And this population was making minimal net CO2 emissions because they were in a very well established pattern of burning and regeneration.
True, slash and burn agriculture can produce some significant emissions but these would be returned to a regrowth forest sink in less than a century. And remember, these were much smaller populations than today and their impact was much less and, therefore, more easily repaired by nature.
So while the AGO and IPCC can do perverted things with regrowth forest sinks, the agriculture at that time was essentially in equilibrium. The removal of forest by man created the capacity of that site to subsequently absorb the same amount of CO2 as was originally emitted.
The same goes for firestick farmers. 5000 years ago they were already in a new equilibrium where the volume of CO2 burned each year was re-absorbed over the following years until burned again.
If there was an early anthropogenic impact on CO2 levels it would have been when blackfellas first arrived in Australia and introduced the fire regime that modified the landscape. But that was 50,000 to 60,000 years ago, not 5000 as Ruddiman has claimed. Ditto the North American modification.
So that leaves us with about 4 million hectares of static cultivation in about 10 regions that is supposed to have bucked the global climate trend line. Fat chance.
It is also worth noting that Ruddiman is drawing inferences from the three earlier CO2 peaks over the past 400 millenia and trying to suggest a pattern which is broken by the most recent one. But three events does not a pattern make, especially when they are as varied as the ones we have had.
Having read Ruddimans book quickly (skipping some parts I’m familiar with) I found it very refreshing. An independent look at climate thats not bogged down in the entrenched and somewhat tedious (IMHO)positions often displayed here for instance. Im more accustomed to looking at speculative hypothesis constructively as well as destructively, and supending disbelief for a while on innovative ideas. Wegener was “wrong” about continental drift for a long time before he was eventually proved right. Ruddiman might even be a Wegener.
He really does raise interesting questions about the odd time course of atmospheric CO2 and Methane over the last 8000 years. He’s had to revise his original hypothesis substantially in light of criticism, and that interesting too.
I found his fig 12.2 really fascinating, showing records of Sea-Ice blocking seaports in Iceland stretching back to the year 1000AD. From 1000 AD to 1200Ad they were ice free. During the “Little Ice Age 1600 AD to about 1960 AD they were blocked with Ice many weeks of the year.
The medieval warm period certainly existed in Iceland!, and we’ve only just left a mini-ice age on these data.
I was wrong though, in what I said before implying he knows huge amounts about agriculture – there relatively little of that in the book. He’s more a climate specialist.
The recent discoveries that trees emit methane might give strong support to parts of his hypothesis though.