Foretelling the Future
I’m in an archaeological state of mind.
This week I will be traveling and working on some new assignments. So blogging will be light–and probably archaeologically related. On that note, I recently came across this neat story that talks about the use of computer modeling in archaeology, and the similar aims and challenges it shares with climate modeling:
Archaeologists can treat the past as a proving ground for calibrating their models. This allows them to refine a model and improve its accuracy before it is applied to contemporary situations by soil and agricultural scientists. “If we can predict the past really well, then that gives us a good chance of predicting the future,” said Barton.
This is similar to the way climate modelers calibrate their models with ancient climate data gathered from sources like tree rings, pollen and ice cores. Reenacting the past and comparing the outcome to what actually happened is one effective way to test a model. Large differences between what the model says and what past evidence says can expose weaknesses in the model.
Some of the most fascinating (and on-going) archaeological modeling is part of the Village Ecodynamics Project, which attempts to sort out the social and ecological factors that led to the depopulation across a huge swath of the American Southwest in the 12th century. The Anasazi cultural collapse is of enduring fascination to scientists and the general public. But I’ve come to suspect that there are connecting dots to a larger story that doesn’t get nearly as much attention, perhaps because the ruins aren’t as visually spectacular or well-preserved.
Generally agree, but notice that climate modellers do NOT calibrate their models on ancient climate. For one thing, they do not have data on ancient climate, and 90% of Climategate is about criticisms of paleoreconstructions. They have calibrated some paleoreconstructions based on recent (post 1850) instrumental measurements of temperature, but even this ran into great problems (proxy reconstructions “diverged” from thermometers, a problem that was “solved” by simply not using the divergent data, something conveniently called “a trick” in order to “hide the decline” showed by tree-ring reconstructions after 1960.
The very instrumental measurements also came under fire, since the adjustments for non-climatic factors affecting thermoters (such increasing amounts of cements, machines and other heat-making or heat-capturing devices around meteo statios) were utterly superficial and may be misleading.
The main “calibration” of climate models comes from checking that in the second half of the 20th century CO2 concentrations were increasing while temperatures (as measured by meteo stations) were rising. The very same correlation did not obtain before 1960/70, during a long cooling period with increasing CO2 from the 1940s to the 1960s, but never mind.
Once this was “established”, several models were proposed to explore the possible climate effect of exogenously changing the CO2 concentration of the future. These models, based on the 1960/98 record, generally “predicted” increasing temps up to 2100 or beyond. The “uncertainty” of such predictions was not tested in reality, but reflected the differences observed between different models (all based on the same or similar baseline parameters).
When turning to the distant past, some climatologists have speculated that since intensity or frequency of El Niño depends on higher sea temperatures, and these on CO2, some ancient periods with higher CO2 like the Pliocene should exhibit a quasi permanent state of El Niño in the El Niño Southern Oscillation. But no archeo evidence turned out to that effect. Moreover, the main researcher in this field (Eric Guilyardi) has forced CO2 concentrations (now 50% above preindustrial levels, expected to rise to 4 times in the worst IPCC scenarios) to up to more than 10 times the preindustrial level, without been “successful” in eliciting a permanent El Niño in his models. Should this lead to the abandonment of the theory linking CO2 to temperature and El Niño? Nope, apparently. People are still torturing the data (and models) in the hope they finally confess.
Thus the example seems a bit out of place in the present context.
I think the development of anthropology as a science is perhaps just as interesting to those of us looking at climate change as some of the results we have found. Their arguments have been just as fierce, arcane and destructive of archaeology’s contribution after the Sixties as anything we have seen here and may see in the short term future.
I think a lot of human response to past changes in the climate will be really difficult to tease out of normal nomadic movements. So really archaeology should be expected to be able to help us study the effects on agricultural communities–which still would help carry the record back further than we have it now.
Keith, other than Jared Diamond’s Collapse, are there any books you’d recommend?
Tom,
I actually liked Guns, Germs, and Steel better than Collapse. Other than than, archaeology is a broad field, so what areas interest you the most, or what regions of the world?
But if you’re looking for something with relevance to the sorts of sustainability issues we face today, then I’d highly recommend Anasazi America.
Oh, and Joseph Tainter’s The Collapse of Complex Societies is a classic, and much more highly regarded by scholars than Diamond’s book.
I liked GG&S much better as well. I’ll check out Tainter’s book and Anasazi America.
When I was in the Navy I read an awful lot of Heyerdahl, and that started me following the catfights in the academic literature. When I went to uni on the GI Bill I was reading stuff by Colin Turnbull (The Forest People, The Mountain People) just as fun stuff to read. How about you?
Archaeologists have thought a lot about changing climates and the way humans respond to them, and lots of archaeological publications are relevant to sustainability and climate change. Most of the actual archaeology hasn’t reached a wider audience, except as filtered and oversimplified by Diamond and other writers. Tainter has published a lot of good stuff, but there are plenty of others writing on similar topics. The Archaeology of Global Change, edited by Charles Redman and others (Smithsonian Books 2004), comes to mind, as well as Redman’s Human Impacts on Ancient Environments (University of Arizona Press 1999). For archaeological applications of computer modeling, The Model-Based Archaeology of Socionatural Systems, edited by Timothy Kohler and Sander van der Leeuw (School for Advanced Research Press 2007) is a good place to start.
For the Southwest and the Anasazi so-called collapse, there’s Environmental Change and Human Adaptation in the Ancient American Southwest, edited by David Doyel and Jeff Dean (University of Utah Press 2006) and the not-quite-published-yet Leaving Mesa Verde, edited by Tim Kohler, Mark Varien, and Aaron Wright (due out any day now from the University of Arizona Press). When I say so-called collapse, I’m not trying to start any fights; clearly in some ways it makes good sense to think of events in the Four Corners region in the A.D. 1200s as a collapse of cultural systems established in those places. But it was more complicated than that, and many people responded to the environmental and social problems they faced by moving and reorganizing, not just collapsing.
I am a rank amateur, but I have been fascinated by archaeological history for years. I have found that the disputes between some of the different schools of thought in some areas of archaeology even makes the climate wars seem tame.
It was my interest in the Roman and Medieval periods of history that first started my skepticism of the CAGW hypothesis. Lamb was the go to writer on the subject of world climate and still has not been refuted adequately to this day. You can chart the course of empires in the climate history as shown by Lamb.
Oh, GG&S still has to be the best. I used the concept of “unnatural selection” on a daily basis. I am always impressed at the corn and apple “unnatural selection” going from the size of a “pinky end” to the monsters of today.
But, sadly to say, the Europeans under the banner of “correct religion” (In it for the Gold per se) destroyed most of the archeological information that would give a lot of researchers information to a multitude of cultures. It is always about being “right”, whatever that might be.
The events in the Four Corners region in the A.D. 1200s makes fascinating reading.
The contortions some were forced to make when it was shown that cannibalism was practiced as a normal course of events, and not just as a ritual, made for interesting reading.
Tom, archaeology was far more vitriolic than Climate Science ever tried to be.
Ever wondered why the Venus De Milo has no arms? 😉
Jim (6):
Thanks for stopping by and making some great recommendations. My list was made on the fly, so I’m glad you added Redman and Dean et al.
[All, I have a bunch of professional archaeologists who lurk at this blog; Jim, who is an archaeologist at BYU, might be the first to comment.]
JohnB (10):
The fierce academic debates you refer to within archaeology are just that–within the field. They don’t spill over into the public because their competing theories don’t have implications for public policy.
That said, there is a major law that is coming up on a 20 anniversary that has hugely impacted the field of archaeology–for better and worse. From a scientific perspective, this law has been fairly problematic. But it is a human rights law, so that has made the debate over it quite interesting. I’m being coy, but anyone familiar with what American museums and federal institutions have been doing with their archaeological collections for the last 20 years will know what I’m referring to.
More on this at a later date.
One other thing, regarding this comment from Jim:
“But it was more complicated than that, and many people responded to the environmental and social problems they faced by moving and reorganizing, not just collapsing.”
This is true. Here’s a Science Times piece by George Johnson on the latest thinking related to this.
It’s funny–I always like the romantic attitude of Thor Heyerdahl in his fights against the academic establishment regarding pre-Columbian contact between continents. It may have shaped some of my attitudes about climate change.
But what’s funny is that I just realized that Jared Diamond’s book, Guns, Germs and Steel sort of publicly popped Heyerdahl’s thesis without ever referring to it.
Heyerdahl made a cogent case for man’s ability to travel between continents long before the Europeans got around to it. And indeed, it now seems certain that they did do so. But the idea that such voyages were common now seems absurd, for the simple reason that the various continents did not develop antibodies for each others’ diseases.
So while Heyerdahl was probably trivially right in describing man’s ability to navigate to far shores, he would probably have been disappointed to see that such voyages were rare and had no perceptible impact on the cultures on either side of the oceans.
Bit sad, that.
The most important information is the most mundane. We may have more mundane information now than ever, but it is as a grain of sand. The models are a toy, a game, they will not achieve anything remarkable until we have at least a handful of sand.
People are so impatient – and so many of these impatient people seem to have a thing for the toys and the games. The ‘Greats’ in archaeology (and climatology) are, and will remain, the Masters of the Mundane.