Shiprock, New Mexico and climate change.
June 26, 2014 3:24 PM Subscribe
This past weekend, we drove through Shiprock, New Mexico and I started wondering how much humans have changed the landscape. Pre-Columbus - what was the landscape like? Was there more water and groundcover - or was it always arid and (almost) desolate?
From what I've read, the Colorado Plateau, which encompasses Shiprock, has looked pretty much the same for a very long time once it stopped being the bottom of a shallow sea. There have been somewhat wetter periods, but it's mostly been pretty dry for a pretty long time; there's evidence from places like Chaco Culture Historical Park (south of Shiprock) that at least in limited areas, there were periods when it was wetter and more amenable to farming and irrigation, but even when Chaco was being built, the people building it were having to travel a fair distance for trees large enough for their building needs.
posted by rtha at 3:40 PM on June 26, 2014
posted by rtha at 3:40 PM on June 26, 2014
Pretty much always that way through human history in the area, aside from ice ages and continental drift that may have occurred in the millennia prior. Some time ago, there was a vibrant civilization there, but theories suggest it was greatly lessened by an extended drought.
posted by LionIndex at 3:40 PM on June 26, 2014
posted by LionIndex at 3:40 PM on June 26, 2014
The climate has warmed and cooled twice during recorded history. The earliest of those is known as the "Roman warm period" and coincided with the Roman empire. The second one is the "Medieval warm period". The cycle takes a thousand to fifteen hundred years, and is driving by cyclic changes in solar radiation.
During the Medieval warm period, the SW desert was more fertile and had more rain. It wasn't by any stretch of the imagination a rain forest, but it was a lot less dry than now. That was the period in which the Mesa Verde cliff dwellings flourished, for example, which was possible because there was enough rain to grow crops on top of the mesa.
Once that warm period ended, the rains failed, and the people living there eventually packed up and left. (And there are other remnants of native activity in the SW that date from that period, which largely become abandoned about the same time, probably for the same reason.)
So yes, there's been a lot of change. But it wasn't the result of human activity.
posted by Chocolate Pickle at 3:57 PM on June 26, 2014
During the Medieval warm period, the SW desert was more fertile and had more rain. It wasn't by any stretch of the imagination a rain forest, but it was a lot less dry than now. That was the period in which the Mesa Verde cliff dwellings flourished, for example, which was possible because there was enough rain to grow crops on top of the mesa.
Once that warm period ended, the rains failed, and the people living there eventually packed up and left. (And there are other remnants of native activity in the SW that date from that period, which largely become abandoned about the same time, probably for the same reason.)
So yes, there's been a lot of change. But it wasn't the result of human activity.
posted by Chocolate Pickle at 3:57 PM on June 26, 2014
This book will have some of the answers.
The aridity predates mankind. The area has a double rain shadow-from the Sierra mountains in California that are a fairly recent orogeny (geologically speaking anyway) and the Mogollon rim (also fairly recent) that forms the southern and western boundary of the Colorado Plateau. Before these two uplifts occurred the area was fairly wet-more like great plains than the modern desert. While Geologically recent, this all occurred long, long before humans even evolved in Africa, much less moved to North America (10-20 million years ago if i remember correctly). It is also at very high average altitude-7000 feet or so above sea level. The thin air definitely affects things as well and the two are the defining characteristics for life on the plateau. As chocolate pickle states, the area does show ample evidence of wetter and dryer states, but that is relative. Wet periods show maybe 20-25" of rain a year and drought periods can be as little as 5-6" (or even 0 for small isolated areas and years). The only wet areas are the isolated peaks around Flagstaff and small areas right on the edge were runoff gets concentrated.
Humans have been in the area for many, many thousands of years and have altered the area at least as much as any of the other parts of North America. I have personally stood on old embankments used to divert water to fields and refuse heaps full of pottery shards and metate's from settlements and walked the old ballcourts around some old pueblo's on the plateau. They most definitely altered the landscape on that small human scale. Population has always been fairly low in this area outside of a few scattered settlements-Canyon de Chelly area and Mesa Verde. There is pretty good evidence the inhabitants also used fire to keep fields open and control plant growth also (just like the rest of North America).
Recent activity has had some small effect on reducing the ground water (such as it is) and drying up some of the seeps and springs, but this effect is minor and isolated to small areas, such as Sedona and Flagstaff which are a very small part of the whole ecosystem.
The major archaeological records haven't really been explored much past the recent history (meaning the rise of the pueblo/Anasazi culture in the last 1-2,0000 years) mostly because there just isn't much to study-some rock heaps and hearths are all the predate the actual ruins from the more recent cultures.
posted by bartonlong at 4:55 PM on June 26, 2014 [2 favorites]
The aridity predates mankind. The area has a double rain shadow-from the Sierra mountains in California that are a fairly recent orogeny (geologically speaking anyway) and the Mogollon rim (also fairly recent) that forms the southern and western boundary of the Colorado Plateau. Before these two uplifts occurred the area was fairly wet-more like great plains than the modern desert. While Geologically recent, this all occurred long, long before humans even evolved in Africa, much less moved to North America (10-20 million years ago if i remember correctly). It is also at very high average altitude-7000 feet or so above sea level. The thin air definitely affects things as well and the two are the defining characteristics for life on the plateau. As chocolate pickle states, the area does show ample evidence of wetter and dryer states, but that is relative. Wet periods show maybe 20-25" of rain a year and drought periods can be as little as 5-6" (or even 0 for small isolated areas and years). The only wet areas are the isolated peaks around Flagstaff and small areas right on the edge were runoff gets concentrated.
Humans have been in the area for many, many thousands of years and have altered the area at least as much as any of the other parts of North America. I have personally stood on old embankments used to divert water to fields and refuse heaps full of pottery shards and metate's from settlements and walked the old ballcourts around some old pueblo's on the plateau. They most definitely altered the landscape on that small human scale. Population has always been fairly low in this area outside of a few scattered settlements-Canyon de Chelly area and Mesa Verde. There is pretty good evidence the inhabitants also used fire to keep fields open and control plant growth also (just like the rest of North America).
Recent activity has had some small effect on reducing the ground water (such as it is) and drying up some of the seeps and springs, but this effect is minor and isolated to small areas, such as Sedona and Flagstaff which are a very small part of the whole ecosystem.
The major archaeological records haven't really been explored much past the recent history (meaning the rise of the pueblo/Anasazi culture in the last 1-2,0000 years) mostly because there just isn't much to study-some rock heaps and hearths are all the predate the actual ruins from the more recent cultures.
posted by bartonlong at 4:55 PM on June 26, 2014 [2 favorites]
Still not human-caused, but in the category of interesting differences from the present day: during the Old Kingdom of Ancient Egypt, Egypt would have mostly been a savannah rather than desert as it is now:
For one that's more likely human-caused: (though this might just qualify as resource depletion rather than climate change?) during Roman times, in what's now southern Libya which is in the middle of the Sahara desert, there was a civilization called the Garamantes by Greek and Roman sources that subsisted off of underground water supplies that no longer exist.
posted by XMLicious at 4:57 PM on June 26, 2014
4.2 kiloyear BP aridification eventA few thousand years before that Britain would have been directly connected to mainland Europe.
For one that's more likely human-caused: (though this might just qualify as resource depletion rather than climate change?) during Roman times, in what's now southern Libya which is in the middle of the Sahara desert, there was a civilization called the Garamantes by Greek and Roman sources that subsisted off of underground water supplies that no longer exist.
posted by XMLicious at 4:57 PM on June 26, 2014
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posted by ecorrocio at 3:37 PM on June 26, 2014 [1 favorite]