3 hours ago by Eric Sorensen
Washington State University researchers have detailed the role of localized climate change in one of the great mysteries of North American archaeology: the depopulation of southwest Colorado by ancestral Pueblo people in the late 1200s.
In the process, they address one of the mysteries of modern-day climate change: How will humans react?
Writing in Nature Communications, WSU archaeologist Tim Kohler and post-doctoral researcher Kyle Bocinsky use tree-ring data, the growth requirements of traditional maize crops and a suite of computer programs to make a finely scaled map of ideal Southwest growing regions for the past 2,000 years.
Their data paint a narrative of some 40,000 people leaving the Mesa Verde area of southwest Colorado as drought plagued the niche in which they grew maize, their main food source. Meanwhile, the Pajarito Plateau of the northern Rio Grande saw a large population spike.
The plateau "also happens to be the place where you would want to move if you were doing rain-fed maize agriculture, the same type of agriculture that people practiced for centuries up in southwest Colorado," said Bocinsky, who built the data-crunching programs while earning a WSU Ph.D. with support from a National Science Foundation graduate research fellowship.
People try to 'keep on keeping on'
The dramatic changes in the Southwest took place near the end of the Medieval Warm Period, the warmest in the Northern Hemisphere for the last 2,000 years. The period had a smaller temperature change than we're seeing now, and its impact on the Southwest is unclear. But it is clear the Southwest went through a major change.
"At a very local scale, people have been dealing with climate fluctuations of several degrees centigrade throughout history," said Bocinsky. "So we need to understand how people deal with these local changes to generate predictions and help guide us in dealing with more widespread changes of that nature."
Bocinsky, the paper's lead author, said the study is particularly significant for modern-day subsistence farmers of maize, or corn, the world's largest food staple.
"People are generally going to try and find ways to keep on keeping on, to do what they've been doing before changing their technological strategy," he said. "That was something extremely interesting to me out of this project."
Tree rings yield precipitation, temperature info
To get a more granular look at the changing climate of the Southwest, Bocinsky and Kohler used more than 200 tree-ring chronologies, which use the annual rings of ancient trees to reconstruct the area's climate patterns over time. Pines at lower elevations will have their growth limited by rainfall, making their rings good indicators of precipitation. High-elevation trees get good rain but are susceptible to cold, making them good indicators of temperature.
The shifting patterns of rainfall and temperature let Bocinsky and Kohler isolate to a few square kilometers the areas that would receive just under a foot of rainfall a year, the minimum needed for ancestral maize varieties still farmed by contemporary Pueblo people.
The area in what is now southwest Colorado's Mesa Verde National Park ended up being one of the best places to grow maize, with good conditions more than 90 percent of the time. The Pajarito Plateau ended up being highly suitable as well, with slopes that would shed cold air and precipitation levels suited to rain-fed agriculture.
Large disparities in small areas
Such big climate differences in such a small area illustrates how some areas could be hit harder than others by the extremes of global climate change, said Bocinsky. He said it is telling that, when the Pueblo people moved, they moved to where they could preserve their farming techniques. He said that could be important to keep in mind as farmers, particularly subsistence farmers on marginal lands, face localized climate impacts in the future.
"When we are looking for ways to alleviate human suffering, we should keep in mind that people are going to be looking for places to move where they can keep doing their type of maize agriculture, keep growing the same type of wheat or rice in the same ways," he said. "It's when those niches really start shrinking on the landscape that we start having a major problem, because you've got a lot of people who are used to doing something in one way and they can no longer do it that way."
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User comments : 5
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jwbrighton
1 / 5 (2) 1 hour ago
Localized Climate change???? You mean weather patterns! More complete BS from the wackos!
ryggesogn2
not rated yet 1 hour ago
Adapt, die or move.
bill_testy_75
5 / 5 (1) 1 hour ago
This has been common knowledge for decades. Maybe even centuries.
foolspoo
not rated yet 1 hour ago
This is irresponsible and ignorant Eric. If you care to investigate your work, you will discover that there is only a single climate on this planet. ignorance like this tends to substantiate the views of lesser minds. see our first poster on this article.
craig james
not rated yet 2 minutes ago
The question concerning scientist and global warming is why the global temperatures have dropped 1.08F from 1998 to late 2014. This is not possible according to the AGW hypothesis. The almost two decade decline refutes the premise that each year's increase in CO2 will cause higher temperatures that peak about 10 years later.
Failed predictions about climate change are an embarrassment.
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3 hours ago by Eric Sorensen
Washington State University researchers have detailed the role of localized climate change in one of the great mysteries of North American archaeology: the depopulation of southwest Colorado by ancestral Pueblo people in the late 1200s.
In the process, they address one of the mysteries of modern-day climate change: How will humans react?
Writing in Nature Communications, WSU archaeologist Tim Kohler and post-doctoral researcher Kyle Bocinsky use tree-ring data, the growth requirements of traditional maize crops and a suite of computer programs to make a finely scaled map of ideal Southwest growing regions for the past 2,000 years.
Their data paint a narrative of some 40,000 people leaving the Mesa Verde area of southwest Colorado as drought plagued the niche in which they grew maize, their main food source. Meanwhile, the Pajarito Plateau of the northern Rio Grande saw a large population spike.
The plateau "also happens to be the place where you would want to move if you were doing rain-fed maize agriculture, the same type of agriculture that people practiced for centuries up in southwest Colorado," said Bocinsky, who built the data-crunching programs while earning a WSU Ph.D. with support from a National Science Foundation graduate research fellowship.
People try to 'keep on keeping on'
The dramatic changes in the Southwest took place near the end of the Medieval Warm Period, the warmest in the Northern Hemisphere for the last 2,000 years. The period had a smaller temperature change than we're seeing now, and its impact on the Southwest is unclear. But it is clear the Southwest went through a major change.
"At a very local scale, people have been dealing with climate fluctuations of several degrees centigrade throughout history," said Bocinsky. "So we need to understand how people deal with these local changes to generate predictions and help guide us in dealing with more widespread changes of that nature."
Bocinsky, the paper's lead author, said the study is particularly significant for modern-day subsistence farmers of maize, or corn, the world's largest food staple.
"People are generally going to try and find ways to keep on keeping on, to do what they've been doing before changing their technological strategy," he said. "That was something extremely interesting to me out of this project."
Tree rings yield precipitation, temperature info
To get a more granular look at the changing climate of the Southwest, Bocinsky and Kohler used more than 200 tree-ring chronologies, which use the annual rings of ancient trees to reconstruct the area's climate patterns over time. Pines at lower elevations will have their growth limited by rainfall, making their rings good indicators of precipitation. High-elevation trees get good rain but are susceptible to cold, making them good indicators of temperature.
The shifting patterns of rainfall and temperature let Bocinsky and Kohler isolate to a few square kilometers the areas that would receive just under a foot of rainfall a year, the minimum needed for ancestral maize varieties still farmed by contemporary Pueblo people.
The area in what is now southwest Colorado's Mesa Verde National Park ended up being one of the best places to grow maize, with good conditions more than 90 percent of the time. The Pajarito Plateau ended up being highly suitable as well, with slopes that would shed cold air and precipitation levels suited to rain-fed agriculture.
Large disparities in small areas
Such big climate differences in such a small area illustrates how some areas could be hit harder than others by the extremes of global climate change, said Bocinsky. He said it is telling that, when the Pueblo people moved, they moved to where they could preserve their farming techniques. He said that could be important to keep in mind as farmers, particularly subsistence farmers on marginal lands, face localized climate impacts in the future.
"When we are looking for ways to alleviate human suffering, we should keep in mind that people are going to be looking for places to move where they can keep doing their type of maize agriculture, keep growing the same type of wheat or rice in the same ways," he said. "It's when those niches really start shrinking on the landscape that we start having a major problem, because you've got a lot of people who are used to doing something in one way and they can no longer do it that way."
Explore further: Researchers see violent era in ancient Southwest
More from Earth
Related Stories
Researchers see violent era in ancient Southwest
Aug 04, 2014
It's a given that, in numbers terms, the 20th Century was the most violent in history, with civil war, purges and two World Wars killing as many as 200 million people.
Scientists chart an ancient baby boom—in southwestern Native Americans from 500 to 1300 AD
Jun 30, 2014
Washington State University researchers have sketched out one of the greatest baby booms in North American history, a centuries-long "growth blip" among southwestern Native Americans between 500 to 1300 A.D.
Study reveals troubling loss in Mexico's maize genetic diversity
Sep 03, 2014
(Phys.org) —The genetic diversity of maize, or corn, is declining in Mexico, where the world's largest food crop originated, report researchers in Mexico and at the University of California, Davis.
New report highlights how climate change may affect water in Colorado
Aug 06, 2014
(Phys.org) —As Colorado's climate continues to warm, those who manage or use water in the state will likely face significant changes in water supply and demand, according to a new report on state climate change released ...
Is rainfall a greater threat to China's agriculture than warming?
Apr 04, 2012
New research into the impact of climate change on Chinese cereal crops has found rainfall has a greater impact than rising temperature. The research, published in the Journal of the Science of Food and Agriculture found ...
Corn in a changing climate: Adaptive ability of crops can reduce damages from warming weather
Dec 17, 2012
The past year has not been kind to corn. Though it has long been the nation's largest crop, the one-two punch of historic drought and record-high temperatures in July and August combined to damage U.S. corn ...
Recommended for you
Land use looms as large factor in global warming
1 hour ago
For the world's deteriorating environment, don't blame burning fossil fuels exclusively. Land use and land cover changes contribute about 40 percent to "radiative forcing," a key underlying factor in global warming, according ...
Global climate trend since Nov. 16, 1978 shows +0.14 C increase per decade
2 hours ago
Dr. John Christy, a professor of atmospheric science and director of the Earth System Science Center at The University of Alabama in Huntsville, and Dr. Roy Spencer, an ESSC principal scientist, use data ...
A climate guide to a weird future
2 hours ago
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Deforestation may be at root of Brazil drought
4 hours ago
Vera Lucia de Oliveira looks to the sky, hoping for any sign of rain.
Small drains mean big problems at 'baby beaches'
20 hours ago
High fecal counts frequently detected at so-called "baby beaches" may not be diaper-related. UC Irvine researchers found that during summer months, small drainpipes emptying into enclosed ocean bays have a disproportionate ...
Protect the world's deltas
20 hours ago
Extensive areas of the world's deltas—which accommodate major cities such as Shanghai, Dhaka and Bangkok—will be drowned in the next century by rising sea levels, according to a Comment piece in this ...
User comments : 5
Adjust slider to filter visible comments by rank
Display comments: newest first
jwbrighton
1 / 5 (2) 1 hour ago
Localized Climate change???? You mean weather patterns! More complete BS from the wackos!
ryggesogn2
not rated yet 1 hour ago
Adapt, die or move.
bill_testy_75
5 / 5 (1) 1 hour ago
This has been common knowledge for decades. Maybe even centuries.
foolspoo
not rated yet 1 hour ago
"localized climate change"
This is irresponsible and ignorant Eric. If you care to investigate your work, you will discover that there is only a single climate on this planet. ignorance like this tends to substantiate the views of lesser minds. see our first poster on this article.
craig james
not rated yet 2 minutes ago
The question concerning scientist and global warming is why the global temperatures have dropped 1.08F from 1998 to late 2014. This is not possible according to the AGW hypothesis. The almost two decade decline refutes the premise that each year's increase in CO2 will cause higher temperatures that peak about 10 years later.
Failed predictions about climate change are an embarrassment.
Please sign in to add a comment. Registration is free, and takes less than a minute. Read more
Click here
to reset your password.
Sign in to get notified via email when new comments are made.
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