What happened in the past when the climate changed?

What happened in the past when the climate changed?
The effects of climate change are most pronounced in high latitude and high-altitude areas. Credit: Jade d'Alpoim Guedes, UC San Diego

Once again, humanity might be well served to take heed from a history lesson. When the climate changed, when crops failed and famine threatened, the peoples of ancient Asia responded. They moved. They started growing different crops. They created new trade networks and innovated their way to solutions in other ways too.

So suggests new research by Jade d'Alpoim Guedes of the University of California San Diego and Kyle Bocinsky of the Crow Canyon Archaeological Center in Colorado, Washington State University and the University of Montana.

Their paper, published in the journal Science Advances, describes a computer model they developed that shows for the first time when and where in Asia staple crops would have thrived or fared poorly between 5,000 and 1,000 years ago.

When the climate cooled, people moved away or turned to pastoralism—herds can thrive in grassland where food grains can't. And they turned to trade. These strategies eventually coalesced into the development of the Silk Road, d'Alpoim Guedes and Bocinsky argue. In some areas they also diversified the types of crops they planted.

With their new computer model, the researchers were able to examine in detail how changing climate transformed people's ability to produce food in particular places, and that enabled them to get at the causes of cultural shift.

"There's been a large body of literature in archaeology on past climates, but earlier studies were mostly only able to draw correlations between changes in climate and civilization," said lead author d'Alpoim Guedes, an assistant professor in the Department of Anthropology and Scripps Institution of Oceanography at UC San Diego. "What we're showing in this work is exactly how changes in temperature and precipitation, over space and time, would have actually impacted people—by affecting what they could and couldn't grow."

The barley growing niche though time. Credit: R. Kyle Bocinsky and Jade d'Alpoim Guedes

D'Alpoim Guedes is an archaeologist who specializes in paleoethnobotany—analyzing ancient plant remains—to understand how human subsistence strategies changed over time. Bocinsky is a computational archaeologist. The duo developed their model by combining contemporary weather station data from across Asia with a hemisphere-wide paleoclimate reconstruction to create a simulation across space and time of how temperature in Asia changed. They also added data on archaeological sites and the record of seeds found there.

One major transition in climate—global cooling at the time—happened around 3,700 to 3,000 years ago. And what is true now was true then: changing temperatures don't affect all regions of the globe equally. The effects are most pronounced in high latitude and high-altitude areas, and d'Alpoim Guedes and Bocinsky show how dramatic the changes were, for example, in Mongolia and the Tibetan Plateau. There, around 3,500 years before the present, broomcorn and foxtail millet would have failed to come to harvest about half of the time. People had to abandon the crop in favor of more cold-tolerant ones like wheat and barley.

They also argue that cooling temperatures made it increasingly difficult to grow key grain crops across Northern China between AD 291 and 360, something that may have ended up playing a key role in the relocation of the Chinese capital to from Xi'an to what is now Nanjing, in the south of the country.

The broomcorn millet growing niche though time. Credit: R. Kyle Bocinsky and Jade d'Alpoim Guedes

This was not a painless move—not like finding a better apartment across town. Historical records report on catastrophic harvests (read: famines). And there were major migrations of people, accompanied, the researchers say, by the myriad little conflicts these migrations often bring, as well as bloody struggles.

Climate change also stimulated the development of transportation infrastructure across Asia, the co-authors say, including the later Sui Dynasty's decision to invest in a major capital public project and create China's Grand Canal. The Grand Canal, now a UNESCO World Heritage Site, is the world's longest and oldest canal, linking the Yellow and Yangtze rivers. It was a major facilitator for the movement of people and their trade goods.

D'Alpoim Guedes and Bocinsky's paper in Science Advances [DOI: 10.1126/sciadv.aar4491] carries a positive title—Climate change stimulated agricultural innovation and exchange across Asia—but the co-authors also warn against a completely Pollyanna view.

The foxtail millet growing niche though time. Credit: R. Kyle Bocinsky and Jade d'Alpoim Guedes
"Crises are opportunities for culture change and innovation," Bocinsky said. "But the speed and scale of our current climate change predicament are different."

The impacts of warming going forward are going to be quicker and greater, and humanity has had 4000 years to adjust to a cooler world, d'Alpoim Guedes said. "With global warming these long-lasting patterns of adaptation will begin to change in ways that are unpredictable," she said. "And there might not be the behavioral flexibility for this, given current politics around the world."

The buckwheat growing niche though time. Credit: R. Kyle Bocinsky and Jade d'Alpoim Guedes

Also mechanized, industrialized agriculture and global agricultural policy are pushing us toward mono-culture of crops, said d'Alpoim Guedes. We need to move in the opposite direction instead. "Studies like ours show that bet-hedging and investing in diversity have been our best bets for adapting to change," she said. "That is what allowed us to adapt in past, and we need to be mindful of that for our future, too."

For those wishing to reproduce the paper's findings: The code is open source and any user of the free statistical software R can download the package the authors are making available and run the analysis themselves. Researchers can also extend d'Alpoim Guedes and Bocinsky's findings by running analysis on other crops and other locations in different parts of the world. It is even possible, the co-authors say, to modify their code and then, potentially, to project for future crop failures.

The rice growing niche though time. Credit: R. Kyle Bocinsky and Jade d'Alpoim Guedes

Explore further

Computer models find ancient solutions to modern problems

More information: J. d'Alpoim Guedes at University of California, San Diego in La Jolla, CA el al., "Climate change stimulated agricultural innovation and exchange across Asia," Science Advances (2018). DOI: 10.1126/sciadv.aar4491 , http://advances.sciencemag.org/content/4/10/eaar4491
Journal information: Science Advances

Citation: What happened in the past when the climate changed? (2018, October 31) retrieved 18 April 2019 from https://phys.org/news/2018-10-climate.html
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Oct 31, 2018
so, after all this balogna analaysis , the same obvious point comes out.

climate change aka former fraud known as global warming pandemic, is not the problem. the problem is food production and distribution and it ALWAYS HAS BEEN.

our 'solutions' over the past hundred years have enabled such unprecedented success, that we have come to the point of realizing we cannot continue to grow let alone sustain a population of seven billion human beings without dealing with the problem of supply chain disruptions. so, if there is any solution , it is preventing war. and doing so , in order to help maximize the efficiency of our international trading and finance system.

once war comes, a supply chain disruption comes, and then, major global food shortages. which has ZERO to do with 'climate' and everything to do with industrial agriculture , transport, and distribution ..all of which fit under the rubric of production and trade.

Oct 31, 2018
When climate changed in the past humans responded by adapting?! That's crazy! They should have limited CO2 emissions because that's the best way to deal with climate change.

Oct 31, 2018
No, food production problems are only one entirely foreseeable consequence of pumping billions and billions of tons of heat-trapping greenhouse gases into the planet's atmosphere for decade after decade.
Just to mention a few more: 1) Rising sea levels, driving coastal city populations inland and destroying valuable property and cultural icons. 2) Ever more intense weather disasters --- see for example "THIS IS HOW THE WORLD ENDS: Will we soon see category 6 hurricanes?" by Jeff Nisbet at The Guardian - another article hypothesized category 6 hurricanes in a 2011 Scientific American article as well. Add worse wildfires, floods, droughts. 3) Mass migrations which overwhelm the nations where migrants understandably seek refuge --- already has been going on, affected the so-called "Arab Spring" protests and the war in Syria, as well as at our own borders. 4) Mass species extinctions, thus losing crucial biodiversity --- already happening. 5) Human and animal health threats.

Oct 31, 2018
5) continued: threats to human, animal and plant health short of actual extinction, but extremely
debilitating.
"After one look at this planet, any visitor from outer space would say, `I want to see
the manager.'" ---- William S. Burroughs, sardonic but deadly serious as usual.

Nov 01, 2018
5) continued: threats to human, animal and plant health short of actual extinction, but extremely
debilitating.
"After one look at this planet, any visitor from outer space would say, `I want to see
the manager.'" ---- William S. Burroughs, sardonic but deadly serious as usual.

Well said !
balogna boy zeevk(another antigoracle sockpuppet) as ever being an example of how baboonish brains think alike (the conclusion always being he himself making him look baffoonish)

Nov 01, 2018
When climate changed in the past humans responded by adapting?! That's crazy! They should have limited CO2 emissions because that's the best way to deal with climate change.


When mama baboon screamed, antigoracle popped into existence, forgetting to ask his daddy, and hence now we see a frisky little monkey that never grew up to understand science.

Nov 01, 2018
zeevk: If you had capitalized your sentences, I would have given you a five rating. :/

Nov 01, 2018
Helo: What are you literally going nuts about? Climate has always changed. And CO2 is not a poison, if so, I suggest chopping off all our heads.

Nov 01, 2018
"The climate has always changed" is what is sometimes described as a "Zombie Fallacy."
Cf. Fallacy: The Counterfeit of Argument (1959) by Holther & Fearnside (if you have $188 or so that is, I was given a copy by Prof. Candido Zanoni when he was dispersing his huge library in Nicholson Hall/U. of Minnesota/Twin Cities to grad students and undergrads), OR a really exhaustive explication of formal and informal logical howlers. WHAT PEOPLE LIKE YOU NEED is at the very least to acquaint yourselves with the skepticalscience.com website's "Most Used Climate Myths," at the upper left of the front page.
It's stunning, luger! (rhymes with "Dunning Kruger") --- luger is German for `liar,' Dunning Kruger effect describes individuals who are so deluded they think actual experts/scientists etc. failed to notice what these deluded individuals think are profound refutations, blunders, insights etc. etc. ad infinitum, ad nauseum.
Just cease and desist from tedious silliness.

Nov 01, 2018
"CO2 is not a poison." This is what can be described in various ways, as part of various different kinds of fallacious reasoning --- some enthymematic arguments, for instance, are SO BOGUS, they instantiate more than one fallacy. This is one example. First of all, practically ANY organic substance can indeed be "poisonous" depending on the background circumstances and the amount of the substance, as well as the impinging causes and the correctly described dynamics of a system with many moving parts. AGAIN: just go to the skepticalscience.com site and carefully and closely read the "Most Used Climate Myths," "CO2 is not a poison" is one.

Nov 01, 2018
Helo: What are you literally going nuts about? Climate has always changed. And CO2 is not a poison, if so, I suggest chopping off all our heads.


1) administer poison to (a person or animal), either deliberately or accidentally.
"he tried to poison his wife"

2) adulterate or contaminate with poison.
"the Amazon basin is being poisoned by the mercury used by gold prospectors"

3) treat (a weapon or missile) with poison in order to augment its lethal effect.
"poisoned arrows"

4) prove harmful or destructive to.
"his disgust had poisoned his attitude toward everyone"

5) Chemistry
(of a substance) reduce the activity of (a catalyst).

If the increase in CO2 causes global climate change I think definition 4 applies.

Nov 01, 2018
When climate changed in the past humans responded by adapting?! That's crazy! They should have limited CO2 emissions because that's the best way to deal with climate change. -aksdad

I think you missed the part about "bloody struggles." Maybe you find that an acceptable part of "adapting." I don't.

Nov 01, 2018
@SteveS
If the increase in CO2 causes global climate change I think definition 4 applies
Definitely #4

CO2 being poisonous is analogous to Iodine in Humans:
we need it to survive, but...
-if we get too much it will kill us
-if we don't have enough, it will kill us
https://www.ncbi....3063534/

this is the problem o_c_c can't grasp or come to grips with, taking such precautions to protect his/her tightly held beliefs that he/she ignored FACE studies and sh*tloads of links and references provided explaining why too much CO2 is bad and "poisonous"
https://skeptical...nced.htm

Nov 04, 2018
CO2 is essential for life on this planet.

Nov 04, 2018
@condolf52 --- So is being able to deal with relentlessly silly muppets who think pumping BILLIONS and BILLIONS {Carl Sagan Voiceover} of heat-trapping, greenhouse gases into the atmosphere of our local third planet from the local sun is endlessly viable and very wise policy.
Cultivate that essential skill, or else go bonkers.

"After one look at this planet, any visitor from outer space would say, `I want to see the
manager.'" ---- William S. Burroughs

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