12. Climate & Culture

2021-03-17. Drawing A Line In The Mud: Scientists Debate When 'Age Of Humans' Began. By Rebecca Hersher, National Public Radio. Excerpt: Humans have changed the Earth in such profound ways that scientists say we have entered a new geological period: the Anthropocene Epoch. But when did the new epoch officially begin? ...Teams are studying 11 locations on five continents, looking for a place where rock, mud or ice perfectly capture the global impact of humans. ...ultimately only one site will be crowned the "golden spike" location for the Anthropocene: the place on Earth where a line in the rock, mud or ice exemplifies the unique markers of the age of humans. ...For example, there is a line of pollen and dust in a specific ice core from Antarctica that is the official reference point for the beginning of the Holocene epoch, which commenced when the last ice age ended about 12 thousand years ago. The golden spike location for the end of the age of dinosaurs about 66 million years ago is a line in a cliff in Tunisia, where global debris from a meteor impact is clearly visible. ..."There are some people who see an old Anthropocene that goes all the way back to when we see humans controlling and using fire, a hundred thousand years ago" ...Others point to the dawn of agriculture as the moment that humans began to have large-scale impacts on the planet. Still others...point to colonialism as the turning point. ...But the geologists on the Anthropocene Working Group disagree with the idea that the age of humans began hundreds or even thousands of years ago. They argue that industrialization and the nuclear age are the best geological markers of the new epoch. Specifically, scientists on the golden spike teams are zeroing in on a period in the 1940s and 1950s when some humans began detonating nuclear bombs.... [https://www.npr.org/2021/03/17/974774461/drawing-a-line-in-the-mud-scientists-debate-when-age-of-humans-began


2021-01-28.  Drought, Not War, Felled Some Ancient Asian Civilizations. By Richard J. Sima, Eos/AGU. Excerpt: Radiocarbon dating, luminescent sand grains, and climate records point to drought as the reason for the civilizations’ demise. When we read about the fall of ancient civilizations in history books, we may think of warfare and other struggles on the human stage as leading causes for a culture’s decline. But climate change also accounts for many a society’s ruin. Such seems to be the case for the central Asian civilizations of the Otrār oasis located at the junction of the Syr Darya and Arys Rivers in what is now southern Kazakhstan. In a new study published in the Proceedings of the National Academy of Sciences of the United States of America, an interdisciplinary team of researchers report that the Otrār oasis had already been in a prolonged period of decline long before the Mongols invaded. ...The clues lie in irrigation canals that the ancient civilizations of Transoxania relied on for agriculture. ...Transoxania’s canals were previously thought to have been destroyed by the Mongols during their invasion, helping to precipitate decline in Transoxania. But Macklin and his colleagues were able to determine that much to their surprise, the canals fell into disrepair before Mongols ever set foot in the region. They used a combination of radiocarbon dating and a technique called optically stimulated luminescence (OSL), which dates the last time that sand was exposed to sunlight. ...The researchers also reconstructed climate records in the region over the past 2,000 years, which revealed that the canals were abandoned during periods of prolonged drought that both weakened the civilizations before the Mongols arrived and stunted their recovery afterward. Archaeological records further corroborated the coincident timing of the region’s cultural decline.... [https://eos.org/articles/drought-not-war-felled-some-ancient-asian-civilizations]


2020-08-24. Ancient megadrought may explain civilization’s ‘missing millennia’ in Southeast Asia. By Charles Choi, Science Magazine. Excerpt: A megadrought that lasted more than 1000 years may have plagued Southeast Asia 5000 years ago, setting up dramatic shifts in regional civilizations, suggests a new study of cave rocks in northern Laos. The researchers believe the drought began when the drying of the distant Sahara Desert disrupted monsoon rains and triggered droughts throughout the rest of Asia and Africa. For years, archaeologists studying mainland Southeast Asia—an area encompassing modern-day Cambodia, Laos, Myanmar, Malaysia, Thailand, and Vietnam—have been puzzled by what they call “the missing millennia,” a period from roughly 6000 to 4000 years ago with little evidence of human settlements. University of Pennsylvania archaeologist Joyce White, a co-author on the new paper, says she and others long thought this was because researchers hadn’t yet pinpointed where people of the era lived. Now, she believes the settlements could be missing because a megadrought devastated their populations and drove them to find water elsewhere. To re-create the climate of that time, White and her colleagues investigated stalagmites in Tham Doun Mai, a cave in northern Laos.... [https://www.sciencemag.org/news/2020/08/ancient-megadrought-may-explain-civilization-s-missing-millennia-southeast-asia]

 

2020-06-22. Ancient Rome Was Teetering. Then a Volcano Erupted 6,000 Miles Away. By Katherine Kornei, The New York Times. Excerpt: Scientists have linked historical political instability to a number of volcanic events, the latest involving an eruption in the Aleutian Islands. ...This eruption was one of the largest of the last few millenniums, Dr. McConnell and his collaborators concluded, and the sulfate aerosols it created remained in the stratosphere for several years. These tiny particles are particularly good at reflecting sunlight, which means they can temporarily alter Earth’s climate. “They’ve created, for a short term, global cooling events,” said Jessica Ball, a volcanologist at the California Volcano Observatory, who was not involved in the research. ...There’s good evidence that the Northern Hemisphere was colder than normal around 43 B.C. Trees across Europe grew more slowly that year, and a pine forest in North America experienced an unusually early autumn freeze. Using climate models to simulate the impact of an Okmok eruption, Dr. McConnell and his collaborators estimated that parts of the Mediterranean, roughly 6,000 miles away, would have cooled by as much as 13.3 degrees Fahrenheit.... [https://www.nytimes.com/2020/06/22/science/rome-caesar-volcano.htmlSee also New York Times article [https://www.nytimes.com/2020/06/22/science/rome-caesar-volcano.html] “We can absolutely say this volcanic eruption generated extreme climate,” says Joseph McConnell, a glaciologist at the Desert Research Institute and the study’s lead author. If the eruption did indeed contribute to famine and other disruptions, it could have helped the Roman Empire consolidate its control, McConnell says. “The end of the republic happened during these two extreme years of climate,” he says. “It’s a possible coincidence, but it doesn’t seem likely.”....

2020-01-15. Megadrought Helped Topple the Assyrian Empire. By Mary Caperton Morton, Eos/AGU. [https://eos.org/articles/megadrought-helped-topple-the-assyrian-empire] Excerpt: Paleoclimate records shed light on the ancient civilization’s meteoric rise and catastrophic collapse....

2019-12-31. A warning from ancient tree rings: The Americas are prone to catastrophic, simultaneous droughts. By Paul Voosen, Science Magazine.

2019-12-05. How a volcanic eruption helped create modern Scotland. By Sid Perkins, Science Magazine.


2019-08-16. ‘Mystery’ volcano that cooled the ancient world traced to El Salvador. By Katherine Kornei, Science Magazine. 


2019-07-24. Ancient global climate events rippled unevenly across the globe. By Sid Perkins, Science Magazine. 

2019-02-05. Before Global Warming, Humans Caused Global Cooling, Study Finds. By Niraj Chokshi, The New York Times.

2018-11-15. Why 536 was ‘the worst year to be alive’. By Ann Gibbons, Science Magazine. 

2018-08-02. Severe Drought May Have Helped Hasten Ancient Maya’s Collapse. By Jenessa Duncombe, Eos/AGU. 

2017-10-23. Volcanic Woes May Have Contributed to Ancient Egypt’s Fall. By JoAnna Wendel, Eos/AGU. 

2016-06-17. Rising temperatures and humans were a deadly combo for ancient South American megafauna. By Lizzie Wade, Science. 

2016-01-19. Early Agriculture Has Kept Earth Warm for Millennia. By Sarah Stanley, Earth & Space News (EoS; AGU).

2015-07-08. Timing and climate forcing of volcanic eruptions for the past 2,500 years. M. Sigl et al, Nature.

2015-01-27. Long dry spell doomed Mexican city 1,000 years ago. By Robert Sanders, UC Berkeley News Center.

2012-11-09. Development and Disintegration of Maya Political Systems in Response to Climate Change | by Douglas J. Kennett et al, Science Magazine: Vol. 338 no. 6108 pp. 788-791.  Editor's description: Climate has affected the vitality of many different societies in the past, as shown by numerous records across the globe and throughout human history. One of the most obvious and spectacular examples of this is from the Classic Maya civilization, whose advanced culture left highly detailed records of all aspects of their existence between 300 and 1000 C.E. Kennett et al. (p. 788; see the cover) present a detailed climate record derived from a stalagmite collected from a cave in Belize, in the midst of the Classic Maya settlement. The fine resolution and precise dating of the record allows changes in precipitation to be related to the politics, war, and population fluctuations of the Mayans. -|- Abstract:  The role of climate change in the development and demise of Classic Maya civilization (300 to 1000 C.E.) remains controversial because of the absence of well-dated climate and archaeological sequences. We present a precisely dated subannual climate record for the past 2000 years from Yok Balum Cave, Belize. From comparison of this record with historical events compiled from well-dated stone monuments, we propose that anomalously high rainfall favored unprecedented population expansion and the proliferation of political centers between 440 and 660 C.E. This was followed by a drying trend between 660 and 1000 C.E. that triggered the balkanization of polities, increased warfare, and the asynchronous disintegration of polities, followed by population collapse in the context of an extended drought between 1020 and 1100 C.E. Read the full article: http://www.sciencemag.org/content/338/6108/788 [subscription needed]

2010 Dec 6. Did Climate Change Drive Prehistoric Culture Change? By Michael Balter, Science. Excerpt: A new study finds a strong correlation between changing climate and changing culture in the prehistoric United States…
...The team found that nearly all of the transitions between one cultural period and the next occurred at times of ecological and environmental changes…
...The authors don't claim that climate change directly drove cultural change, but they do argue that prehistoric humans periodically "adjusted their tool kits" in response to climate changes…

2009 November 2. In the Mediterranean, Killer Tsunamis From an Ancient Eruption. By William J. Broad, The NY Times. Excerpt: The massive eruption of the Thera volcano in the Aegean Sea more than 3,000 years ago produced killer waves that raced across hundreds of miles of the Eastern Mediterranean to inundate the area that is now Israel and probably other coastal sites, a team of scientists has found.
The team, writing in the October issue of Geology, said the new evidence suggested that giant tsunamis from the catastrophic eruption hit “coastal sites across the Eastern Mediterranean littoral.” Tsunamis are giant waves that can crash into shore, rearrange the seabed, inundate vast areas of land and carry terrestrial material out to sea.
The region at the time was home to rising civilizations in Crete, Cyprus, Egypt, Phoenicia and Turkey.
For decades, scholars have suggested that the giant eruption, just 70 miles from Crete, might have brought about the mysterious collapse of Minoan civilization at the peak of its glory....

2009 July 24. An Amazon Culture Withers as Food Dries Up. By Elisabeth Rosenthal, The NY Times. Excerpt: XINGU NATIONAL PARK, Brazil — As the naked, painted young men of the Kamayurá tribe prepare for the ritualized war games of a festival, they end their haunting fireside chant with a blowing sound — “whoosh, whoosh” — a symbolic attempt to eliminate the scent of fish so they will not be detected by enemies. For centuries, fish from jungle lakes and rivers have been a staple of the Kamayurá diet, the tribe’s primary source of protein.
But fish smells are not a problem for the warriors anymore. Deforestation and, some scientists contend, global climate change are making the Amazon region drier and hotter, decimating fish stocks in this area and imperiling the Kamayurá’s very existence. Like other small indigenous cultures around the world with little money or capacity to move, they are struggling to adapt to the changes.
...The Intergovernmental Panel on Climate Change says that up to 30 percent of animals and plants face an increased risk of extinction if global temperatures rise 2 degrees Celsius (3.6 degrees Fahrenheit) in coming decades. But anthropologists also fear a wave of cultural extinction for dozens of small indigenous groups — the loss of their traditions, their arts, their languages....

2008 November 7. Rise and Fall of Chinese Dynasties Tied to Changes in Rainfall. By David Biello, Scientific American. Excerpt: In the late ninth century a disastrous harvest precipitated by drought brought famine to China under the rule of the Tang dynasty. By A.D. 907—after nearly three centuries of rule—the dynasty fell when its emperor, Ai, was deposed, and the empire was divided. According to the atmospheric record contained in a stalagmite, one of the causes of that downfall may have been climate change.
"We think that climate played an important role in Chinese history," says paleoclimatologist Hai Cheng of the University of Minnesota, a member of the scientific team that harvested and analyzed the stalagmite from Wanxiang Cave in Gansu Province in northwest China. The stalagmite reveals, for example, that the vital rains of the Asian monsoon weakened at the time of the downfalls of the Tang, Yuan and Ming dynasties over the past 1,810 years.
...Composed of calcium carbonate leached from dripping water, the 4.6-inch- (11.7-centimeter-) long stalagmite preserves a record of rainfall in this region, which is on the edge of the area impacted by the Asian monsoon. The region gets less rainfall when the monsoon is mild and more when it is strong...
These periods of strong and weak rains, when compared with Chinese historical records, coincide with periods of imperial turmoil or prosperity....
In fact, the collapse of the Tang Dynasty coincides with that of the Mayan civilization—both due to extreme drought. "We have demonstrated that the cave record correlates well with many other records, including the Little Ice Age in Europe, temperature changes [across the] Northern Hemisphere, and major solar variability," Cheng notes....

2008 August 31. For the first time in human history, the North Pole can be circumnavigated. By Geoffrey Lean, The Independent. Excerpt: Open water now stretches all the way round the Arctic, making it possible for the first time in human history to circumnavigate the North Pole... New satellite images, taken only two days ago, show that melting ice last week opened up both the fabled North-west and North-east passages, in the most important geographical landmark to date to signal the unexpectedly rapid progress of global warming.
Last night Professor Mark Serreze, a sea ice specialist at the official US National Snow and Ice Data Center (NSIDC), hailed the publication of the images...as "a historic event", and said that it provided further evidence that the Arctic icecap may now have entered a "death spiral". Some scientists predict that it could vanish altogether in summer within five years, a process that would, in itself, greatly accelerate.
...scientists...have long regarded the disappearance of the icecap as inevitable as global warming takes hold, though until recently it was not expected until around 2070.
Many scientists now predict that the Arctic ocean will be ice-free in summer by 2030 – and a landmark study this year by Professor Wieslaw Maslowski at the Naval Postgraduate School in Monterey, California, concluded that there will be no ice between mid-July and mid-September as early as 2013....

Summer 2007. Forest Magazine. Thirsting for Water. By Allen Best. Excerpt: ...The dust traveled far, even to New York City. In Kansas, Oklahoma, Texas and Colorado, where the Dust Bowl was most severe, the roiling clouds were deadly. The young and old, even the formerly robust, succumbed to pneumonia. The luckier ones, the quitters, abandoned the dryland farms ... and migrated westward, ....
Several decades of wet weather had supported the widespread plowing of grasslands in a semi-arid climate. Then came drought, lasting the better part of the decade. In all, about a third of a million people left the Great Plains. It was, until Hurricane Katrina, the greatest population displacement in the United States caused by an environmental event.
The Dust Bowl, say climatologists, is unlikely to occur again.
Farmers and government scientists learned much from the experience about how to farm the land-and where not to. But drought most certainly will return, perhaps even more harshly. And turning to the American Southwest, ...experts say new evidence reveals a clearer picture of extended and sometimes severe droughts in the past 1,100 years that very well may reappear-this time with an overlay of hotter temperatures caused by increased levels of greenhouse gases. What effect these human-caused emissions will have on precipitation is still uncertain. On the matter of temperature, however, nearly all the computer models reach one conclusion: It will get hotter, much hotter, in places like Tucson, Colorado Springs and Reno. And hotter-even if precipitation stays the same-means drier. In other words, the "average" of the future will resemble what in the past we called drought.
...WHAT THE TREES SAY
...Climates of the past can be documented in various ways, but one of the most important methods is by studying tree rings, a scientific discipline called dendrochronology. ...
What these tree rings say is that the Southwest was far more arid in the past. ... A period from 800 to 1300 A.D. was generally more arid and punctuated by what paleoclimatologists call megadroughts. Some lasted thirty years. Archaeologists think that one of the final megadroughts, from about 1270 to 1300, may have partly caused the Ancestral Pueblo (also called the Anasazi) to vacate their cliff-dwelling communities at Mesa Verde in Colorado and Chaco Canyon in Arizona.....


 

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