Skip to comments.Monsoon link to fall of dynasties[China]
Posted on 11/07/2008 8:53:13 AM PST by BGHater
The demise of some of China's ruling dynasties may have been linked to changes in the strength of monsoon rains, a new study suggests.
The findings come from 1,800-year record of the Asian monsoon preserved in a stalagmite from a Chinese cave.
Weak - and therefore dry - monsoon periods coincided with the demise of the Tang, Yuan and Ming imperial dynasties, the scientists said.
A US-Chinese team report their work in the journal Science.
Stalagmites are largely made up of calcium carbonate, which precipitates from groundwater dripping from the ceiling of a cave.
Chemical analysis of a 118mm-long stalagmite from Wangxiang Cave, in Gansu province, north-west China, told the history of strong and weak cycles in the monsoon - the rains that water crops to feed millions of people in Asia.
It also shows that, over the last 50 years, greenhouse gases and aerosols have taken over from natural variability to become the dominant influence on the monsoon.
The record came from a stalagmite found in Wanxiang Cave, China
The stalagmite grew continuously from 190AD to 2003
(Excerpt) Read more at news.bbc.co.uk ...
Maybe of interest, weather and ancient China.
So ancient Chinese were seeking “change?”
That’s interesting, it’s like Diamond’s idea in “Collapse”, that societies that don’t have conservationism (notice I didn’t say “environmentalism”) are vulnerable to changes in weather patterns. A lot of the ancient religions were based on weather and seasons because back then farmers literally lived and died by that.
‘[plus two failed invasions of Japan]’
Heh, weather played a huge part on the latter invasion.
Yeah. But not weather in China.
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Notice how they try to make it a ‘global warming’ thing too..
I like that closing sentence -- "future decision-making could be made based on scientific data and not on political expediency". I wouldn't count on it, but that would be great.Caves reveal clues to UK weatherAt Pooles Cavern in Derbyshire, it was discovered that the stalagmites grow faster in the winter months when it rains more. Alan Walker, who guides visitors through the caves, says the changes in rainfall are recorded in the stalactites and stalagmites like the growth rings in trees. Stalagmites from a number of caves have now been analysed by Dr Andy Baker at Newcastle University. After splitting and polishing the rock, he can measure its growth precisely and has built up a precipitation history going back thousands of years. His study suggests this autumn's rainfall is not at all unusual when looked at over such a timescale but is well within historic variations. He believes politicians find it expedient to blame a man-made change in our weather rather than addressing the complex scientific picture.
by Tom Heap
Eh? Obviously, if there's an enrichment of C14 for a period, the following period will have appeared to be older -- but it wasn't! As volcanic eruptions are basically entirely C12, they are not the source of the surfeit of C14.Stalagmites reveal past climateThe researchers examined four stalagmites from Crevice Cave, the longest cave known in Missouri, located about 75 miles south of St. Louis. The stalagmites appeared to have been broken by natural forces such as floods or earthquakes and were found about 80 feet below the ground surface, says Dorale. The team determined when the stalagmite layers were deposited, then deduced paleotemperatures and the general types of vegetation growing in the vicinity during that era by examining the carbon and oxygen isotopes within the calcium carbonate. The profile showed that the area had been covered by forest 75,000 years ago, but by 71,000 years ago, it was savannah and by 59,000 years ago, had become a prairie. Between 55,000 and 25,000 years ago, the forest had returned and persisted. Dorale explains that the pattern is consistent with climatological records from the ocean.
by Kristina Bartlett and Devra WexlerStalagmite discovery throws doubt on carbon datingThe formations, recovered from a cavern which was created when sea levels were about 100m (330ft) lower than today, showed that more than 20,000 years ago there were dramatic shifts in the amount of radioactive carbon - often known as "carbon-14" - in the atmosphere. Because the ratio of carbon-14 to its stable cousin, carbon-12, is used as the basis of carbon dating of fossils, any widespread variation in that balance would confuse the dating of items such as plants or animals which existed around those times. "It means we have tended to underestimate the true age of objects from 20,000 to 40,000 years ago by up to 8,000 years," said Dr David Richards, of the School of Geographical Sciences at the University of Bristol. However, he added, "this may change the timings, but it won't change the order of events."
by Charles Arthur
11 July 2001
Here's another segment: An Anglo-American team found large variations in levels of the carbon-14 isotope, used as the basis of carbon dating, preserved in a 19in stalagmite recovered from a submerged cave in the Blue Holes of the Bahamas, limestone caverns created when sea levels were nearly 330ft lower than today. These findings suggested dramatic changes in the amount of radioactive carbon in Earth's atmosphere during the last Ice Age, much greater than previously thought, probably as a result of changes in the strength of the planet's magnetic field. The field shields Earth from cosmic rays that create carbon-14 in the atmosphere, altering levels of the isotope during the past 45,000 years.Dating study 'means human history rethink'The scientists calculated the age of ancient limestone formations in caves using carbon dating. The results were checked using a newer, more accurate method known as uranium dating. They found that the carbon dates were wrong by thousands of years and that the further back in time they went, the more out-of-date they were. The reason is that carbon dating measures radioactive carbon and there may have been much more of it in the distant past than previously thought.
29 June, 2001Carbon dating 'might be wrong by 10,000 years'Their study could force a reappraisal of when certain events occurred, notably in the period when modern humans lived alongside Neanderthals in Europe. It suggests that modern humans might have lived in Europe for longer than thought and that prehistoric paintings recently found in the Chauvet cave, in southern France, might be 38,000-years-old rather than the estimated 33,000 years... Radiocarbon dating, which depends on the steady decay of carbon-14, is less reliable if an artefact is older than 16,000 years. But the changes in radiocarbon, and dating, fluctuate greatly up to 45,000 years, the limit of the study.
by Roger Highfield
Saturday 30 June 2001
Carbon Dating Revision May Rewrite HistoryThese findings suggested dramatic changes in the amount of radioactive carbon in Earth's atmosphere during the last Ice Age, probably as a result of changes in the strength of the planet's magnetic field. The field shields Earth from the cosmic rays that create carbon-14 in the atmosphere, and this would have altered the levels of the isotope during the past 45,000 years.
Whoops, loused up the formatting during editing.
So, there is historical precedent for the climate changing?
......The stalagmites appeared to have been broken by natural forces such as floods or earthquakes and were found about 80 feet below the ground surface, .....
Cavers creed..... take only pictures, leave only foot prints
Any other Cavers here?
Yeah. I used to be a member of NSS but they started supporting plugging caves from exploration by the commons.
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