Posted on 02/12/2006 8:49:59 PM PST by presidio9
The warming of the world during the last century is greater – and more widespread – than any other shift in the global climate in the last 1,200 years, researchers reported Thursday.
The analysis of data from tree rings, fossil shells, ice cores and actual temperature measurements from 14 locations on three continents shows that the current warming trend is the most extensive change — warm or cold — since the time of the Vikings.
In their report in the current issue of the journal Science, climatologists Timothy Osborn and Keith Briffa of the University of East Anglia, home to the leading British climate research center, stop short of blaming the 20th-century warming on industrial emissions or other human factors.
But Osborn and Briffa say the geographic extent of the current warming, whatever the reason, is more widespread and more pronounced than the one that turned Greenland green 1,000 years ago.
Their analyses for tree ring and other climate "proxies" from Europe, Asia and North America do show two other pronounced climate shifts during the same period: the Medieval Warm Period from 890 to 1170 and the Little Ice Age, which gripped the Northern Hemisphere from 1580 to 1850.
The Medieval warming, which encouraged the Vikings to settle previously inhospitable regions of Greenland and Iceland, is sometimes cited by critics of modern global warming theories as evidence that the Earth can experience widespread warming independent of human activity.
"It's good that they acknowledge that the last thousand years contained two warm periods with a cold one in between," says S. Fred Singer, president of the Virginia-based Science Policy Project, which frequently disputes claims of global warming.
"But it still doesn't prove that the 20th century was unique," Singer said.
The Bush administration has acknowledged the widespread warming of recent decades, but has sought further research on the causes.
The administration also has declined to join 140 other nations in signing the Kyoto climate accord, which calls on industrial nations to reduce their industrial emissions.
While the study's emperature measurements only go back to the 1800s, researchers were able to reconstruct the Northern Hemisphere's climate back as far as the ninth century.
Researchers correlated temperature records with 14 long-term climate proxies, ranging from fossil shells in the Chesapeake Bay to tree rings in Mongolia.
"Both individually and taken as a whole, these reconstructions support the conclusion that it is likely that the late 20th century was the warmest period in the past millennium or longer," Osborn says.
Averaged across the globe, the increase in temperatures is numerically small — about one degree above normal and about two degrees warmer than during the late 1800s.
The increase, however, has been especially sharp in recent years, with all 10 of the warmest years on record occurring since the mid-1990s.
The warming has been linked to accelerated melting of mountain glaciers and polar ice sheets throughout the world, warmer sea surface temperatures, the earlier arrival of spring in the Northern Hemisphere and other changes.
Many scientists predict the warming will increase if man-made releases of carbon dioxide and other greenhouse gases are not curbed.
Hi Quant,
Actually you're right. Mt. St. Helen's made a mess around the world for quite a time. So did Krakatoa. There are probably more "natural" causes to a lot of pollution.
Regarding the bogus bit, may I suggest reading a book titled 1421, authored by Gavin Menzes.
The book is titled 1421 and the author is Gavin Menves. He has a web site which a quick reference to Google will bring up. The book is most interesting.
Based on what I've seen of it, that book consists largely of fanciful speculation. It's a well-established fact that Chinese seafarers reached East Africa and entirely possible that they explored other locations. But the climate record does not support any possible circumnavigation of Greenland in any craft not specially outfitted for icebound polar navigation circa 1421. No evidence exists to suggest that the Chinese possessed such equipment. Even reaching Greenland in those days (without meteorological satellite data or modern telecommunications) would make one quite lucky. Superior Chinese shipbuilding technology, however, probably would allow their fleet to weather some nasty storms, but even the Titanic couldn't survive an iceberg.
I had never heard that they had either. Another poster posted the title of the book that claims they did. It is kind of difficult to believe, but I would be interested in reading about the claims.
Maybe cutting down all those trees to make their homes and ships,
then burning down captured towns and chieftain's funeral boats
released all those greenhouse gases...
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Well, then, we should all celebrate a return to the famine, death, and despair of the onset of the Little Ice Age over the relative prosperity of the Medivial Warm Period - because who cares about the welfare of serfs when polar bears might just be starving somewhere?
Why was it warmer during the Viking era? Was it CO2 from burning villages?
Ummmm...except, Greenland still isn't green, at least not yet.
Why is it that we must always point to the obvious when discussing this subject with journalists and "scientists".
In any case, what are they saying to the Chinese, who are filling the air with dirty coal smoke? Nada, nada, nada. Fact is that in 1930, the air in New York and other east coast cities was full of soot. That was because they heated with coal. By 1970, after switching to heating oil, they had clean air.
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