0845217169 - From Fred Pearce <[email protected]>...

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From: Fred Pearce <[email protected]> To: keith briffa <[email protected]> Subject: new sciwentist feature Date: 13 Oct 96 10:32:49 EDT Keith, This is my first draft of the dendrochronology feature. I wonder if you have time to go through look. I hope you recognise the quotes, but please makes changes if they think they misrepresent you. And if you can answer any of the questions in square brackets that would be most useful. Ideally, can you not change the full text but make notes, remarks, answers referring to it. As ever, haste is of the essence. Regards --Fred Pearce It was one of the largest volcanic eruptions of the past 10 000 years. Mount Changbai [correct?] in China blasted 50 cubic kilometres of rock into the air and deluged much of the far east with hot pumice. Radiocarbon dated the explosion at early in the 11th century. But it took Keith Briffa, sitting in his office in Norwich and juggling data from tree rings round the world, to pinpoint the precise year: 1032. Volcanoes scatter the atmosphere with dust that deflects sunlight and cools the world beneath for a year or more. And when the world cools, trees grow less. That year's growth rings are smaller and less dense. By analysing those rings, Briffa and his colleagues at the Climatic Research Unit in the University of East Anglia have charted these sudden and dramatic shocks to the climate system, from Changbai to Pinatubo in 1991. Larches in the forests of the northern Urals, for instance, have revealed that 1032 was the coldest summer there in a thousand years, more than 6 degrees cooler than the long-term average. Four of the five coldest summers in Europe and North America during the past four centuries (1601, 1641, 1669, and 1912) coincided with known major volcanic events. "We are pretty certain the fifth one, in 1699, did too," says Briffa. "But the geologists haven't found the volcano yet." It is clever work. But the science of tree-ring analysis, dendrochronology, is more than just a party piece for botanists. Every ring in every tree round the world contains a memory of the climate the year it was formed. Reading these rings holds the potential, Briffa believes, to answer one of the most vital questions of our time: has human activity started to warm the planet? With colleagues in laboratories and field stations from Dublin to eastern Siberia, he has within the past year [correct?] begun an attempt to construct a history, year by year, of temperatures across northern Europe and Asia over the past 10 000 years, right back to the waning of the last ice age. The tam, funded by the European Union, hope to help show whether the warming seen across the planet in the past century, and especially since around 1980, is within the limits of normal natural variability, or the start of man-made global warming. For climatologists, the search for an irrefutable "sign" of anthropogenic warming
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This note was uploaded on 12/16/2009 for the course CLMT 0032456 taught by Professor Ellison during the Spring '09 term at Abraham Baldwin Agricultural College.

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0845217169 - From Fred Pearce <[email protected]>...

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