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2013-06-06. Slicing Open Stalagmites to Reveal Climate Secrets.

posted Jun 8, 2013, 9:30 AM by Alan Gould
For GSS Climate Change chapter 7. Excerpt: ...Stacy Carolin..., a PhD student at Georgia Tech, is breaking ground in the field of paleoclimatology, the study of ancient climates, using an unconventional but increasingly prevalent tool: “speleothems,” a catch-all term for cave formations that includes stalagmites.... In a study released today in the journal Science, Carolin and her colleagues outline 100,000-year-old rainfall conditions in Borneo, mapped from chemical clues in cave formations there. ...Researchers look for formations that have already fallen over or broken off, so as not to damage the cave,...and study the ancient atoms within to discover how old they are and how much rainfall there was at different points in their past (speleothems form when rainwater drips through the limestone, picking up acid and minerals that pile up in the cave). ...Stalagmites are “the next generation of climate records,” says Larry Edwards, an earth scientist at the University of Minnesota. ...Edwards pioneered the isotope dating technique that catalyzed a boom in speleothem studies over the last decade. Until recently, dating speleothems...Scientists needed to track down thorium and uranium isotopes that existed in absurdly small quantities, around one part per trillion, and their tools could only locate one out of ten million of those… like finding a needle in a haystack in a cave on a different planet. In the late eighties, Edwards began experimenting with different ways to use a mass spectrometer to improve the search, and today ...he says, “of all the climate records, [speleothems] are among the best dated.” ...benefits to stalagmites abound: They reach deep into history, up to 500,000 years in some cases, longer than most ice cores and far longer than tree rings. ...Where in the past paleoclimatologists had been mostly limited to ice at high altitudes and the poles, trees in temperate zones, and lakes with ancient sediment, once reading speleothems became easier “all of a sudden the rest of the world was opened for climate records,” Edwards says.... http://climatedesk.org/2013/06/slicing-open-stalagmites-to-reveal-climate-secrets/. Tim McDonnell, Climate Desk.