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. |
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