Ice Core Study
Lonnie Thompson and his research team have drilled ice cores from Quelccaya that date back almost 2,000 years and have used them to study changes in atmospheric conditions over this period. In these samples, the oxygen isotope ratio, oxygen-18 to oxygen-16, has risen abruptly in the last 50 years, an indicator of regional warming. As the ice cap is retreating, it is exposing almost perfectly preserved, unfossilized plant specimens that have been dated to 5,200 years before present, indicating that it has been more than 50 centuries since the ice cap was smaller than it is today.
Ice cores taken from Upper Fremont Glacier in the U.S. state of Wyoming show an oxygen isotope profile similar to that of the Quelccaya ice cores at the end of the Little Ice Age, a period of cooler global temperatures between the years 1550 and 1850. The sudden alterations in the oxygen isotope ratio found in ice core samples from these two glaciers, which are at great distance from each other, provide evidence of a sudden global climate change in the mid-latitude regions of the planet at this time.
Read more about this topic: Quelccaya Ice Cap
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