"Glaciers are great climate indicators," says Richard Alley, a glaciologist at The Pennsylvania State University, in an e-mail.
"Although they respond to many things (such as increased snowfall, for example), they are controlled primarily by changes in summer temperatures.
Warming melts ice—and it is almost that simple." A glacier's response to climate can be very sensitive to even the slightest temperature fluctuations: "Just one degree [Celsius] has forced glaciers to move back and forth," Schaefer says.
As researchers determine precisely when and where glaciers have advanced and retreated, they can add to a global map of summer temperatures during the Holocene epoch, which spans from 10,000 years ago, after the last ice age, to today.
Today, only carved terrain and rocky remnants remain, including the popular leftover that lies a short walk east of West 62nd Street.Umpire Rock is just one of many enormous boulders—from Antarctica to New Zealand—created under the weight and movement of glacial ice.With increasingly sophisticated techniques, Schaefer and other scientists are more closely studying the chemical footprints on these rocks, thereby gaining valuable insights into climate change."Everything humans do to the climate now is on top of this." Shedding new light on the climate Schaefer and other scientists are using a combination of old stonemason tools and cutting-edge machinery, along with some basic geochemistry, to decipher and date this distribution of ancient temperatures.
Schaefer thinks a better understanding of variations in this era could fill in missing key predictors for Earth's future climate."We can only evaluate how dramatic changes will be if we know this natural variability," Schaefer says.