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Scientists explain insights from ancient Tibetan ice core

A short film about an expedition to Tibet’s Guliya Glacier, where scientists drilled a Stone Age ice core going back 600,000 years. Plus a report on what the ice core reveals.

This short film above provides an overview of an autumn 2015 expedition to the Guliya Glacier in Tibet, where scientists drilled ice cores that could yield some of the oldest ice yet found on Earth outside the polar regions. BPCRC media specialist Pam Theodotou created the film, using field footage collected by expedition member Giuliano Bertagna.

Scientists discussed their analysis of one of the cores drilled on this expedition earlier this month (December 14, 2017) at the annual American Geophysical Union meeting in New Orleans. The ice at the bottom of this core appears to have formed during the Stone Age, more than 600,000 years ago, long before modern humans appeared. Researchers from the United States and China have been studying the core — which is nearly as long as the Empire State Building is tall — to assemble one of the longest-ever records of Earth’s climate history.

Guliya Glacier is located in Tibet’s western Kunlun Mountains, one of Earth’s largest supplies of freshwater ice outside of the Arctic and Antarctica. In 2015, the research team drilled through the ice cap until they hit bedrock, in order to obtain this very ancient ice. They recovered five ice cores, the longest of which is more than 1,000 feet (300 meters) long.

The cores are composed of compressed layers of snow and ice that settled on the western Kunlun Mountains year after year, long ago. In each layer, the ice captured chemicals from the air and precipitation during wet and dry seasons. Today’s researchers are able to analyze the chemistry of the different layers to measure historical changes in climate.

Paleoclimatologist Lonnie Thompson of Ohio State University was co-leader of the international research team that obtained the cores. He reported at the AGU meeting that the new data from these cores lend support to computer models of projected climate changes, providing dramatic evidence of a recent and rapid temperature rise at some of the highest, coldest mountain peaks in the world. Thompson said in a statement:

The ice cores actually demonstrate that warming is happening, and is already having detrimental effects on Earth’s freshwater ice stores.

The researchers reported that there has been a persistent increase in both temperature and precipitation in Tibet’s Kunlun Mountains over the last few centuries. In this region, the average temperature has risen 2.7 degrees Fahrenheit (1.5 degrees Celsius) in the last 50 years and the average precipitation has risen by 2.1 inches per year over the past 25 years.

Of particular interest to the researchers is a projection from the Intergovernmental Panel on Climate Change (IOCC) that future temperatures on the planet will rise faster at high altitudes than they will at sea level. Thompson said:

Generally, the higher the elevation, the greater the rate of warming that’s taking place.

These scientists pointed out that, around the world, hundreds of millions of people depend on high-altitude glaciers for their water supply. The Guliya Glacier is one of many Tibetan Plateau ice caches that provide fresh water to Central, South, and Southeast Asia. Thompson said:

There are over 46,000 mountain glaciers in that part of the world, and they are the water source for major rivers.

Lonnie Thompson cuts an ice core retrieved from the Guliya Glacier in the Kunlun Mountains in Tibet in 2015. Photo via Giuliano Bertagna, courtesy of the Byrd Polar and Climate Research Center.

The oldest ice core drilled in the Northern Hemisphere was found in Greenland in 2004 by the North Greenland Ice Core Project and was dated to roughly 120,000 years, while the oldest continuous ice core record recovered on Earth to date is from Antarctica, and extends back 800,000.

Over the next few months, the American and Chinese research teams will analyze the chemistry of the Guliya Glacier ice core in even more detail. They will look for evidence of temperature changes caused by ocean circulation patterns in both the North Atlantic and tropical Pacific Oceans, which drive precipitation in Tibet as well as the Indian monsoons. For instance, one important driver of global temperatures, El Niño, leaves its chemical mark in the snow that falls on tropical glaciers.

Bottom line: U.S. and Chinese researchers report of their analysis of the oldest ice core ever drilled outside the polar regions, from the Guliya Glacier in Tibet’s Kunlan mountains. The ice appears to contain more than half a million years of climate history.

Read more from Ohio State University

Eleanor Imster

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