Heatwave on the top of the world

by jakedai | March 6, 2007 at 07:39 am

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Yesterday, I wrote about a new study showing the effects of climate change on the Tibetan Plateau. Today, in my inbox through Google Alerts, came an article about a study by Chinese glaciologists in 2001 and 2002 on Everest's Rongbuk Glacier. In the study, the glaciologists took core samples from the East Rongbuk Glacier and were able to compare gas content in the snow layers to ascertain temperature differentials and thus melting rates in the glacier over the centuries.

This is both fascinating and an important study for their research has shown that rising temperatures have been hitting the Top of the World, too. And, when one factors in the importance of the Himalayan watershed to some 2 billion people in India, China, Pakistan, Nepal, Burma, Bangladesh, etc., this finding becomes even more important...and frightening.

And, from a personal side, this was an interesting article because I was on Everest in 2001 for the 2001 Mallory & Irvine Research Expedition. On May 7, 2001, my friends Tap Richards, John Race, and I started off from Rongbuk Basecamp on the first summit bid of the expedition. But, at about 20,000 feet on the East Rongbuk Glacier, we came across a strange site: a group of Tibetan yak herders were carrying two Chinese men back down the mountain. Both men, Mr. Gao and Mr. Li, we very sick with combinations of High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE). After a quick inspection, we knew that these men would die on the mountain if we did not abort our summit bid, mobilize our team, and begin the arduous project of getting the incapacitated men back downhill.

None of us batted an eye at this, for the summit was not worth sacrificing human lives. Many hours later, with the help of our entire team, the team of expedition leader Russell Brice, and the efforts of many kind Tibetan yak men, we had Mr. Gao and Li in our basecamp tents on supplemental oxygen and inside Gamov bags. Once they were stabilized, we put the men in our emergency jeep and rushed them out of basecamp and on to the hospital in Shigatse.

Why do I tell you this? Well, it happens that Mr. Gao and Mr. Li were both glaciologists taking core samples on the east Ronguk Glacier for the study mentioned below. It is a small world, and I am happy to hear the findings of their team, and hope that both men were able to return to Everest in 2002 and participate more fully in the research!

Heatwave on the top of the world

Relatively little is known about climate change in the Himalayas and the Tibetan plateau. There are very few meteorological stations, and instrumental records from glaciers, lakes or tree growth rings are rare and difficult to interpret. However, in 2001 and 2002, Chinese scientists drilled three ice cores in the eastern summit of the East Rongbuk glacier that covers the north pass of Mount Everest, at 6518 meters above sea level. These ice cores were analyzed in collaboration with the LGGE and the LSCE, and they have shown that a new climate marker exists, the ice core gas content, which can reconstruct the changes in summer temperatures on this very high site.

(PressZoom) - The French Intergovernmental Panel on Climate Change ( IPPC, or GIEC in French ) has just announced the conclusions of its 4th report, which restates that global warming has increased the average temperature by 0.74°C over the last century. However, there is very little information about some parts of the planet, such as central Asia. A new study by French researchers from the Laboratory of Glaciology and Geophysics of the Environment ( LGGE, CNRS / Université Joseph Fourier, Grenoble, France ) and the Laboratory of Sciences of the Cliamte and the Environment ( LSCE / IPSL, CEA / CNRS / Université de Versailles Saint-Quentin, France ), in collaboration with Chinese, Russian and American researchers, proves that the recent warming has also affected the ice cap on Mount Everest, in the heart of the Himalayas. This result was published on February 7, 2007 in the European Journal "Climate of the Past".

Relatively little is known about climate change in the Himalayas and the Tibetan plateau. There are very few meteorological stations, and instrumental records from glaciers, lakes or tree growth rings are rare and difficult to interpret. However, in 2001 and 2002, Chinese scientists drilled three ice cores in the eastern summit of the East Rongbuk glacier that covers the north pass of Mount Everest, at 6518 meters above sea level. These ice cores were analyzed in collaboration with the LGGE and the LSCE, and they have shown that a new climate marker exists, the ice core gas content, which can reconstruct the changes in summer temperatures on this very high site.

At these altitudes, the surface snow partially melts in the summer and the melt water percolates1 through the snow cover to refreeze deep down. This process affects the density and size of air bubbles contained in the ice, that is, its gas content. So the gas content is directly related to the intensity of the summer ice melt. By measuring accurately the gas content throughout two of the three ice cores taken from the top of Everest, researchers have been able to follow the changes over time, going right back to 2,000 years ago. They noted a very marked decrease in the quantity of gas trapped in the 20th century ice, compared with the content in older ice, which reflects recent increases in the summer melts on the glacier surface. Although the team has not as yet been able to quantify exactly the temperature change over time using this new marker of trapped gas, their research clearly shows that global warming has also affected the ice cap on top of the world.

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1. Melt water flows down through the snow under the effect of gravity.

In France, this work was supported by CNRS' international French-Chinese scientific cooperation program ( in the context of the "CLEAH2 project" ), and in China by the French Embassy.

2. Climate and Environment in Antarctica and the Himalayas

Glaciological drilling on the sides of Mount Everest. Chinese Himalayas. © S. Hou, CAREERI, China

BIBLIOGRAPHY

Summer temperature trend over the past two millennia using air content in Himalayan ice. Hou S., Chappellaz J., Jouzel J., Chu P.C., Masson- Delmotte V., Qin D., Raynaud D., Mayewski P.A., Lipenkov V.Y. et Kang S., Climate of the Past 3, 89-95, 2007.

Online at: http://www.clim-past.net/...2007/cp-3-89-2007.pdf

CONTACTS

Contact chercheur

Jérôme Chappellaz

T 04 76 82 42 64

chappellaz@lgge.obs.ujf-grenoble.fr

Contact communication INSU/CNRS

Dominique Armand

T 01 44 96 43 68

dominique.armand@cnrs-dir.fr

Contact presse

Priscilla Dacher

T 01 44 96 46 06

priscilla.dacher@cnrs-dir.fr