How will climate change affect the Himalayas? Scientists trek to find out.

Almost half of the world gets its water from the Himalayas and other high mountains, but little is known about how global warming will affect these sources. A team of scientists ventured to the roof of the world to investigate. 

|
David Putnam
Rinchen Zoe plateau, Bhutan Himalaya.

The distribution of water in Asia's highest mountains and driest deserts tells an important story of climate change.

Almost half the world's population gets its water from glacier melt and rainfall in the Himalayas and other lofty peaks, yet little is understood about how climate change will affect these water sources. Now, using sophisticated technology and old-fashioned fieldwork, scientists are looking into the past to solve this mystery.

"We're trying to understand the relationships between climate and glaciers and Earth's water resources from the perspective of Earth's paleoclimate," geologist Aaron Putnam of the Lamont Doherty Earth Observatory said in a talk at the Columbic Club in New York on March 12. He described his recent expeditions along the Silk Road, from the Tien Shan Mountains to the Taklamakan Desert to the Bhutanese Himalayas.

Tien Shan Mountains

Putnam and colleagues set out in 2010 to the Tarim Basin in Northwest China, right in the center of Asia. Within the Tien Shan Mountains, a range that extends some 1,740 miles (2,800 kilometers), the scientists studied masses of soil and rock debris built up by glaciers, called moraines, which held clues to the past climate. [Stunning Scenes: From the Himalayas to the Taklamakan Desert]

To determine the ages of the moraines, the researchers used a technique known as beryllium-10 exposure dating. Cosmic radiation constantly bombards the Earth's surface, changing the form of some of the elements, like beryllium, in rocks. Based on these changes, the scientists could determine how long the moraines had been there, which allowed researchers to reconstruct the glaciers' past positions. "We can see what the ice looked like and know exactly when the ice was there," Putnam said.

Deep in the desert

Next, Putnam and colleagues ventured to the Taklamakan Desert. New roads have made the desert accessible, "so we were able to access lands people had died trying to visit even a decade ago," Putnam said. He described the area as a parched, desolate landscape with endless expanses of sand dunes.

As the researchers trekked through the desert, they noticed silts, mud cracks, remnants of trees, even shells — all telltale signs of water. To find out when this wet period took place, the scientists used radiocarbon dating, a technique that measures the ratio of different forms of carbon to find an object's age. The scientists also used dendrochronology, a method of determining trees' ages based on their growth rings. The results suggested the wet period occurred from the mid-1100s to the late 1800s.

Putnam and his team then traveled to the easternmost part of the desert to an enormous dry lakebed called Lop Nor. They did radiocarbon dating of shells on the lake's shoreline, finding the shells' ages matched those of the other samples from formerly wet areas. That span of time, from the 12th century to the 19th century, was a cold period in North Atlantic regions. "When it got cold in the North Atlantic, it got wet in the mid-latitude desert regions," Putnam said.

The onset of wet conditions in the Taklamakan Desert corresponds with the rise of Genghis Khan and the Mongol Empire, the largest contiguous land empire in history. The Mongols relied heavily on horses, which would have needed lots of grass to eat. Putnam and his team think the wetting of the desert allowed grasslands to expand, enabling the Mongols to spread throughout Asia. [10 Surprising Ways Weather Changed History]

Atop the Himalayas

Next, Putnam and his colleagues headed south to the Himalayas of Bhutan, an area swept by the monsoon. "We don't know how the monsoon will affect glacier behavior in the Himalayas," Putnam said, adding, "We just needed to go there and use good old-fashioned fieldwork to figure it out." The team made a six-day trek to their study site, a glacier-laden plateau.

The journey wasn't easy; it took 25 horses and mules to carry all of the supplies from the deep jungles up to the icy peaks. The team hiked over 15,400-foot-high (4,700 meters) mountain passes, home to creatures like the Himalayan blue sheep, or bharal.

Finally, the team crested Bhutan's Rinchen Zoe plateau. They ventured out onto the glaciers and took ice sample to measure the amount of melt. The scientists used the same beryllium dating method as before to determine the age of the glacial deposits, work that is currently in progress. The team had to leave before the snows came with the approaching winter.

Though the scientists haven't finished their analysis yet, it's clear that the glaciers have substantially receded over the last century, Putnam said, and this will have an impact on the many people who depend on the mountains for water.

With the current global warming trend, Putnam expects to see a northward expansion of the deserts. The insights gained on these expeditions were only possible through fieldwork, Putnam said. "In my opinion, there's no substitute for collecting fundamental data from the natural world," he said.

Follow Tanya Lewis @tanyalewis314. Follow us @livescience, Facebook or Google+. Original article on LiveScience.com.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to How will climate change affect the Himalayas? Scientists trek to find out.
Read this article in
https://www.csmonitor.com/Science/2013/0322/How-will-climate-change-affect-the-Himalayas-Scientists-trek-to-find-out
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe