A Visit to Ground Zero in the Climate Change Sweepstakes

I visited Nepal last week for the first time in 15 years. Back then, Nepal was a cool place to test your metal on a trek. Today, it is a disaster-in-the-making as the globe warms.

Nepal — a tiny sliver of a country sandwiched between India, Pakistan, China, Bhutan and Bangladesh — is home to a polyglot population that speaks some 70 different languages. Despite appalling poverty, a recent civil war, and armed soldiers patrolling the capital city of Katmandu, the Nepalese are at ease, friendly, and warmhearted. Everywhere, children dressed in colorful clothes laughed and romped about, and were quick with a spirited “hello” for westerners.

Though traditions are still strong, Nepal shows signs of change: brick factories displacing paddy fields, thick smog clouding the Katmandu sky, and teenage boys sporting piercings and blond streaks in their dark hair. But the real transformational juggernaut is melting glaciers.

To many foreigners, Nepal means mountains – Mount Everest or Annapurna. For the people of South and East Asia, the Himalayas are a lot more than a tourist attraction; they are the fountain of life.

Glaciers Are The World's Largest Source of Fresh Water

Some 70 percent of the world’s fresh water is stored in glaciers, and the Himalayas and their neighboring peaks on the Tibetan Plateau have more glaciers than anywhere else besides the poles. The meltwater from these glaciers feeds no fewer than seven major rivers -- the lifeline for more than a billion people:

• Pakistan's Indus,
• the Ganges in India and Bangladesh,
• the Brahmaputra (which flows through Tibet, India and Bangladesh),
• Southeast Asia's Mekong and Salween, and
• the Yangtze and Huang Ho (Yellow) in China.

Agriculture in Asia is a 12-month-a-year enterprise. Summer rains normally supply plenty of water to support the crops – usually rice. In dryer seasons, the farmers depend upon water from the rivers. Because the Himalayan glaciers are plentiful, those rivers flow during the dry season. In the future that could change.

Glaciers are rivers in slo-mo. Typically, new ice is added to the glacier near the top where the temperatures are coldest, and lost due to melting at the bottom where temperatures are warmer. If there is more melting than freezing, the glacier shrinks, and if that happens year after year after year, the glacier simply melts away.

This composite image from the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) instrument shows how India's Gangotri Glacier has retracted since 1780. (Image courtesy of NASA EROS Data Center, Sept. 9, 2001)

Because of global warming, the Himalayan glaciers are shrinking.

How Glaciers Are Measured

There are a number of ways to document a shrinking glacier.

• The easiest and most common is to track the length of a glacier from the peak to its endpoint down the slope. These kinds of measurements indicate most glaciers are retreating back up the slope at a rate of 10–15 meters every year.
• Another method is to assess the areal extent of the entire glacial system by either piecing together measurements from individual glaciers or from airborne or space-borne observations. This approach indicates that since 1950 the area covered by the Himalayan glaciers has decreased by about 20 percent.
• The third method looks at the glaciers' thickness over time. Because optical measurements cannot be used, this is the most difficult. A common approach has been to sink a measuring pole into the glacier and record the height of the ice each year. These kinds of measurements have generally confirmed that the Himalayan glaciers are thinning as well as shrinking.
  

In fact, Natalie Kehrwald from Ohio State University and colleagues just reported in Geophysical Research Letters that the Naimona’nyi Glacier, which supplies the headwaters for the Ganges, Indus, and Brahmaputra, has lost all of the ice that might have accumulated since the mid-twentieth century.

Scientists don't know for sure how long it will take for these glaciers to be totally lost, but some estimates are as little as 20 or 30 years. Without the meltwater those glaciers provide, the seven great Himalayan rivers will dry up to a trickle during the dry season, meaning crops will fail and hundreds of millions of people could starve.

While many Nepalese see the future coming and are ready to accommodate change, I suspect that disappearing glaciers is more than they bargained for.