Glaciers melting in a warming world

UP and down the icy spine of South America, the glaciers are melting, the white mantle of the Andes Mountains washing away at an ever faster rate.

“Look. You can see. Chacaltaya has split in two,” scientist Edson Ramirez said as he led a visitor up toward a once-grand ice flow high in the thin air of the Bolivian cordillera.

In the distance below, beneath drifting clouds, sprawled two-mile-high La Paz, a growing city that survives on the water running off the shoulders of these treeless peaks.

Chacaltaya, a frozen storehouse of such water, will be gone in seven to eight years, said Ramirez, a Bolivian glaciologist.

They’ll disappear far beyond Bolivia. From Alaska in the north, to Montana’s Glacier National Park, to the great ice fields of wild Patagonia at South America’s southern tip, the “rivers of ice” are melting, shrinking, retreating.

In east Africa, the snows of Mount Kilimanjaro are vanishing. In the icebound Alps and Himalayas, the change has been stunning. From South America to south Asia, new glacial lakes threaten to overflow and drown villages.

Space satellites have helped measure the global trend, but scientists such as Rajendra K Pachauri, a native of north India, have long seen what was happening on the ground.

“I know from observation,” Mr Pachauri said at an international climate conference in Argentina. “If you go to the Himalayan peaks, the rate at which the glaciers are retreating is alarming. And this is not an isolated example. I’ve seen photographs of Mount Kilimanjaro 50 years ago and now. The evidence is visible.”

Global temperatures rose about 1 degree Fahrenheit in the 20th century. French glaciologists working with Ramirez and scientists at La Paz’s San Andres University estimate the Bolivian Andes are warming faster, currently at a half-degree Fahrenheit per decade.

An international study concluded in November that winter temperatures have risen as much as 7 degrees Fahrenheit over 50 years in the Arctic, where permafrost is thawing and sea ice is shrinking. Pacific islands are losing land to encroaching seas, oceans expanding as they warm and as they receive runoff from the Greenland ice cap and other sources. Those sources include at least one gushing new river of meltwater in western China, where thousands of Himalayan and other glaciers are shrinking. In the Italian Alps, 10% of the ice melted away in the European heat wave of 2003 and experts fear all will be gone in 20 to 30 years.

Such rapid run-off would do more than feed rising seas. It would end centuries of reliable flows through populated lands, jeopardising water supplies for human consumption, agriculture and electricity.

Here in impoverished Bolivia, the government has barely begun to plan for climate change. Tomas Quisbert, a hydrological engineer with the water company serving the two million people of the La Paz region, said 95% of its supplies come from the mountains, either rain runoff or glacier melt.

Ramirez and fellow scientists are seeking government support to do a complete assessment of water in the La Paz basin, linked to computer modelling of future regional climate and its impact. They’ll soon move on from 17,500-foot-high Chacaltaya as it shrinks toward oblivion. But in 13 years of study of the glacier, the scientists have gathered a rich lode of data representative of countless small glaciers across the region.

Chacaltaya was once the world’s highest ski slope, but no one has skied down its tongue of snow-coated ice since 1998. The melt has exposed rock across its midsection, splitting the glacier in two. Ramirez said it is now probably a mere 2% the size it once was.

Chacaltaya and other Andean glaciers had been retreating since the 18th century, when the “Little Ice Age” ended locally, but the rate has picked up dramatically in recent decades, melting three times faster since the 1980s than in the mid-20th century.

“What we see in the Andes is happening in Kilimanjaro and in the Himalayas,” said glaciologist Lonnie Thompson.

“We’ve just been in southeast Alaska, and 1,987 out of 2,000 glaciers are retreating there,” the Ohio State University scientist said in a telephone interview from Columbus.

The glaciers - “water towers of the world” - are the most visible indicators that we are in the first phase of global warming, said Thompson.