STEVE INSKEEP, host:
Tropical glaciers sounds like an oxymoron, but there are such unique ice floes dotted throughout Ecuador, Peru and Bolivia. That's in the upper part of South America, in the Andes. Most of the world's tropical glaciers are located in those high altitudes, and scientists say that the Earth's warming is quickly destroying them.
For NPR's Climate Connections with National Geographic, NPR's Julie McCarthy reports on the meltdown in Bolivia. And her story starts on a mountain near the capital, La Paz.
JULIE McCARTHY: A 90-minute trek up the lip of Zongo, one in a string of glaciers that drape La Paz like an icy necklace, reveals a startling sight.
We are looking at the retreat since 1980.
Mr. PATRICK GINO(ph) (Glaciologist): Yeah. And that's about 100 meter of glacier, of ice lost during that short period. That's a real measurement of retreat.
McCARTHY: Looking down from a weather station, glaciologist Patrick Gino(ph) says the glacier is both retreating and thinning.
Mr. GINO: So we lose about 100 meter of thickness, and we don't know if there is another 100 meters, no, and how long these part of the glacier will survive.
McCARTHY: Gino leads a snowshoe-clad team of French-funded scientists who are here to help Bolivia quantify the damage of global warming on its tropical glaciers. In muffled footsteps, they make their way to the equipment they have scattered across the glacier, measuring wind speed, humidity, solar radiation and snowfall. Twice a month, Gino's team scours Zongo that soars over 20,000 feet above sea level. Even at the bottom half, near 16,000 feet, climbers are breathless.
We've made it to the glacier, and we've made it to one of your measuring sticks.
Mr. GINO: So, we are digging a 10-meters hole in the glacier, and put this kind of stakes in the ice, in the glacier.
Mr. GINO: At night, the glacier is melting, the level is going down. The stakes are appearing.
McCARTHY: They're appearing. They're more visible through the snow.
Mr. GINO: They're more visible. And we measure how much has been lost.
McCARTHY: The stakes measure the removal of snow and ice through melting, wind erosion and evaporation, or what's called ablation. And they show the glacier has lost 29 feet of thickness since 2006. By contrast, other equipment measures the accumulation of snow. Data show for the past decade, ablation or melting has outpaced accumulation, meaning the mass balance of this glacier is in disequilibrium. Patrick Gino says Zongo is replacing its melted ice, but not fast enough to stop the glacier from shrinking.
Mr. GINO: Because the glacier didn't get enough snow during accumulation to replace all the melting.
McCARTHY: Scientists in Bolivia also say the point at which snow can survive melting is moving up the mountain, to an altitude of 18,000 feet, and that those glaciers at altitudes lower than that are becoming especially vulnerable to the Earth's warming. At over 20,000 feet, Zongo is considered high elevation. But Gino says the nearby glacier of Chacaltaya, once billed as the world's highest ski resort at 17,000 feet, has all but vanished.
Mr. GINO: It remained (unintelligible) in 1997, and there was a maximum of about 20 meter ice thickness. And now, what I saw last week, there are may be 2 meter.
McCARTHY: Two meters? Since 1997, it's lost 18 meters.
Mr. GINO: Yeah. I think the last two meters, I'm not sure that you can see them next year.
(Soundbite of water flowing)
McCARTHY: You can actually stand under the lip of Zongo and hear it melting.
(Soundbite of water flowing)
McCARTHY: But that's normal for the summer wet season, November through March, which is also when the glacier replenishes itself. In this season, it can snow, sleet and rain on Zongo.
At midday, humid air from the Amazon basin just over the ridge envelops the glacier in an eerie shroud of fog. All the precipitation is good if the glaciuer is performing its natural function, which, says World Bank Climate Change expert Walter Vergara, is to store water in the form of ice in the wet season and release it in the dry season - acting, he says, like a savings account for water.
Mr. WALTER VERGARA (Climate Change Expert, World Bank): This is how the glaciers have played our water regulation rule in the mountains. But once the glaciers disappear, this savings account is gone.
McCARTHY: Ice core shows Zongo to be some 20,000 years old. But at the current rate of melting, scientists say it could last just 40 or 50 more years.
This is no abstract debate. Zongo glacier fuels the hydroelectric dams that power La Paz. Others stressed glaciers provide drinking water. Bolivia's Institute of Hydrology predicts water shortages as early as 2009 in the industrial city of El Alto that has become a mecca for poor migrants from the barren highlands, where experts say changing weather patterns have caused crops to fail.
(Soundbite of thunder storm)
McCARTHY: El Nino also hastens glacier melting here by bringing dryer, hotter weather. But this year, La Nina has brought colder, wetter weather that tends to give glaciers a reprieve, but has also produced flooding so severe that President Evo Morales recently declared a national disaster. Analysts say the floods of La Nina have created a false impression that there is an excess of water.
(Soundbite of flowing water)
McCARTHY: It impoverished El Alto. A swollen river flooded Angel Kintayak Wakida's(ph) home. From his doorstep, the glacial peeks that provide the city's drinking water loom like timeless monuments in the distance. I asked Wakida what happens if water from the glaciers turns to a trickle?
Mr. ANGEL KINTAYAK WAKIDA: (Spanish spoken)
McCARTHY: I can't even answer a question about glaciers going away, he says. I don't know what we'd do. We have no idea and don't know what to anticipate.
Melting glaciers potentially affect tens of millions of people like Wakida from Ecuador to Peru to Bolivia - places with little capacity to fend off a crisis. The World Bank is trying to mitigate the long-term consequences of the Andes fragile glaciers disappearing, with projects to conserve water and build reservoirs.
In the case of Bolivia, the bank's Walter Vergara says the biggest producers of greenhouse gases that contribute to global warming owe South America's poorest country a huge debt.
Mr. VERGARA: And those countries that are the most energy-intensive - like the United States and China - in my view, in my personal view, have a moral obligation to reverse direction, to stop, to make all efforts possible.
McCARTHY: If the problem is this serious today, Vergara says, imagine what it will be like in 10 years.
Julie McCarthy, NPR News, La Paz, Bolivia.
INSKEEP: You can hear more stories in this series at npr.org/climateconnections. And you can find the latest global warming features from National Geographic magazine at the same place.