The following articles several each from three continents represent the tip of the iceberg in terms of glacier retreat. The world is warmer and glaciers are not happy from The Arctic to the Antarctic from Asia to America.
Patagonian ice in rapid retreat
|
By Jonathan Amos
BBC News Online science staff |
The dense, blue ice of the San Rafael Glacier
|
One of South America's leading natural tourist destinations, the San Rafael Glacier in Chile, is retreating at an alarming rate, say UK scientists.
"If the glacier retreats further up valley, it will cease to calve icebergs into the Laguna San Rafael, and one of the reasons why this area attracts so many tourists will be largely gone."
The San Rafael Glacier is part of the Northern Patagonian Icefield.
|
It is one of the fastest-moving glaciers in the world, flowing at 17m a day.
Falling from an altitude near to 3,000m right down to sea level, it is driven on by gravity and the mass of prodigious quantities of snowfall high up in the Andes.
Now, Glasser and Aberystwyth colleague Dr Krister Jansson, together with Dr Stephan Harrison from Oxford University, have been able to show that the glacier's front wall stands 1km further back in the water compared with the early 1990s.
Calving activity off the 70m-high vertical ice cliff has been dramatically reduced, too.
"We first went there 13 years ago.
Tourists visit the site to see icebergs break off
|
"People put paint marks on the rock wall where the glacier was then; they even built a lookout post directly over the front of the glacier in 92," Dr Glasser said.
"This year, the glacier is nowhere near this point - it's about a kilometer back from where it was.
"We've looked at the precipitation records closest to this area and they show no obvious change over the last 100 years, but they do have a rise in temperature recorded."
Mirrored recession
Scientists concede their historical data on the extent of glaciers - across much of the world, not just in South America - is patchy. However, they argue a consistent pattern of recession is beginning to emerge with many ice bodies from the Artic to the tropics.
At San Rafael, the glacier's position was recorded once in the late 1800s as being more than 10km further out into the sea than it is now.
And moraine, the sediments dumped by the glacier, about 12km from the present ice front are currently being dated by the UK team - but are expected to be 3,000-5,000 years old.
"So it seems this glacier was relatively stable for 3,000-5,000 years and then suddenly, in the last 100 years, it came back.
Dr Harrison added: "In recent years, the glaciers of the Northern Patagonian Icecap have been melting rapidly as a result of global warming, and the San Rafael Glacier has mirrored this retreat.
"The Patagonian icefields are losing ice more rapidly than any other comparable ice masses on Earth and we must see this as the inevitable consequence of global climate change."
Last year, US researchers working in the Patagonian icefields reported similar concerns. The Nasa-led study, published in the journal Science, looked at ice loss in 63 areas, comparing data from three decades.
The researchers found ice was lost at a rate sufficient to push up ocean waters by 0.04mm per year during the period from 1975 through to 2000.
|
|
|||||||||||
|
Thursday, November 13, 2003 Our Warming World: Effects of climate change bode ill for Northwest THE MOUNTAINSAbout a dozen snow-moving machines sit behind the Traveler's Rest convenience store at Snoqualmie Pass, waiting for the winter snowpack that draws thousands of skiers and snowboarders up Interstate 90 each winter.
Nowadays, though, managers of the Summit at Snoqualmie ski resort are looking at the sky kind of worried. While the slopes there are the most convenient to Seattle, they also sit at about 3,200 feet above sea level. That makes it the lowest Washington ski resort -- the most vulnerable to global warming. Scientists already have noted decreases in spring snowpack. With snow levels likely to rise at the rate of 300 feet for every degree of warming, a Snoqualmie skiing season that's now four months long on average stands to shrink to less than three months in 20 years, researchers say. In 40 years, it could be down to two months. Last year's opening, delayed nearly a month by lack of snow, could be a sign of things to come. Imagine -- snowless in Snoqualmie. "We rely 100 percent on natural snow," said Jon Pretty, the Summit at Snoqualmie marketing manager. "If Mother Nature isn't able to make it snow, we're de facto out of business." It's not just snow that's being affected. Ice is, too. Old advertising slogans touted the North Cascades as "America's Alps." But the region's glaciers have lost some 30 percent of their girth in the last century, according to researchers from Nichols College in Dudley, Mass. They've been monitoring 117 North Cascades glaciers since 1984. All of them are receding. Seven have disappeared. A big snow year in 1998-99 helped preserve them, although the dearth of snow last year again had many shriveling. The only ones that don't seem to be on the wane are those at high elevations, near the crest of the mountain range, said Rob Burrows, a geologist at North Cascades National Park and Recreation Complex. "I don't think our glaciers are going to disappear in the next 50 years," he said. Maybe not, but Nichols College's Mauri Pelto, who has been monitoring them longer than anyone, says most could be gone by then. Just outside the park lies the continent's best-studied example of glacier-wasting. Some 25 miles northeast of Darrington, the South Cascade Glacier has lost a third of its mass in 45 years. The meltoff was particularly high from the mid-'70s to mid-'90s, reflecting a regional pattern. And U.S. Geological Survey scientists calculate that the glacier has probably lost two-thirds of its ice in the last century. Carved by the hand of nature By JAMES GELUSO
Shrinking glaciers spell trouble for Skagit River
The prospect of shrinking glaciers alarmed the city of Bellingham, which depends on the Nooksack River for its drinking water. The city paid Pelto to study the Deming Glacier, which feeds the Nooksack, as part of a long-term water supply forecast. The trend over the past 20 years has been clear, Pelto said. There have been more warm years than cool years, and the glaciers have been shrinking. The glaciers have lost about 20 percent of their total size. They have retreated up the mountainside, and gotten thinner. Glaciers grow in the winter. Some of the snow that falls on top melts and freezes several times over a summer, eventually becoming firn, the ice that makes glaciers blue. During the summer, some of the firn melts off and the glacier shrinks. If the amount of ice that melts off is the same as the amount of new ice in a year, the glacier will stay the same size — staying in equilibrium, the glaciologists say. Glaciers often grow in a cold year, then shrink in a warm year. "The water will also be less sediment laden and warmer," Pelto wrote in an academic paper on the effects of glacial shrinkage. "The impact will be less water for the fall salmon runs, and less food in amount and processing for stream invertebrates on which salmon feed downstream in the Sauk and Skagit Rivers." Pelto conducts his studies of the North Cascades from Nichols College in Massachusetts. That may not be the best place from which to study glaciers, but it's where he has his year-round job as an environmental science professor. The glaciers are one of the clearest indicators of climate change. It's often referred to as global warming, and that's what is happening to the glaciers, but the change is more complex. One of the predictions of scientists is that the warming climate will lead to more extreme weather. For a glimpse of the future, Pelto points to the Lewis Glacier near Rainy Pass. In 1990, the glacier disappeared entirely, and the summertime runoff from the basin was just a quarter of what it had been when the glacier was there. Not all the glaciers will disappear, Pelto said. A larger, higher glacier like Easton will keep shrinking for several more years, but the top of the glacier is high enough that it will likely still be collecting snow each year. Eventually, it will reach an equilibrium, smaller than it is now, but not melted away completely. It's the more plentiful small glaciers that will disappear, quietly, a few feet every year. |
|||||||||||
blue and white towers.
|
Melting glaciers threaten Peru
|
||||||||||||||||||
|
Thousands of people in the Andes mountains of Peru are
having their lives affected in both a practical and cultural way by
climate change, which is causing the region's glaciers to melt.
This is already having a major impact of some aspects of life for the people who live in the mountains - and the government of the country is worried that the situation could get much worse. In the last three decades, Peruvian glaciers have lost almost a quarter of their area. "This is an indicator which gave us some concern on how the future was going to be on these tropical glaciers," Patricia Iturregui, head of the Climate Change Unit of Peru's National Council for the Environment, told BBC World Service's One Planet programme. "All our estimations on the basis of this data are that in the next 10 years the top tropical glaciers of Peru - and eventually other Andean countries - above 5,500 metres will disappear if climate conditions remain as the last 10 years." Nasa fears The most immediate threat is coming from the change to water supplies in the area. During the dry season, river water comes exclusively from the glaciers, which melt naturally at that time of year. They then replenish themselves in the wet season. But this balance has been upset - the glaciers are melting faster than they can replenish themselves. As they thaw, dozens of new lakes have spread all over the highland. "We are in the process of desertification," stressed Ms Iturregui. "The retreat of the glaciers is definitely going to mean a shortfall in the water supply in years to come." Conversely, the fact that the glaciers are not replenishing themselves is also a potential threat to life in the region, as in the dry season they are the sole source of fresh water. And there are further impacts on the lives of people in the mountains. "Now, glaciers are sliding over the bedrock," said glacier expert Cecil Portocarrero. "This is causing problems - not only for water resources but also for tourism, for climbers."
Bolivian glaciers shrinking fast
Huayna Potosi: The cities below depend on the
meltwaters
Glaciers in the Bolivian Andes are shrinking at an alarming rate, say scientists.
To our right, the glacier climbed near vertically to the towering peak of Huayna Potosi (6,050 metres/19,850 feet). Lines could be made out on the ice wall - fractures, Alvaro informed me, which one day would be the starting point of an avalanche. All around us on the snow were small insects, blown up in a cloud from their tropical Amazon home and dropped on to this white carpet to take their last confused steps. And echoing up from far below came the distant gurgle of running water. Data collection Crossing this glacier is a weekly event for Alvaro, a 22-year-old student working with the French Institut de Recherche pour le Developpement (IRD). From a measuring station located 5,200 m above sea level, he records data showing precipitation, wind speed, air temperature and other variables that help the team from the IRD map the changing form of the glacier. For a decade now, in fair and foul weather, the team has been collecting data on this and two other glaciers in the Cordillera Real mountain range, which curves around La Paz and off north towards Peru. The results have been alarming. Losing mass The Zongo glacier has retreated by around 10 metres and lost about one metre of depth every year.
The nearby Chalcaltaya glacier, known as the world's highest ski-field, has lost over 40% of its thickness and surface area. The key factor accelerating mass loss on these glaciers is increasingly frequent El Nino events in this part of the world, a climate phenomenon that may or may not be being pumped up by global warming. "This is a problem for the glaciers because it means lower precipitation and higher temperatures," explained Dr Robert Gallaire, head of the La Paz IRD unit. Glaciers are shrinking all over the planet. But tropical glaciers, most of which are in the Andes, are losing ground fastest. Tropical glaciers These low-latitude high-altitude glaciers are particularly sensitive to changes in climate because their season of accumulation is summer, when radiation levels are at their peak. In Europe or elsewhere, glaciers accumulate during the cold season, allowing some recovery. In the Andes, the run-off goes on all year, leaving smaller glaciers, like Chacaltaya, exposed. "Chacaltaya no longer has enough inertia," said Dr Gallaire. "The bare rock around the glacier works as an oven, speeding the melting. Even in 2000/1 when we had a strong La Nina year with a lot of snowfall, it continued to lose mass." Important water source Run-off from glaciers in the Cordillera Real contributes to reservoirs that supply 1.5 million people in La Paz and the neighboring city El Alto. It also feeds a series of hydroelectric plants that satisfy the two cities' energy needs. If current warming trends continue, Dr Gallaire fears that within 50 years the loss of glaciers will impact heavily on these water supplies. .Alaskan glaciers melting faster 
The loss is greatest at highest elevations
US scientists have found that glaciers in Alaska are retreating much
faster than originally thought.
The researchers say the resulting melt waters are sufficiently large to drive up global sea levels by 0.14 millimetres per year.
The study by Dr Keith Echelmeyer, of the University of Alaska Fairbanks Geophysical Institute, and colleagues used laser altimetry to measure the volume changes of 67 Alaskan glaciers from the mid-1950s to the-mid 1990s. Their work, published in the journal Science, adds to the growing evidence that the level of recent glacier wastage - from polar regions to the tropics - has been underestimated. Short of data "There is some historical evidence that at the turn of the last century glaciers were thinning but not so that people noticed it much," Dr Keith Echelmeyer told the BBC.
"What we see over the last 50 years is that they have thinned quite substantially and then over the last five to 10 years there has been an acceleration." Scientists who suspect human activities such as the burning of fossil fuels are causing an unnatural global temperature rise believe glacier wastage may be a good indicator of what is happening. But Dr Echelmeyer is hesitant to say the recent changes his team have seen are the result of a warmer climate because he feels there is currently insufficient data to come to firm conclusions. Greatest loss "Climate is changing and this is affecting the glaciers - and they are being a good indicator of that," he said. "Now, whether it's warming up of the climate or less snowfall, it is hard to say. That will take further investigation and an analysis of glacier flow, for example." Glaciers in Alaska and neighbouring Canada cover 90 thousand square kilometres, or approximately 13% of the mountain glacier area on Earth. Dr Echelmeyer's team surveyed the volume and area changes of part of this region from an aircraft equipped with a laser altimetry system. The researchers measured the volume loss by checking glacier elevation and volume data on US Geological Survey maps from the 1950s. "Most glaciers have thinned several hundred feet at low elevations in the last 40 years and about 60 feet at higher elevations," Dr Echelmeyer said. Higher levels The team has calculated that Alaskan glaciers are responsible for at least 9% of the global sea-level rise during the past century, and Alaska's glaciers raise the level of Earth's oceans by more than one-tenth of a millimetre each year.
Skiers beware: Melting glaciers mean unpredictable hazards
By BBC News Online's environment correspondent Alex Kirby
If you are contemplating a trip to the Alps, best go sooner rather than later. The longer you leave it, the less likely you are to find much sign of the glaciers. They have drawn generations of climbers and tourists to the Alps from Europe and beyond. But since 1850, western Europe's glacial area has shrunk by up to 40%, and the volume by more than 50%. The melting is happening, and it appears to be gathering pace. Scientists from Zurich University have monitored two specific regions of the Swiss Alps, the Engadin and the Simplon, for approaching half a century. This year they reported "a pronounced and dramatic shrinkage of both the extent and number of ice bodies". "In the Engadin", they said, "24 of the investigated 54 ice patches have vanished since 1955. In the Simplon area, 10 of 31 ice bodies have melted away completely since 1967." Sub-surface melting Longer-term studies suggest that the Alpine glaciers have been retreating for the last 150 years, and some scientists believe they could disappear completely by 2050.
Satellite studies carried out by the US Geological Survey's Glims project (Global Land Ice Measurement from Space) reported evidence in June 2001 of glacier shrinkage in the Pyrenees, between France and Spain. The number of Spanish glaciers has fallen from 27 in 1980 to 13 today. It is not only the glaciers themselves that are warming, but the rock and soil beneath the surface as well. Scientists have discovered that Europe's permafrost, the frozen earth covering mountain areas like the Alps, is melting. Underground temperatures have risen by nearly a degree in the past decade - three times faster than at any other time in the last century. Buildings and villages will be increasingly at risk. Further afield, the rate of glacier retreat in Russia's Caucasus mountains is about the same as Switzerland's.
|
||||||||||||||||||
