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by Tim Radford

Glaciers are melting slowly – but surely

May 20, 2013 in Warming

EMBARGOED until 2301 GMT on Sunday 19 May

Glacier in the Tian Shan mountains of Central Asia, where ice loss is considerable Image: Andrzej Barabasz (Chepry)

Glacier in the Tian Shan mountains of Central Asia, where ice loss is considerable
Image: Andrzej Barabasz (Chepry)

By Tim Radford

Although hundreds of the world’s glaciers are shrinking fast, far more are losing ice much more slowly, new research has established. But it shows that, almost everywhere, the glaciers are in retreat.

LONDON, 20 May – Forget, for the moment, the Greenland and Antarctic ice sheets: what about all the other stuff? What kind of difference does the melting of glaciers in Scandinavia, or Alaska, or the Himalayas make to the ocean levels?

Alex Gardner of Clark University, Massachusetts, and 15 colleagues from the US, Canada and Europe decided to take a closer look: their answer is that shrinking glaciers lost 259 billion tonnes (259 gigatonnes) of mass in the form of meltwater every year between 2003 and 2009, give or take 28 gigatonnes, an amount equal to around 30% of observed sea level rise.

This equals the combined losses from the permanent ice sheets that blanket, in layers thousands of metres thick, the two vast land masses of Greenland and Antarctica.

The scientists report their findings in the journal Science. They used both measurements on the ground – necessarily selective – and measurements from orbiting satellites, which naturally give a bigger picture, but also a more imprecise one.

The satellites carried instruments specifically designed to study ice loss: one was called GRACE, short for gravity recovery and climate experiment, and the other was called ICEsat – an ice, cloud and land elevation satellite. The first measured tiny changes in gravity as the ice melts away. The second used lasers to measure changes in height, and therefore volume.

The scientists also consulted an authoritative store of geographical data, the Randolph Glacier Inventory, which defines 19 glacier regions with a total area under flowing ice of 729,400 square kilometres. They chose the dates under study because for those six years, ICEsat and GRACE were both in orbit, and sending back data, and thus providing a record of both seasonal and overall ice loss during that time.

Long-term concern

 

The conclusion was that although the 300 most closely-observed glaciers, the ones that have caused the most alarm, are indeed losing mass at a disturbing rate, this is not the whole picture. The other 160,000 glaciers distributed across the planet are losing ice overall at a slower rate.

This sounds like relatively good news, considering that global anxiety about retreating glaciers was based mostly on direct measurements of famous or easy-to-observe ice flows. But the research confirms the big picture: that glaciers are in retreat almost everywhere.

And this spells problems in the long run everywhere: glaciers store winter water for summer irrigation, city water supplies and hydroelectric power. They keep rivers navigable, and they maintain mountain ecosystems.

If they shrink, that’s not good news for mountain creatures or the people, forests, plains and settlements downstream. The largest losses were from Arctic Canada, Alaska, coastal Greenland, the southern Andes and the high peaks of Asia. There was little loss from Antarctica’s glaciers. – Climate News Network

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by Tim Radford

Rockies and Everest lose ice and snow

May 15, 2013 in Warming

EMBARGOED until 2301 GMT on Tuesday 14 May

Himalayan melt water sustains many thousands who live downstream Image: Pavel Novak

Himalayan melt water sustains many thousands who live downstream
Image: Pavel Novak

By Tim Radford

The Rocky Mountains of North America have lost significant amounts of their snow cover since 1980, with climate change caused by human activities thought partly responsible.

LONDON, 15 May – Around 20% of the snow cover in North America’s greatest mountain range has been lost – because of warmer springs in the last three decades.

Scientists from the American Geophysical Union and the US Geological Survey report that they had established a pattern of snowfall in the northern and southern Rockies: when the snowpack was large in the northern Rockies, it might be correspondingly meagre in the southern mountains and vice versa.

But since the 1980s, snowpack declines have occurred simultaneously along the entire length of the Rocky Mountains, with unusually severe declines in the north.

Now research has begun to establish the cause. Researchers write in Geophysical Research Letters that, using monthly data collected from 1895 to 2011, they have been able to tease apart the different influences of winter temperatures, spring warming and overall precipitation on the April volume of the snowpack.

“Snow deficits were consistent throughout the Rockies due to lack of precipitation during the cool seasons during the 1930s – coinciding with the Dust Bowl era.

“From 1980 on, warmer spring temperatures melted snowpack throughout the Rockies early, regardless of winter precipitation,” said Greg Pederson of the Northern Rocky Mountain Science Center in Bozeman, Montana.

“The model in turn shows temperature as the major driving factor in snowpack declines over the past 30 years.”

Runoff from the Rocky Mountain snows accounts for 60 to 80% of the annual water supply for more than 70 million people in the western US. The timing of snowmelt affects the levels of water available for crop irrigation and hydro-electric power. It can also influence the risk of regional floods and bush fires.

The researchers blame both natural variation – the influence of cyclic Pacific Ocean phenomena such as El Niño and La Niña, for example – and global warming from human activity for the change.

Snowline heads uphill

 

“Regardless of the ultimate causes, continuation of present snowpack trends in the Rocky Mountains will pose difficult challenges for watershed management and conventional water planning in the American West”, said co-author Julio Betancourt.

Meanwhile, at the American Geophysical Union’s meeting in Cancun, Mexico, researchers report that the world’s highest peak, Mt Everest, is beginning to lose its snow and ice.

They report, after studies of satellite imagery of the mountain and the Sagarmatha National Park, that the Everest region in the Himalayas has been warming, and snow precipitation declining, for the last 20 years.

Everest glaciers have shrunk by 13% in the last 50 years and the snowline has moved 180 metres uphill. As the glaciers dwindle, the rocks and debris they carry are being exposed: the debris-covered sections of the glaciers have increased by 17% since the 1960s.

Once again, the researchers suspect that human-induced climate change may be responsible: this connection however is much harder to establish. But the majority of glaciers in the region are retreating at an ever-faster rate.

“The Himalayan glaciers and ice caps are considered a water tower for Asia, since they store and supply water downstream during the dry season”, said the scientist Sudeep Thakuri. “Downstream populations are dependent on melt water for agriculture, drinking and power production. – Climate News Network

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Avatar of Kieran Cooke

by Kieran Cooke

Ground slows glacier ice loss

May 12, 2013 in Science

EMBARGOED until 2301 GMT on Sunday 12 May

One of the valley walls of the Petermann glacier in northern Greenland Image: NASA/Michael Studinger

One of the valley walls of the Petermann glacier in northern Greenland
Image: NASA/Michael Studinger

By Kieran Cooke

New understanding of some of Greenland’s major glaciers suggests they may not melt in the future nearly as fast as they are doing now.

LONDON, 13 May – Scientists tread very carefully when it comes to glaciers. While the consensus is that glaciers around the world are generally in retreat, there are the exceptions:

in the west of the Himalayas some glaciers have been found to be growing, not shrinking. In Antarctica some glaciers are gaining mass balance while others are losing it. Meanwhile glaciers in other parts of the world, particularly in the Andes,  are disappearing at an ever increasing rate.

The impact of climate change on the Greenland ice sheet has been well documented: Arctic temperatures are rising at levels well above the global average, and ice-loss has been accelerating.

This has raised concerns that these constantly increasing rates of ice loss will lead to a rise in sea levels that could threaten coastal communities around the world. Yet the future contribution of Greenland’s glaciers to sea-level rise is uncertain.

A new study published in the journal Nature questions whether present trends of ice loss on the Greenland ice sheet will be maintained.

The report – Future Sea-level Rise from Greenland’s Major Outlet Glaciers in a Warming Climate – looks at the behaviour of the four major fast flowing glaciers in Greenland. The Petermann, Kangerdlugssuaq, Helheim and Jakobshavn glaciers together drain about 22% of the island’s ice sheet.

Lower loss expected

 

By building up a computer model of these four glaciers, scientists have revealed that the shape of the ground beneath the ice has a marked impact on the way the ice moves, with the rate at which the glaciers are losing ice depending critically on the shape of the fjords in which they sit and the topography of the rock below them.

In turn, this has led the scientists to doubt whether present rates of ice loss and the “calving” of icebergs from the glaciers will be maintained.

“…While these glaciers may show several bursts of retreat and periods of high iceberg formation in future, the rapid acceleration seen in recent years is unlikely to continue unchecked”, says the report.

The computer model suggests that, because of the influence of various topographical features, the projected sea level rise from ice loss of these four glaciers will be of the order of between 2cm and 5cm by 2200 – considerably lower than previous estimates which have been based solely on the extrapolation of current trends.

However, the rate of  calculated ice loss will still be considerable: the model predicts that the combined ice loss of the four will amount to between 30 gigatonnes (Gt) and 47Gt per year over the present century. One Gt of ice is equivalent to one cubic kilometre of water. By way of comparison, Lake Geneva contains 90Gt of water.

More clarity needed

 

“I am excited by the way we have managed to create a detailed picture of the workings of the glaciers”, says Dr Faezeh Nick, of the Universite Libre de Bruxelles, lead author of the study.

“It turns out that if the fjord a glacier sits in is wide or narrow, it really affects the way the glacier reacts. The important role of the terrain below the ice shows we need to get a much clearer picture of the rest of Greenland’s glaciers before we have the whole story.”

Work on the modelling of the glaciers was carried out under the EU-funded Ice2sea programme which links scientific expertise among 24 institutions in Europe and elsewhere.

Professor David Vaughan, head of the programme, told Climate News Network that though there were various ways of analysing the behaviour of glaciers, the new computer modelling could be vital in assessing future levels of ice loss.

“The key point is that we actually need to know about the land beneath the ice if we are going to come up with really good projections on future ice loss and the contribution to sea level rise of these glaciers. This computer modelling could be a big step forward and adds to our understanding of how glaciers behave.” – Climate News Network

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by Paul Brown

Andes’ tropical glaciers ‘going fast’

April 9, 2013 in Warming

FOR IMMEDIATE RELEASE

The peak of Chacaltaya, where snowfall is diminishing Image: DiverDave

The peak of Chacaltaya, where snowfall is diminishing
Image: DiverDave

By Paul Brown

Within the last three decades the glaciers of the tropical Andes have receded by between nearly a third and a half, scientists say – with the warming of the Pacific to blame.

LONDON, 9 April – The glaciers of the tropical Andes have shrunk by between 30 and 50% in 30 years and many will soon disappear altogether, cutting off the summer water supply for millions of people, according to scientists studying the region’s climate.

Their findings are particularly significant because glaciers in the tropics, 99% of which are in the Andes, are regarded as among the most sensitive indicators of climate change on the planet, according to the Intergovernmental Panel on Climate Change (IPCC).

In the Andes glaciers contribute to irrigation, hydroelectricity generation and water supply. For example, 15% of the water consumed in La Paz, the capital of Bolivia, comes from glaciers, a figure that doubles in the summer. The region, with 3.5 million people, is heavily dependent on melt water for its survival (and see our story of 25 January, Andean glaciers show record melting).

Many of the crops along hundreds of kilometres on the dry eastern slopes of the Andes rely on irrigation from glacier melt water in the summer.

The research covers 300 years of glacier history in South America. The glaciers reached their maximum extent during what is termed the Little Ice Age, between 1650 and 1730, when the world was colder. Rivers like the Thames in London and Seine in Paris froze over during some winters.

By studying rocky debris piled up during the Little Ice Age and then left behind as the glaciers retreated after 1750 the researchers have been able to chart their progress.

Rain replaces snow

 

Since then there has been a gradual decline in the length and mass of the glaciers, but this has accelerated dramatically during the last 30 years. Aerial photographs and satellite records have shown how quickly the area has changed.

Although the temperature in the region has increased by 0.7°C in this period, the warming is not thought to be the major cause of the retreat. Instead it is the warming of the Pacific Ocean since the 1970s that is the problem.

The influence of the warmer sea on the climate means that instead of snowing at higher altitudes in the tropical Andes, it frequently rains. As a result the snowpack has no opportunity to build up, leaving the glaciers bare and exposed to sunlight.

The study, published in the journal The Cryosphere, includes measurements and other work done by scientists in Bolivia, Peru, Ecuador and Colombia in collaboration with Albany University in the United States, Zurich University in Switzerland and Savoie University in France.

The glaciers cover 1,900 square kilometres, but many of them are not expected to survive the predicted increase in temperature of 4°C to 5°C by the end of this century. Some are already disappearing. The Chacaltaya glacier above La Paz disappeared in 2010.

Smaller glaciers (less than a square kilometer in size) are most vulnerable, and the lower the altitude the faster they are melting. At a height of 5,400 metres melting can be as high as 80 to 100% already, as in the case of the glacier above La Paz. Most glaciers at this altitude are expected to disappear in the next 10 to 15 years. – Climate News Network

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by Kieran Cooke

Climate change: One more problem for Pakistan

March 24, 2013 in Development Issues

EMBARGOED until 0001 GMT on Sunday 24 March

Floodwaters in Pakistan, 2010 Image: DVIDSHUB

Floodwaters in Pakistan, 2010
Image: DVIDSHUB

By Kieran Cooke

The growing menace of deadly bombings, attacks by US drones, continuing tensions with neighbouring India, power and food shortages and political instability as a general election looms in May -  as if Pakistan doesn’t have enough troubles, climate change is threatening the country.

The Indus river, originating on the Tibetan Plateau and flowing for nearly 2,000 miles through the disputed  territory of Jammu and Kashmir and finally down to the province of Sindh and out into the Arabian Sea, is key to life in Pakistan.

The majority of Pakistan’s 190 million people are involved in agriculture: the Indus, fed by glaciers high up in the Hindu Kush-Karakoram Himalaya mountain range, provides water for 90% of the country’s crops. Meanwhile hydro-power facilities based on the Indus generate around 50% of Pakistan’s total electricity.

Climate change is now threatening this vital waterway – and the future of millions in Pakistan. In recent weeks it has launched, in collaboration with the United Nations Development Programme (UNDP), its first ever national policy on climate change.

“Pakistan is among the most vulnerable countries facing climate risks”, says Marc-Andre Franche, the UNDP’s Pakistan director. ”Mechanisms need to be devised for greener, more resilient options for growth and sustainable development… the climate change clock is ticking too fast and the time to act is here and now.”

Pakistan’s scientists say that in order for the new policy to be effective a number of steps need to be urgently taken to mitigate the impacts of climate change. These include developing high temperature-tolerant crop strains, comprehensive flood warning systems and more reservoirs on the upper Indus. But there are serious doubts about funding for such schemes.

Ghulam Rasul, chief meteorologist at the Pakistan Meteorological Department, says weather patterns are becoming increasingly erratic. In the 1999 to 2002 period Pakistan was hit by severe droughts as the flow in the Indus and its tributaries fell dramatically. But from 2010 to 2012 a series of unusually intense monsoons caused the Indus to burst its banks, resulting in widespread floods: thousands were killed and millions displaced.

“Pakistan’s climate-sensitive agrarian economy now faces larger risks from variability in monsoon rains, floods and extended droughts”, says Rasul. “I urge the world to assist Pakistan to deal with climate change.”

Economy at risk

 

According to data gathered from 56 meteorological stations throughout Pakistan, there has been a marked increase in heat waves and rising temperatures in the vast Indus Delta in recent years.

In an article in the Pakistan Journal of Meteorology, Rasul and others say there is a greater incidence of tropical cyclones and of saline intrusion in coastal regions. Already wheat and banana harvests in the Indus Delta are being affected.

Rising temperatures are also causing health problems among the area’s population. In many cases farmers in the region -  among the poorest people in the world – are abandoning their lands and migrating to already overcrowded cities.

If this trend continues it could have devastating consequences for the wider economy. Sindh and the Indus Delta have become one of the world’s premier cotton-producing areas, feeding Pakistan’s economically vital textile industry. Falling cotton production in the region would not only hurt Pakistan: it would also trigger a substantial rise in world cotton prices.

Meanwhile in the mountainous far north most glaciers are in retreat, though some in the Karakoram range are stable or even – for as yet unknown reasons – expanding. Experts say that while melting glaciers might offset temperature rises and act as a form of insurance against drought in the short term,  the long term prognosis is not good.

David Grey, former senior water advisor at the World Bank and now visiting Professor of Water Policy at Oxford University,
says that although there is insufficient data to come to an accurate long term assessment of what will happen to the Indus, there are deep anxieties.

“We all have very nasty fears that the flows of the Indus could be severely, severely affected by glacier melt as a consequence of climate change. Now what does that mean to a population that lives in a desert – without the river, there would be no life? I don’t know the answer to that question”, he says. “But we need to be concerned about that. Deeply, deeply concerned.” – Climate News Network

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by alex kirby

Canadian glaciers are melting fast

March 7, 2013 in Warming

FOR IMMEDIATE RELEASE

Canada's far north is melting - and there's probably no going back Image: David

Canada’s far north is warming – and there’s probably no going back
Image: David

By Alex Kirby

Many of the Canadian far north’s glaciers are likely to have melted by the end of the century, researchers believe, making significant sea-level rise inevitable.

LONDON, 7 March – Canada’s Arctic Archipelago glaciers will melt faster than ever in the next few centuries, research by European-funded scientists has shown.

They say 20% of the Canadian Arctic glaciers may have disappeared by the end of this century, which would mean an extra sea level rise of 3.5cm

The results of the research, part of the EU-funded ice2sea programme, will be published in Geophysical Research Letters this week, and the paper, Irreversible mass loss of Canadian Arctic Archipelago glaciers, is now available online.

The researchers developed a climate model for the island group in the north of Canada in which they simulated the shrinking and growing of glaciers in this area.

The model correctly “predicted” the ice mass loss measured over the last ten years, and the researchers then used it to look forward to project the effect of future climate change on the Arctic Archipelago glaciers.

The most important result of the research is that it shows that the melting will probably be irreversibie, according to lead author Dr Jan Lenaerts of Utrecht University.

He says: “Even if we assume that global warming is not happening quite so fast, it is still highly likely that the ice is going to melt at an alarming rate. The chances of it growing back are very slim.”

One main reason for this expected irreversibility is that snow melting on tundra, and sea ice loss from around the glaciers, will intensify regional warming.

Snow and sea ice reflect the sunlight, and when they disappear a large part of the sunlight will instead be absorbed by the land and the sea, raising the local temperature significantly.

Successful backcasting

 

In one scenario considered by the scientists 20% of the volume of the glaciers disappears by the end of this century. This would be accompanied by an average global temperature rise of 3°C.

But the regional rise around the Canadian ice caps - a form of glacier in which the ice flows to the sea in many directions – would be 8°C. And this is not an extreme scenario, Dr Lenaerts says.

Canada’s Arctic Archipelago glaciers are one of the largest ice bodies in the world after Greenland and the Antarctic. If they  melted completely, global average sea level would rise by 20 cms. Since the year 2000 the temperature in this area has risen by 1-2°C and the ice volume has already decreased significantly.

Professor David Vaughan, the programme leader of ice2sea, who is based at the British Antarctic Survey in Cambridge, UK, says: “Added to glaciers in Alaska, the Russian Arctic and Patagonia, these apparently small contributions add up to significant sea-level rise.

“A key success of this study was in showing that the model performed well in reproducing recently observed changes. That success gives us confidence in how the model predicts future changes”.

Glaciers in many parts of the world are undergoing rapid melting, although some experts argue that natural variability needs to be taken into account as well as climate change (and see our story of 3 March, Glaciers on the slide.) – Climate News Network

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by Kieran Cooke

Glaciers on the slide

March 3, 2013 in Film reviews

EMBARGOED till 0001 GMT on Sunday 3 March

Greenland's glaciers face trouble - and so do many elsewhere Image: Christine Zenino

Greenland’s glaciers face trouble – and so do many others across the world
Image: Christine Zenino

By Kieran Cooke

If seeing really is believing, then James Balog’s film Chasing Ice is probably prompting a widespread outburst of faith. It shows the graphic evidence of how fast glaciers are melting worldwide.

LONDON, 3 March – You’d have to worry about James Balog’s knees. He has an operation on one leg and then, for a bit of gentle recuperation, goes walking on a glacier. Not surprisingly, before too long he needs to return to the surgeon’s table: then it’s back to the ice once more, only this time Balog is being lowered down into a crevasse, a cascade of freezing glacier melt water rushing within inches of his camera.

Balog is a photographer who has specialised for many years in what he describes as the “contact zone” between humans and nature. His work includes photos and documentaries on animals and forests, on the 2004 tsunami in Southeast Asia, on Hurricane Katrina and much, much more.

In 2006 he was given an assignment by National Geographic magazine to photograph glaciers and ice formations. He became a glacier groupie and the following year started the Extreme Ice Survey (EIS), photographing and filming glaciers round the world. Chasing Ice, released in the US last year and now doing the rounds of selected cinemas in the UK, captures the work of the EIS project.

Balog was once a climate change sceptic. Not any more. He and his team set up 28 time lapse cameras filming glaciers from Mount Everest in Nepal to Alaska, Greenland, Iceland and the Rockies in the US. Every half hour of daylight the cameras would click away, recording changes in glacier shape and size. The results, seen in the film, are startlingly clear.

“This is the memory of the landscape”, says Balog, standing by one of his cameras at a glacier in Greenland and holding up a small file of  film. “I never imagined you could see glaciers this big disappearing in such a short space of time. That landscape is gone and may never be seen again in the history of civilisation.”

Balog now tours the world with his photos and film showing, in his words,  “how extraordinary amounts of ice are disappearing with shocking speed.”  He wants people to see for themselves the visual evidence of climate change. “Seeing is believing”, he says.

Up an ice field on crutches

 

Chasing Ice is visually stunning: at one point young members of the survey team are camped out on the ice overlooking the Illulissat or Jakobshavn glacier half way up the west coast of Greenland. They’ve been there for days – the wind its threatening to blow the tent away, the cold is intense.

Then, in little over an hour, a piece of glacier more than half the size of Manhattan Island breaks or “calves” away. It’s the first time such a large-scale calving event has been captured on film. Giant pieces of ice shoot 600 feet up in the air, the glacier doing cartwheels, the deep, roaring sound echoing like the last breath of some giant, fatally wounded animal.

“The only way that you can really try to put it into scale with human reference is if you imagine Manhattan, and all of a sudden, all of those buildings just start to rumble, and quake, and peel off, fall over, and roll around”, says one of the film-makers.  “This whole massive city just breaking apart in front of your eyes.”

The film was not an easy one to make, with delicate electronic equipment being placed in some of the harshest conditions on the planet. Cameras would have to be secured by elaborate systems of anchors and wires. At one point Balog’s team return to the cameras to find the equipment has failed and months of  filming has been lost.

And then there are those knees. Towards the end of the film Balog is seen struggling up an ice field on crutches. There’s a postcript saying his knees have been repaired once again, this time with the aid of stem cell surgery. The EIS project is ongoing. Let’s hope the knees keep going as well. – Climate News Network

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by Kieran Cooke

Nepal’s glaciers retreat – but why?

February 23, 2013 in Science

EMBARGOED until 0001 GMT Saturday 23 February

Nepal's Khumbu glacier Image: McKay Savage

Nepal’s Khumbu glacier                                    Image: McKay Savage

By Kieran Cooke

One of the Climate News Network’s editors, Kieran Cooke, was among a group of journalists recently investigating the impact of climate change in Nepal and the Himalayas. In the last of his reports from the region he describes the difficulties of establishing why so many of Nepal’s glaciers appear to be shrinking.

KATHMANDU, 21 February – Mohan Bdr. Chand is at the sharp end of glacier research. A climate researcher at Kathmandu University, Chand is carrying out vital field work, looking at high mountain glaciers as indicators of climate change.

The work involves spending time clambering up and down the ice, taking measurements and readings to calculate mass balance – the sum of the snowfall which builds up on a glacier and the melting that shrinks it.

“Getting to a glacier can take five days from Kathmandu – two days driving and three days trekking”, says Chand, one of only a few native glacier specialists in Nepal. “We stay on the glacier for over two weeks at heights of between 5,000 and 6,000 metres. Conditions are tough, with altitude sickness a big problem.

“What we’re seeing is that almost all glaciers in Nepal are in retreat”, says Chand. “There are a few in the far west of the country which appear to be stable or increasing in size, but these – influenced by westerly winds rather than the Indian monsoon – are very much the exception.”

Calculating mass balance is seen as critical to understanding a glacier’s long-term behaviour. According to a 2011 study by the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD), there are an estimated 54,000 individual glaciers in the Hindu Kush-Himalayan region, an area of mountains stretching from Afghanistan in the west to Yunnan in southwest China in the east.

“The glaciers in much of the region show signs of shrinking, thinning and retreating”, said the study.

What is noteworthy is how little detailed knowledge there is of this region, which is considered to be highly vulnerable to climate change and to be warming faster than many other areas on the planet.

Retreat rates vary

 

“A serious lack of reliable and consistent data severely hampers scientific knowledge about the state of Himalayan glaciers”, said a late 2012 report by the United Nations Environment Programme’s global environmental alert service.

The region has been referred to as a “white spot”, a term in the 2007 IPCC (Intergovernmental Panel on Climate Change’s) Fourth Assessment Report used to describe an area with “little or no data”.

Confusion was added to the debate when, in the same IPCC report, it was suggested that the probability of  the Himalayan glaciers disappearing by 2035 “is very high if the Earth keeps warming at the present rate.”

It was a claim the IPCC later said should never have been published, but one that was eagerly seized on by climate sceptics in efforts to try to undermine the whole body of the Panel’s work.

Mohan and his team are investigating two glaciers – one at Rikhashambha in north-central Nepal at 6,000 metres, described as a valley glacier, and one at Yala to the east, on the border with Tibet at between 5,100 and 5,700 metres, described as a plateau-type glacier.

“In general plateau-type glaciers – mostly found in Tibet – seem to be retreating faster than valley types”, says Dr Mohan. “The number of glacial lakes at high altitudes is increasing, with between 20 and 26 in Nepal. If these burst, they pose a serious danger.

“Rising temperatures and sudden rainfalls of great intensity are factors that seem to be causing the retreat of some glaciers. But recently it’s been realised that black carbon could have a major impact on the mass balance of glaciers.”

Black carbon – particulate matter that in South Asia comes mainly from the burning of wood and waste and from cooking fires, or from coal-burning and diesel exhausts – falls on snow and darkens the surface, in the process reducing reflectivity and causing the surface to absorb more heat.

Data too sparse

 

Most of the black carbon falling on the Himalayas and the south of the Tibetan plateau comes from the plains of India, while that of the eastern and northern sections of the plateau comes mainly from China.

According to recent ICIMOD estimates, black carbon is probably responsible for a large part – around 30% by some calculations – of glacial retreat in the region.

ICIMOD and other bodies admit there is far too little field data available to draw solid conclusions, whether on overall glacial melt or on the influence of black carbon. Part of this is to do with the inhospitable terrain. Also, in a tense region where transboundary cooperation is severely limited, studies that have been done often use differing methodologies.

Advances in satellite technology have significantly increased the volume and quality of data gathering across the region. However, satellite survey results have shown considerable variation, with one survey finding large glacial retreat and another a much smaller rate of melt. Scientists say there is often no substitute for fieldwork but admit that the extent of such activity is still woefully inadequate.

“We will return to the glaciers in May to take more measurements”, says Chand. It is gruelling work but needs to be done if a full picture of what’s going in the glaciers of the Himalayas is to emerge. – Climate News Network

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by alex kirby

Ice melt means uneven sea-level rise

February 20, 2013 in Science

FOR IMMEDIATE RELEASE

Greenland's ice will have distant impacts Image: Christine Zenino

Greenland’s ice will have distant impacts             Image: Christine Zenino

By Alex Kirby

Research shows that some parts of the world are likely to experience much more sea-level rise than others this century, with parts of the Pacific Ocean particularly affected.

LONDON, 20 February – Scientists say the sea-level rise caused by climate change during the rest of this century will not affect all parts of the world equally, because of the ways sea, land and ice interact.

They say parts of the Pacific are likely to see the highest rise. This region is where many low-lying island countries most vulnerable to sea level rise are already struggling. In the Indian Ocean the Seychelles face a similar plight. Their peoples will need evacuation if the scientists’ high-end predictions are correct. Northern Europe, on the other hand, will experience a below-average increase.

The team, from Italy’s University of Urbino and the University of Bristol, UK, report their findings in a paper, The gravitationally consistent sea-level fingerprint of future terrestrial ice loss, published in Geophysical Research Letters online.

Scientists have known for some time that sea level rise around the globe will not be uniform. The team investigated how ice loss will continue to add to rising sea levels until the year 2100. The researchers, from the European Union’s Ice2sea project, show in detail the global pattern of sea-level rise that would result from two scenarios of ice-loss from glaciers and ice sheets.

Improved projections of the contribution of ice to sea-level rise produced by Ice2sea will feed into the fifth assessment report of the Intergovernmental Panel on Climate Change. In 2007, the IPCC’s fourth report highlighted ice-sheets as the most significant remaining uncertainty in projections of sea-level rise.

The researchers found that ice melt from glaciers and from the Greenland and Antarctic ice sheets is likely to be critically important to regional sea-level change in the equatorial Pacific ocean.

Legacy of the Ice Age

 

There the rise will be greater than the global average increase, affecting in particular western Australia, Oceania and the small atolls and islands in the region, including Hawaii. Another area which should expect an above-average increase is the east coast of South Africa and Madagascar.

The study focussed on three effects that lead to the unequal distribution of sea-level rise. First, land is both subsiding into and emerging from the sea because of a massive ice loss at the end of the last Ice Age 10,000 years ago, when billions of tonnes of ice covering parts of North America and Europe melted.

This caused a major redistribution of mass on the Earth, but the crust responds to such changes so slowly that it is still changing shape. Secondly, the warming of the oceans changes the distribution of water across the globe.

The third effect is the way the sheer mass of frozen water on Antarctica and Greenland exerts a gravitational pull on the surrounding liquid water, pulling in enormous amounts and raising the sea-level close to the coasts. As the ice melts its pull decreases and the water previously attracted pours away, to be redistributed around the globe.

Co-author Professor Giorgio Spada said: “The most vulnerable areas are those where the effects combine to give the sea-level rise that is significantly higher than the global average.” In Europe the level would rise, but it would be slightly lower than the average.

“We believe this is due to the effects of the melting polar ice relatively close to Europe – particularly Greenland’s ice”, he said. “This will tend to slow sea-level rise in Europe a little, but at the expense of higher sea-level rise elsewhere.”

The team considered two scenarios in its modelling. One was the “most likely” or “mid-range” and the other closer to the upper limit of what could happen.

Stark contrast

 

Professor Spada said: “The total rise in some areas of the equatorial oceans worst affected by the terrestrial ice melting could be 60cm if a mid-range sea-level rise is projected, and the warming of the oceans is also taken into account.”

Another co-author, Jonathan Bamber, professor of physical geography at Bristol University, UK, told the Climate News Network: “Northern Europe will be influenced by mass loss from Greenland, and places like Scotland and Scandinavia will probably see close to zero sea-level rise from the melting ice, leaving aside thermal expansion of the sea.

“But if you take the high-end scenario, there’s a reasonable chance the rise could reach a metre in the western Pacific.”

Professor David Vaughan, Ice2sea programme coordinator, said: “The urgent job now is to understand how the global sea-level rise will be shared out around the world’s coastlines. Only by doing this can we really help people understand the risks and prepare for the future.”

A spokesman for the Association of Small Island States (Aosis), told a UN climate conference two years ago that whole nations would be washed away by sea level rise.

He said the people of Kiribati, Tuvalu, most of the Cook Islands, the Marshall Islands and the Maldives, which are just a few metres above sea level now, could be lost. – Climate News Network

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Avatar of Tim Radford

by Tim Radford

Andean glaciers show record melting

January 25, 2013 in Science

 

The Pastoruri glacier in Peru’s Cordillera Blanca is one of the Andean glaciers monitored by the scientists in the study published in The Cryosphere. Image: Edubucher/Wikimedia Commons

The Pastoruri glacier in Peru’s Cordillera Blanca is one of the Andean glaciers monitored by the scientists in the study published in The Cryosphere. Image: Edubucher/Wikimedia Commons

EMBARGOED until 0001 GMT on Friday 25 January

By Tim Radford

Tropical glaciers in the Andes are melting faster than at any time in the last three centuries, scientists say — and the cause must be the warming of the atmosphere.

LONDON, 25 January – Glaciers in the tropical Andes are in retreat. They are losing ice at an accelerating rate and, in the most comprehensive study so far, scientists identify the cause as atmospheric warming.

A team from France, Switzerland, the US, Bolivia, Peru, Ecuador and Colombia report in the journal The Cryosphere, published by the European Geosciences Union,  that they tried to measure the mass of ice at high altitude and compare those measurements with records that date back more than 60 years.

They conclude that – although the glaciers have been retreating ever since the coldest point of the Little Ice Age between the 16th and 19th centuries – this retreat is now at an unprecedented rate: the fastest for 300 years.

Atmospheric temperatures have warmed by 0.7°C in the last 50 years. Rain and snowfall levels have not changed significantly, and cannot explain the accelerating loss of ice, so atmospheric warming must be the cause.

An essential source of water

 

In fact, accelerating rates of glacial retreat have been reported consistently over much of the northern hemisphere in recent decades. But the tropical Andes are a special case. They are home to 99% of all the glaciers in the tropics, and are therefore particularly sensitive indicators of climate change.

Millions depend on the seasonal melt water to provide drinking water, irrigation for crops and hydroelectric power in the region. Not surprisingly, the glaciers at low altitudes – those below 5,400 metres – are melting at the greatest rate: losing 1.35 metres of thickness of ice a year on average since the late 1970s.

“Because the maximum thickness of these small, low-altitude glaciers rarely exceeds 40 metres, they will probably completely disappear within the coming decades”, says Antoine Rabatel, of the Laboratory for Glaciology and Environmental Geophysics in Grenoble, France, who led the study.

Altogether, the scientists surveyed 1,000 square kilometres of glacier – about half of all the area covered by ice in the mountains at the beginning of the century. They collected data and used remote sensing, satellite imagery and aerial photographs to monitor the changes.

“The ongoing recession of Andean glaciers will become increasingly problematic for regions depending on water resources supplied by glacierised mountain catchments, particularly in Peru,” they report. – Climate News Network

 

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