| | Originally Posted by JaJae  It's pointless symbolism about a chance something might happen that would have literally no negative effects, yet at the same time it's used to bring about an emotional response. Melting ice will have plenty of negative effects, not just in the Arctic, but all around the world. Global meltdown: scientists isolate areas most at risk of climate change | Environment | The Guardian Originally Posted by link Global meltdown: scientists isolate areas most at risk of climate change
# Ian Sample, science correspondent
# The Guardian,
# Tuesday February 5, 2008
Scientists have long agreed that climate change could have a profound impact on the planet; from melting ice sheets and withering rainforests, to flash floods and droughts.
Now a team of climate experts has ranked the most fragile and vulnerable regions on the planet, and warned they are in danger of sudden and catastrophic collapse before the end of the century.
In a comprehensive study published today, the scientists identify the nine areas that are in gravest danger of passing critical thresholds or "tipping points", beyond which they will not recover.
Although the scientists cannot be sure precisely when each region will reach the point of no return, their assessment warns it may already be too late to save Arctic sea ice and the Greenland ice sheet, which they regard as the most immediately in peril. By some estimates, there will not be any sea ice in the summer months within 25 years.
The next most vulnerable area is the Amazon rainforest, where reduced rainfall threatens to claim large areas of trees that will not re-establish themselves. The scientists also expressed concerns over the Boreal forests in the north, and have predicted that El Niño, the climate system which has a profound impact on weather from Africa to North America, will become more intense. The scientists are so concerned they have called for an early warning system to monitor each of these fragile ecosystems.
The international team, whose study appears in the Proceedings of the National Academy of Sciences, represents some of the world's most prestigious organisations, including the Potsdam Institute for Climate Impact Research in Germany, the University of East Anglia and Oxford University's Environmental Change Institute. The scientists polled 52 environmental experts and combined their responses with discussions among 36 leading climate researchers at a workshop at the British embassy in Berlin. Each was asked to rank regions at greatest risk of climate change in the next century.
"There's a perception that global warming is something that will happen smoothly into the future, but some of these ecosystems go into an abrupt decline when warming reaches a certain threshold," said Tim Lenton, an environmental scientist at the University of East Anglia and lead author of the study.
"If we know when the different tipping points are, we can use them to inform targets to limit global warming. It gives us something to aim for," he added.
Last year, the UN's expert panel of climate scientists warned average temperatures could increase by as much as 6.4C by the end of the century, with a rise of 4C most likely. Such a rise would bring food and water shortages to vulnerable parts of the world, displace millions of people and wipe out hundreds of species.
In the latest study, the scientists calculate Arctic sea ice will go into irreversible decline once temperatures rise between 0.5C to 2C above those at the beginning of the century, a threshold that may already have been crossed. There is already a 50% chance that the Greenland ice sheet will soon begin melting unstoppably, although it could take hundreds of years to melt completely. The meltwater would raise global sea levels by seven metres.
A temperature rise of 3C could see more intense El Niños, with profound effects on the weather from Africa to North America.
Warming of 3C to 5C could reduce rainfall in the Amazon by 30%, lengthening the dry season. The Boreal forests could also pass their tipping point, with large swaths dying off over the next 50 years. In Africa, more rainfall may regreen the Sahel region, but the west African monsoon could collapse, leading to twice as many unusually dry years by the end of the century. The Indian summer monsoon is predicted to become erratic and in the worst case scenario, begin to flip chaotically, unleashing flash floods one year and droughts the next.
Measurements of the western Antarctic ice sheet show the balance of snowfall and melting has shifted and it is now shrinking. According to the study, a local warming of more than 5C could trigger uncontrollable melting, adding five metres to sea levels within 300 years. Under the same warming, Atlantic currents that power the Gulf Stream could be severely disrupted.
"If you can get some warning that you're nearing one of these thresholds, you can get to work on adapting to it. You could work harder on reducing emissions, or you might use it as impetus to try other options," said Lenton.
Explainer: What could happen next
If greenhouse gas emissions continue unchecked, the global average temperature will reach 2C above pre-industrial levels by 2050, according to the government's 2006 Stern report on climate change.
One of the first impacts will be droughts and floods, as rainfall increases at high latitudes and drops in the tropics. Some glaciers will disappear, though crop yields in some countries could rise, scientists believe.
Last year, a report from the Intergovernmental Panel on Climate Change, concluded that human activity was "very likely" to be behind most of the warming seen in recent decades. It predicted a rise of between 2.4C and 6.4C by 2100.
The most likely rise, of 4C by the end of the century, would cause droughts across Africa, and a fall in harvests of 15% to 35%. Globally, crop yields would fall 10%.
Sea levels would rise by up to 59cm, with Bangladesh and Vietnam among the worst hit, along with coastal cities such as New York, London, Tokyo, Kolkata and Karachi. In Britain alone, there would be 1.8 million people at risk of flooding. The western Antarctic and Greenland ice sheets would begin to melt irreversibly and Europe would lose 80% of its Alpine glaciers. Across the Arctic, half of the tundra is at risk.
A 4C rise is predicted to drive 20% to 50% of land species to extinction and put 80m more Africans at risk of malaria as mosquitoes thrive. Melting ice caps may trigger more volcanic eruptions - climate-change - 03 April 2008 - New Scientist Environment Originally Posted by link Melting ice caps may trigger more volcanic eruptions
* 10:38 03 April 2008
* NewScientist.com news service
* Catherine Brahic
A warmer world could be a more explosive one. Global warming is having a much more profound effect than just melting ice caps – it is melting magma too.
Vatnajökull is the largest ice cap in Iceland, and is disappearing at a rate of 5 cubic kilometres per year.
Carolina Pagli of the University of Leeds, UK, and Freysteinn Sigmundsson of the University of Iceland have calculated the effects of the melting on the crust and magma underneath.
They say that, as the ice disappears, it relieves the pressure exerted on the rocks deep under the ice sheet, increasing the rate at which it melts into magma. An average of 1.4 cubic kilometres has been produced every century since 1890, a 10% increase on the background rate.
Frequent eruptions
In Iceland there are several active volcanoes under the ice. The last big eruption was in 1996 at Gjàlp, and before then in 1938 – a gap of 58 years. But Pagli and Sigmundsson say that the extra magma produced as the ice cap melts could supply enough magma for similar eruptions to take place every 30 years on average.
Predicting the eruptions precisely will be tricky, though, as the rate of magma migration to the surface is unknown.
The situation in Iceland does not necessarily mean magma will be melting faster around the world. Vatnajökull sits atop a boundary between plates in the Earth's crust, and it is this configuration that is allowing the release in pressure to have such a great effect deep in the mantle.
But the thinning ice has another effect on volcanoes which will be more widespread.
As the amount of weight on the crust changes, geological stresses inside the crust will also change, increasing the likelihood of eruptions. "Under the ice's weight, the crust bends and as you melt the ice the crust will bounce up again," explains Bill McGuire of University College London in the UK, who was not involved in the study.
Unexpected activity
Pagli say places likely to be at increased risk of eruption due to ice-melt include Antarctica's Mount Erebus, the Aleutian Islands and other Alaskan volcanoes.
The shifting stress might even cause eruptions in unexpected places.
"We think that during the Gjàlp eruption, magma reached the surface at an unusual location, mid-way between two volcanoes, because of these stress changes," says Pagli.
McGuire thinks the Vatnajökull study is based on "perfectly reasonable" physics. However, he says that climate change presents an even more explosive threat. "It's not just unloading the crust that triggers volcanic activity but loading as well."
He and his team are looking into the effects that rising sea-levels – also a consequence of melting ice caps – will have on volcanoes. "We are going to see a massive increase in volcanic activity globally," he told New Scientist. "If we look back at previous warm periods, that is what happened." Millions face glacier catastrophe | Science | The Observer Originally Posted by link Millions face glacier catastrophe
Global warming hits Himalayas
* Robin McKie, science editor
* The Observer,
* Sunday November 20, 2005
* Article history
Nawa Jigtar was working in the village of Ghat, in Nepal, when the sound of crashing sent him rushing out of his home. He emerged to see his herd of cattle being swept away by a wall of water.
Jigtar and his fellow villagers were able to scramble to safety. They were lucky: 'If it had come at night, none of us would have survived.'
Ghat was destroyed when a lake, high in the Himalayas, burst its banks. Swollen with glacier meltwaters, its walls of rock and ice had suddenly disintegrated. Several million cubic metres of water crashed down the mountain.
When Ghat was destroyed, in 1985, such incidents were rare - but not any more. Last week, scientists revealed that there has been a tenfold jump in such catastrophes in the past two decades, the result of global warming. Himalayan glacier lakes are filling up with more and more melted ice and 24 of them are now poised to burst their banks in Bhutan, with a similar number at risk in Nepal.
But that is just the beginning, a report in Nature said last week. Future disasters around the Himalayas will include 'floods, droughts, land erosion, biodiversity loss and changes in rainfall and the monsoon'.
The roof of the world is changing, as can be seen by Nepal's Khumbu glacier, where Hillary and Tenzing began their 1953 Everest expedition. It has retreated three miles since their ascent. Almost 95 per cent of Himalayan glaciers are also shrinking - and that kind of ice loss has profound implications, not just for Nepal and Bhutan, but for surrounding nations, including China, India and Pakistan.
Eventually, the Himalayan glaciers will shrink so much their meltwaters will dry up, say scientists. Catastrophes like Ghat will die out. At the same time, rivers fed by these melted glaciers - such as the Indus, Yellow River and Mekong - will turn to trickles. Drinking and irrigation water will disappear. Hundreds of millions of people will be affected.
'There is a short-term danger of too much water coming out the Himalayas and a greater long-term danger of there not being enough,' said Dr Phil Porter, of the University of Hertfordshire. 'Either way, it is easy to pinpoint the cause: global warming.'
According to Nature, temperatures in the region have increased by more than 1C recently and are set to rise by a further 1.2C by 2050, and by 3C by the end of the century. This heating has already caused 24 of Bhutan's glacial lakes to reach 'potentially dangerous' status, according to government officials. Nepal is similarly affected.
'A glacier lake catastrophe happened once in a decade 50 years ago,' said UK geologist John Reynolds, whose company advises Nepal. 'Five years ago, they were happening every three years. By 2010, a glacial lake catastrophe will happen every year.'
An example of the impact is provided by Luggye Tsho, in Bhutan, which burst its banks in 1994, sweeping 10 million cubic metres of water down the mountain. It struck Panukha, 50 miles away, killing 21 people.
Now a nearby lake, below the Thorthormi glacier, is in imminent danger of bursting. That could release 50 million cubic metres of water, a flood reaching to northern India 150 miles downstream.
'Mountains were once considered indomitable, unchanging and impregnable,' said Klaus Tipfer, of the United Nations Environment Programme. 'We are learning they are as vulnerable to environmental threats as oceans, grasslands and forest.'
Not only villages are under threat: Nepal has built an array of hydro-electric plants and is now selling electricity to India and other countries. But these could be destroyed in coming years, warned Reynolds. 'A similar lake burst near Machu Picchu in Peru recently destroyed an entire hydro-electric plant. The same thing is waiting to happen in Nepal.'
Even worse, when Nepal's glaciers melt, there could be no water to drive the plants. 'The region faces losing its most dependable source of fresh water,' said Mike Hambrey, of the University of Wales.
A Greenpeace report last month suggested that the region is already experiencing serious loss of vegetation. In the long term, starvation is a real threat.
'The man in the street in Britain still isn't sure about the dangers posed by global warming,' said Porter. 'But people living in the Himalayas know about it now. They are having to deal with its consequences every day.'
· Additional reporting: Amelia Gentleman and Felix Lowe Climate change in the Andes | When ice turns to water | Economist.com Originally Posted by link When ice turns to water
Jul 12th 2007 | MACUSANI, PERU
From The Economist print edition
Glacial melting poses potentially costly problems for Peru and Bolivia
FOR centuries, the run-off from the glaciers atop the spectacular snow-capped mountains of the Carabaya range has watered the pastures where alpacas graze around the small town of Macusani. More recently, the mountains have provided the town with drinking water and hydroelectricity, as well as hopes of attracting tourists to one of Peru's poorest areas. But in Carabaya, as across the Andes, the glaciers are melting fast. Their impending disappearance has large, and possibly catastrophic, implications for the country's economy and for human life.
Peru is home to the world's biggest expanse of tropical glaciers. Of the 2,500 square kilometres (965 square miles) of glaciers in the four countries of the tropical Andes—Bolivia, Colombia, Ecuador and Peru—70% are in Peru and 20% in Bolivia. The last comprehensive satellite survey by Peru's National Environmental Council, carried out in 1997, found that the area covered by glaciers had shrunk by 22% since the early 1960s. In the Carabaya range, they had receded by 32%.
Partial surveys by geologists suggest that the rate at which the glaciers are melting has speeded up over the past decade. The glacier at Pastoruri, in the Cordillera Blanca range north of Lima, shrank by more than 40% between 1995 and 2006, with the loss of ice caves popular with tourists, according to Marco Zapata, a glaciologist at the government's Natural Resources Institute. He reckons it will be gone by 2015. That is the fate that has already overtaken many smaller glaciers in Bolivia, and that of Cotacachi in Ecuador. Chacaltaya, above Bolivia's capital, La Paz, has almost disappeared; it is the site of the country's only ski resort, whose future is now uncertain.
“We are already experiencing the effects of global warming,” says Nancy Rossel, the mayor of Macusani. To those who doubt its existence, she offers to show them pictures taken ten years ago of Allinccapac, the mountain above the town, and “they can see how far the glaciers have receded.” A report by a team from the World Bank published last month in the bulletin of the American Geophysical Union (AGU), a scientific association based in Washington, DC, confirms most of the mayor's fears. It predicts that many of the lower glaciers in the Andes will be gone in the next decade or so, and that glacial runoff may dry up altogether within 20 years. It also paints a troubling picture of the future impact on water and power supplies.
One danger is that as the ice melts, newly formed lakes may send water cascading down mountainsides, triggering mudslides that are potentially lethal for the villages below. Another is that if there are no glaciers to regulate water flow, flood will alternate with drought.
That is a particular worry for Peru. After decades of migration from the Andes, two out of three Peruvians now live on its desert coast. Lima, with 8m people, is the world's second largest city located in a desert, after Cairo. Big irrigation projects have made the desert bloom and enabled an agro-export boom. Yet most of Peru's fresh water lies east of the Andes. Water for both irrigation and human consumption from the short, coastal rivers will become more irregular. The government says it needs to spend about $4.5 billion to bring domestic potable-water coverage up from its current level of 78% to the regional norm of over 90%. Billions more will be needed to divert water along tunnels beneath the Andes if glacial melting accelerates.
Another problem is that more than 70% of Peru's electricity comes from hydroelectric dams sited on the glacier-fed rivers. If their flow becomes more irregular, so will power supply. Once the glaciers disappear, Peru will have to invest $1.5 billion a year in thermal generation, according to the AGU article.
Some of these problems are common to neighbouring countries. The Bolivian Mountain Institute, an NGO, reckons that glacial melting threatens water supplies to La Paz and its satellite city, El Alto, and will aggravate existing conflicts between farmers and miners over use of the water from the marshes of the Altiplano, the high intermontane plain. In Chile, glaciers are receding at a slower rate than in its tropical neighbours. But there are worries there about the long-term impact on hydroelectric supply.
It is easier to monitor glacial melting than to remedy the problems it is likely to cause. A public debate is only just starting, led mainly by NGOs. Peru's government, faced with immediate problems of poverty and poor public services, has found it hard to focus on what seems a distant threat. However, officials have suggested that new hydroelectric schemes should be built only on rain-fed rivers to the east of the Andes.
César Portocarrero, a glacier expert with Practical Action, an NGO, argues that the first step is to encourage farmers to reduce their water use. He worries that the flow of water to Chavimochic, a large irrigation project on the north coast, could start to fall after 2020. He is also working on a plan to build small dams on mountain lakes to regulate river levels. This could work well for Macusani, because unlike the coast it enjoys a rainy season. At least such dams could help the alpacas, even if they don't attract the tourists. |
06-27-2008, 08:04 AM
