David Fogarty PlanetArk 11 Jun 10;
Increased melting of glaciers and snow in the Himalayas and Tibetan Plateau threatens the food security of millions of people in Asia, a study shows, with Pakistan likely to be among the nations hardest hit.
A team of scientists in Holland studied the impacts of climate change on five major Asian rivers on which about 1.4 billion people, roughly a fifth of humanity, depend for water to drink and to irrigate crops.
The rivers are the Indus, which flows through Tibet and Pakistan, the Brahmaputra, which carves its way through Tibet, northeast India and Bangladesh, India's Ganges and the Yangtze and Yellow rivers in China.
Studies in the past have assumed that a warmer world will accelerate the melting of glaciers and snow in the Himalayas and Tibetan Plateau, which act like water towers, the study published in the latest issue of the journal Science says.
But a lack of data and local measurement sites has hampered efforts to more precisely figure out the magnitude of climate change impacts on particular countries, the numbers of people affected in coming decades and the likely effects on crops.
The issue is crucial for governments to assess the future threats from disputes over water, mass migration and therefore political risk for investors.
Lead author Walter Immerzeel and his team conducted a detailed analysis looking at the importance of meltwater for each river, observed changes to Himalayan and Tibetan glaciers and the effects of global warming on the water supply from upstream basins and on food security.
Immerzeel, a hydrologist at Dutch consultancy FutureWater and Utrecht University, said he believed his team was the first to use a combination of computer modeling, satellite imagery and local observations for all major Asian basins.
They found that meltwater was extremely important for the Indus basin and important for the Brahmaputra basin, but played only a modest role for the Ganges, Yangtze and Yellow rivers.
WARNING SIGNAL
The Brahmaputra and Indus basins are also most susceptible to reductions of flow because of climate change, threatening the food security of an estimated 60 million people, or roughly the population of Italy.
"The effects in the Indus and Brahmaputra basins are likely to be severe owing to the large population and the high dependence on irrigated agriculture and meltwater," the authors say in the study.
For the Yellow River in northern China, the reverse appeared true with climate change likely to lead to more rainfall upstream, which, when retained in reservoirs, could benefit irrigation downstream.
The findings are a warning signal for Pakistan in particular whose growing population of 160 million people is heavily dependent on the Indus to grow wheat, rice and cotton from which the nation earns hard currency.
Immerzeel said adaptation was crucial.
"The focus should be on agriculture as this is by far the largest consumer of water," he told Reuters in an email interview.
"You could think of measures such as different crop varieties which are less water consuming, different water management, or by providing economic incentives to farmers to use less water."
(Editing by Nick Macfie)
Study: Shrinking glaciers to spark food shortages
Michael Casey, Associated Press Yahoo News 10 Jun 10;
DUBAI, United Arab Emirates – Nearly 60 million people living around the Himalayas will suffer food shortages in the coming decades as glaciers shrink and the water sources for crops dry up, a study said Thursday.
But Dutch scientists writing in the journal Science concluded the impact would be much less than previously estimated a few years ago by the U.N. Intergovernmental Panel on Climate Change. The U.N. report in 2007 warned that hundred of millions of people were at risk from disappearing glaciers.
The reason for the discrepancy, scientists said, is that some basins surrounding the Himalayas depend more on rainfall than melting glaciers for their water sources.
Those that do count heavily on glaciers like the Indus, Ganges and Brahamaputra basins in South Asia could see their water supplies decline by as much as 19.6 percent by 2050. China's Yellow River basin , in contrast, would see a 9.5 percent increase precipitation as monsoon patterns change due to the changing climate.
"We show that it's only a certain areas that will be effected," said Utrecht University Hydrology Prof. Marc Bierkens, who along with Walter Immerzee and Ludovicus van Beek conducted the study. "The amount of people effected is still large. Every person is one too many but its much less than was first anticipated."
The study is one of the first to examine the impact of shrinking glaciers on the Himalayan river basins. It will likely further fuel the debate on the degree that climate change will devastate the river basins that are mostly located in India, Pakistan, Nepal, Bangladesh, Bhutan and China.
Scientists for the most part agree glaciers are melting at an accelerated rate as temperatures increase. Most scientists tie that warming directly to higher atmospheric concentrations of greenhouse gases such as carbon dioxide.
Some glaciers, such as in the Himalayas, could hold out for centuries in a warmer world. But more than 90 percent of glaciers worldwide are in retreat, with major losses already seen across much of Alaska, the Alps, the Andes and numerous other ranges, according to researchers in the United States and Europe.
Some scientists have come under fire for the 2007 U.N. report, which includes several errors that suggested the Himalayas could disappear by 2035, hundreds of years earlier than data actual indicates. The mistake — the 2350 apparently was transposed as 2035 — opened the door for attacks by climate change skeptics.
The findings by the Dutch team in Science were greeted with caution with glacial experts who did not take part in the research. They said the uncertainties and lack of data for the region makes it difficult to say what will happen in the next few decades to the water supply.
Others like Zhongqin Li, director of the Tianshan Glaciological Station in China, said the study omitted several other key basins in central Asia and northwest China which will be hit hard by the loss of water from melting glaciers.
Still, several of these outside researchers said the findings should reaffirm concerns that the region will suffer food shortages due to climate change, exasperating already existing concerns such as overpopulation, poverty, pollution and weakening monsoon rains in parts of South Asia.
"The paper teaches us there's lot of uncertainty in the future water supply of Asia and within the realm of plausibility are scenarios that may give us concern," said Casey Brown, an assistant professor of civil and environmental engineering at the University of Massachusetts.
"At present, we know that water concerns are already a certainty - the large and growing populations and high dependence on irrigated agriculture which makes the region vulnerable to present climate variability," he said.
"This paper is additional motivation to address these present concerns through wise investments in better management of water resources in the region, which for me means forecasts, incentives, efficiency."
Birkens and his fellow researchers said governments in the region should adapt to the projected water shortages by shifting to crops that use less water, engaging in better irrigation practices and building more and larger facilities to store water for extended periods of time.
"We estimate that the food security of 4.5 percent of the total population will be threatened as a result of reduce water availability," the researchers wrote. "The strong need for prioritizing adaptation options and further increasing water productivity is therefore eminent."
Global warming spells doom for Asia's rivers
Robert Saiget (AFP) Google News 10 Jun 10;
BEIJING — The livelihood of thousands of Tibetans living on China's highest plateau is under threat as global warming and environmental degradation dry up water sources for three mighty Asian rivers, experts say.
Dwindling glaciers and melting permafrost in the mountains surrounding the fragile Qinghai-Tibet plateau are leading to erosion of grasslands and wetlands, threatening the watershed of the Yangtze, Yellow and Mekong rivers.
One prominent US environmental campaigner has even warned that the looming water crisis could trigger a major regional food shortage, as the rivers help irrigate vast wheat fields and rice paddies in China and southeast Asia.
"The melting of the glaciers is a fairly serious phenomenon," Xin Yuanhong, a government scientist who headed a major environmental survey of the Yangtze source region, told AFP.
"We expect that under current conditions, up to 30 percent of the glaciers in this region could disappear within 10 years. If global warming worsens, the glaciers will melt faster and the situation will worsen."
The region provides nearly half of the water volume of the Yellow River, 25 percent of the Yangtze's water and 15 percent of the Mekong, Southeast Asia's most important waterway.
Up to 580 million people live in the basins of the three rivers -- all major grain-producing areas that have been hit by serious droughts and falling water levels in the last few months.
In 2005, China launched a 7.5 billion yuan (1.1-billion-dollar) programme to arrest erosion in the source area, in what was described as the nation's biggest-ever ecological conservation project.
"As the permafrost melts, the land loses its capacity to absorb water," Xin said. "As more water runs off, there is more erosion, while the drier conditions allow for a rise in the rodent population, which further decimates the soil."
As part of the conservation effort about 20,000 Tibetan herdsmen had migrated off the grasslands and been resettled in permanent villages by the start of this year, the state Xinhua news agency has said. Grazing has been restricted, while more and more herds are being raised in enclosures.
For many Tibetan herdsmen, resettlement in villages has meant an end to a traditional nomadic life that goes back centuries.
About half of the 270,000 people in Yushu prefecture -- which covers most of the source area -- rely on herding or the livestock industry to make their livings, according to government sources and media reports.
Officials at a Yushu environmental protection association refused to comment when contacted by AFP, apparently due to the sensitivity of the issue.
Besides desertification and grassland shrinkage, the region's lakes and wetlands are also drying up, experts say.
"From 1976 to 2008, grassland marshes and swamplands have shrunk by over 32 percent" in the three river source area, Wang Genxu, a water expert at Qinghai's Institute of Mountain Hazards and the Environment, told AFP.
"The area of lakes in the region has been reduced by 228 square kilometres (140 square miles), about 8.6 percent of the overall lakeland area," said Wang, whose institute is attached to the China Academy of Sciences.
At a regional summit in April, Thai Prime Minister Abhisit Vejjajiva warned that the Mekong was "threatened by serious problems arising from both the unsustainable use of water and the effects of climate change".
The Mekong "will not survive" without good management, he said.
Earlier this year, water on the so-called "Mighty Mekong" dropped to its lowest level in 50 years in northern Thailand and Laos, alarming communities who depend on the river for food, transport, drinking water and irrigation.
At the summit in the Thai resort town of Hua Hin, China denied its policies in the upper Mekong -- including the construction of dams and massive water use -- were to blame for lower water levels.
But prominent US environmentalist Lester Brown warned last week on a trip to Beijing that the situation could provoke a serious food crisis in Asia, severely curtailing crop growth in China and elsewhere.
"The melting of these mountain glaciers in the Himalayas and the Tibetan plateau represents the most massive projected threat to food security we have ever encountered," Brown said.
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