Thursday, January 22, 2009

When will the water run out?

Climate change, increased industrial demand and wanton wastefulness: is 'peak water' upon us?

A goat walks along the sun-baked bed of Cyprus's largest reservoir at Kouris

A goat walks along the sun-baked bed of Cyprus's largest reservoir at Kouris. Photograph: Reuters

Peak oil may be the least of our problems, scientists warned today. Growing industrial demand for water in developing countries such as China, rapidly expanding urban populations and the efficiency with which we use water have increased the risk of "peak water" – a resource that most of us presume will be infinite – entering a terminal decline.

Of course, we already knew one of the big eco-bummers of our modern lives is that products from beer to microchips use inordinate amounts of water. Last August, the WWF revealed that each Brit effectively uses 4,645 litres of water a day to produce the food on our tables and the T-shirts on our backs; see our world map for an idea of where Britain's "borrowed water" comes from.

Unsurprisingly, one of the solutions advocated by this new report is a better use of the water we have. To that end, the authors have estimated the water footprint of everyday food and drink, which encouragingly shows that one litre of beer consumes less water (300 litres) than one litre of orange juice (850 litres). One kilogram of coffee is reportedly more thirsty (21,000 litres of water) than one kilogram of hamburger (16,000 litres). Take a look at our image gallery to see the hidden water cost of everything from your daily cuppa to a glass of wine.

According to the report, this is adding up to a global crisis. "We are facing a crisis of running out of sustainably managed water," says Peter Gleick, the author of the sixth edition of the World Water report by California's Pacific Institute. Despite human demand accounting for over 50% of the world's accessible freshwater, the report warns that billions of people still lack access to basic water services. Developing countries, it notes, will suffer worst from peak water because of supply problems exacerbated by flooding, drought and water pollution. Developed countries won't be entirely spared though, as Peter Preston discovered in Spain last year.

The World Water report continues by singling out China as a country in danger of water stress because of its inefficient water use and large projects such as the Three Gorges Dam scheme. "[Chinese] Rivers and lakes are dead and dying, groundwater aquifers are overpumped, uncounted species of aquatic life have been driven to extinction, and direct adverse impacts on both human and ecosystem health are widespread and growing," warns Gleick.

His team also highlights how climate change is adversely affecting water global supplies and its impact on food production.

"The stress on global food production from temperatures alone is going to be huge, and that doesn't take into account water supplies stressed by the higher temperatures," said David Battisti, the lead author of another study published earlier this month.

Gleick's report is keen to stress that the concept of peak water, or more specifically "peak ecological water", isn't completely analogous to peak oil. Unlike oil, some water supplies are infinitely renewable. But even those regions with a water supply that could be exhausted are only likely to suffer peak water locally – whereas peak oil will be a global issue.

Global warming increasing death rate of US trees, scientists warn

Studies find wide range of tree species are dying with serious long-term effects for biodiversity and carbon dioxide release

Global warming prompts increase in tree deaths

A black bear wanders through a meadow dotted with fallen trees on July 8, 2007 in Yellowstone National Park, Wyoming. Photograph: Jeff Hutchens/Getty Images

Trees in the western United States are dying twice as quickly as they did three decades ago and scientists think global warming is to blame.

In their surveys, ecologists found that a wide range of tree species were dying including pines, firs and hemlocks and at a variety of altitudes. The changes can have serious long-term effects including reducing biodiversity and turning western forests into a source of carbon dioxide as they die and decompose. That could lead to a runaway effect that speeds up climate change.

"The trend was pervasive across a wide variety of forest types, across all elevations, in trees of all sizes and among major species," said Phillip van Mantgem of the US Geological Survey (USGS). "At the same time, the rate of new establishment of trees didn't change."

If these trends continued, he said, forests will become sparser and store less carbon. "It introduces the possibility that western forests could be come net sources or carbon dioxide to the atmosphere, further speeding up global warming."

The forest survey, carried out by a team of scientists led by van Mantgem, is published tomorrow in the journal Science. It showed that death rates of trees overall had more than doubled since 1955. In the Pacific north-west and British Columbia, deaths had doubled in 17 years. In California, the death rate took 25 years to double.

The work is the first large-scale study of death rates in forests or temperate regions. Much of the world's population – in North America, Europe, most of China and large portions of Russia – live near temperate forests so what happens in these forests has global importance, according to Jerry Franklin, a professor of forest resources at the University of Washington and a co-author of the study.

The researchers think that warming global temperature is the most likely cause for the dramatic decline. From the 1970s to 2006, the period that includes most of the surveyors' tree data, the average annual temperature of the western US increased by 0.3C-0.4C, and increased even more at the higher elevations that are normally covered in forests.

"While this may not sound like much, it has been enough to reduce winter snowpack, cause earlier snowmelt, and lengthen the summer drought," said van Mantgem. This longer summer drought means less water for trees and it also encourages the growth of insects and diseases that attack the plants. Recent outbreaks of tree-killing bark beetles in the western US have already been linked to warmer temperatures.

Mark Harmon, a forest ecologist at Oregon State University, said another concern from the study is that a climate feedback loop could develop from the increased death rate of trees. As temperatures rise, the smaller forests will not only absorb less CO2 but will emit more greenhouse gases ias the dead material decays. This, in turn, would lead to even higher levels of global warming.

The data for the research was gathered by several generations of scientists counting trees over more than 50 years. It included forests in Oregon, Washington, California, Arizona, Colorado, New Mexico and south-western British Columbia. All were older than 200 years, with many being established more than 500 years ago. Death rates in old forests tend to be more stable since they mostly contain very old trees.

"With many of our long-lived trees that grow very large, each year as they become larger and older, the probability of living the next year increases," said Franklin. "You might imagine that, as a tree gets larger and older, the probability of death would increase but it does not – it decreases for many of our species."

In most forests, it is the youngest trees that are most likely to die. "Often they are shaded by larger, taller trees and so they grow more slowly," said Nathan Stephenson of the USGS. "They are less resilient to changes in the environment and they also don't have as well-developed root systems so, if they run into a drought, they're more likely than a large tree to suffer."

In the latest survey, the research team found that trees of all ages were dying more quickly.

The team also ruled out factors such as overcrowding, forest fragmentation or air pollution. The main air pollutant that harms trees in the western US, for example, is ozone. "In California, where most of our forests are concentrated, ozone is fairly severe," said Stephenson. "Over the time period of the study, there was no trend in ozone and it might even have declined slightly."

Scientists solve enigma of Antarctic 'cooling'

Research 'kills off' climate sceptic argument by showing average temperature across the continent has risen over the last 50 years

West Antarctic, in red, has warmed far more than the east over the last 50 years

West Antarctica, shown in red, has warmed far more than the east over the last 50 years Photograph: EJ Steig/Nasa

Scientists have solved the enigma of the Antarctic apparently getting cooler, while the rest of the world heats up.

New research shows that while some parts of the frozen continent have been getting slightly colder over the last few decades, the average temperature across the continent has been rising for at least the last 50 years.

In the remote and inaccessible West Antarctic region the new research, based on ground measurements and satellite data, show that the region has warmed rapidly, by 0.17C each decade since 1957. "We had no idea what was happening there," said Professor Eric Steig, at the University of Washington, Seattle, and who led the research published in Nature.

This outweighs the cooling seen in East Antarctica, so that, overall, the continent has warmed by 0.12C each decade over the same period. This matches the warming of the southern hemisphere as a whole and removes the apparent contradiction.

The issue, which had been highlighted by global warming sceptics, was an annoyance, said Steig, despite the science having been reasonably well understood. "But it has now been killed off," he said.

Gareth Marshall, climatologist at British Antarctic Survey, commented: "This work allows us to look at the continent as a whole, which we have not been able to do before with confidence. It fills a big hole in the data in West Antarctica – it is the final piece in the jigsaw."

The rapid warming now revealed in the west concerns some scientists. The new analysis suggests the West Antarctic ice sheet, like that in Greenland, is precariously balanced, said Professor Barry Brook at the University of Adelaide. "Even losing a fraction of both would cause a few metres of sea level rise this century, with disastrous consequences," he said.

It was well known that a small part of Antarctic was warming – the peninsula that protrudes northwards towards South America and is the site of many research stations. But researchers knew that East Antarctica had cooled a little in recent decades and thought that might be the case across the continent's great mountain range in West Antarctica.

Temperature records have been taken on the ground since the first weather stations were built in 1957. But all but two of the 42 are very close to the coast and therefore give no information on the vast interior of the continent. Satellite data, in contrast, can take the temperature of the entire region by measuring the intensity of the infrared radiation reflected from the snow pack and has been available since 1980.

Steig's team found the mathematical relationships between the weather station data and satellite data, tested them, and then used them to go back in time to estimate temperatures across the continent back to 1957. Their statistical model has now been validated by an ice core drilled into the Rutford ice stream in West Antarctica by the British Antarctic Survey, from which temperature records can be measured. That independent work also came up with a warming of 0.17C a decade for the region, and stretched the trend back to at least 1930.

The cooling seen in East Antarctica is caused in part by the ozone hole that opens each year in the atmosphere. The ozone hole causes an increase in westerly winds which, by a complex interaction of wind, sea and ice, results in lower temperatures in the east. Emissions of ozone-destroying gases have now almost been eliminated and the hole is expected to recover by mid-century. When that happens, there will be a rapid catch up of temperatures, says Marshall.

The 2007 report from the UN's Intergovernmental Panel on Climate Change said that the impact of greenhouse gas emissions could be seen on every continent bar Antarctica. The new work, along with another recent study, now clearly shows that the rising temperature of the continent cannot be explained by natural climate variation alone.

Tibet shepherds live on climate frontier

From: The Christian Science Monitor


For Tenzin Dorje, the road home keeps getting longer. Each year the Tibetan shepherd must walk farther to find streams where his sheep can drink.

“I am an old man,” he says, clutching the neck of his cane. Sometimes he trudges six hours a day, twice his old route. He has contemplated learning to ride a motorbike like his grandson, but fears it might be too discomfiting for an 80-year-old man.

The problem is that streams in the province of western China where he lives are drying up, receding into the mountains.

As recent years have brought higher temperatures and altered how snowmelt trickles down from glaciers on the Tibetan-Qinghai plateau, water is becoming scarce.

Mr. Tenzin lives in a small village nestled amid dramatic mountains peaks. Strings of Tibetan prayer flags flap against a still-brilliant blue sky. Yet this apparent purity and timelessness masks another reality: He is living on the frontier of climate change


Tenzin’s village is on the slopes of the rugged Qilian mountains in western Gansu province. Glaciers on the mountains are the primary source of water for humans, farms, and industry in his village of Baijiaowan and for others north and south of the range.

The streams distinguish the landscape, including a string of oasis towns along the Old Silk Road, from the abutting Gobi Desert. Today, the desert is expanding.

“The climate is changing,”says Zhang Mingquan, a professor of earth and environmental sciences at Lanzhou University, in the provincial capital. “Snow is the source of the stream water, and now the stream water is less than before.”

Recent years have seen higher temperatures and less precipitation. As a result, mountaintop ice is receding.

The Chinese Academy of Social Sci ences estimates that the glacial area on the Tibetan-Qinghai plateau, the world’s largest ice sheets outside the poles, is shrinking about 7 percent each year.

It might seem that melting glaciers would bring more water in the short term. But that isn’t necessarily the case, says Michael MacCracken of the Climate Institute in Washington.

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Even Antarctica is now feeling the heat of climate change

From: New Scientist

It's official: there is nowhere left to hide from global warming. The notion that Antarctica is the last continent not to be heating up because of climate change is dead, according to a new study.

The results suggest that the southernmost continent is warming roughly as fast as the rest of the planet. They overturn previous suggestions that only the Antarctic peninsula, which stretches points north towards South America, was heating up while the continent's interior cooled.

When the Intergovernmental Panel on Climate Change published its 2007 report, it declared: "it is likely there has been significant anthropogenic warming over the past 50 years averaged over each continent (except Antarctica)".

The exception wasn't made because there was proof that Antarctica was cooling, says Gareth Williams of the British Antarctic Survey, but because there was not sufficient proof that the continent was warming. Since then, data from isolated parts of the seventh continent have confirmed Antarctica is not immune to global warming.

And now, Eric Steig of the University of Washington, Seattle, and colleagues have used satellite data covering the entire continent to show that on average the entire continent warmed by 0.5°C between 1957 and 2006. On average, the planet has warmed 0.6°C in 50 years.

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