A new study conducted in Mexico provides evidence that women with higher exposure to phthalates may be more at risk of delivering premature babies.
Women with higher exposure to phthalates during their third trimester of pregnancy were up to four times as likely to have their babies early.
This is the first human study to investigate associations between exposure to phthalates and preterm birth rates. Other studies examining the link between urinary phthalate markers and gestational age at birth have found mixed results.
Early births are of concern because they are associated with long-term health problems and are the leading cause of neonatal mortality in the United States, accounting for more than one third of infant deaths. While causes are elusive, environmental factors may contribute to preterm births. It is hypothesized that phthalates may act as endocrine disruptors, mimicing the action of hormones in the body.
Phthalates soften plastics and act as solvents in a wide range of industrial and consumer applications. Personal care products (perfumes, lotions and cosmetics), medical devices, coatings in some pharmaceuticals, food packaging and vinyl (flooring, construction products) may contain phthalates. Human exposure is common because of their widespread use.
Thirty women who delivered preterm babies (less than 37 weeks’ gestation) and 30 others who delivered full term babies participated in this study. Researchers collected urine during participants' third trimester of pregnancy and measured 11 phthalate residues.
The study reported a 2 to 4-fold increased likelihood of preterm births in women whose total phthalate exposure was above – versus below – the median. Phthalate residues were detected in all samples and their concentrations were generally similar to those reported for US women.
This is the first study on the topic. These results thus need to be confirmed in other populations.
Tuesday, August 4, 2009
Anxiety, inattention, poor decisions increase in kids with higher lead levels
Higher blood lead levels in children were associated with specific learning and behavior changes, including more anxiety and deficits in planning, abstract thinking and determining appropriate behavior, finds this large study from India.
A study of young children in India has found that higher blood lead levels are associated with a suite of behavioral and thinking problems that can alter attention, abstract thinking and appropriate behavior. The largest effects and most vulnerable areas found were on executive function and inattention.
This study is one of the first to pinpoint specific childhood behaviors and cognitive skills affected by lead exposure, most notably anxiety, social problems and overall executive function (planning, problem solving, behavior control). The study also contributes further information about newly found links between increased lead exposure and more ADHD-like behavior – especially inattention rather than hyperactivity – in children.
A low threshold level for exposure to the metal was not found, which agrees with prior studies that also have found no “safe” level for childhood lead exposure. The results have implications for policies regarding lead exposure levels in the US and around the world, say the authors.
Lead is a notorious neurotoxin – so called because it affects learning, memory and other brain functions to lower IQ. Many countries have banned its use in common products, such as paint and gasoline. These bans have propelled blood levels to drop in people worldwide. Other products, such as inexpensive jewelry, keys, electronics and some children's toys, still contain lead. Older buildings with the leaded paint and contaminated soil still represent major sources of lead exposure for children.
To examine lead's impact on certain behaviors, researchers measured blood lead levels in 756 children from ages 3-7 who were attending preschools and elementary schools in Chennai, India. Teachers assessed the children's cognition, attention and behavior using standardized testing tools and questionnaires. Statistical methods were used to compare the levels of lead biomarkers with measures of anxiety, social problems, hyperactivity, inattention, Attention Deficit/Hyperactivity Disorder (ADHD) and executive function.
The measured mean blood lead level was 11.4 micrograms per deciliter. The Centers for Disease Control's level of concern for blood lead is 10 micrograms per deciliter.
The researchers found that children with higher blood levels also had statistically significant higher anxiety and poor sociability and a greater risk of ADHD. A significant association was also found between higher lead levels and poor executive function – the ability to plan, think abstractly, problem solve, remember and determine/control appropriate behavior.
The authors report that they "identified no threshold for these effects" and point out that it is an "important finding for policy decision making as it suggests that there might be no safe level of lead exposure
A study of young children in India has found that higher blood lead levels are associated with a suite of behavioral and thinking problems that can alter attention, abstract thinking and appropriate behavior. The largest effects and most vulnerable areas found were on executive function and inattention.
This study is one of the first to pinpoint specific childhood behaviors and cognitive skills affected by lead exposure, most notably anxiety, social problems and overall executive function (planning, problem solving, behavior control). The study also contributes further information about newly found links between increased lead exposure and more ADHD-like behavior – especially inattention rather than hyperactivity – in children.
A low threshold level for exposure to the metal was not found, which agrees with prior studies that also have found no “safe” level for childhood lead exposure. The results have implications for policies regarding lead exposure levels in the US and around the world, say the authors.
Lead is a notorious neurotoxin – so called because it affects learning, memory and other brain functions to lower IQ. Many countries have banned its use in common products, such as paint and gasoline. These bans have propelled blood levels to drop in people worldwide. Other products, such as inexpensive jewelry, keys, electronics and some children's toys, still contain lead. Older buildings with the leaded paint and contaminated soil still represent major sources of lead exposure for children.
To examine lead's impact on certain behaviors, researchers measured blood lead levels in 756 children from ages 3-7 who were attending preschools and elementary schools in Chennai, India. Teachers assessed the children's cognition, attention and behavior using standardized testing tools and questionnaires. Statistical methods were used to compare the levels of lead biomarkers with measures of anxiety, social problems, hyperactivity, inattention, Attention Deficit/Hyperactivity Disorder (ADHD) and executive function.
The measured mean blood lead level was 11.4 micrograms per deciliter. The Centers for Disease Control's level of concern for blood lead is 10 micrograms per deciliter.
The researchers found that children with higher blood levels also had statistically significant higher anxiety and poor sociability and a greater risk of ADHD. A significant association was also found between higher lead levels and poor executive function – the ability to plan, think abstractly, problem solve, remember and determine/control appropriate behavior.
The authors report that they "identified no threshold for these effects" and point out that it is an "important finding for policy decision making as it suggests that there might be no safe level of lead exposure
Tesco hides figures after missing target to reduce plastic bag usage
Britain’s biggest supermarket chain has published misleading figures giving the impression that it had met an industry target to halve the use of plastic bags.
The Times has learnt that Tesco, which claims to be one of the greenest retailers, missed the target and tried to conceal its actual performance.
Hilary Benn, the Environment Secretary, called on Tesco and other supermarkets to be more honest with customers about how many plastic bags they were issuing. He urged them to publish individual figures so that shoppers could compare them.
The Government has threatened to ban free carriers unless supermarkets make progress in cutting the number through voluntary agreements.
Most plastic bags end up in landfill sites where they can take up to 1,000 years to decompose. Supermarkets issue more than 4,700 tonnes of plastic bags every month and most are used only once.
Seven supermarket chains — Tesco, Asda, Sainsbury’s, Co-op, Marks & Spencer, Somerfield and Waitrose — signed an agreement last year committing them to cutting the number of bags by 50 per cent over the three years to May 2009. This month they reported, via the Waste and Resources Action Programme (Wrap), the independent waste watchdog, that they had not met the target, collectively achieving a 48 per cent reduction from 870 million bags in May 2006 to 450 million in May 2009.
Tesco issued a statement on the same day saying: “Our customers are now using more than 50 per cent fewer carrier bags than they did before.” However, after being questioned by The Times, Tesco admitted that its figure had been calculated in a different way to the one issued by Wrap.
It said that its figure had been adjusted to account for growth in sales and did not reflect the chain’s actual performance. A senior source at Tesco said that the actual reduction had been significantly less than 50 per cent but the company was concerned about negative publicity.
A Tesco spokeswoman said that it would not be publishing the actual number of bags used and would not be revealing by how much that number had declined. She said: “We gave Wrap the absolute number. I don’t think it would be appropriate for me to give you that figure.”
Tesco continues to defend its policy, claiming that measures such as giving Clubcard reward points for reusing bags is more effective. It said on its website: “We believe that climate change will only be tackled successfully if people are encouraged to change their behaviour willingly.”
Speaking to The Times, Mr Benn said: “I would encourage stores to let customers know what progress they are making. I would encourage that information to be made available.”
Mr Benn said that he was not yet persuaded of the case for a ban but said that the Government needed to set the industry a clearer target. “We are going to review progress in summer 2010. We will see how we are going in a year’s time.”
The Times has learnt that Tesco, which claims to be one of the greenest retailers, missed the target and tried to conceal its actual performance.
Hilary Benn, the Environment Secretary, called on Tesco and other supermarkets to be more honest with customers about how many plastic bags they were issuing. He urged them to publish individual figures so that shoppers could compare them.
The Government has threatened to ban free carriers unless supermarkets make progress in cutting the number through voluntary agreements.
Most plastic bags end up in landfill sites where they can take up to 1,000 years to decompose. Supermarkets issue more than 4,700 tonnes of plastic bags every month and most are used only once.
Seven supermarket chains — Tesco, Asda, Sainsbury’s, Co-op, Marks & Spencer, Somerfield and Waitrose — signed an agreement last year committing them to cutting the number of bags by 50 per cent over the three years to May 2009. This month they reported, via the Waste and Resources Action Programme (Wrap), the independent waste watchdog, that they had not met the target, collectively achieving a 48 per cent reduction from 870 million bags in May 2006 to 450 million in May 2009.
Tesco issued a statement on the same day saying: “Our customers are now using more than 50 per cent fewer carrier bags than they did before.” However, after being questioned by The Times, Tesco admitted that its figure had been calculated in a different way to the one issued by Wrap.
It said that its figure had been adjusted to account for growth in sales and did not reflect the chain’s actual performance. A senior source at Tesco said that the actual reduction had been significantly less than 50 per cent but the company was concerned about negative publicity.
A Tesco spokeswoman said that it would not be publishing the actual number of bags used and would not be revealing by how much that number had declined. She said: “We gave Wrap the absolute number. I don’t think it would be appropriate for me to give you that figure.”
Tesco continues to defend its policy, claiming that measures such as giving Clubcard reward points for reusing bags is more effective. It said on its website: “We believe that climate change will only be tackled successfully if people are encouraged to change their behaviour willingly.”
Speaking to The Times, Mr Benn said: “I would encourage stores to let customers know what progress they are making. I would encourage that information to be made available.”
Mr Benn said that he was not yet persuaded of the case for a ban but said that the Government needed to set the industry a clearer target. “We are going to review progress in summer 2010. We will see how we are going in a year’s time.”
Nobel Halo Fades Fast for Climate Change Panel
Two years ago, an international scientific panel seized worldwide attention by reporting that human activity was warming the planet in ways that could greatly disrupt human affairs and nature.
The work of the group, the Intergovernmental Panel on Climate Change, shared the 2007 Nobel Peace Prize with former Vice President Al Gore. After two decades of delivering climate reports to the world without fanfare, it suddenly had a wide following.
But as the panel gears up for its next climate review, many specialists in climate science and policy, both inside and out of the network, are warning that it could quickly lose relevance unless it adjusts its methods and focus.
Although the panel, founded in 1988 and operating under the United Nations’ auspices, has garnered awards and acclaim, there is scant evidence that nations are acting on its warnings. Emissions of heat-trapping gases have grown. Talks about a new climate treaty remain largely deadlocked.
“Like grabbing the tail of a tiger, the I.P.C.C. has gotten the world’s attention, but now the challenge is to get the tiger to head in the right direction,” said Michael MacCracken, a longtime contributor to panel reports and a chief scientist for the Climate Institute, a nonprofit group. “For the I.P.C.C., this means providing guidance that will minimize climate impacts and maximize investments in a prosperous and sustainable future.”
Environmentalists assert that the reports by the panel are watered down by a requirement that sponsoring governments approve its summaries line by line.
Some experts fret that the organization, charged with assessing fast-evolving science, has failed to keep pace with an explosion of climate research.
At the same time, scientists who question the likelihood of a calamitous disruption of the Earth’s climate accuse the panel of cherry-picking studies and playing down levels of uncertainty about the severity of global warming.
“It just feels like the I.P.C.C. has gone from being a broker of science to a gatekeeper,” said John R. Christy, a climate scientist at the University of Alabama, Huntsville, and a former panel author.
In an interview, Rajendra K. Pachauri, chairman of the I.P.C.C., rejected the charge of bias, noting layers of transparent peer review.
But he acknowledged the challenges that the group faces in translating complex science in a way that produces meaningful responses.
Under its charter, the group cannot recommend a course of action to cut climate risks. It has laid out specific paths for emissions of greenhouse gases that governments would need to follow to avoid overheating the planet, but governments need not follow those paths.
For example, Dr. Pachauri noted that while the leaders of the Group of 8 industrial nations pledged last month to try to limit global warming to 2 degrees Fahrenheit beyond the planet’s current temperature, they failed to embrace the emissions reductions that the panel says would be needed to keep that promise.
Finding ways to guide nations without being prescriptive is a prime focus as the network of scientists embarks on its fifth assessment of research on climate trends, projections and policy options.
While the new study is not scheduled for release until 2014, its shape will be determined at an October meeting of government representatives from more than 80 countries.
In preparation for that meeting, 200 scientists who have held leading roles in the climate assessments met in Venice last month to identify new priorities. Building on a “vision document” developed by Dr. Pachauri, they began writing an outline of the fifth report to present to the government representatives meeting in Bali in October.
One goal for the next report is a much more thorough assessment of how fast and far seas could rise from unabated warming. The panel’s 2007 report expressly excluded the influence of melting ice sheets because of limited understanding of how fast they could melt.
Shying away from discussing such possibilities because there is low scientific confidence can imply there is also a low probability they may occur, said Stephen H. Schneider, a climatologist at Stanford and longtime panel member. That is not necessarily the case, he said.
More attention will be devoted to research on the potential for dangerous changes in ocean chemistry as seas absorb billions of tons of carbon dioxide. Another focus will be large-scale artificial methods of countering warming, called geo-engineering.
The panel will also try harder to identify anticipated impacts of climate change on certain regions, and options for fostering resilience in especially vulnerable places like sub-Saharan Africa.
Dr. Pachauri noted that the panel put its Nobel Prize winnings, around $670,000, into an account for helping the world’s poorest countries respond to drought, flood and other climate risks. (Mr. Gore gave his share to the Alliance for Climate Protection. )
But tens of billions of dollars in aid will be needed as explosive population growth and shifting climate patterns make poor nations more vulnerable, according to a variety of studies.
Some specialists in climate modeling warn that governments may have overinflated expectations that science can reliably forecast how global warming will play out locally.
Gavin A. Schmidt, a climate modeler at the Goddard Institute for Space Studies in Manhattan, part of the National Aeronautics and Space Administration, said that efforts to use computer simulations of local conditions to forecast specific results of climate shifts over a decade or so were still in early stages of development.
“Simply hoping that higher resolution will magically improve predictability at smaller scales is just wishful thinking,” Dr. Schmidt said in an e-mail message.
Other scientists involved in shaping the next report worry that the runaway growth in peer-reviewed studies of climate change is making a broad, fair assessment of such research impossible.
For a meeting in Budapest last year on the future of the climate panel, Neville Nicholls, a lead writer on several parts of the last report, submitted a chart showing that 4,500 climate studies were published in 2007, triple the total a decade earlier.
Given that the hundreds of scientists on the panel volunteer their time, this presents a daunting challenge, said Dr. Nicholls, a climate scientist at Monash University in Victoria, Australia.
He proposes that the group write more focused, expeditious reports on issues relevant to setting policy.
Dr. Nicholls suggested that the panel could eventually shift to reviewing the flow of research on more basic questions through a constantly updated Wikipedia-style system.
The panel already does occasional special reports, with one coming next year on the potential of renewable energy technologies to cut greenhouse emissions, and another in 2011 on limiting risks from drought and other climate-driven disasters.
Christopher Field, a participant and chairman of one section of the forthcoming assessment, said that an important focus was psychological and sociological research on how people act in the face of uncertain but substantial threats.
“We’ve identified the nature of the problem, and social science shows it’s of the toughest category,” said Dr. Field, who directs the Carnegie Institution department of global ecology at Stanford.
One hope is that the final October outline, once approved, will encourage governments to invest more resources in such research, so that the 2014 report can incorporate findings.
In the end, perhaps the most vital shift is for the panel to pay more attention to the murkier but most consequential possibilities in a warming world, said Dr. Schneider.
The panel, he said, could do more to distinguish between outcomes from warming that research shows are truly unlikely, like a shutdown of Atlantic Ocean currents, and those that are possible but uncertain. One example of this kind, he said, is the chance that the planet could heat up far more than climate models project; another is the possible sustained disintegration of ice sheets.
Dr. Schneider noted that society relied on risk analyses of this sort all the time, with issues like choosing treatments for rare but poorly understood cancers (Dr. Schneider survived such an episode) and with assessing military strategies.
It may be uncomfortable for scientists who seek certainty in data to turn to the issue of how to weigh uncertain threats. But decision makers are not well served if the spectrum of poorly known possibilities, along with the level of uncertainty, are not also conveyed by experts, he said.
“If you say nothing until you have high confidence and solid evidence,” he said, “you’re failing society.”
The work of the group, the Intergovernmental Panel on Climate Change, shared the 2007 Nobel Peace Prize with former Vice President Al Gore. After two decades of delivering climate reports to the world without fanfare, it suddenly had a wide following.
But as the panel gears up for its next climate review, many specialists in climate science and policy, both inside and out of the network, are warning that it could quickly lose relevance unless it adjusts its methods and focus.
Although the panel, founded in 1988 and operating under the United Nations’ auspices, has garnered awards and acclaim, there is scant evidence that nations are acting on its warnings. Emissions of heat-trapping gases have grown. Talks about a new climate treaty remain largely deadlocked.
“Like grabbing the tail of a tiger, the I.P.C.C. has gotten the world’s attention, but now the challenge is to get the tiger to head in the right direction,” said Michael MacCracken, a longtime contributor to panel reports and a chief scientist for the Climate Institute, a nonprofit group. “For the I.P.C.C., this means providing guidance that will minimize climate impacts and maximize investments in a prosperous and sustainable future.”
Environmentalists assert that the reports by the panel are watered down by a requirement that sponsoring governments approve its summaries line by line.
Some experts fret that the organization, charged with assessing fast-evolving science, has failed to keep pace with an explosion of climate research.
At the same time, scientists who question the likelihood of a calamitous disruption of the Earth’s climate accuse the panel of cherry-picking studies and playing down levels of uncertainty about the severity of global warming.
“It just feels like the I.P.C.C. has gone from being a broker of science to a gatekeeper,” said John R. Christy, a climate scientist at the University of Alabama, Huntsville, and a former panel author.
In an interview, Rajendra K. Pachauri, chairman of the I.P.C.C., rejected the charge of bias, noting layers of transparent peer review.
But he acknowledged the challenges that the group faces in translating complex science in a way that produces meaningful responses.
Under its charter, the group cannot recommend a course of action to cut climate risks. It has laid out specific paths for emissions of greenhouse gases that governments would need to follow to avoid overheating the planet, but governments need not follow those paths.
For example, Dr. Pachauri noted that while the leaders of the Group of 8 industrial nations pledged last month to try to limit global warming to 2 degrees Fahrenheit beyond the planet’s current temperature, they failed to embrace the emissions reductions that the panel says would be needed to keep that promise.
Finding ways to guide nations without being prescriptive is a prime focus as the network of scientists embarks on its fifth assessment of research on climate trends, projections and policy options.
While the new study is not scheduled for release until 2014, its shape will be determined at an October meeting of government representatives from more than 80 countries.
In preparation for that meeting, 200 scientists who have held leading roles in the climate assessments met in Venice last month to identify new priorities. Building on a “vision document” developed by Dr. Pachauri, they began writing an outline of the fifth report to present to the government representatives meeting in Bali in October.
One goal for the next report is a much more thorough assessment of how fast and far seas could rise from unabated warming. The panel’s 2007 report expressly excluded the influence of melting ice sheets because of limited understanding of how fast they could melt.
Shying away from discussing such possibilities because there is low scientific confidence can imply there is also a low probability they may occur, said Stephen H. Schneider, a climatologist at Stanford and longtime panel member. That is not necessarily the case, he said.
More attention will be devoted to research on the potential for dangerous changes in ocean chemistry as seas absorb billions of tons of carbon dioxide. Another focus will be large-scale artificial methods of countering warming, called geo-engineering.
The panel will also try harder to identify anticipated impacts of climate change on certain regions, and options for fostering resilience in especially vulnerable places like sub-Saharan Africa.
Dr. Pachauri noted that the panel put its Nobel Prize winnings, around $670,000, into an account for helping the world’s poorest countries respond to drought, flood and other climate risks. (Mr. Gore gave his share to the Alliance for Climate Protection. )
But tens of billions of dollars in aid will be needed as explosive population growth and shifting climate patterns make poor nations more vulnerable, according to a variety of studies.
Some specialists in climate modeling warn that governments may have overinflated expectations that science can reliably forecast how global warming will play out locally.
Gavin A. Schmidt, a climate modeler at the Goddard Institute for Space Studies in Manhattan, part of the National Aeronautics and Space Administration, said that efforts to use computer simulations of local conditions to forecast specific results of climate shifts over a decade or so were still in early stages of development.
“Simply hoping that higher resolution will magically improve predictability at smaller scales is just wishful thinking,” Dr. Schmidt said in an e-mail message.
Other scientists involved in shaping the next report worry that the runaway growth in peer-reviewed studies of climate change is making a broad, fair assessment of such research impossible.
For a meeting in Budapest last year on the future of the climate panel, Neville Nicholls, a lead writer on several parts of the last report, submitted a chart showing that 4,500 climate studies were published in 2007, triple the total a decade earlier.
Given that the hundreds of scientists on the panel volunteer their time, this presents a daunting challenge, said Dr. Nicholls, a climate scientist at Monash University in Victoria, Australia.
He proposes that the group write more focused, expeditious reports on issues relevant to setting policy.
Dr. Nicholls suggested that the panel could eventually shift to reviewing the flow of research on more basic questions through a constantly updated Wikipedia-style system.
The panel already does occasional special reports, with one coming next year on the potential of renewable energy technologies to cut greenhouse emissions, and another in 2011 on limiting risks from drought and other climate-driven disasters.
Christopher Field, a participant and chairman of one section of the forthcoming assessment, said that an important focus was psychological and sociological research on how people act in the face of uncertain but substantial threats.
“We’ve identified the nature of the problem, and social science shows it’s of the toughest category,” said Dr. Field, who directs the Carnegie Institution department of global ecology at Stanford.
One hope is that the final October outline, once approved, will encourage governments to invest more resources in such research, so that the 2014 report can incorporate findings.
In the end, perhaps the most vital shift is for the panel to pay more attention to the murkier but most consequential possibilities in a warming world, said Dr. Schneider.
The panel, he said, could do more to distinguish between outcomes from warming that research shows are truly unlikely, like a shutdown of Atlantic Ocean currents, and those that are possible but uncertain. One example of this kind, he said, is the chance that the planet could heat up far more than climate models project; another is the possible sustained disintegration of ice sheets.
Dr. Schneider noted that society relied on risk analyses of this sort all the time, with issues like choosing treatments for rare but poorly understood cancers (Dr. Schneider survived such an episode) and with assessing military strategies.
It may be uncomfortable for scientists who seek certainty in data to turn to the issue of how to weigh uncertain threats. But decision makers are not well served if the spectrum of poorly known possibilities, along with the level of uncertainty, are not also conveyed by experts, he said.
“If you say nothing until you have high confidence and solid evidence,” he said, “you’re failing society.”
Seismic boom: Breaking the quake barrier
THE convoy was more than 30 kilometres from the Kunlun fault in Tibet when the jeeps suddenly lurched. They had hit a series of parallel cracks, remnants of a magnitude 7.8 earthquake that struck the year before. "It was like driving on steps," recalls Yann Klinger, a geologist from the Paris Institute of Geophysics in France.
The cracks were clear signs that the ground had been squeezed like a sponge then released, violently wrenching it apart. Yet they were much too far from the fault line to be explained by the quake. Mystified, the team took some measurements and moved on.
It transpired that Klinger and his team had stumbled upon the aftermath of a "supershear" earthquake - one that slipped at such blistering speeds that the rip in the Earth overtook its own seismic waves. This created the earthquake equivalent of a sonic boom, capable of striking anything in its path like a hammer blow. While some seismologists had suspected such a quake could happen, physical evidence of their power had been lacking.
Seven years on, and the evidence is mounting that these kinds of earthquakes may be more common than we thought, and not just in remote regions like Tibet. A series of new maps reveals an abundance of so-called "superhighway" faults around the globe where the conditions are just right for earthquakes to zip through the ground at great speed. Worldwide, 60 million people live in these zones - many of them in regions that were not previously considered at risk from earthquakes. And even in places where buildings are designed to cope with the biggest quakes, no one knows if they will be able to withstand a supershear.
Until supershear quakes came on to the scene in the late 1990s, earthquakes were thought to come with an inbuilt speed limit. When a fault slips at a weak point, the break propagates along the fault line. Mathematical equations show that ruptures cannot propagate at speeds in a so-called "forbidden zone", between around 3 and 3.5 kilometres per second. At these speeds, the fault's frictional sliding would have to convert heat into mechanical energy - something that is thermodynamically impossible. Since a rupture can never accelerate through this zone, the possibility of quakes faster than 3.5 kilometres per second was ruled out.
For many years only one observation contradicted this received wisdom. In 1984, Ralph Archuleta at the University of California, Santa Barbara, reported that the Imperial valley earthquake that struck California in 1979 briefly ruptured faster than 3.5 kilometres per second, the speed that a type of seismic wave called a shear wave travels at (Journal of Geophysical Research, vol 89, p 4559).
With only indirect evidence that this "supershear" earthquake had occurred, however, plus the mathematical unlikeliness that it had taken place and a lack of any other reports of earthquakes moving at such incredible speeds, the paper was largely dismissed. "That observation did not go down very well with seismologists," says Ares Rosakis at the California Institute of Technology in Pasadena.
Archuleta's observations languished in obscurity for nearly two decades until a wager between an engineer and a geologist meant that they were finally tested out in the lab.
Rosakis had studied the dynamics of ruptures in other settings, such as artificial materials. In previous experiments funded by the US navy, he had been investigating how explosions affect materials that have been glued together, and had seen supershear ruptures occur along the glued interface. So why not in the Earth itself? His sceptical colleague Hiroo Kanamori, in the geology department at Caltech, disagreed. After all, a fault under pressure is nothing like a glued surface and earthquakes are not triggered by explosions. The bet was set - an expensive bottle of wine was at stake.
To simulate an earthquake, Rosakis and Kanamori took two slabs of a polymer that transmits light when under pressure and pressed them together, the join representing a geological fault. They shone a light through the fault zone and then triggered a tiny electrical pulse to produce a rupture along the fault line. The patterns made by the light allowed them to see the seismic waves produced as the rupture moved through the fault. Sure enough, the quake produced seismic waves - first compressional waves, followed by the shear waves. And as Kanamori had predicted, the rupture itself trailed well behind its seismic waves.
With Rosakis on the verge of losing the bet, they put the slabs under slightly higher pressure by squeezing the fault tighter. Then, when they triggered a rupture, something odd happened: a fresh "daughter" crack suddenly appeared ahead of the main "mother" rupture, travelling much faster. The daughter crack then expanded rapidly, and joined up with the mother rupture, causing the entire rupture to immediately start travelling faster than its shear waves, leapfrogging the "forbidden" speeds. Not only that, it continued to produce new shear waves, which added to the first batch to produce a new, more powerful shock wave called a "Mach front", which trailed behind the rupture in the shape of a boat's wake (see diagram) (Science, vol 303, p 1859). This is similar to what happens when jet fighters break the sound barrier and travel at Mach speeds; they create pressure waves as they speed through the air, but travel fast enough to catch up with them. The waves constructively interfere with each other to become one explosive sonic boom, extending in an expanding cone behind the aircraft.
These lab experiments began to show that earthquakes could, in theory, go supershear. But it was the Earth itself that provided the real-world evidence. In 1999, the most seismically active continental fault of the 20th century - the North Anatolian fault in Turkey - slipped to cause the magnitude 7.6 Izmit earthquake. Unlike the California quake of 1979, this time there was no shortage of seismic stations around the fault to record the speed of the shear waves produced in the quake. Measurements of ground motion also provided evidence of the speed at which the fault ruptured. It all added up to a quake that went supershear, says Michel Bouchon at the University of Grenoble in France, who led one of two teams that independently showed that Izmit reached velocities of up to 5 kilometres per second (Geophysical Research Letters, vol 28, p 2723).
Now there was no longer any denying that, both in theory and practice, earthquakes can go supershear and seismologists around the world set about looking for more examples in the aftermath of new quakes. They found plenty. There is now evidence that at least three major quakes around the world since Izmit have gone supershear, including Kunlun, where Klinger's team had found the then-mysterious cracks. Thankfully, there have only been a handful of such quakes recently and most have been in remote areas.
This will not always be the case, of course. Some geologists suspect that the devastating San Francisco earthquake of 1906 may have been a supershear. Gregory Beroza of Stanford University in Palo Alto, California, and colleagues argue that such a rupture would explain a long-standing mystery. We know from ground measurements that the crust slipped a certain distance, but seismic data recorded by distant stations showed that the earthquake did not last long enough to produce displacement over such a distance. However, a rupture travelling at supershear speeds would have torn through the ground much faster, producing the observed rip in a shorter time than a normal quake (Bulletin of the Seismological Society of America, vol 98, p 823).
Understanding earthquakes after the event is only half the battle, however. What everyone wants to know is where the next one might hit. Now seismologists David Robinson, Shamita Das and colleagues at the University of Oxford think they have come up with an answer. They compared known supershear quakes for similarities and used these to try and anticipate where in the world the next one is most likely to strike.
The only faults shown to have generated supershear quakes so far have been "strike-slip" faults, where bodies of rocks rub by each other laterally, with very little vertical movement. For this reason, Robinson figured that other kinds of faults, where bodies of rock slide over one another, for example, could be ignored. Next, he discounted ocean-based strike-slip faults as none have so far been found to have reached supershear speeds, plus they are unlikely to pose significant danger to populations. The main risk of an ocean quake is a tsunami, but strike-slip faults tend not to create them because they do not cause the significant uplift of the ocean floor typically needed for a tsunami.
That still left a huge number of strike-slip faults on land to sift through. But Robinson reasoned that all of the supershear ruptures seen so far have been on long, straight sections of faults. This might be because a rupture cannot accelerate to supershear speeds on a convoluted fault path. "We liken it to driving along a road," he says - the rupture slows down for corners, like a car during a turn. So based on previous theoretical modelling and the straightness of known supershear faults such as Kunlun, Robinson looked for unbroken faults on land that do not deviate by 5 degrees or more over a distance of 100 kilometres. That narrowed it down to 26 sections on 11 different fault systems around the world, including parts of the San Andreas fault in California (see map). He called them "superhighways".
Worryingly, when they added the population distribution within a 50-kilometre radius of these faults, they found a network of superhighway faults primed to rumble near major cities. Seven of the 26 superhighways lie within reach of heavily populated areas, each potentially affecting more than 2 million people. One runs straight through the middle of San Francisco, while the cities of Rangoon and Mandalay in Burma sit at either end of the longest superhighway. "The density of population in some areas of Asia we looked at is incredibly high. That really surprised me," says Robinson, who presented his findings at the Seismological Society of America's annual meeting in April.
The maps were welcomed by geologists. "Robinson's work is excellent," says Bouchon. "The supershear earthquakes we have observed up to now have always occurred on long strike-slip faults with very linear segments and simple geometry," he says. Rosakis, however, points out that the roughness of the fault interface and the fault's inclination could also play a part. "It would, to my mind, be too simplistic to say that [long and straight faults] are the only characteristic," he says.
For his part, Robinson concedes that his maps are only intended to scratch the surface. There may be other conditions in which supershear quakes could occur, he says.
Danger zone
If Robinson's maps are correct, it could mean that regions previously thought to be outside of the worst effects of an earthquake, and maybe even beyond its reach altogether, could be caught unawares by a supershear quake. The Mach front's high amplitude means that it travels further through the ground than normal shear waves, putting millions more people at risk.
The most recent building rules in the US, established in the late 1990s, place tight restrictions on the design of structures within 5 kilometres of an active fault. That's because these regions are considered vulnerable to the so-called "near source pulse" of an earthquake, says Swaminathan Krishnan of the earthquake engineering simulation group at Caltech. But with a supershear quake, many relatively unfortified buildings outside the 5-kilometre zone in, say, San Francisco or parts of Los Angeles, could also be at risk, says Krishnan.
Mach fronts also shake the ground differently to an ordinary earthquake, and that means current building standards may not be enough, even in well-prepared areas like California. Laboratory experiments suggest that the shock front strikes with greater ferocity than typical seismic waves. Buildings would experience all the force of the quake's accumulated shear waves at once. If an individual seismic wave is a "gentle slap", the Mach front is a "big hammer", explains seismologist Harsha Bhat of the University of California, Los Angeles. "It's a sudden impact hitting on a structure."
Recent work by Bhat and Eric Dunham of Stanford University also suggests that a building would be struck by two Mach fronts in rapid succession - one from the shear waves, followed by another made up of accumulated Rayleigh waves, a type of seismic wave that travels along the surface at around 3 kilometres per second. "It's still too early to say which Mach front is more devastating," says Bhat.
Unfortunately, most city planners and civil engineers are unlikely to take heed of the warnings of seismologists based on laboratory experiments. "Engineers are practical animals," says Krishnan. "We don't yet have enough data to support these theories."
That's why Krishnan is currently embarking on a project with Rosakis to simulate in a three-dimensional computer model what happens to buildings of various sizes as they are struck by a Mach front. "If our modelling shows serious issues, it will generate a lot of discussion," he says. However, Dunham points out that the smoking gun that Mach fronts are killers will come from a real quake. "Observations would be the most definitive," he says. "To really nail this down, you need lots of seismic stations fairly close."
What is needed now is more data on actual quakes that go supershear. As geologists wait for the next big one to strike, however, they are hoping that they will be proved right in an uninhabited desert - and certainly nowhere near a big city.
The cracks were clear signs that the ground had been squeezed like a sponge then released, violently wrenching it apart. Yet they were much too far from the fault line to be explained by the quake. Mystified, the team took some measurements and moved on.
It transpired that Klinger and his team had stumbled upon the aftermath of a "supershear" earthquake - one that slipped at such blistering speeds that the rip in the Earth overtook its own seismic waves. This created the earthquake equivalent of a sonic boom, capable of striking anything in its path like a hammer blow. While some seismologists had suspected such a quake could happen, physical evidence of their power had been lacking.
Seven years on, and the evidence is mounting that these kinds of earthquakes may be more common than we thought, and not just in remote regions like Tibet. A series of new maps reveals an abundance of so-called "superhighway" faults around the globe where the conditions are just right for earthquakes to zip through the ground at great speed. Worldwide, 60 million people live in these zones - many of them in regions that were not previously considered at risk from earthquakes. And even in places where buildings are designed to cope with the biggest quakes, no one knows if they will be able to withstand a supershear.
Until supershear quakes came on to the scene in the late 1990s, earthquakes were thought to come with an inbuilt speed limit. When a fault slips at a weak point, the break propagates along the fault line. Mathematical equations show that ruptures cannot propagate at speeds in a so-called "forbidden zone", between around 3 and 3.5 kilometres per second. At these speeds, the fault's frictional sliding would have to convert heat into mechanical energy - something that is thermodynamically impossible. Since a rupture can never accelerate through this zone, the possibility of quakes faster than 3.5 kilometres per second was ruled out.
For many years only one observation contradicted this received wisdom. In 1984, Ralph Archuleta at the University of California, Santa Barbara, reported that the Imperial valley earthquake that struck California in 1979 briefly ruptured faster than 3.5 kilometres per second, the speed that a type of seismic wave called a shear wave travels at (Journal of Geophysical Research, vol 89, p 4559).
With only indirect evidence that this "supershear" earthquake had occurred, however, plus the mathematical unlikeliness that it had taken place and a lack of any other reports of earthquakes moving at such incredible speeds, the paper was largely dismissed. "That observation did not go down very well with seismologists," says Ares Rosakis at the California Institute of Technology in Pasadena.
Archuleta's observations languished in obscurity for nearly two decades until a wager between an engineer and a geologist meant that they were finally tested out in the lab.
Rosakis had studied the dynamics of ruptures in other settings, such as artificial materials. In previous experiments funded by the US navy, he had been investigating how explosions affect materials that have been glued together, and had seen supershear ruptures occur along the glued interface. So why not in the Earth itself? His sceptical colleague Hiroo Kanamori, in the geology department at Caltech, disagreed. After all, a fault under pressure is nothing like a glued surface and earthquakes are not triggered by explosions. The bet was set - an expensive bottle of wine was at stake.
To simulate an earthquake, Rosakis and Kanamori took two slabs of a polymer that transmits light when under pressure and pressed them together, the join representing a geological fault. They shone a light through the fault zone and then triggered a tiny electrical pulse to produce a rupture along the fault line. The patterns made by the light allowed them to see the seismic waves produced as the rupture moved through the fault. Sure enough, the quake produced seismic waves - first compressional waves, followed by the shear waves. And as Kanamori had predicted, the rupture itself trailed well behind its seismic waves.
With Rosakis on the verge of losing the bet, they put the slabs under slightly higher pressure by squeezing the fault tighter. Then, when they triggered a rupture, something odd happened: a fresh "daughter" crack suddenly appeared ahead of the main "mother" rupture, travelling much faster. The daughter crack then expanded rapidly, and joined up with the mother rupture, causing the entire rupture to immediately start travelling faster than its shear waves, leapfrogging the "forbidden" speeds. Not only that, it continued to produce new shear waves, which added to the first batch to produce a new, more powerful shock wave called a "Mach front", which trailed behind the rupture in the shape of a boat's wake (see diagram) (Science, vol 303, p 1859). This is similar to what happens when jet fighters break the sound barrier and travel at Mach speeds; they create pressure waves as they speed through the air, but travel fast enough to catch up with them. The waves constructively interfere with each other to become one explosive sonic boom, extending in an expanding cone behind the aircraft.
These lab experiments began to show that earthquakes could, in theory, go supershear. But it was the Earth itself that provided the real-world evidence. In 1999, the most seismically active continental fault of the 20th century - the North Anatolian fault in Turkey - slipped to cause the magnitude 7.6 Izmit earthquake. Unlike the California quake of 1979, this time there was no shortage of seismic stations around the fault to record the speed of the shear waves produced in the quake. Measurements of ground motion also provided evidence of the speed at which the fault ruptured. It all added up to a quake that went supershear, says Michel Bouchon at the University of Grenoble in France, who led one of two teams that independently showed that Izmit reached velocities of up to 5 kilometres per second (Geophysical Research Letters, vol 28, p 2723).
Now there was no longer any denying that, both in theory and practice, earthquakes can go supershear and seismologists around the world set about looking for more examples in the aftermath of new quakes. They found plenty. There is now evidence that at least three major quakes around the world since Izmit have gone supershear, including Kunlun, where Klinger's team had found the then-mysterious cracks. Thankfully, there have only been a handful of such quakes recently and most have been in remote areas.
This will not always be the case, of course. Some geologists suspect that the devastating San Francisco earthquake of 1906 may have been a supershear. Gregory Beroza of Stanford University in Palo Alto, California, and colleagues argue that such a rupture would explain a long-standing mystery. We know from ground measurements that the crust slipped a certain distance, but seismic data recorded by distant stations showed that the earthquake did not last long enough to produce displacement over such a distance. However, a rupture travelling at supershear speeds would have torn through the ground much faster, producing the observed rip in a shorter time than a normal quake (Bulletin of the Seismological Society of America, vol 98, p 823).
Understanding earthquakes after the event is only half the battle, however. What everyone wants to know is where the next one might hit. Now seismologists David Robinson, Shamita Das and colleagues at the University of Oxford think they have come up with an answer. They compared known supershear quakes for similarities and used these to try and anticipate where in the world the next one is most likely to strike.
The only faults shown to have generated supershear quakes so far have been "strike-slip" faults, where bodies of rocks rub by each other laterally, with very little vertical movement. For this reason, Robinson figured that other kinds of faults, where bodies of rock slide over one another, for example, could be ignored. Next, he discounted ocean-based strike-slip faults as none have so far been found to have reached supershear speeds, plus they are unlikely to pose significant danger to populations. The main risk of an ocean quake is a tsunami, but strike-slip faults tend not to create them because they do not cause the significant uplift of the ocean floor typically needed for a tsunami.
That still left a huge number of strike-slip faults on land to sift through. But Robinson reasoned that all of the supershear ruptures seen so far have been on long, straight sections of faults. This might be because a rupture cannot accelerate to supershear speeds on a convoluted fault path. "We liken it to driving along a road," he says - the rupture slows down for corners, like a car during a turn. So based on previous theoretical modelling and the straightness of known supershear faults such as Kunlun, Robinson looked for unbroken faults on land that do not deviate by 5 degrees or more over a distance of 100 kilometres. That narrowed it down to 26 sections on 11 different fault systems around the world, including parts of the San Andreas fault in California (see map). He called them "superhighways".
Worryingly, when they added the population distribution within a 50-kilometre radius of these faults, they found a network of superhighway faults primed to rumble near major cities. Seven of the 26 superhighways lie within reach of heavily populated areas, each potentially affecting more than 2 million people. One runs straight through the middle of San Francisco, while the cities of Rangoon and Mandalay in Burma sit at either end of the longest superhighway. "The density of population in some areas of Asia we looked at is incredibly high. That really surprised me," says Robinson, who presented his findings at the Seismological Society of America's annual meeting in April.
The maps were welcomed by geologists. "Robinson's work is excellent," says Bouchon. "The supershear earthquakes we have observed up to now have always occurred on long strike-slip faults with very linear segments and simple geometry," he says. Rosakis, however, points out that the roughness of the fault interface and the fault's inclination could also play a part. "It would, to my mind, be too simplistic to say that [long and straight faults] are the only characteristic," he says.
For his part, Robinson concedes that his maps are only intended to scratch the surface. There may be other conditions in which supershear quakes could occur, he says.
Danger zone
If Robinson's maps are correct, it could mean that regions previously thought to be outside of the worst effects of an earthquake, and maybe even beyond its reach altogether, could be caught unawares by a supershear quake. The Mach front's high amplitude means that it travels further through the ground than normal shear waves, putting millions more people at risk.
The most recent building rules in the US, established in the late 1990s, place tight restrictions on the design of structures within 5 kilometres of an active fault. That's because these regions are considered vulnerable to the so-called "near source pulse" of an earthquake, says Swaminathan Krishnan of the earthquake engineering simulation group at Caltech. But with a supershear quake, many relatively unfortified buildings outside the 5-kilometre zone in, say, San Francisco or parts of Los Angeles, could also be at risk, says Krishnan.
Mach fronts also shake the ground differently to an ordinary earthquake, and that means current building standards may not be enough, even in well-prepared areas like California. Laboratory experiments suggest that the shock front strikes with greater ferocity than typical seismic waves. Buildings would experience all the force of the quake's accumulated shear waves at once. If an individual seismic wave is a "gentle slap", the Mach front is a "big hammer", explains seismologist Harsha Bhat of the University of California, Los Angeles. "It's a sudden impact hitting on a structure."
Recent work by Bhat and Eric Dunham of Stanford University also suggests that a building would be struck by two Mach fronts in rapid succession - one from the shear waves, followed by another made up of accumulated Rayleigh waves, a type of seismic wave that travels along the surface at around 3 kilometres per second. "It's still too early to say which Mach front is more devastating," says Bhat.
Unfortunately, most city planners and civil engineers are unlikely to take heed of the warnings of seismologists based on laboratory experiments. "Engineers are practical animals," says Krishnan. "We don't yet have enough data to support these theories."
That's why Krishnan is currently embarking on a project with Rosakis to simulate in a three-dimensional computer model what happens to buildings of various sizes as they are struck by a Mach front. "If our modelling shows serious issues, it will generate a lot of discussion," he says. However, Dunham points out that the smoking gun that Mach fronts are killers will come from a real quake. "Observations would be the most definitive," he says. "To really nail this down, you need lots of seismic stations fairly close."
What is needed now is more data on actual quakes that go supershear. As geologists wait for the next big one to strike, however, they are hoping that they will be proved right in an uninhabited desert - and certainly nowhere near a big city.
Kayaking To A Different View Of The Rio Grande
For more than 1,200 miles, the Rio Grande defines a boundary between two tense global neighbors — Mexico and the U.S. Its reputation for lawlessness makes it easy to forget that it's also a scenic river with birds, lush plants and even a little whitewater.
That's the message that Eric Ellman, executive director of Los Caminos del Rio, wants to get out to the world.
"We're trying to change the way people see the Rio Grande and the Rio Grande Valley," he explains.
One Paddle At A Time
For two years, Ellman has offered kayak trips on a stretch of river that begins on a Class 2 rapid below an irrigation dam.
"This is about as good a teaching rapid as I can imagine," he says, while paddling into a riffle with his yellow lab, Buster, lying blissfully in the front of his kayak. "You can see all this beautiful clean water just sweeping right at you. There's a little wave; you can get on it, get off it. Go back in this eddy. Try it again."
Ellman is an outdoor fanatic, travel writer and former New York City bicycle messenger who, at 52, finds himself amid the grapefruit orchards and taquerias of South Texas, promoting tourism on the Rio Grande. When he arrived in 2000, he found the cool river that bisects this sweltering land to be inviting, but no one else did.
"They assume it's illegal. They assume it's dangerous. They assume it's dirty. Every reason in the world," he says. "And then the local superstitions: there are whirlpools, the dangerous currents, alligators. There was a huge alligator scare here last year."
When the locals realized that gators were not swallowing kayaks, and the water is relatively clean, Ellman encountered enthusiastic support on both sides of the border.
"Perhaps Mexicans on this side think of the river as a barrier that's more mental than physical," says Jeffrey Salcedo, a business promoter with the Mexican city of Reynosa, and a backer of Ellman's. "Because when we cross the river, we're accustomed to being detained and questioned. It's not so difficult to change this mentality because these water sports have been very successful. We just need to promote them."
And things are happening. Last November was the first annual Big River Festival on the lower Rio Grande, featuring canoe races with 40 competitors from both countries.
Now the cities of Laredo and Nuevo Laredo, upstream, are sponsoring a 33-mile canoe race on their stretch of river as part of RioFest in October. Ellman says he learned, to his surprise, the federal agencies that control and patrol the river welcomed boaters.
"And it demonstrated to everybody who was watching that this is not only possible but it's actually something that the powers that be encourage," he says.
Eyes In The Air
For its part, the U.S. Border Patrol is in favor of private watercraft on the Rio Grande, believing the more good people who use the river, the fewer bad people are likely to.
Sonny Montes, a small-business owner, recently moved from Seattle back to the Rio Grande Valley, where his family has lived for 150 years. Now he's a regular paddler down here on the river.
Asked what kind of reaction he gets from people in the Valley when he tells them he's going down to the river to kayak, Montes says they call him crazy.
"But you know what I tell 'em?" he asks. "I tell 'em we have the best security in the world because the Border Patrol has patrols in the air. They have patrols in the river, and they have eyes along the border."
The organization of which Eric Ellman is director, Caminos del Rio, has long sought recognition of the cultural and historic importance of the lower Rio Grande. Earlier this month, Rep. Henry Cuellar, a Democrat from the Rio Grande Valley, asked Congress to declare the riverlands from Laredo to Brownsville a National Heritage Corridor.
But try as they might to make the Rio Grande a tourist destination, it remains the world's busiest border for drug smuggling, and that fact is unforgettable on the water.
As evidence, a 16-year-old avid kayaker named Casey Richardson balances on top of the cab of a black pickup truck submerged in the gentle current.
It's one of at least 30 sunken drug vehicles ditched by traffickers that have been identified in this stretch of river. Rio Grande visionaries hope that one day, there might be more kayakers than drug smugglers.
That's the message that Eric Ellman, executive director of Los Caminos del Rio, wants to get out to the world.
"We're trying to change the way people see the Rio Grande and the Rio Grande Valley," he explains.
One Paddle At A Time
For two years, Ellman has offered kayak trips on a stretch of river that begins on a Class 2 rapid below an irrigation dam.
"This is about as good a teaching rapid as I can imagine," he says, while paddling into a riffle with his yellow lab, Buster, lying blissfully in the front of his kayak. "You can see all this beautiful clean water just sweeping right at you. There's a little wave; you can get on it, get off it. Go back in this eddy. Try it again."
Ellman is an outdoor fanatic, travel writer and former New York City bicycle messenger who, at 52, finds himself amid the grapefruit orchards and taquerias of South Texas, promoting tourism on the Rio Grande. When he arrived in 2000, he found the cool river that bisects this sweltering land to be inviting, but no one else did.
"They assume it's illegal. They assume it's dangerous. They assume it's dirty. Every reason in the world," he says. "And then the local superstitions: there are whirlpools, the dangerous currents, alligators. There was a huge alligator scare here last year."
When the locals realized that gators were not swallowing kayaks, and the water is relatively clean, Ellman encountered enthusiastic support on both sides of the border.
"Perhaps Mexicans on this side think of the river as a barrier that's more mental than physical," says Jeffrey Salcedo, a business promoter with the Mexican city of Reynosa, and a backer of Ellman's. "Because when we cross the river, we're accustomed to being detained and questioned. It's not so difficult to change this mentality because these water sports have been very successful. We just need to promote them."
And things are happening. Last November was the first annual Big River Festival on the lower Rio Grande, featuring canoe races with 40 competitors from both countries.
Now the cities of Laredo and Nuevo Laredo, upstream, are sponsoring a 33-mile canoe race on their stretch of river as part of RioFest in October. Ellman says he learned, to his surprise, the federal agencies that control and patrol the river welcomed boaters.
"And it demonstrated to everybody who was watching that this is not only possible but it's actually something that the powers that be encourage," he says.
Eyes In The Air
For its part, the U.S. Border Patrol is in favor of private watercraft on the Rio Grande, believing the more good people who use the river, the fewer bad people are likely to.
Sonny Montes, a small-business owner, recently moved from Seattle back to the Rio Grande Valley, where his family has lived for 150 years. Now he's a regular paddler down here on the river.
Asked what kind of reaction he gets from people in the Valley when he tells them he's going down to the river to kayak, Montes says they call him crazy.
"But you know what I tell 'em?" he asks. "I tell 'em we have the best security in the world because the Border Patrol has patrols in the air. They have patrols in the river, and they have eyes along the border."
The organization of which Eric Ellman is director, Caminos del Rio, has long sought recognition of the cultural and historic importance of the lower Rio Grande. Earlier this month, Rep. Henry Cuellar, a Democrat from the Rio Grande Valley, asked Congress to declare the riverlands from Laredo to Brownsville a National Heritage Corridor.
But try as they might to make the Rio Grande a tourist destination, it remains the world's busiest border for drug smuggling, and that fact is unforgettable on the water.
As evidence, a 16-year-old avid kayaker named Casey Richardson balances on top of the cab of a black pickup truck submerged in the gentle current.
It's one of at least 30 sunken drug vehicles ditched by traffickers that have been identified in this stretch of river. Rio Grande visionaries hope that one day, there might be more kayakers than drug smugglers.
SAfrica: Rich nations must pay for climate change
South Africa says it and other developing countries won't consider the next round of climate change talks successful unless rich nations pay up.
South African officials meeting Tuesday to discuss strategy ahead of the December climate change talks in Copenhagen said at least 1 percent of global GDP should be set aside by rich nations.
That money would help developing countries conduct research and take other steps to cope with climate change. It also could help them obtain technology to reduce their carbon emissions.
Alf Wills, a top South African environmental official, summed up the position: "No money, no deal."
South Africa, more industrialized than most on the continent, is Africa's main carbon emitter.
South African officials meeting Tuesday to discuss strategy ahead of the December climate change talks in Copenhagen said at least 1 percent of global GDP should be set aside by rich nations.
That money would help developing countries conduct research and take other steps to cope with climate change. It also could help them obtain technology to reduce their carbon emissions.
Alf Wills, a top South African environmental official, summed up the position: "No money, no deal."
South Africa, more industrialized than most on the continent, is Africa's main carbon emitter.
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