Sustainable seas? Overfishing easing in places

rabcakes and fish sticks won't be disappearing after all.
Two years after a study warned that overfishing could cause a collapse in the world's seafood stocks by 2048, an update says the tide is turning, at least in some areas.
"This paper shows that our oceans are not a lost cause," said Boris Worm of Dalhousie University in Halifax, Nova Scotia, lead author of both reports. "I'm somewhat more hopeful ... than what we were seeing two years ago."




It's personal as well as scientific.
"I have actually given thought to whether I will be hosting a seafood party then," Worm said, meaning 2048.
Ray Hilborn of the University of Washington challenged Worm's original report, leading the two — plus 19 other researchers — to launch the study that led to the new findings. They're being published in Friday's edition of the journal Science.
The news isn't all good.
Of 10 areas of the world that were studied, significant overfishing continues in three, but steps have been taken to curb excesses in five others, Hilborn and Worm report. The other two were not a problem in either study.
Hilborn noted that 63 percent of fish stocks remain below desired levels. It takes time to rebuild after steps are taken to reduce the catch.
Michael Fogarty of the National Oceanic and Atmospheric Administration noted a dramatic recovery of haddock on Georges Bank, off New England, as well as improvements in redfish, scallop and other fish. But still others, such as cod and flounder, remain vulnerable, he said at a briefing.
"We feel confident that the tide of overexploitation can be reversed on a global basis," Fogarty said, citing such steps as exclusion areas, changes in fishing gear, assignments of rights to harvest and incentives for fishers to take a long-term view.
Alaska, New Zealand success storiesTwo areas, Alaska and New Zealand, have led the world in terms of management success by not waiting until drastic measures are needed to conserve, the report said. These areas were not a problem in either study.
Regions where excess exploitation has halted are Iceland, southern Australia, the Northeast U.S., the Newfoundland-Labrador area and the California Current, which flows south along the U.S. West Coast.
Still being overfished, the report said, are the North and Baltic seas and the Bay of Biscay region.
A newly developing problem is the movement of major fishing efforts to the developing world, with foreign fleets operating off east and west Africa under access agreements with local governments. These fleets compete with local fishers and almost all the fish they catch is taken to industrialized countries.
"The prognosis for Africa is not nearly as good as it is for wealthier areas," commented Tim McClanahan of the Wildlife Conservation Society in Mombasa, Kenya.
"Prior to this study, evaluations of the status of world fish stocks and communities were based on catch records for lack of a better alternative. Results were controversial because catch trends may not give an accurate picture of the trends in fish abundance," Ana Parma of Centro Nacional Patagonico in Argentina, said in a statement.
"This is the first exhaustive attempt to assemble the best-available data on the status of marine fisheries and trends in exploitation rates," she said. The new analysis includes catch data, stock assessments, scientific trawl surveys, small-scale fishery data and computer modeling results.
The research was funded by the National Science Foundation and the University of California, Santa Barbara.
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Oyster breakthrough in Chesapeake BayA separate study, also in Science, reports that researchers have successfully restored populations of native oysters to the Chesapeake Bay.
The local oyster population had collapsed after years of overfishing. Researchers launched the restoration effort in 2004, constructing artificial reefs in protected areas of the Great Wicomico River in Virginia.
The oysters are thriving in these areas, demonstrating how similar recovery efforts might work elsewhere, according to the researchers from the Virginia Institute of Marine Science of the College of William and Mary.
That research was funded by the U.S. Army Corps of Engineers, Blue Crab Advanced Research Consortium and the National Oceanic and Atmospheric Administration.

White Roofs Catch on as Energy Cost Cutters

Returning to their ranch-style house in Sacramento after a long summer workday, Jon and Kim Waldrep were routinely met by “We’d come home in the summer, and the house would be 115 degrees, stifling,” said Mr. Waldrep, a regional manager for a national company.

He or his wife would race to the thermostat and turn on the air-conditioning as their four small children, just picked up from day care, awaited relief.

All that changed last month. “Now we come home on days when it’s over 100 degrees outside, and the house is at 80 degrees,” Mr. Waldrep said.

Their solution was a new roof: a shiny plasticized white covering that experts say is not only an energy saver but also a way to help cool the planet.

Relying on the centuries-old principle that white objects absorb less heat than dark ones, homeowners like the Waldreps are in the vanguard of a movement embracing “cool roofs” as one of the most affordable weapons against climate change.

Studies show that white roofs reduce air-conditioning costs by 20 percent or more in hot, sunny weather. Lower energy consumption also means fewer of the carbon dioxide emissions that contribute to global warming.

What is more, a white roof can cost as little as 15 percent more than its dark counterpart, depending on the materials used, while slashing electricity bills.

Energy Secretary Steven Chu, a Nobel laureate in physics, has proselytized for cool roofs at home and abroad. “Make it white,” he advised a television audience on Comedy Central’s “Daily Show” last week.

The scientist Mr. Chu calls his hero, Art Rosenfeld, a member of the California Energy Commission who has been campaigning for cool roofs since the 1980s, argues that turning all of the world’s roofs “light” over the next 20 years could save the equivalent of 24 billion metric tons in carbon dioxide emissions.

“That is what the whole world emitted last year,” Mr. Rosenfeld said. “So, in a sense, it’s like turning off the world for a year.”

This month the Waldreps’ three-bedroom house is consuming 10 percent less electricity than it did a year ago. (The savings would be greater if the family ran its central air during the workday.)

From Dubai to New Delhi to Osaka, Japan, reflective roofs have been embraced by local officials seeking to rein in energy costs. In the United States, they have been standard equipment for a decade at new Wal-Mart stores. More than 75 percent of the chain’s 4,268 outlets in the United States have them.

California, Florida and Georgia have adopted building codes that encourage white-roof installations for commercial buildings.

Drawing on federal stimulus dollars earmarked for energy-efficiency projects, state energy offices and local utilities often offer financing for cool roofs. The roofs can qualify for tax credits if the roofing materials pass muster with the Environmental Protection Agency’s Energy Star program.

Still, the ardor of the cool-roof advocates has prompted a bit of a backlash.

Some roofing specialists and architects argue that supporters fail to account for climate differences or the complexities of roof construction. In cooler climates, they say, reflective roofs can mean higher heating bills.

Scientists acknowledge that the extra heating costs may outweigh the air-conditioning savings in cities like Detroit or Minneapolis.

But for most types of construction, they say, light roofs yield significant net benefits as far north as New York or Chicago. Although those cities have cold winters, they are heat islands in the summer, with hundreds of thousands of square feet of roof surface absorbing energy.

The physics behind cool roofs is simple. Solar energy delivers both light and heat, and the heat from sunlight is readily absorbed by dark colors. (An asphalt roof in New York can rise to 180 degrees on a hot summer day.) Lighter colors, however, reflect back a sizable fraction of the radiation, helping to keep a building — and, more broadly, the city and Earth — cooler. They also re-emit some of the heat they absorb.

Unlike high-technology solutions to reducing energy use, like light-emitting diodes in lamp fixtures, white roofs have a long and humble history. Houses in hot climates have been whitewashed for centuries.

Before the advent of central air-conditioning in the mid-20th-century, white- and cream-colored houses with reflective tin roofs were the norm in South Florida, for example. Then central air-conditioning arrived, along with dark roofs whose basic ingredients were often asphalt, tar and bitumen, or asphalt-based shingles. These materials absorb as much as 90 percent of the sun’s heat energy — often useful in New England, but less so in Texas. By contrast, a white roof can absorb as little as 10 percent or 15 percent.

“Relative newcomers to the West and South brought a lot of habits and products from the Northeast,” said Joe Reilly, the president of American Rooftile Coatings, a supplier. “What you see happening now is common sense.”

Around the country, roof makers are racing to develop products in the hope of profiting as the movement spreads from the flat roofs of the country’s malls to the sloped roofs of its suburbs.

Years of detailed work by scientists at the Lawrence Berkeley Laboratory have provided the roof makers with a rainbow of colors — the equivalent of a table of the elements — showing the amount of light that each hue reflects and the amount of heat it re-emits.

White is not always a buyer’s first choice of color. So suppliers like American Rooftile Coatings have used federal color charts to create “cool” but traditional colors, like cream, sienna and gray, that yield savings, though less than dazzling white roofs do.

In an experiment, the National Laboratory in Oak Ridge, Tenn., had two kinds of terra-cotta-colored cement tiles from American Rooftile installed on four new homes at the Fort Irwin Army base in California. One kind was covered with a special paint and reflected 45 percent of the sun’s rays — nearly twice as much as the other kind. The two homes with roofs of highly reflective paint used 35 percent less electricity last summer than the two with less reflective paint.

Still, William Miller of the Oak Ridge laboratory, who organized the experiment, says he distrusts the margin of difference; he wants to figure out whether some of it resulted from different family habits.

Hashem Akbari, Dr. Rosenfeld’s colleague at the Lawrence Berkeley laboratory, says he is unsure how long it will take cool roofs to truly catch on. But he points out that most roofs, whether tile or asphalt-shingle, have a life span of 20 to 25 years.

If the roughly 5 percent of all roofs that are replaced each year were given cool colors, he said, the country’s transformation would be complete in two decades.

a wall of heat

Jellyfish Stir Up Oceans, May Influence Climate

Jellyfish and other related creatures may be playing an unwitting role in the Earth's climate by stirring up the oceans, according to aThe findings are helping to revive a decades-old debate over whether animals in the ocean can contribute significantly to ocean mixing, the process by which warm water on the surface combines with the cold water far below. Mixing is a key regulator of the Earth's temperature and the ocean's nutrients.

It also plays a role in global climate change because carbon dioxide in the air can dissolve in the surface water and then get pulled into the depths and stored there. "It's important for us to understand the dynamics of the ocean in order to really understand what's going to happen to climate over land," says John Dabiri, a bioengineer at Caltech University in Pasadena and co-author of the paper.

Ocean Mixers

Tides and winds are known to be major players in ocean mixing, but some researchers believe that animals might also contribute. Dabiri and his graduate student Kakani Katija decided to find out by filming dozens of jellyfish as they swam in the wild. Studying the movies shows that the simple animals drag water behind them as they swim. It's a little bit like a bicyclist in the Tour de France, says Dabiri: "When Lance Armstrong is riding down the road, he's actually taking quite a bit of the surrounding air along with him, and the animals are doing something similar in the water."

To avoid predators, jellyfish and related animals often hide far below the ocean's surface during the day and swim to the surface at night to feed, according to William Dewar, an oceanographer at Florida State University in Tallahassee who was not involved with the study.

Changing The Carbon Balance

If the work is correct, then it could mean that they're ferrying cold water to the surface and warm water into the depths of the sea with each feeding cycle. In the process, they may be taking dissolved carbon dioxide with them far beneath the sea, changing the overall carbon balance in the atmosphere.

But, Dewar adds, there's a still a long way to go before scientists can say for sure that animals like jellyfish are helping to regulate the climate. Larger-scale studies need to be carried out to understand where marine animals are living and how they move. "What I think we can say at the moment is that it's a plausible idea," he says. new study in this week's issue of the journal Nature.

Libya and Canada sign nuclear deal

Libya and Canada have signed a memorandum of intent on nuclear power, the fourth signed by Tripoli in the past two years, an official said on Thursday.

The memorandum foresees cooperation between the two countries in research and the mining, processing and transport of uranium, as well as its use in medicine and desalination projects.

Since July 2007, Libya has signed another three similar agreements with France, Russia and Ukraine.

OPEC member Libya is also the African continent's third largest oil producer after Nigeria and Angola, pumping nearly two million barrels of crude oil per day. It hopes to increase production to three million bpd by 2013.

Glass leaf 'sweats' to generate electricity

Artificial photosynthesis has yet to be cracked, but electrical engineers in the US think that synthetic leaves could be used to generate electricity in a different way – by sweating.

Natural leaves constantly lose water through evaporation in a process called transpiration, which draws water from the roots to the very top of even the tallest trees.

The new synthetic leaves also lose water through evaporation to create that mechanical water pump effect, and use it to generate power.

Flowing bubbles

Michel Maharbiz at the University of California, Berkeley, working with colleagues at the University of Michigan and MIT, built their leaves from glass wafers shot through with a branching network of tiny water-filled channels arranged like the veins of a leaf.

The smaller channels extend to the edge of the plate and have open ends that allow water to evaporate, drawing fluid along the leaf's central stem at a rate of 1.5 centimetres per second.

The researchers added metal plates to the walls of the central stem and connected them to a circuit. The charged plates and the water within the stem create a sandwich of two conducting layers separated by an insulating layer – in effect, a capacitor.

The leaf is transformed into a source of power by periodically interrupting the water flowing into the leaf with air bubbles. Thanks to the different electrical properties of air and water, every time a bubble passes between the plates the capacitance of the device changes and a small electric current is generated, which passes to an external circuit where it's used to pump up the voltage on a storage capacitor.

"We use the mechanical energy in the liquid flow to change the capacitance and add energy to the capacitor," says Maharbiz.

Energy scavenger

Each bubble results in an increase in output voltage of some 2 to 5 microvolts, and the device has a power density of some 2 microwatts per cubic centimetre. "I think we could easily reach hundreds of microwatts per cubic centimetre [with modifications]," he says.

That is still a fraction of the power density of power systems such as fuel cells or batteries, but it's a respectable figure for an energy scavenging system, Maharbiz says.

The device could be scaled up to produce artificial trees that generate power entirely through evaporation wherever there's a cyclical change in humidity. Although the modest power output is not enough to rival solar technology, Maharbiz thinks it could act as a complementary technology – the sunlight that generates solar power could also drive transpiration to boost the electricity generated.

Breaking the tension

Abraham Stroock at Cornell University in Ithaca, New York, thinks this is the first attempt to generate electricity from evaporation-driven flow. Although he points out that one US firm Voltree has succeeded in generating tiny quantities of power from the pH difference between soil and the roots of real trees.

"One challenge with the new study is that a bubble is used to generate the current in the capacitor," Stroock says. Bubbles prevent transpiration taking place over long distances because they break the tension that allows the water column to be pulled along like a piece of string.

Maharbiz says he can get round this issue by using solid insulators instead of bubbles, that spin in place as the water is pulled passed like a water wheel to create the permittivity differences needed to generate power.

Study: Global warming speeds CO2 release

Global warming is speeding the release of carbon dioxide, a chief greenhouse gas, from underground peat in subarctic wetlands, Dutch research indicates.
The research suggests rising temperatures are adding to the magnitude and velocity of global warming, Free University plant ecologist Ellen Dorrepaal and colleagues write in the journal Nature.
Their research shows that raising temperatures about 1 degree Celsius accelerates total ecosystem respiration rates by as much as 60 percent, creating an effect that can last at least eight years.
This is greater than previously thought, highlighting the extreme sensitivity of northern peatland carbon reservoirs to global warming, the researchers say.
Peat is an accumulation of partially decayed plant matter that forms in wetlands, or peatlands. The peatlands, forming for 360 million years, cover about 2 percent of the earth's land mass and contain 550 gigatons (10 to the ninth power) of carbon.
The subarctic region is just south of the true arctic, covering much of Alaska, Canada, southern Greenland, the north of Scandinavia, Siberia, northern Mongolia and parts of China.

Past warming shows gaps in climate knowledge: study

A dramatic warming of the planet 55 million years ago cannot be solely explained by a surge in carbon dioxide levels, a study shows, highlighting gaps in scientists' understanding of impacts from rapid climate change.
During an event called the Palaeocene-Eocene Thermal Maximum, global temperatures rose between 5 and 9 degrees Celsius within several thousand years. The world at that time was already warmer than now with no surface ice.
"We now believe that the CO2 did not cause all the warming, that there were additional factors," said Richard Zeebe, an oceanographer with the University of Hawaii at Manoa.
"There may have been an initial trigger," he told Reuters on Wednesday from Hawaii. This could be a deep ocean warming that caused a catastrophic release of methane from hydrate deposits under the seabed.
Methane is a potent greenhouse gas but much of it is oxidised into CO2 when it is released from hydrate deposits.
Zeebe and his colleagues estimated the amount of CO2 released during the Palaeocene-Eocene event by studying sediment cores from seabeds around the globe. Their study is published in the latest issue of Nature Geoscience.
FUTURE WARMING
They estimated about 3 trillion tons of carbon (11 trillion tons of CO2) was released over several thousand years from the methane deposits, leading to a 70 percent rise in atmospheric CO2 levels from pre-event levels.
But Zeebe said this could only explain a 1 to 3.5 degree Celsius rise in temperatures, adding that a commonly accepted scientific range for a doubling of CO2 is between 1.5 and 4.5 degrees Celsius.
This meant other factors must have been at work to drive up temperatures between 5 and 9 degrees Celsius.
"If this additional warming which we do not really understand, was caused as a response to the CO2 warming, then there is a chance that also a future warming could be more intense than people anticipate right now," Zeebe said.
He said the study suggested there could be atmospheric or ocean processes as yet unknown or poorly understood that might have accelerated the warming. Possibilities could be changes in ocean currents, a much larger release of methane or even greater impacts from higher CO2 levels than currently thought.
At present, CO2 levels have already risen from 280 parts per million to nearly 390 ppm since the Industrial Revolution and could exceed a 70 percent increase during this century, a rate much faster than the Palaeocene-Eocene event, Zeebe said.
While this would cause initial effects, much worse could follow in the coming decades and centuries as the oceans, land and atmosphere tried to deal with the higher CO2 levels, he said.
"The carbon that we put into the atmosphere right now is going to stay there for a very long time. Much of it will stay there for tens of thousands of years."