Health & Science

Do wind farms raise temperatures?

Wind farms may provide energy without generating greenhouse gases, but new research finds that their turbines have a surprising environmental cost: They make the region around them a little warmer. Researchers from two universities studied four wind farms in Texas over the course of nine years. As the farms expanded from some 100 turbines to more than 2,350, nearby surface temperatures increased by an average of 1.3 degrees Fahrenheit at night, as the spinning blades churned up turbulence that prevented cool air from settling to the ground. That doesn’t mean the wind farms contribute to global climate change; there is no heating of the air. The massive turbines do, however, disrupt normal layering of air, so that warmer air stays near the ground instead of rising. The study is a reminder that no means of energy generation is without its costs, John Dabiri, an expert in wind power at the California Institute of Technology, tells DiscoveryNews.com. “It shows that we need to think carefully about the unintended environmental consequences of any large-scale energy development,’’ Dabiri said, “including green technologies.’’

America’s huge sleep deficit

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Nearly one in three American workers is sleep-deprived, and the resulting epidemic of drowsiness is causing serious injuries and health problems. A new report by the Centers for Disease Control and Prevention shows that more than 40 million workers in the U.S. get less than the minimum six hours of sleep per night that doctors recommend. “If you hit the snooze button more than twice, you are probably sleep-deprived,” psychologist and sleep expert Michael J. Breus tells WebMD.com. Night-shift workers, 44 percent of whom don’t get enough rest, are the hardest hit, and they often hold jobs in transportation and health care, two of the fields in which workers logged the least amount of shut-eye. Lack of sleep has been linked to an increased risk of obesity, cardiovascular disease, and diabetes. It can also impair attention and short-term memory, posing particularly dangerous problems for medical workers and those driving and operating heavy machinery. Researchers estimate that sleepiness causes 20 percent of traffic accidents and plays a role in thousands of fatal on-the-job mishaps each year.

The secret behind birds’ GPS

Scientists have long marveled at how migratory birds’ keen sense of direction works to keep them on course over thousands of miles, even at night. Previous research has hinted that they navigate by sensing the earth’s magnetic field, but only now do researchers appear to have solved part of the mystery of that process. As many as 53 individual neurons in birds’ brain stems “encode the direction, intensity, and polarity” of the earth’s magnetic field, Baylor College of Medicine neuroscientist David Dickman tells The Chronicle of Higher Education. Once magnetoreceptive cells detect a magnetic field, the neurons work “like a compass” to inform the bird of its heading and position. Dickman and his colleague Le-Qing Wu made their discovery by putting pigeons in a dark room and monitoring how the neurons changed in reaction to variations in an artificial magnetic field. Researchers are still searching for the cells that detect magnetic signals before they are registered in the neurons; Dickman says he is already doing experiments to identify a possible receptor located in the pigeons’ inner ear.

Pacific sharks disappearing

Overfishing has decimated shark populations worldwide, raising the possibility that some species may disappear. Researchers at the University of Hawaii sent divers on 1,600 underwater surveys to count reef sharks—such as whitetips, blacktips, and nurse sharks—living near 46 Pacific islands. They found that shark numbers have decreased by some 90 percent over the past several decades in the vicinity of the most populated islands, including the main Hawaiian Islands and American Samoa. The finding supports other studies that suggest that large sharks are being butchered in record numbers around the globe, in part to feed an increasing demand for shark-fin soup, which is considered a delicacy in China and other Asian countries. The U.S. prohibits shark fishing in some of the waters researchers surveyed, but illegal fishing appeared to be commonplace. The study found that shark populations decline dramatically any time they live near humans. A coastal population of just 100 people was found to be enough to cut local shark numbers by 20 percent. Without better protection, study author Julia Baum tells The Washington Post, Pacific reef sharks “will be fished out within the next 10 years.”