Category Archives: Scientific American

Courtesy Aurel Persiou

When Evidence Melts Away

On a recent visit to Crystal Ice Cave in Idaho, climate and cave researchers had to wade through frigid, knee-deep water to reach the ice formations that give the cave its name. Cavers are good-humored about the hardships of underground exploration, but this water was chilling for more than one reason: it was carrying away some of the very clues they had come to study.

Ice is an invaluable source of information about the earth’s past. Pollen trapped in ice from polar ice caps and mountaintop glaciers documents plant life up to 1.5 million years ago, and gas bubbles and water isotopes reveal glimpses of ancient temperatures.

Polar ice samples cannot necessarily reveal what the climate was like in, say, New Mexico or other temperate regions, however. So a decade ago a small group of researchers began meeting to discuss the potential of cave ice, some of which is more than 3,000 years old. Since then, studies have confirmed that cave ice can illuminate some questions about how lower altitudes and latitudes responded to climate swings. But by this summer, when the scientists found themselves wading through the meltwater in Crystal Ice Cave during their biennial workshop, the main question had changed from what the ice could tell them to how to retrieve enough before it disappeared.

Thus far researchers have not won much funding for long-term studies of ice caves. Part of the reason is that obtaining a sample is a massive, expensive effort, requiring intense drilling, helicopters and refrigerated vans. And geochemist Zoltán Kern of the Hungarian Academy of Sciences in Budapest notes that he understands funders’ qualms because scientists have not yet figured out how to convert complicated cave ice data into tidy climate records. But this much is clear, says George Veni, director of the National Cave and Karst Research Institute in Carlsbad, N.M.: before the ice melts, “the main thing is to try and collect as much of it as possible.”

First published by Scientific American: [html] [html en español] [pdf].

See also my previous feature stories on cave ice in Science Magazine and EARTH Magazine.

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Mexico Is Poised for Energy Boom

Mexico reopened its energy market to outside producers in August for the first time in more than 75 years. Until now, private companies could only serve as contractors to the national hydrocarbon or electricity monopolies.

Mexicans formerly took pride in keeping a major natural resource in national hands. Pemex, the state petroleum monopoly, provided almost a third of federal revenues. Yet Pemex’s production began dropping in the mid-1990s. In 2013, the U.S. Energy Information Administration (EIA) predicted (PDF) that by 2025 Mexican oil production would plunge by more than 50 percent from 2010 levels, despite the presence of the equivalent of 450 billion barrels of oil in Mexico, on par with Saudi Arabia’s resources. On August 25, citing the reforms, the EIA predicted a turnaround in the decline over the next few years and a return to growth by 2025. Mexico is now on the verge of an oil and gas boom. Continue reading

Hitting Rock Bottom

Fishing boats have dragged nets across the seafloor in pursuit of bottom-feeding fish and crustaceans since the Middle Ages. In recent decades, motorized fishing fleets, powered by government subsidies, have taken heavier nets deeper and farther offshore. The annual haul from international waters in 2010 was reported to be worth more than $600 million.

To see how bottom trawling is changing the ocean’s bottom, ecologist Antonio Pusceddu of the Marche Polytechnic University in Ancona, Italy, and his team took seafloor sediment samples at trawled and untouched sites off Spain’s northeastern coast between 500 and 2,000 meters below the surface. They then counted the number of individuals and species in those samples and measured the amount of carbon in the sediment. Continue reading

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Health Benefits of Bike Sharing Depend on Age, Gender

In the middle of the evening rush hour last November 29 more than 1,000 London cyclists staged a “die-in” to protest the traffic deaths of fellow riders and to demand more investment in bike-friendly roads. London’s streets may have grown friendlier to cyclists since the 2010 introduction of its Barclays Cycle Hire bike-sharing system but according to those at the protest, London is still too dangerous. The hundreds of cities that have launched bicycle-sharing systems in the last decade offer similar reasons for doing it: Bicycling reduces car traffic and pollution in city centers and is healthy exercise. But although all road-users benefit from less-crowded streets, a recent study suggests that the health benefits of bike-sharing programs depend on who is doing the riding.London’s bike-sharing program had registered 191,702 users at last count. Public health researcher James Woodcock at the University of Cambridge in England and his colleagues imagined, and calculated, how those riders lives might have been different had they not used the bikes. They examined data from 2.1 million hours of use between April 2011 and March 2012 and compared the health impact of those 2.1 million hours with the alternatives: more walking, public transit use or driving. To their surprise, the team reports in the February 13 BMJ (British Medical Journal), the switch to cycling may not have been helpful for young women. The health benefits also seem to differ by age, with older riders of both genders gaining more benefits than younger ones.

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