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timothy oleson

Clues to limestone weathering written in Western Wall

Builders and masons take note: When it comes to the durability of limestone, grain size matters. New research combining field and lab data shows that fine-grained limestone is more susceptible than its coarser-grained cousins to a one-two punch of chemical and mechanical weathering. The findings, which arose in part from observations of Jerusalem’s historic Western Wall, could have implications for Earth’s carbon cycle and landscape — as well as for architectural preservation.

16 Oct 2014

Ice (Re) Cap: October 2014

From Antarctica to the Arctic; polar caps, permafrost and glaciers to ocean-rafted sea ice; and burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. Here are a few of the latest updates.

12 Oct 2014

Saturn's polar hexagon stable over time

Saturn’s peculiar polar “hexagon” has proven perplexing for scientists studying the atmospheric phenomenon since Voyager 1 and 2 first observed it in the early 1980s. Now, an international team has completed the most thorough study of the six-sided jet stream yet, using images and data collected between 2008 and 2014 by the Cassini spacecraft.

07 Oct 2014

Out of Africa, time and again

There is widespread agreement among scientists based on fossil and geochemical evidence that modern humans evolved in Africa between 200,000 and 100,000 years ago before spreading around the world. But the timing and route of this dispersal, and whether it occurred as a single exodus or in multiple pulses, remain contested. Now, a new study throws its weight behind a multiple-dispersal hypothesis, suggesting a first group of modern humans left Africa as early as 130,000 years ago, followed by a second about 80,000 years later.

27 Sep 2014

Climate impacting a few of our favorite foodstuffs

Researchers have found that the number of foggy winter days in California’s agriculture-heavy Central Valley has dropped 46 percent on average over the past three decades. Fog shields the valley from sunlight and contributes to the amount of “winter chill” — the amount of time spent between zero and 7 degrees Celsius during winter dormancy — that fruit and nut trees there experience. Sufficient winter chill is necessary for buds, flowers and fruit to develop properly, and although winter chill has previously been observed to have decreased since the 1950s, no one had conducted a long-term analysis of fog occurrence trends in the area, according to Dennis Baldocchi and Eric Waller of the University of California at Berkeley.

24 Sep 2014

Bare Earth Elements: Search the seafloor firsthand (and live!)

If you’ve ever wanted to take a dive into the ocean depths and explore the seafloor below the waves, but just haven’t had the time (or financing) to build your own deep-sea submersible, here’s another solution. NOAA’s 68-meter Okeanos Explorer — the only federally funded ship dedicated to “solely to exploration” — is currently trolling the Atlantic Ocean on the three-week third leg of a mission dubbed “Our Deepwater Backyard: Exploring Atlantic Canyons and Seamounts 2014,” and it’s offering to take guests along for part of the ride.

24 Sep 2014

Virtual water: Tracking the unseen water in goods and resources

Trading in “virtual water” — rainfall and irrigation water used in the production of food commodities or other goods and services, but that isn’t part of the final product — between water-rich and water-poor regions has been suggested as a means to allay water scarcity. And recently, the virtual water concept has gained a foothold among a number of governments and multinational businesses, potentially shaping approaches to water sustainability in the future.

21 Sep 2014

Red Planet Roundup: September 2014

As Curiosity and Opportunity rove around Mars, the Mars Reconnaissance Orbiter (MRO), Mars Express and Mars Odyssey orbit above, and scientists on Earth study the Red Planet from afar, new findings are announced almost weekly. Here are a few of the latest updates.

12 Sep 2014

New climate record challenges ideas about recent glaciations

Predicting how a changing climate and rising sea levels might impact humans in the future requires an understanding of how Earth has changed in the past. So scientists are continually seeking more and better data to help illuminate earlier conditions.
 

08 Sep 2014

Nutrient runoff feeding Baltic Sea dead zone

Low-oxygen, or hypoxic, deep waters now extend over an area of about 60,000 square kilometers in the Baltic Sea, a tenfold increase compared to 115 years ago, according to a recent study published in Proceedings of the National Academy of Sciences. The hypoxic zone has fluctuated substantially in that period, but much of the expansion has occurred in recent decades as a result of large inputs of nutrients like nitrogen and phosphorus from human activities such as agriculture, reported Jacob Carstensen of Aarhus University in Denmark and colleagues.
 

03 Sep 2014

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