ITHACA, N.Y., March 6 (UPI) -- October's "Superstorm" Sandy was not a freak occurrence but a predictable consequence of loss of arctic sea ice because of global warming, U.S. researchers say.
Scientists at Cornell University and Rutgers University said the severe loss of summertime arctic sea ice has increased the frequency of atmospheric blocking events like the one that steered Hurricane Sandy west into the densely populated New York City area.
The decrease in sea ice appears to enhance Northern Hemisphere jet stream meandering and intensify arctic air mass invasions toward middle latitudes, leading to the increase in blocking, they said.
Such a strong atmospheric, high-pressure blocking pattern over Greenland and the northwest Atlantic Ocean prevented Sandy from steering northeastward and out to sea like most October hurricanes and tropical storms from the Caribbean, the researchers said.
Instead, Sandy traveled up the Atlantic Coast and turned left "toward the most populated area along the Eastern Seaboard" and converged with an extratropical cyclone that transformed it into a monster tempest, the scientists said.
"If one accepts this evidence and ... takes into account the record loss of arctic sea ice this past September, then perhaps the likelihood of greenhouse warming playing a significant role in Sandy's evolution as an extratropical superstorm is at least as plausible as the idea that this storm was simply a freak of nature," the researchers wrote in the journal Oceanography.
Evidence of Milky Way 'fireworks' seen
NASHVILLE, March 6 (UPI) -- While the core of the Milky Way galaxy is a pretty tame place, cosmically speaking, evidence suggests it wasn't always that calm, U.S. astrophysicists say.
Kelly Holley-Bockelmann at Vanderbilt University and Tamara Bogdanovic at the Georgia Institute of Technology said some "forensic" clues point to all manner of celestial fireworks in the galactic center several million years ago.
A single event -- a violent collision and merger between the galactic black hole at the Milky Way's center and intermediate-sized black hole in one of the small "satellite galaxies" that circle our galaxy --could have produced the features seen today that suggest a more violent past, they said.
One puzzling characteristic of the galactic center, they said, is the fact that it contains the three most massive clusters of young stars in the entire galaxy, containing hundreds of young, hot stars that are much larger than the Sun.
Because these stars typically burn out in "only" a few million years because of their extreme brightness, there had to have been a relatively recent burst of star formation at the center, they said.
Holley-Bockelmann and her colleagues set about creating a theoretical model to explain such characteristics.
In their model, about 13 billion years ago the path of one of the smaller satellite galaxies orbiting the Milky Way was diverted so that it began drifting inward toward the core, and about 10 million years ago it reached the galactic center.
The smaller black hole would have circled the galactic black hole for several million years before it was ultimately consumed.
As the smaller black hole circled closer and closer, it would have churned up the dust and gas in the vicinity, and the violent gravitational tides produced by the process could easily have compressed the molecular clouds in the core to the super densities required to produce the young stars that are now located on the central black hole's doorstep.
"The gravitational pull of the satellite galaxy's black hole could have carved nearly 1,000 stars out of the galactic center," Bogdanovic said.
Fences may be only hope for Africa's lions
NEW YORK, March 6 (UPI) -- Almost half of Africa's lions are facing extinction and fencing them in -- and keeping humans out -- may be their only hope for survival, conservationists say.
Writing in the journal Ecology letters, researchers said nearly half of Africa's wild lion populations might decline to near extinction during the next 20-40 years without urgent conservation measures, including fenced reserves.
"It is clear that fences work and unfenced populations are extremely expensive to maintain," Craig Packer of the University of Minnesota said.
Conservation costs are lower and lion population sizes and densities are greater in reserves secured by wildlife-proof fences, Packer said.
Separating lion and human populations will be essential for the species' survival, researchers said.
"These findings highlight the severity of the lion conservation crisis today and the limited choices we have to ensure a future for the species," Luke Hunter, president of big-cat advocacy group Panthera, said.
"No one wants to resort to putting any more fences around Africa's marvelous wild areas, but without massive and immediate increases in the commitment to lion conservation, we may have little choice," he said.
It is estimated that fewer than 30,000 lions remain in Africa in just 25 percent of the species' original natural habitat, a Panthera release said Wednesday.
Robot fish has sense that mimics nature
TALLIN, Estonia, March 6 (UPI) -- European researchers say they've created the first robot fish with a guidance system based on a sense organ possessed by all living fish.
For 14 years a research project funded by the European Union has been working to develop efficient underwater robots based on biological principles.
Now researchers say they've developed a robot fish controlled with the help of lateral line sensors that mimic the sensing organ found in nature.
In living fish -- and now in the robot version -- lateral line sensors create a flow "landscape" that helps them orient themselves, navigate and control their movements.
"So far flow in robotics is treated as a disturbance that drives the robots away from their planned course," researcher Maarja Kruusmaa of Estonia's Tallin University of Technology said. "We have shown that flow is also a source of information that can be exploited to better control the vehicle."
A fish robot with lateral line sensing can save energy by finding energetically favorable regions in the flow where the currents are weaker or by interacting with eddies so that they help to push the robot forward, the researchers said.
"It is similar to reducing your effort in the tailwind of another cyclist or reducing the fuel consumption of your car by driving behind a truck," Kruusmaa said.