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El Gobierno brasileño aparca los planes para construir presas en el Parque Nacional de Juruena

Al menos 35.000 morsas varadas en Alaska como consecuencia del calentamiento global

Unas 35.000 morsas han quedado varadas en una playa de Alaska debido al derretimiento del hielo ártico, consecuencia del calentamiento global, según ha informado el Instituto Americano de Geofísica.

El pasado 27 de septiembre, las morsas fueron observadas por aire cerca de Point Lay. Cuatro días antes, había solamente 1.500, han explicado los expertos de la USGS. "Eran casi 24 veces más", ha insistido Megan Ferguson, un especialista en la vigilancia aérea de los mamíferos marinos de la agencia Oceanográfica y Atmosférica estadounidense (NOAA).

Ferguson ha hecho hincapié en que se trataba de una estimación visual de los expertos de la NOAA y USGS, y que esta cifra podría ser refinada. También ha señalado que cada vez se están viendo más osos pardos en el lugar y que, en contraste, las ballenas grises que estaban presentes en la zona hasta los años 90 han desaparecido, "signo de un cambio de medio ambiente del Ártico".

Según Jay Chadwick, un investigador en el USGS, el número anormal de morsas varadas "es realmente una consecuencia del calentamiento global" y de la "reducción del hielo" en el Océano Ártico al final del verano . Por lo general, los animales viven en el hielo y pescan en aguas poco profundas, pero con el gran derretimiento del hielo acaecido este verano, las morsas se han reunido en profundidades demasiado grandes para poder alimentarse, por lo que buscaron refugio en el continente para coger peces más fácilmente, explicó Jay.

Esta característica de la morsa del Pacífico y específicamente del fenómeno de mar de Chukchi, según el USGS, "no se producía desde hacía diez años", ha asegurado el Instituto en su sitio web. Los expertos aún no saben si este cambio en el comportamiento de las morsas puede tener un impacto en su mortalidad, ya que creen que los bebés morsas son más frágiles en la tierra y además los animales pierden más energía en busca de presas en el suelo que, cuando están en el hielo.

Ancient magma plumbing found buried below moon's largest dark spot

Scientists have found a nearly square peg underneath a round hole—on the moon. Several kilometers below Oceanus Procellarum, the largest dark spot on the moon’s near side, scientists have discovered a giant rectangle thought to be the remnants of a geological plumbing system that spilled lava across the moon about 3.5 billion years ago. The features are similar to rift valleys on Earth—regions where the crust is cooling, contracting, and ripping apart. Their existence shows that the moon, early in its history, experienced tectonic and volcanic activity normally associated with much bigger planets.

“We’re realizing that the early moon was a much more dynamic place than we thought,” says Jeffrey Andrews-Hanna, a planetary scientist at the Colorado School of Mines in Golden and lead author of a new study of the Procellarum’s geology. The discovery also casts doubt on the decades-old theory that the circular Procellarum region is a basin, or giant crater, created when a large asteroid slammed into the moon. “We don’t expect a basin rim to have corners,” Andrews-Hanna says.

The work is based on data gathered by GRAIL (Gravity Recovery and Interior Laboratory), a pair of NASA spacecraft that orbited the moon in 2012. Sensitive to tiny variations in the gravitational tug of the moon, GRAIL mapped density variations below the surface (because regions of higher density produce slightly higher gravitational forces). Below known impact basins, GRAIL found the expected ringlike patterns, but underneath the Procellarum region, the mysterious rectangle emerged. “It was a striking pattern that demanded an explanation,” Andrews-Hanna says.

Scientists already know that the Procellarum region is rich in radioactive elements that billions of years ago would have produced excess heat. The study team theorizes that as this region cooled, the rock would have cracked in geometrical patterns, like honeycomb patterns seen on Earth in basalt formations, but on a much larger scale. In a study published today in Nature, the researchers propose that these cracks eventually grew into rift valleys, where magma from the moon’s mantle welled up and pushed apart blocks of crust. Lava spilled out and paved over the Oceanus Procellarum, creating the dark spot that is seen today. The extra weight of this dense material would have caused the whole region to sink slightly and form the topographic low that has made the Procellarum seem like a basin.

With the discovery, the moon joins Earth, Mars, and Venus as solar system bodies with mapped examples of rifting. There are also similar features near the south pole of Enceladus, the moon of Saturn that is spewing water into space from cracks in an ice shell.

Andrews-Hanna and colleagues have made a good case, says Herbert Frey, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, even though the newly described features are surprising. The moon is not big enough to have the same strong convective cooling process that Earth has in its interior, he explains, and ordinarily convection is one of the main mechanisms thought to lead to large-scale rifting. So just what caused the rifting remains unclear. “It just means the moon continues to surprise us,” he says. Frey adds that a remaining mystery is why the rectangular features were found only beneath Oceanus Procellarum. Even if the rifting is explained by the excess radioactive elements, there is still no definitive explanation for why only the near side of the moon ended up enriched.

The discovery could also be a death knell for the impact theory for Oceanus Procellarum, an idea first put forth in the early 1970s. A basin there would have been the largest on the moon—larger than the South Pole–Aitken Basin—and second in the solar system only to the Borealis Basin on Mars, which covers the planet’s entire northern hemisphere.

Ryosuke Nakamura, a researcher at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, is still not convinced that an impact can be ruled out. In 2012, he and his colleagues published a paper in Nature Geoscience that found compositional evidence for an impact within Procellarum—a type of pyroxene mineral that is found in other, known impact basins such as South Pole–Aitken and is associated with the melting or excavation of mantle rock from an asteroid impact.

In response to the current study, Nakamura says that the features in the southwestern corner of the Procellarum region look to be circular rather than rectangular, and still consistent with an impact. But Frey, who has long been skeptical of the impact theory, says that the features are as clear as day, and not what you’d expect underneath a basin. “That looks like a rectangle to me.”

Swirling cloud at Titan's pole is cold and toxic

Scientists analyzing data from NASA's Cassini mission have discovered that a giant, toxic cloud is hovering over the south pole of Saturn's largest moon, Titan, after the atmosphere there cooled dramatically.
The scientists found that this giant polar vortex contains frozen particles of the toxic compound hydrogen cyanide, or HCN.
"The discovery suggests that the atmosphere of Titan's southern hemisphere is cooling much faster than we expected," said Remco de Kok of Leiden Observatory and SRON Netherlands Institute for Space Research, lead author of the study published today in the journal Nature.
Titan is the only moon in the solar system that is cloaked in a dense atmosphere. Like our home planet, Earth, Titan experiences seasons. As it makes its 29-year orbit around the sun along with Saturn, each season lasts about seven Earth years. The most recent seasonal switch occurred in 2009, when winter gave way to spring in the northern hemisphere, and summer transitioned to autumn in the southern hemisphere.
In May 2012, while Titan's southern hemisphere was experiencing autumn, images from Cassini revealed a huge swirling cloud, several hundred miles across, taking shape above Titan's south pole. This polar vortex appears to be an effect of the change of season.
A puzzling detail about the swirling cloud is its altitude, some 200 miles (about 300 kilometers) above Titan's surface, where scientists thought the temperature was too warm for clouds to form. "We really didn't expect to see such a massive cloud so high in the atmosphere," said de Kok.
Keen to understand what could give rise to this mysterious cloud, the scientists dove into Cassini's observations and found an important clue in the spectrum of sunlight reflected by Titan's atmosphere.
A spectrum splits the light from a celestial body into its constituent colors, revealing signatures of the elements and molecules present. Cassini's visual and infrared mapping spectrometer (VIMS) maps the distribution of chemical compounds in Titan's atmosphere and on its surface.
"The light coming from the polar vortex showed a remarkable difference with respect to other portions of Titan's atmosphere," says de Kok. "We could clearly see a signature of frozen HCN molecules."
As a gas, HCN is present in small amounts in the nitrogen-rich atmosphere of Titan. Finding these molecules in the form of ice was surprising, as HCN can condense to form frozen particles only if the atmospheric temperature is as cold as minus 234 degrees Farenheit (minus 148 degrees Celsius). This is about 200 degrees Fahrenheit (about 100 degrees Celsius) colder than predictions from current theoretical models of Titan's upper atmosphere.
To check whether such low temperatures were actually possible, the team looked at observations from Cassini's composite infrared spectrometer (CIRS), which measures atmospheric temperature at different altitudes. Those data showed that the southern hemisphere of Titan has been cooling rapidly, making it possible to reach the cold temperature needed to form the giant toxic cloud seen on the south pole.
Atmospheric circulation has been drawing large masses of gas towards the south since the change of season in 2009. As HCN gas becomes more concentrated there, its molecules shine brightly at infrared wavelengths, cooling the surrounding air in the process. Another factor contributing to this cooling is the reduced exposure to sunlight in Titan's southern hemisphere as winter approaches there.
"These fascinating results from a body whose seasons are measured in years rather than months provide yet another example of the longevity of the remarkable Cassini spacecraft and its instruments," said Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory in Pasadena, California. "We look forward to further revelations as we approach summer solstice for the Saturn system in 2017."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson. The CIRS team is based at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Plutón busca recuperar su título de planeta

Plutón fue rebajado en el 2006 a la categoría de "planeta enano" en un debate que fue más allá del mundo científico y que ahora se vuelve a tocar en el Centro Harvard-Smithsonian de Astrofísica (CfA), en Estados Unidos, con una discusión entre expertos de la ciencia planetaria.

Hace ocho años, en el 2006, más de 2.500 expertos de 75 países se reunieron en Praga en la Unión Astronómica Internacional (IAU, por sus siglas en inglés), y establecieron una nueva definición universal de lo que se consideraría un planeta.

Esta definición distinguió entre ocho planetas "clásicos" que giraban en órbitas alrededor del Sol y dejaba fuera a cuerpos "enanos", como Plutón, que quedó al mismo nivel que los más de 50 cuerpos redondos que giran en torno al Sol en el cinturón de Kuiper.

Ocho años después y a menos de un año de que se celebre en Honolulu (Hawai, EEUU) la Asamblea General de la Unión Astronómica Internacional, el Centro Harvard-Smithsonian volvió a abrir el debate. Para ello, invitó a tres expertos con opiniones diferentes.

¿EL TAMAÑO SÍ IMPORTA?

El historiador científico Owen Gingerich, que presidió el comité de definición de planetas de la IAU, defendió el estatus de Plutón como planeta desde un punto de vista histórico y argumentó que "un planeta es una palabra culturalmente definida que cambia con el tiempo".

¿Cómo pudo la Unión Astronómica Internacional decir que Plutón era un planeta enano y luego negarle la posición de planeta? ¿Qué era entonces, solo un enano?, Gingerich considera que la IAU hizo un "abuso del lenguaje" al tratar de definir la palabra planeta y que, por eso, no debía haber expulsado a Plutón.

El punto de vista contrario lo defendió el director asociado del Centro de Planetas Menores, Gareth Williams, quien apoyó la expulsión de Plutón y definió los planetas como "cuerpos esféricos que orbitan alrededor del Sol y que han limpiado su camino", es decir, que han despejado su órbita de otros astros.

Por su parte, el director de la Iniciativa Orígenes de la Vida de Harvard, Dimitar Sasselov, estableció que un planeta es "la masa más pequeña esférica de la materia que se forma alrededor de las estrellas o restos estelares", lo que, a su juicio, devuelve a Plutón al club planetario.

Desde su descubrimiento en 1930 por el estadounidense Clyde Tombaugh, Plutón ha sido objeto de disputas, sobre todo debido a su tamaño, mucho menor que el de la Tierra, e incluso que el de la Luna.

La reivindicación está hecha y la polémica podría volver a despertar durante la Asamblea General de la Unión Astronómica Internacional en el 2015, el mismo año en el que se prevé que llegue a Plutón la sonda "Nuevos Horizontes", enviada por la NASA en el 2006.

¿Cómo afecta el deshielo de la Antártida a la gravedad de la Tierra?

Los glaciares de la Antártida occidental se derriten y su volumen se reduce a un ritmo de 125 kilómetros cúbicos al año. Este deshielo provoca una caída en el campo de la gravedad sobre la región perceptible desde el espacio.

Para monitorear los efectos del cambio climático, la capa de hielo de la Antártida fue dividida convencionalmente en cuencas hidrográficas de distinto tamaño. A partir de esta matriz, las mediciones del Grace pudieron ser procesadas de manera comparativa para averiguar qué cambios sufren los glaciares en cada cuenca y cómo se produce la descarga de hielo a los océanos. 

En cifras absolutas la variación de la gravedad no es muy grande, asegura la revista 'Slate'. Son mucho más importantes las alteraciones que se observan en la altimetría, especialmente en las zonas donde el hielo se derrite más velozmente. Pero lo que alimenta la mayor preocupación son los datos de la paleogeografía, puesto que, según se conoce, en el pasado los periodos de pérdida drástica del peso de los glaciares estuvieron seguidos de un alza en la actividad volcánica. 

Este efecto se debe a la tensión del subsuelo. Las capas de hielo son tan pesadas que hunden la corteza terrestre. Al perder decenas de miles de millones de toneladas de peso anualmente debido a la desaparición de los glaciares, como sucede ahora, la corteza regresa a su forma original. Este rebote disminuye la tensión en las rocas subyacentes, facilitando al magma su ascenso a la superficie y, por ende, las erupciones volcánicas. 

Las mediciones de la otra mitad de la región antártica, la oriental, no han sido suficientes para sacar las mismas conclusiones, pero los sondeos por satélite del continente glacial continúan y pueden implicar más revelaciones. 

Belief in Free Will Not Threatened by Neuroscience

A key finding from neuroscience research over the last few decades is that non-conscious preparatory brain activity appears to precede the subjective feeling of making a decision. Some neuroscientists, like Sam Harris, have argued that this shows our sense of free will is an illusion, and that lay people would realize this too if they were given a vivid demonstration of the implications of the science (see below). Books have even started to appear with titles like My Brain Made Me Do It: The Rise of Neuroscience and the Threat to Moral Responsibility by Eliezer J. Sternberg.

However, in a new paper, Eddy Nahmias, Jason Shepard and Shane Reuter counter such claims. They believe that Harris and others (who they dub “willusionists”) make several unfounded assumptions about the basis of most people’s sense of free will. Using a series of vivid hypothetical scenarios based on Harris’ own writings, Nahmias and his colleagues tested whether people’s belief in free will really is challenged by “neuroprediction” – the idea of neuroscientists using brain activity to predict a person’s choices – and by the related notion that mental activity is no more than brain activity.

The research involved hundreds of undergrads at Georgia State University in Atlanta. They were told about a piece of wearable brain imaging technology – a cap – available in the future that would allow neuroscientists to predict a person’s decisions before they made them. They also read a story about a woman named Jill who wore the cap for a month, and how scientists predicted her every choice, including her votes in elections.

Most of the students (80 per cent) agreed that this future technology was plausible, but they didn’t think it undermined Jill’s free will. Most of them only felt her free will was threatened if they were told that the neuroscientists manipulated Jill’s brain activity to alter her decisions. Similar results were found in a follow-up study in which the scenario descriptions made clear that “all human mental activity just is brain activity”, and in another that swapped the power of brain imaging technology for the mind reading skills of a psychic. In each case, students only felt that free will was threatened if Jill’s decisions were manipulated, not if they were merely predicted via her brain activity or via her mind and soul (by the psychic).

Nahmias et al said their results showed that most people have a “theory-lite” view of free will – they aren’t bothered by claims about mental activity being reduced to neural activity, nor by the idea that such activity precedes conscious decision-making and is readable by scientists. “Most people recognise that just because ‘my brain made me do it,’ that does not mean that I didn’t do it of my own free will,” the researchers said.

As neuroscience evidence increasingly enters the courtroom, these new findings have important implications for understanding how such evidence might influence legal verdicts about culpability. An obvious limitation of the research is its dependence on students in Atlanta. It will be interesting to see if the same findings apply in other cultures.

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This post first appeared on the British Psychological Society’s Research Digest blog.