Even If Emissions Stop, Carbon Dioxide Could Warm Earth for Centuries

Even if carbon dioxide emissions came to a sudden halt, the carbon dioxide already in Earth's atmosphere could continue to warm our planet for hundreds of years, according to Princeton University-led research published in the journal Nature Climate Change. The study suggests that it might take a lot less carbon than previously thought to reach the global temperature scientists deem unsafe.

The researchers simulated an Earth on which, after 1,800 billion tons of carbon entered the atmosphere, all carbon dioxide emissions suddenly stopped. Scientists commonly use the scenario of emissions screeching to a stop to gauge the heat-trapping staying power of carbon dioxide. Within a millennium of this simulated shutoff, the carbon itself faded steadily with 40 percent absorbed by Earth's oceans and landmasses within 20 years and 80 percent soaked up at the end of the 1,000 years.

By itself, such a decrease of atmospheric carbon dioxide should lead to cooling. But the heat trapped by the carbon dioxide took a divergent track.

After a century of cooling, the planet warmed by 0.37 degrees Celsius (0.66 Fahrenheit) during the next 400 years as the ocean absorbed less and less heat. While the resulting temperature spike seems slight, a little heat goes a long way here. Earth has warmed by only 0.85 degrees Celsius (1.5 degrees Fahrenheit) since pre-industrial times.

The Intergovernmental Panel on Climate Change estimates that global temperatures a mere 2 degrees Celsius (3.6 degrees Fahrenheit) higher than pre-industrial levels would dangerously interfere with the climate system. To avoid that point would mean humans have to keep cumulative carbon dioxide emissions below 1,000 billion tons of carbon, about half of which has already been put into the atmosphere since the dawn of industry.

The lingering warming effect the researchers found, however, suggests that the 2-degree point may be reached with much less carbon, said first author Thomas Frölicher, who conducted the work as a postdoctoral researcher in Princeton's Program in Atmospheric and Oceanic Sciences under co-author Jorge Sarmiento, the George J. Magee Professor of Geoscience and Geological Engineering.

"If our results are correct, the total carbon emissions required to stay below 2 degrees of warming would have to be three-quarters of previous estimates, only 750 billion tons instead of 1,000 billion tons of carbon," said Frölicher, now a researcher at the Swiss Federal Institute of Technology in Zurich. "Thus, limiting the warming to 2 degrees would require keeping future cumulative carbon emissions below 250 billion tons, only half of the already emitted amount of 500 billion tons."

The researchers' work contradicts a scientific consensus that the global temperature would remain constant or decline if emissions were suddenly cut to zero. But previous research did not account for a gradual reduction in the oceans' ability to absorb heat from the atmosphere, particularly the polar oceans, Frölicher said. Although carbon dioxide steadily dissipates, Frölicher and his co-authors were able to see that the oceans that remove heat from the atmosphere gradually take up less. Eventually, the residual heat offsets the cooling that occurred due to dwindling amounts of carbon dioxide.

"Scientists have thought that the temperature stays constant or declines once emissions stop, but now we show that the possibility of a temperature increase cannot be excluded," Frölicher said. "This is illustrative of how difficult it may be to reverse climate change -- we stop the emissions, but still get an increase in the global mean temperature."

Source : Science Daily

N.H.Khider

The Era of Neutrino Astronomy Has Begun

Astrophysicists using a telescope embedded in Antarctic ice have succeeded in a quest to detect and record the mysterious phenomena known as cosmic neutrinos -- nearly massless particles that stream to Earth at the speed of light from outside our solar system, striking the surface in a burst of energy that can be as powerful as a baseball pitcher's fastball. Next, they hope to build on the early success of the IceCube Neutrino Observatory to detect the source of these high-energy particles, said Physics Professor Gregory Sullivan, who led the University of Maryland's 12-person team of contributors to the IceCube Collaboration.

"The era of neutrino astronomy has begun," Sullivan said as the IceCube Collaboration announced the observation of 28 very high-energy particle events that constitute the first solid evidence for astrophysical neutrinos from cosmic sources.

By studying the neutrinos that IceCube detects, scientists can learn about the nature of astrophysical phenomena occurring millions, or even billions of light years from Earth, Sullivan said. "The sources of neutrinos, and the question of what could accelerate these particles, has been a mystery for more than 100 years. Now we have an instrument that can detect astrophysical neutrinos. It's working beautifully, and we expect it to run for another 20 years."

The collaboration's report on the first cosmic neutrino records from the IceCube Neutrino Observatory, collected from instruments embedded in one cubic kilometer of ice at the South Pole, was published Nov. 22 in the journal Science.

"This is the first indication of very high-energy neutrinos coming from outside our solar system," said University of Wisconsin-Madison Physics Professor Francis Halzen, principal investigator of IceCube. "It is gratifying to finally see what we have been looking for. This is the dawn of a new age of astronomy."

"Neutrinos are one of the basic building blocks of our universe," said UMD Physics Associate Professor Kara Hoffman, an IceCube team member. Billions of them pass through our bodies unnoticed every second. These extremely high-energy particles maintain their speed and direction unaffected by magnetic fields. The vast majority of neutrinos originate either in the sun or in Earth's own atmosphere. Far more rare are astrophysical neutrinos, which come from the outer reaches of our galaxy or beyond.

The origin and cause of astrophysical neutrinos are unknown, though gamma ray bursts, active galactic nuclei and black holes are potential sources. Better understanding of these neutrinos is critically important in particle physics, astrophysics and astronomy, and scientists have worked for more than 50 years to design and build a high-energy neutrino detector of this type.

IceCube was designed to accomplish two major scientific goals: measure the flux, or rate, of high-energy neutrinos and try to identify some of their sources. The neutrino observatory was built and is operated by an international collaboration of more than 250 physicists and engineers. UMD physicists have been key collaborators on IceCube since 2002, when its unique design was devised and construction began.

IceCube is made up of 5,160 digital optical modules suspended along 86 strings embedded in ice beneath the South Pole. The National Science Foundation-supported observatory detects neutrinos through the tiny flashes of blue light, called Cherenkov light, produced when neutrinos interact in the ice. Computers at the IceCube laboratory collect near-real-time data from the optical sensors and send information about interesting events north via satellite. The UMD team designed the data collection system and much of IceCube's analytic software. Construction took nearly a decade, and the completed detector began gathering data in May 2011.

"IceCube is a wonderful and unique astrophysical telescope -- it is deployed deep in the Antarctic ice but looks over the entire Universe, detecting neutrinos coming through the Earth from the northern skies, as well as from around the southern skies," said Vladimir Papitashvili of the National Science Foundation (NSF) Division of Polar Programs.

The IceCube Neutrino Observatory was built under a NSF Major Research Equipment and Facilities Construction grant, with assistance from partner funding agencies around the world. The NSF's Division of Polar Programs and Physics Division continue to support the project with a Maintenance and Operations grant, along with international support from participating institutes and their funding agencies.

Source: Sience Daily.com

R.S

Does Obesity Reshape Our Sense of Taste?

Obesity may alter the way we taste at the most fundamental level: by changing how our tongues react to different foods.

In a Nov. 13 study in the journal PLOS ONE, University at Buffalo biologists report that being severely overweight impaired the ability of mice to detect sweets.

Compared with slimmer counterparts, the plump mice had fewer taste cells that responded to sweet stimuli. What's more, the cells that did respond to sweetness reacted relatively weakly.

The findings peel back a new layer of the mystery of how obesity alters our relationship to food.

"Studies have shown that obesity can lead to alterations in the brain, as well as the nerves that control the peripheral taste system, but no one had ever looked at the cells on the tongue that make contact with food," said lead scientist Kathryn Medler, PhD, UB associate professor of biological sciences.

"What we see is that even at this level -- at the first step in the taste pathway -- the taste receptor cells themselves are affected by obesity," Medler said. "The obese mice have fewer taste cells that respond to sweet stimuli, and they don't respond as well."

The research matters because taste plays an important role in regulating appetite: what we eat, and how much we consume.

How an inability to detect sweetness might encourage weight gain is unclear, but past research has shown that obese people yearn for sweet and savory foods though they may not taste these flavors as well as thinner people.

Medler said it's possible that trouble detecting sweetness may lead obese mice to eat more than their leaner counterparts to get the same payoff.

Learning more about the connection between taste, appetite and obesity is important, she said, because it could lead to new methods for encouraging healthy eating.

"If we understand how these taste cells are affected and how we can get these cells back to normal, it could lead to new treatments," Medler said. "These cells are out on your tongue and are more accessible than cells in other parts of your body, like your brain."

The new PLOS ONE study compared 25 normal mice to 25 of their littermates who were fed a high-fat diet and became obese.

To measure the animals' response to different tastes, the research team looked at a process called calcium signaling. When cells "recognize" a certain taste, there is a temporary increase in the calcium levels inside the cells, and the scientists measured this change.

The results: Taste cells from the obese mice responded more weakly not only to sweetness but, surprisingly, to bitterness as well. Taste cells from both groups of animals reacted similarly to umami, a flavor associated with savory and meaty foods.

Medler's co-authors on the study were former UB graduate student Amanda Maliphol and former UB undergraduate Deborah Garth.

 

Source:Science daily

N.Haj .Khidr

Fossil of New Big Cat Species Discovered: Oldest Ever Found

The oldest big cat fossil ever found -- which fills in a significant gap in the fossil record -- was discovered on a paleontological dig in Tibet, scientists announced today.

A skull from the new species, named Panthera blytheae, was excavated and described by a team led by Jack Tseng -- a PhD student at the USC Dornsife College of Letters, Arts and Sciences at the time of the discovery, and now a postdoctoral fellow at the American Museum of Natural History (AMNH) in New York.

"This find suggests that big cats have a deeper evolutionary origin than previously suspected," Tseng said.

Tseng's coauthors include Xiaoming Wang, who has joint appointments at USC, the Natural History Museum of Los Angeles County (NHM) and the Page Museum at the La Brea Tar Pits, the AMNH, and the Chinese Academy of Sciences (CAS); Graham Slater of the Smithsonian Institution; Gary Takeuchi of the NHM and the Page Museum at the La Brea Tar Pits; Qiang Li of the CAS; Juan Liu of the University of Alberta and the CAS; and Guangpu Xie of the Gansu Provincial Museum.

DNA evidence suggests that the so-called "big cats" -- the Pantherinae subfamily, including lions, jaguars, tigers, leopards, snow leopards, and clouded leopards -- diverged from their nearest evolutionary cousins, Felinae (which includes cougars, lynxes, and domestic cats), about 6.37 million years ago. However, the oldest fossils of big cats previously found are tooth fragments uncovered at Laetoli in Tanzania (the famed hominin site excavated by Mary Leakey in the 1970s), dating to just 3.6 million years ago.

Using magnetostratigraphy -- dating fossils based on the distinctive patterns of reversals in Earth's magnetic field, which are recorded in layers of rock -- Tseng and his team were able to estimate the age of the skull at between 4.10 and 5.95 million years old.

The new cat takes its name from Blythe, the snow-leopard-loving daughter of Paul and Heather Haaga, who are avid supporters of the Natural History Museum of Los Angeles County.

The find not only challenges previous suppositions about the evolution of big cats, it also helps place that evolution in a geographical context. The find occurs in a region that overlaps the majority of current big cat habitats, and suggests that the group evolved in central Asia and spread outward.

In addition, recent estimates suggested that the genus Panthera (lions, tigers, leopards, jaguars, and snow leopards) did not split from genus Neofelis (clouded leopards) until 3.72 million years ago -- which the new find disproves.

Tseng, his wife Juan Liu, and Takeuchi discovered the skull in 2010 while scouting in the remote border region between Pakistan and China -- an area that takes a bumpy seven-day car ride to reach from Beijing.

Liu found over one hundred bones that were likely deposited by a river eroding out of a cliff. There, below the antelope limbs and jaws, was the crushed -- but largely complete -- remains of the skull.

"It was just lodged in the middle of all that mess," Tseng said.

For the past three years, Tseng and his team have used both anatomical and DNA data to determine that the skull does, in fact, represent a new species.

They plan to return to the site where they found the skull in the summer to search for more specimens.

"We are in the business of discovery," said Wang, curator of vertebrate paleontology at the NHM; adjunct professor of geoscience and biology at USC; and research associate at AMNH. "We go out into the world in search of new fossils to illuminate the past."

Source:Science Daily

N.Haj.Khidr 

As Mars Goes, So Goes Earth?

 

NASA is set to launch MAVEN (Mars Atmosphere and Volatile Evolution), a small scientific satellite, to do some chemical meter-reading in the Martian atmosphere.

"MAVEN will provide key knowledge for understanding how all atmospheres, even our own, have changed since the formation of the solar system," says Paul Withers, a College of Arts & Sciences assistant professor of astronomy, who is one of a BU trio working on the project. Unlike studies of quicker, human-induced climate change, MAVEN will study "the longer, natural changes that occur as every planet's atmosphere slowly boils away."

Billions of years ago, scientists believe, water coursed over the Red Planet's face. Today, its arid surface may be a textbook on how solar heat not only evaporated that liquid, but also thinned the atmosphere by bleeding off nitrogen and carbon dioxide.

When MAVEN takes off from Florida's Cape Canaveral today, Withers will attend his first space launch, with "fingers crossed that all goes well," he says. He'll be joined by John Clarke and Michael Mendillo (GRS'68,'71), both CAS astronomy professors. Clarke, director of BU's Center for Space Physics, has been part of MAVEN's planning for eight years and now works with its instrument team.

MAVEN's goal is to "detail the processes that lead to atoms and molecules escaping into space," Clarke says, "so that we can extrapolate back in time to tell what the conditions were like when Mars was young." Erosion channels on the planet suggest surface water earlier in its history, and the thicker atmosphere and warmer climate that would have gone with it, meaning, he says, "Mars may have begun its history looking much more like Earth," and possibly hosting some form of life.

Another BU study was the first to tie simultaneous ionospheric disruptions on Earth and Mars to a large solar flare, Mendillo says, showing that the sun's effects on Mars could be instructive for the future of Earth's atmosphere.

MAVEN is the first project of its kind, says NASA: rather than crawl on the surface, the satellite will hang out in orbit, using its sensitive instruments "to pinpoint trace amounts of chemicals," according to the space agency. Clarke says BU is the only New England institution assisting the project, which is being led by the University of Colorado at Boulder.

MAVEN will reach Mars in 10 months and then take readings for two years (that's by Earth's calendar; only one Martian year will pass).

Source: science daily

B.N

 

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