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Saturday, January 31, 2009

NASA Scientist Says Global Warming Danger Amounts to 'Planetary Emergency'

By Paul Sisco
Washington
08 October 2008
Two decades after he first told legislators of the dangers of greenhouse gases and global warming, a key climate scientist repeats his message with even greater urgency. Director James Hansen of NASA's Goddard Institute of Space Studies made his comments at the National Press Club in Washington as he was honored for sounding the alarm over planetary climate change. VOA's Paul Sisco reports.



James Hanson
NASA climate scientist James Hansen was among the first to alert the public to the dangers of climate change. He did so at a congressional hearing conducted by then-Senator Tim Wirth.

"In 1988, he stepped to the front of the line of the scientific community to proclaim a human fingerprint on the earth's rising temperature," Wirth said. "It was a brave, a lonely leadership role he played then and he hasn't stopped for one day since."

At a Washington event recalling that hearing, Hansen said the world has long passed dangerous levels for greenhouse gasses in the atmosphere.
"We really have reached a point of a planetary emergency," Hanson said. "And it is because there are tipping points in the climate system which we are very close to and which, if we pass, the dynamics of the system can take over. So the momentum of the system will carry you to very large changes which are out your control."

Some advocates downplay the warnings of global warming and dispute the claim the climate system is reaching a tipping point.

"Most people who work on climate change issues are a lot more optimistic than that and believe there are a suite of technological applications that we will be able to apply that can reverse, or at least adapt, to the consequences of global warming," said Steve Segal, who is the lawyer representing energy interests.

Hansen joined other climate scientists in warning of increasingly violent storms, plant and animal extinctions, melting ice sheets and rising sea levels -- if mankind fails to act.



Greenland, global warming melting
"We have already reached one tipping point and we are going to lose all of the sea ice in the Arctic summer season," Hanson said "...and we know we are going to lose that sea ice because the planet is out of energy balance."

Hansen says Arctic ice will melt completely during each summer in five to ten years but that it can be reversed if mankind stops burning fossil fuels and phases out coal, the chief cause of manmade greenhouse gasses.



From : http://www.voanews.com/english/archive/2008-10/2008-10-08-voa27.cfm






Milky Way — the galaxy — not snack-sized anymore

Seth Borenstein , The Associated Press , Washington Tue, 01/06/2009 8:02 AM Sci-Tech

The latest view of the Milky Way's structure. (AP/Harvard-Smithsonian Center for Astrophysics, Robert Hurt, Mark Reid)
Take that, Andromeda! For decades, astronomers thought when it came to the major galaxies in Earth's cosmic neighborhood, our Milky Way was a weak sister to the larger Andromeda. Not anymore. The Milky Way is considerably larger, bulkier and spinning faster than astronomers once thought, Andromeda's equal.
Scientists mapped the Milky Way in a more detailed, three-dimensional way and found that it's 15 percent larger in breadth. More important, it's denser, with 50 percent more mass, which is like weight. The new findings were presented Monday at the American Astronomical Society's convention in Long Beach, Calif.




That difference means a lot, said study author Mark Reid of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. The slight 5-foot-5, 140-pound astrophysicist said it's the cosmic equivalent of him suddenly bulking up to the size of a 6-foot-3, 210-pound NFL linebacker.
"Previously we thought Andromeda was dominant, and that we were the little sister of Andromeda," Reid said. "But now it's more like we're fraternal twins."
That's not necessarily good news. A bigger Milky Way means that it could be crashing violently into the neighboring Andromeda galaxy sooner than predicted — though still billions of years from now.
Reid and his colleagues used a large system of 10 radio telescope antennas to measure the brightest newborn stars in the galaxy at different times in Earth's orbit around the sun. They made a map of those stars, not just in the locations where they were first seen, but in the third dimension of time — something Reid said hasn't been done before.
With that, Reid was able to determine the speed at which the spiral-shaped Milky Way is spinning around its center. That speed — about 568,000 miles per hour — is faster than the 492,000 mph that scientists had been using for decades. That's about a 15 percent jump in spiral speed. The old number was based on less accurate measurements and this is based on actual observations, Reid said.
Once the speed of the galaxy's spin was determined, complex formulas that end up cubing the speed determined the mass of all the dark matter in the Milky Way. And the dark matter — the stuff we can't see — is by far the heaviest stuff in the universe. So that means the Milky Way is about one-and-a-half times the mass had astronomers previously calculated.
The paper makes sense, but isn't the final word on the size of the Milky Way, said Mark Morris, an astrophysicist at the University of California Los Angeles, who wasn't part of the study.
Being bigger means the gravity between the Milky Way and Andromeda is stronger.
So the long-forecast collision between the neighboring galaxies is likely to happen sooner and less likely to be a glancing blow, Reid said.
But don't worry. That's at least 2 to 3 billion years away, he said.
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On the Net:
The Harvard-Smithsonian Center for Astrophysics: http://www.cfa.harvard.edu/