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Sun Oddly Quiet -- Hints at Next "Little Ice Age"?

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Bianca
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« on: May 06, 2009, 12:39:53 pm »








                                     Sun Oddly Quiet -- Hints at Next "Little Ice Age"?






Anne Minard
for National Geographic News
May 4, 2009

A prolonged lull in solar activity has astrophysicists glued to their telescopes waiting to see what the sun will do next—and how Earth's climate might respond.

The sun is the least active it's been in decades and the dimmest in a hundred years. The lull is causing some scientists to recall the Little Ice Age, an unusual cold spell in Europe and North America, which lasted from about 1300 to 1850.

The coldest period of the Little Ice Age, between 1645 and 1715, has been linked to a deep dip in
solar storms known as the Maunder Minimum.

During that time, access to Greenland was largely cut off by ice, and canals in Holland routinely froze solid. Glaciers in the Alps engulfed whole villages, and sea ice increased so much that no open water flowed around Iceland in the year 1695.

But researchers are on guard against their concerns about a new cold snap being misinterpreted.

"[Global warming] skeptics tend to leap forward," said Mike Lockwood, a solar terrestrial physicist at the University of Southampton in the U.K. (Get the facts about global warming.)

He and other researchers are therefore engaged in what they call "preemptive denial" of a solar minimum leading to global cooling.

Even if the current solar lull is the beginning of a prolonged quiet, the scientists say, the star's effects on climate will pale in contrast with the influence of human-made greenhouse gases such as carbon dioxide (CO2).

"I think you have to bear in mind that the CO2 is a good 50 to 60 percent higher than normal, whereas the decline in solar output is a few hundredths of one percent down," Lockwood said. "I think that helps keep it in perspective."
« Last Edit: May 06, 2009, 12:43:13 pm by Bianca » Report Spam   Logged

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Bianca
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« Reply #1 on: May 06, 2009, 12:42:47 pm »



             






In July 2000 the sun was at a peak in activity, as seen by the speckling of sunspots spied by NASA's Solar and Heliospheric Observatory (SOHO) spacecraft. But the sun was a blank disk in March 2009, when it was the quietest it has been since the 1950s.

The current sunspot deficit has caused some scientists to recall the Little Ice Age of the early 1600s and late 1700s, a prolonged, localized cold spell linked to a decline in solar activity.



Images courtesy

SOHO, the EIT Consortium,
and the

MDI Team
« Last Edit: May 06, 2009, 12:56:15 pm by Bianca » Report Spam   Logged

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Bianca
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« Reply #2 on: May 06, 2009, 12:45:38 pm »






Local Cooling



For hundreds of years scientists have used the number of observable sunspots to trace the sun's roughly 11-year cycles of activity.


Sunspots, which can be visible without a telescope, are dark regions that indicate intense magnetic activity on the sun's surface. Such solar storms send bursts of charged particles hurtling toward Earth that can spark auroras, disrupt satellites, and even knock out electrical grids.

In the current cycle, 2008 was supposed to have been the low point, and this year the sunspot numbers should have begun to climb.

But of the first 90 days of 2009, 78 have been sunspot free. Researchers also say the sun is the dimmest it's been in a hundred years.


The Maunder Minimum corresponded to a profound lull in sunspots—astronomers at the time recorded just 50 in a 30-year period.

http://en.wikipedia.org/wiki/Maunder_minimum


If the sun again sinks into a similar depression, at least one preliminary model has suggested that cool spots could crop up in regions of Europe, the United States, and Siberia.

During the previous event, though, many parts of the world were not affected at all, said Jeffrey Hall, an astronomer and associate director at Lowell Observatory in Flagstaff, Arizona.

"Even a grand minimum like that was not having a global effect," he said.
« Last Edit: May 06, 2009, 01:00:47 pm by Bianca » Report Spam   Logged

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Bianca
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« Reply #3 on: May 06, 2009, 12:54:18 pm »









Wild Cards and Uncertainties



Changes in the sun's activity can affect Earth in other ways, too.

For example, ultraviolet (UV) light from the sun is not bottoming out the same way it did during the past few visual minima.

"The visible light doesn't vary that much, but UV varies 20 percent, [and] x-rays can vary by a factor of ten," Hall said. "What we don't understand so well is the impact of that differing spectral irradiance."

Solar UV light, for example, affects mostly the upper layers of Earth's atmosphere, where the effects are not as noticeable to humans. But some researchers suspect those effects could trickle down into the lower layers, where weather happens.

In general, recent research has been building a case that the sun has a slightly bigger influence on Earth's climate than most theories have predicted.

Atmospheric wild cards, such as UV radiation, could be part of the explanation, said the University of Southampton's Lockwood.

In the meantime, he and other experts caution against relying on future solar lulls to help mitigate global warming.

"There are many uncertainties," said Jose Abreu, a doctoral candidate at the Swiss government's research institute Eawag.

"We don't know the sensitivity of the climate to changes in solar intensity. In my opinion, I wouldn't play with things I don't know."
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Volitzer
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« Reply #4 on: May 06, 2009, 01:06:48 pm »

The question is will Al Gore shut up about Global Warming ??

Probably not.   Roll Eyes
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Bianca
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« Reply #5 on: May 06, 2009, 05:36:44 pm »





Of course not, Vol.


There is too much money to be made......
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« Reply #6 on: May 06, 2009, 05:37:08 pm »








Coils of electrified gas known as coronal loops writhe above sunpots—cooler, dark patches (inset) that appear on the sun's surface in periodic cycles.

The waxing and waning sunspots alter the amount of energy Earth gets from its star, but not enough to impact global climate change, a new study suggests.



Image courtesy

NASA
« Last Edit: May 06, 2009, 05:38:27 pm by Bianca » Report Spam   Logged

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« Reply #7 on: May 06, 2009, 05:40:53 pm »









                                    Don't Blame Sun for Global Warming, Study Says





 
Brian Handwerk
for National Geographic News
September 13, 2006

Sunspots alter the amount of energy Earth gets from the sun, but not enough to impact global climate change, a new study suggests.

The sun's role in global warming has long been a matter of debate and is likely to remain a contentious topic.
 
Solar astronomer Peter Foukal of Heliophysics, Inc., in Nahant, Massachusetts, points out that scientists have pondered the link between the sun and Earth's climate since the time of Galileo, the famous 17th-century astronomer.

"There has been an intuitive perception that the sun's variable degree of brightness—the coming and going of sunspots for instance—might have an impact on climate," Foukal said.

Foukal is lead author of a review paper on sunspot intensity appearing in tomorrow's issue of the journal Nature.

He says that most climate models—including ones used by the Intergovernmental Panel on Climate Change—already incorporate the effects of the sun's waxing and waning power on Earth's weather (related images: our stormy star).

But, Foukal said, "this paper says that that particular mechanism [sunspots], which is most intuitive, is probably not having an impact."
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Bianca
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« Reply #8 on: May 06, 2009, 05:42:18 pm »








Sunspot Impact Simply Too Small



Sunspots are magnetic disturbances that appear as cooler, dark patches on the sun's surface. The number of spots cycles over time, reaching a peak every 11 years.

The spots' impact on the sun's total energy output is easy to see.

"As it turns out, most of the sun's power output is in the visible range—what we see as brightness," said Henk Spruit, study co-author from the Max Planck Institute for Astrophysics in Garching, Germany.

"The sun's brightness varies only because of the blemishes that are also visible directly on pictures: the dark patches called sunspots and the minute bright points called faculae. In terms of brightness changes, in large part, what you see is what you get."

The sun's energy output varies slightly as sunspots wax and wane on the star's surface.

But sunspot-driven changes to the sun's power are simply too small to account for the climatic changes observed in historical data from the 17th century to the present, research suggests.

The difference in brightness between the high point of a sunspot cycle and its low point is less than 0.1 percent of the sun's total output.

"If you run that back in time to the 17th century using sunspot records, you'll find that this amplitude variance is negligible for climate," Foukal said.

The researchers obtained accurate daily sunspot measurements dating as far back as 1874 from institutions such as the Mount Wilson Observatory near Pasadena, California, and the Royal Observatory in Greenwich, England.

Older records exist all the way back to when the telescope was invented in the 17th century, though the data become increasingly patchy with age (see a related graphic of how the Hubble Space Telescope works).

The team also derived the sun's historic strength by looking at the presence or absence of isotopes, such as beryllium 10, in ice samples from Greenland and Antarctic that reflect the past contents of Earth's atmosphere.

Such isotopes are formed when cosmic radiation penetrates the atmosphere.

In periods of high activity, a brighter sun emits more magnetic and plasmatic particles that shield Earth from the galaxy's rays, resulting in fewer isotopes.

Measuring the historical record of such isotopes from ice yields useful, though debatable, estimates of the sun's past power on Earth.

"If you see that these isotopes were low for 50 or 100 years, it's a darn good bet that the sun was more active then," Foukal said.
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« Reply #9 on: May 06, 2009, 05:46:06 pm »









Sun Not Off the Hook for Warming



The authors and other experts are quick to point out that more complicated solar mechanisms could possibly be driving climate change in ways we don't yet understand.

Climate change carries such high stakes that even more unlikely possibilities may capture scientific attention.

"There are numerous studies that find a correlation [between solar variation and Earth climate]," said Sami Solanki of the Max Planck Institute for Solar System Research in Lindau, Germany.

"These authors have looked at the simplest mechanism, and they find that this mechanism does not produce the same level of change that has been observed," he continued.

"This could be suggesting that there are other mechanisms acting for the way that the sun influences climate."

Solar ultraviolet (UV) rays are one possibility, though that theory creates its own challenges.

"UV is only a small fraction of total solar output, so you'd need a strong amplification mechanism in the Earth's atmosphere," study co-author Spruit said.

Magnetized plasma flares known as solar wind could also impact Earth's climate. Solar wind influences galactic rays and may in turn affect atmospheric phenomena on Earth, such as cloud cover.

Such complex interactions are poorly understood but could be crucial to unlocking Earth's climatic puzzle.

"I think the main question," the Max Planck Institute's Solanki said, "is, How does the sun [in general] act on climate? What are the processes that are going on in the Earth's atmosphere?"
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