Post by Mech on Feb 9, 2007 21:13:53 GMT -5
Huge solar storms could zap Earth, scientists warn
Next sunspot cycle may disrupt power, communications
Keay Davidson, Chronicle Science Writer
Tuesday, March 7, 2006
SFGate
www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2006/03/07/MNGAFHJJL91.DTL
An 11-year epoch of increasingly severe solar storms that could fry power grids, disrupt cell-phone calls, knock satellites back to Earth, endanger astronauts in space, and force commercial airliners to change their routes to protect their radio communications and to avoid deadly solar radiation could begin as soon as this fall, scientists announced Monday.
When the solar cycle reaches its peak in 2012, it will hurl at Earth mammoth solar storms with intense radiation and clouds of high-speed subatomic particles millions of miles across, the scientists said.
A storm of that magnitude could short-circuit a world increasingly dependent on giant utilities and satellite communications networks. Such a storm in 1989 caused power grids to collapse, causing a five-hour blackout in Quebec.
Monday's forecast was announced by scientists from agencies including NASA and the National Science Foundation, based on research centered at the National Center for Atmospheric Research in Colorado.
There is disagreement on exactly when the new cycle will begin -- one key researcher predicted the cycle will start in late 2007 or early 2008, and another said it could begin either late this year or in early 2007. But they did agree that the most severe storms won't begin popping on the solar surface for several years, but when they do, they'll be huge.
The solar storms in the past have knocked out huge power grids and screwed up global electronics and data communications, but "the next sunspot cycle will be 30 to 50 percent stronger than the last one," the scientists said in Monday's statement.
Reaching that 50 percent threshold would make it the most intense solar cycle since the late 1950s and the second worst since the early 1700s, Peter Gilman, one of the researchers, said in a phone interview.
Astronomers will monitor the sun daily in the coming months to see how it's doing. Early warning signs will be the formation of large groups of sunspots, which are clusters of solar magnetic fields that are cooler than the rest of the sun.
"I look (at telescopic images of the sun) almost every day, thinking, 'It could be today,' " said David Hathaway, solar physics team leader at NASA's Marshall Space Flight Center in Alabama. He compared it to "waiting for the first sparrow of spring."
Solar storms can happen at any time during an 11-year solar cycle. However, by far the worst storms are likeliest to occur during the period known as "solar maximum," or solar max for short. The last solar max was in 2001.
The scientists are confident of their forecast for 2012 because they've successfully used a new computer model to "forecast" the past. That is, they used records of old solar cycles to figure out how the sun should have behaved during eight past cycles, as far back as the early 20th century. They "forecast" the sun's past behavior -- "hindcasting," they call it -- "with more than 98 percent accuracy" the scientists said.
"I'm really excited about this (discovery)," said NASA's Hathaway. "It's based on sound physical principles, and it finally answers the 150-year-old question: What causes the sunspot cycle?"
The cycle's victims could include space satellites. The coming storms could heat the upper levels of Earth's atmosphere, causing it to expand and exert drag on low-flying satellites -- perhaps enough drag to tug some of them back to Earth. Solar storms have been blamed for the U.S. Skylab space station's premature fall back to Earth in 1979.
Air travelers could be affected, too. Since the end of the Cold War, to avoid headwinds, airlines have increasingly flown subpolar routes to get between the United States and other Northern Hemisphere continents quickly and cheaply. But during solar storms, they must avoid the poles and fly more southerly routes.
They do so partly in order to avoid having their radio communications disrupted over dangerous polar terrain and partly to avoid exposing passengers -- especially pregnant women -- to the increased radiation, said solar-storm expert Joseph Kunches, chief of the forecast and analysis branch of the U.S. National Oceanic and Atmospheric Administration's Space Environment Center in Boulder, Colo.
The northern and northeastern portions of North America are historically more vulnerable to system outages caused by solar storms than California and most of the Western states, said Gregg Fishman, spokesman for the California Independent System Operator. That's possibly because among other things, he said, there's a higher iron and mineral content in the North and Northeast that conducts the ground current more easily and allows for more of an impact during solar storms.
E-mail Keay Davidson at kdavidson@sfchronicle.com.
