It’s happened before: In 1859, sunspots erupted, causing sparks in telegraph offices that set paper on fire. Today, 150 years later, we are much MORE "wired," and sun flares are much more dangerous.
Satellites would be disabled. GPS and radio signals would be scrambled. Electricity grids could burn out, plunging the areas where the flares hit into darkness. Depending on the amount of damage, these outages could last intermittently for years.
In the March 19th edition of the New York Times Kenneth Chang quotes space weather researcher William Murtagh as saying, "There’s always the chance of a big storm, and the potential consequences of a big storm has everyone on the edge of their seats."
Chang quotes NASA’s Antti Pulkkinen as saying, "There’s a sense in the field that we don’t have all the answers."
But they DO have prediction: He quotes physicist Douglas Biesecker as saying, "I believe I can say with confidence there will be a second peak in 2013."
He quotes electrical engineer John Kappenman as saying, "In a sense, we’re playing Russian roulette with the Sun."