The sun is currently in a period of relatively high activity, expected to peak in 2013, and solar storm warnings will likely be more frequent in the coming year. If energy from solar storms comes into contact with Earth's magnetic field, it can increase radiation levels and disturb the ionosphere. These effects have the ability to disrupt satellite operations, radio transmissions and GPS and cellular communications, as well as damage electrical equipment on the ground. For example, electromagnetic energy from a solar storm in 1989 caused widespread power outages throughout Quebec. Despite the increasing frequency of bursts of electromagnetic energy from the sun, the possibility of a direct hit by a truly debilitating storm is still small, and the possibility of any other kind of disruptive electromagnetic pulse is even smaller. Satellites are able to withstand most solar storms, although some minor problems with computer subsystems are possible. An extremely severe electromagnetic storm, sometimes referred to as a 100-year storm, would have the ability to disrupt the electrical grid on the ground. There is some debate within the United States about whether the cost of completely hardening the electrical grid against such a storm is justified. An EMP Commission report released in 2008 concluded that the United States' electrical grid was vulnerable to electromagnetic energy, and the U.S. Department of Defense has estimated that retrofitting all military electrical equipment could cost as much as 10 percent of the initial cost. However, the likelihood of a solar storm being both strong enough and correctly positioned to create major disruptions is very small. Storms this severe only appear a few times during the sun's 11-year cycle. Still, smaller communications disruptions are possible, which could affect equipment used to direct strategic military activity, among other things.
