Power-grid expert Kappenman warns that, under the right conditions, a CME could have planetary scale consequences that would take more than a couple of days to recover from, in part because damaged transformers would be difficult to replace quickly.
"It's hard to manufacture these 200-ton devices," he says. "In the best of times, they take a year to a year and a half to make. There was nearly a three-year backlog a few years ago."
Better space weather forecasts
New understanding of the physics of reconnection helps to explain why today's forecasts of Earth-bound CMEs are better than in the past, when "forecasters had to rely on estimates and 'rules of thumb' in developing forecasts," Viereck says.
Until a few years ago, the commonly held scientific view was that two kinds of solar events affect us—short-duration events caused by solar flares and long-duration events from CMEs. Scientists incorrectly used different mechanisms to explain how the two occurred. "It appears that there is only one acceleration mechanism," says Szabo, who notes that the scale of the magnetic reconnection produced is the only difference.
Although a geomagnetic storm forecast today is more accurate than in the past, it can only give an accurate warning up to a few hours, at most. To improve those lead times and also give more advance notice of the damage potential of an incoming CME, researchers say, they need more complete data about how the storms are produced on the sun and how they change over time. With such insights, they might be able to model more precisely how CMEs will behave when they reach Earth.
This modeling would be aided by observations that somehow capture the direction of the magnetic field within the CME as it leaves the sun and by "a better understanding of how the magnetic field will change and evolve as the CME makes its multiday transit from the sun to Earth," Viereck says.
But observations of CMEs on and near the sun—whose surface temperature is about 5,500 degrees Celsius—are extremely difficult to accomplish. Because intense heat disables electronics, it is very difficult to station a data-gathering spacecraft close to the sun. Although NASA's MESSENGER spacecraft currently orbits Mercury, the solar system's innermost planet, "even at the orbit of Mercury, which is 60 solar radii, it is probably not adequate," Gombosi says. "We need to go to three to five solar radii."
Other obstacles confront space weather forecasters as well. Even though satellites give very reliable information of when a CME started out from the sun, no one knows how to predict the north-south component of a geomagnetic storm, Gombosi says, and there are no tools able to measure that. Viereck says modelers also need a more detailed picture of the exact conditions in Earth's magnetosphere at the moment a CME hits.
Don't expect better forecasts as the sun nears solar maximum next year. "We are still at least a decade away from developing a detailed enough understanding that can be converted in any sort of operational forecasting," Szabo notes.