A massive solar storm could knock out power along the I-95 corridor between Washington, D.C. and New York City for months – if not longer – according to a new report by British insurance market Lloyd's.
Such solar storms, which release billions of charged particles from the sun, are rare but not unprecedented. During the past several years there have been 16 so-called X-class flares emitted by the sun, some of which have knocked GPS and military satellites offline. But a storm large enough to impact power grids on Earth is rare.
The "Carrington Event," which occurred 154 years ago in September 1859, is the largest recorded solar storm to ever strike Earth. It temporarily put telegraph wires out of commission and even set fire to some of them. Storms of that size are expected to occur approximately once every 150 years. More common are storms the size of one that knocked power offline for several minutes in Quebec in 1989. These types are expected to occur about once every 50 years.
A storm the size of the Carrington Event, Lloyd's estimates, could knock power offline for as many as 40 million people for up to two years.
"The duration of outages will depend largely on the availability of spare replacement transformers," according to the report. "If new transformers need to be ordered, the lead-time is likely to be a minimum of five months. The total economic cost for such a scenario is estimated at $.6-$2.6 trillion."
The I-95 corridor is considered to be most at risk because of its population density, aging power grids and its magnetic latitude (particles associated with a solar flare are more likely to hit the area than they are to hit further north or south).
According to a study published in March 2012, there is about a 1-in-8 chance of an "extreme" solar flare that would cause billions of dollars in damage occurring during the next decade. . There are expected to be more flares during the next year or so as the sun reaches the height of its 11 year "solar cycle," when storms are more frequent and severe.
Neil Smith, who worked on the Lloyd's report, says the likelihood of a solar storm damaging power grids is terrifying insurance companies, but should be worrying everyone.
"The risk is beyond insurance, it's a societal and systemic issue," he says. "As a member of society, we're terrified of the prospect that this might happen."
After the 1989 storm that hit Quebec, the Canadian government invested $1.2 billion in "hardening" the power grid in the province, which should make it less vulnerable to a solar storm.
Few areas of the United States have similar hardening, and with the government cutting costs, it seems unlikely to be a priority anytime soon. In 2010, H.R. 5026, the GRID Act, a bill designed to protect electric grids nationwide, passed the House of Representatives, but was never picked up by the Senate.
The bill would have required the North American Electric Reliability Corporation, a nonprofit corporation established after the Northeast blackout of 2003 that now oversees the continent's power grid, to create standards "adequate to protect the bulk-power system from any reasonably foreseeable geomagnetic storm event." The bill would have also required power companies to have backup transformers available in case of a failure.
According to Smith, a minor solar storm might not be enough to get politicians to act.
"We've seen mild ones and it's not been significant to have anything happen," he says. "More needs to be done to directly address the issue and look at building resilience into the grid."