Wildcard: Massive Solar Storm


On Sept. 1, 1859, astronomer Richard Carrington watched a massive solar flare erupt from the surface of the sun. The “Carrington event” sent a stream of charged particles toward Earth — producing the largest disturbances in Earth’s magnetic field ever recorded, lighting the night sky with beautiful auroras visible as far south as Cuba, and causing major telegraph outages.

The probability of an extreme solar-weather event as large as the Carrington event of 1859 occurring in the next decade has been estimated at about 12 percent.

The intensity of solar weather peaks on an 11-year cycle, with the next expected peak in 2012–2015. Measured elements of solar weather include solar flares, coronal mass ejections, solar wind, and solar energetic particles.

Solar flares emit streams of charged particles; when the particles reach Earth, they cause changes in the planet’s magnetic field and electrical environment that can, for instance, induce DC currents in power grids with the potential to disrupt and damage electrical systems.


  • Solar weather has the potential to disrupt the electric grid, communications, satellites, and GPS systems.
  • The probability of a solar megastorm is surprisingly high, forecast at 12% over the next decade.
  • Such a storm could cause widespread, prolonged loss of electric power, interrupting transport, communications, and the provision of basic necessities.


  • Electric power grid. Solar weather events can disrupt electrical transmission by inducing surge currents in transmission lines that cause transformers and power plant equipment to fail. The most frequently cited example is a 1989 event that disabled the entire power grid of Quebec and caused significant disturbances in the US as well.
  • Spacecraft. High-energy particles impinging on satellites can cause electronic components to generate spurious signals and instructions, leading to incorrect data, temporary malfunctions, or permanent damage.
  • Communications. Disruption to high-frequency radio communications impacts both land-to-land and land-to- satellite signaling. This effect is largest near auroras and the planet’s poles.


Planning for a major solar-weather event is a work in progress. Actions on several fronts are needed to achieve even a modest level of preparedness.

According to Mike Hapgood, head of the space environment group of the British research and technology agency RAL Space, writing in the journal Nature, “We need a much better understanding of the likelihood of space weather disruptions and their impacts, and we need to develop that knowledge quickly.”

  • Better prediction. Understanding of the physics of solar weather and the availability of better measurements are improving scientists’ ability to forecast solar storms. The US Space Weather Prediction Center currently can forecast the arrival of a strong geomagnetic storm 10 to 60 minutes in advance with roughly 50% accuracy. Unfortunately, such a warning provides little time for utilities, satellite operators, and others to respond.
  • Better organization, planning, and coordination. Government agencies need to be better prepared to lead preparation and response to a solar megastorm. A 2011 report prepared for the US Department of Homeland Security recommends, “Because present coordination between agencies dealing with space weather is far less than optimum, the entire effort should have someone in charge with authority to resolve inter-agency problems.”
  • Redundant systems. In some cases, it will be necessary to create or retain backup systems so that essential functionalities can be maintained in case of primary system failure. For example, as of 2008, FAA policy was to maintain legacy systems for air navigation as a backup to GPS-based systems.


  • Even if the estimate of a 12% chance of a “Carrington event” in the next decade is high by a factor of ten, the probability is still great enough to merit inclusion in business risk strategies.
  • Businesses should consider creating contingency plans for an extended failure of the electrical grid at key facilities. They should seek to understand primary, secondary, and tertiary impacts of such an event, as well as how operations for their customers and key partners would be impacted. Consumer- facing companies need to understand how daily life—and purchasing—would be altered by this kind of wildcard event.
  • Governments at all levels should consider creating contingency plans for an extended failure of the electrical grid that is local or regional in scope. The plans should address emergency provision of basic necessities to the general population, and also meet the needs of special populations including infants and children, the elderly, and those requiring ongoing medical care at all levels.