Solar superstorms are estimated to occur once every 100-200 years, with the last one hitting Earth in 1859.
Scientists says it is inevitable a major solar flare will hit earth sometime in the near future – but it is impossible to predict more than about 30 minutes before it actually happens.
A report into extreme space weather by a group of experts at the Royal Academy of Engineering in London points out that modern society’s reliance on electronics makes us far more vulnerable than in the past.
In the past half century, there have been a number of “near misses” when an explosive “coronal mass ejection” from the Sun has been flung into space, narrowly missing Earth.
In 1989 a relatively minor solar storm knocked out several key electrical transformers in the Canadian national grid, causing major power blackouts. Similar solar storms significantly increased atmospheric radiation levels in 1956, 1972, 1989 and 2003.
Chair of the REA’s working group on solar storms, Professor Paul Cannon, says the British government should set up a space weather board to oversee measures aimed at minimising the impact of solar storms.
If the 1859 solar superstorm occurred today national electricity grids would be put under severe strain, he says.
The performance of satellites, GPS navigation, aviation and possibly the mobile phone network, particularly the new 4G network (which relies on GPS satellites for timing information) would all be degraded.
Solar flares regularly disrupt Earth’s magnetosphere, the magnetic envelope surrounding Earth, but that envelope largely protects the surface of the planet itself from space weather – with one exception.
Changes in magnetic fields cause electric currents and vice versa. Energy impacting on the planet’s magnetosphere causes electric currents to form on the ground. Called geomagnetically-induced currents or GICs, such currents extend some 60 miles underground, electrifying any conductors – power grid lines, or oil pipes along the way.
A big enough electrical surge from a GIC can knock out the transformers in a power grid. Electric companies can protect the grid from such surges by shutting down or lowering the power load on the system, but this costs money so they also do not wish to reduce power output unless it is really necessary. New analysis by scientists at NASA’s Goddard Space Flight Center in Greenbelt published online in Space Weather on February 23, 2012, provides some basic guidelines to help model some of the largest, most damaging GICs.
“Our main goal here is to provide the initial piece that power engineers need to calculate the risk that such a large 100-year GIC could pose,” says Antti Pulkkinen – a solar scientist at Goddard and at Catholic University in Washington, D.C.
Ground conductivity, geographical placement, the frequency of the electrical currents and the area to be considered are the four factors required for risk analysis. Each modelling scenario is applicable in any direction for a few hundred, up to a thousand, kilometres.
Understanding how events on the Sun could affect something as small as a single transformer on Earth will require sketching out the physics with minute attention to detail, and requires a multi-disciplinary approach.
“We need a good group of solar and geospace experts, power engineers, and risk analysis experts, all working together in a coherent way,” says Antti.
Lev Pustil’nik and Gregory Yom Din at Tel Aviv University in Israel say the effects of space weather could also influence terrestrial weather so severely it can have dramatic effects on agriculture causing, causing crop failures, death and starvation.
They tested their theory by tracking sunspot records and food prices in regions where agriculture is vulnerable to variations in space weather if it meets three conditions.
Pustil’nik and Yom Din say medieval England is vulnerable because it is in the north Atlantic, dependent on wheat which is vulnerable to weather changes and also isolated from mainland Europe.
Detailed records of English food prices survive dating back to 1259. Accurate space weather records as measured by the number of sunspots date back to the time of Galileo and can be extrapolated further back using other dating methods.
That’s allowed Pustil’nik and Yom Din to look for correlations.
Wheat prices are significantly correlated with space weather events such as solar maxima and minima, particularly during the so-called Maunder minimum between 1580 and 1700 when solar activity was low.
All the nine cycles of solar activity during this period are characterized by systematically excessive wheat prices in the years of solar activity minimum, as compared with the prices during the next maximum, they say, adding that the level of significance is in excess of 99 per cent.
The result has important implications for the future. The global food market means that few places are genuinely isolated from the rest of the world, but Pustil’nik and Yom Din say global warming is pushing more regions closer to the type of critical vulnerability that makes space weather a worry.