Northern lights slash a surprising amount of winter energy bills. Here’s why.

Over many Finnish winters, scientist Timo Asikainen made an observation in his grandma’s old house common to many: When it was cold, money spent on electricity went up. It turns out, though, those cold spells and his energy bills were influenced by an unexpected source in plain sight, the aurora borealis.

More than 90 million miles away from Earth, the sun is constantly spewing out charged particles in our direction, sometimes triggering the ultimate celestial light show - an aurora, also known as the northern and southern lights. Now, Finnish scientists have determined that such strong geomagnetic activity around the country can cause warmer weather and lower electricity consumption over a winter season.

In a new study, Asikainen and his graduate student Veera Juntunen found that auroral activity altered electricity consumption by as much as 14 percent in Finland. Very high geomagnetic activity led to a reduction of as much as 600 gigawatt hours of consumption compared to when activity was average - about the monthly heating energy of about 330,000 Finnish households, Asikainen said.

“Never it has been really thought that this kind of space weather effect could influence electricity consumption,” said Juntunen, the study co-author and doctoral student at University of Oulu.

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How auroras affect winter temperatures

Over the past decade, Asikainen, a researcher in the Space Climate group at the University of Oulu, and his colleagues have explored how space weather can affect our planet’s weather and climate. Space weather describes the space environment between the sun and Earth, which is influenced by the sun’s electrically charged particles and can impact our technologies.

But the new study is the first to show how this space weather can effect electricity consumption on Earth.

While the sun can influence Earth’s temperatures with its ultraviolet radiation, its stream of energetic particles can also affect other aspects of our weather system - including if cold blasts of air will escape from the Arctic.

Nobody knows all the nitty-gritty details yet, but Asikainen said the journey begins where our upper atmosphere meets space. Charged particles from the sun aimed at Earth can temporarily disturb the protective magnetic bubble surrounding our planet called the magnetosphere. Solar particles can travel along Earth’s magnetic field lines into our upper atmosphere, where it excites molecules and releases photons of light that we see as an aurora.

The precipitating particles that cause auroras, he said, leave their energy high in the atmosphere and lead to the creation of molecules like nitric oxides. These molecules last a very long time in the dark polar atmosphere during winter and can move very slowly - over a span of weeks to a month - to our stratosphere where the ozone layer is. Here, the molecules can destroy ozone, which helps regulate our planet’s temperature.

Ozone absorbs ultraviolet radiation from the sun and infrared radiation coming up from lower in the atmosphere. Changes in ozone, Asikainen said, influence the temperature of the polar stratosphere. In the polar stratosphere, ozone loss is associated with cooling of the stratosphere - strengthening swirling cold winds known as the polar vortex.

Residents in northern Europe and the United States know the polar vortex all too well, and there is another in the southern hemisphere. The stratosphere’s polar vortex is a whirlpool of cold air blowing around the polar region during winter. A weaker polar vortex undulates and can unleash Arctic blasts to lower latitudes. A strong, tightly wound polar vortex keeps the Arctic air at the pole.

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Impacts on electricity consumption

In the study, the team analyzed decades of geomagnetic activity to discern any connections between auroras, winter temperatures and electricity consumption.

They found that when geomagnetic activity was lower than normal, the polar vortex became weaker and caused extreme and harsh winter weather in Finland around a month later. Conversely, high geomagnetic activity strengthened the polar vortex to keep it more tightly wound, inducing warmer winter temperatures about a month later as well. The effects were only seen in winters when stratospheric winds traveling over the equator blew in a certain direction.

Using electricity consumption data from the 1990s to today, they found the geomagnetic activity highly correlated with energy consumption. The close connection was impressive to the authors and other experts.

“I was very surprised to see how good the correlation of power consumption with breaking of the polar vortex was,” space scientist Tuija Pulkkinen, who was not involved in the research, said in an email. Most people live and consume energy in southern Finland, so she noted the effects of the polar vortex were felt all the way down to the mid-latitudes.

Traditionally, she said, it was assumed that our rapidly varying space weather has no influence on the atmosphere on time scales like seasonal weather. But the new study shows that drivers from space, including auroral currents and energetic particle precipitation, are important factors to consider when understanding Earth’s weather and climate.

“This would indicate that we could use long-term space weather (or solar activity) predictions to anticipate electric power consumption needs, which would be immensely helpful for the power industry,” said Pulkkinen, who is a space physics professor at the University of Michigan.

The authors agree the findings could help improve weather models and forecasts further in advance, as current weather forecasts are only somewhat reliable weeks out. Six months ahead of time, Asikainen and his team correctly predicted the breakup of the polar vortex this winter season, using statistical models to gauge geomagnetic activity and determine the probability of changes in the stratosphere.

“I hope, in the future, there would be a model that could use these results to predict electricity consumption in winter,” Juntunen said. “It would benefit also people using electricity for heating.”