By Hannah Osborne
The sun has entered an unusually quiet period, with the number of sunspots appearing on the surface unusually low. This level of activity is so low, some scientists have suggested we may be entering a “deep” solar minimum, and potentially even a Grand Minimum—the last of which took place in the 17th century and coincided with a mini ice age.
The sun has an 11-year cycle where activity waxes and wanes. This is caused by the strengthening and weakening of its magnetic field. The point when activity is highest is known as the solar maximum, which is characterized by more sunspots appearing on the surface. The solar minimum is where activity falls, and far fewer sunspots appear. The last solar maximum peaked in 2014.
In April last year, scientists at the National Oceanic and Atmospheric Administration predicted the forthcoming solar minimum would be similar to the last cycle. In a statement, Lisa Upton, Ph.D., solar physicist with Space Systems Research Corp, said the next solar cycle would be much like the last, with a weak maximum and a “long, deep minimum.” However, she also said there was “no indication” we are approaching a solar minimum in line with the last Grand Minimum—known as the Maunder Minimum.
Mathew Owens, Professor of Space Physics at the University of Reading, U.K., told Newsweek that entering a solar minimum is not unusual, but the level of activity currently taking place is out of the ordinary. “The Sun has been ‘spotless’ for a large fraction of the last year, which is indeed quieter than is typical,” he said in an email. “It’s still a little early to say where it fits relative to other minima we’ve seen. If it does continue in this fashion, it may well rank up there with the longer minima on record. But at present it is not unprecedented; in fact, the very previous solar minimum [2009-2010] was longer.”
Solar minimums in the sun’s normal cycle have little to no effect on Earth’s temperature, with energy output from the Sun only dropping by around 0.1 percent.
“The Earth’s surface temperature during the Maunder Minimum was probably about 1 degree Celsius colder than the 19th century (before human-induced global warming kicked off) and that period is sometimes called The Little Ice Age. However it is difficult to ascribe all that cooling to the Sun because it just so happened that there were quite a few big volcanic eruptions during that period and they also have a cooling effect.”
Haigh said in terms of global temperatures, the solar minimum is little to worry about. If anything, it could help slightly mitigate current anthropogenic warming. This effect will dissipate when activity on the sun picks up again, however.
Owens said he expects the sun’s quiet period to come to an end in the near future: “Based on past solar cycles, I’d expect activity to pick up very soon, in the coming few months. But the Sun can always surprise us.”
This article appeared on the Newsweek website at https://www.newsweek.com/sun-deep-solar-minimum-unusually-quiet-1504795