By Ron Cowen
Already sluggish, the sun may be slipping into several decades of hibernation that could exert a cooling effect on Earth’s climate, several new studies suggest.
During the last extended period of solar dormancy, from 1645 to 1715, Europe plunged into some of the coldest winters on record. But Earth’s atmosphere, which now contains an abundance of greenhouse gases, differs in composition compared with three centuries ago, and solar physicists say they’re unsure how a long solar hiatus would affect the planet’s 21st century climate.
It’s also possible that the beginning of the next 11-year solar cycle — which is marked by the emergence of dark blemishes called sunspots at high solar latitudes — may simply be delayed by a few years, rather than shut down for decades.
The scientists base their findings on multiple observations of the sun’s outer atmosphere, visible surface and the movement of magnetic fields inside the sun. The sun’s 11-year cycle is governed by flows of hot gas, or plasma, in the sun that transport parcels of the solar magnetic field.
Three teams presented their results June 14 during a press briefing at a meeting in Las Cruces, N.M., of the American Astronomical Society’s Solar Physics division.