Jan 11, 2017

As Earth Warms Up, The Sun Is Remarkably Quiet

by
Bob Henson
,
Category 6
Solar material bursts from the sun in this close-up from a video captured on July 9-10, 2016, by NASA’s Solar Dynamics Observatory, or SDO. The imagery is colorized here in red for easy viewing. Image: NASA/SDO/GSFC/Joy Ng
Solar material bursts from the sun in this close-up from a video captured on July 9-10, 2016, by NASA’s Solar Dynamics Observatory, or SDO. The imagery is colorized here in red for easy viewing. Image: NASA/SDO/GSFC/Joy Ng

If you’re looking toward the sun to help explain this decade’s record global heat on Earth, look again. Solar activity has been below average for more than a decade, and the pattern appears set to continue, according to several top solar researchers. Solar Cycle 24, the one that will wrap up in the late 2010s, was the least active in more than a century. We now have outlooks for Cycle 25, the one that will prevail during the 2020s, and they’re calling for a cycle only about as strong as--and perhaps even less active than--Cycle 24.

Weak solar cycles tend to produce fewer solar storms, those dramatic bursts of magnetized material from the sun that generate spectacular auroral displays and play havoc with satellite-based systems and power grids on Earth. However, solar storms that do emerge during weak cycles can be among the most potent, notes Scott McIntosh (National Center for Atmospheric Research). Just as a catastrophic hurricane can occur in an otherwise quiet season, a quiet solar cycle can still cause devastating space weather, McIntosh told me. “If you look at the record of extreme events from the sun, they most often occur in weak cycles, and they almost always occur in the deep, descending part of the cycle,” he said.