"What if we went into another Maunder Minimum? Would that actually stop global warming"? asks Gerald Meehl, a researcher at the National Center for Atmospheric Research in Boulder, Colo., who led the team that conducted the study. "The short answer is: No. It slows it down for a while. But the minute the sunspots come back and the solar output goes back up, the temperature pops back up" close to where it would have been if the sun spots hadn't taken a powder, and the warming trend resumes.
The notion that the sun could be heading for a grand minimum hit the headlines two years ago, when three research teams using independent measures suggested that the next sunspot cycle's activity could be substantially lower than the current cycle's.
One sign: A fairly steady decline in the strength of the spots' magnetic fields over a 13-year-period. If the trend is to continue, scientists said, they anticipated a spotless sun by around 2022.
"We still see a decrease in the sunspot magnetic fields," says Matt Penn, a researcher with the National Solar Observatory in Tucson, who took part in the study. "The results are consistent with what we presented in 2011. It seems the trend is continuing along that line" leading to a cut-off in sunspot production.
More recently, research has suggested that the strength of the suns' magnetic field during one solar minimum – when the field is at its strongest – is a harbinger of the size of the peak for the next sunspot maximum. Over the past three sunspot cycles, those fields at solar minimum have been getting weaker, with the weakest appearing during the most recent minimum.