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Sunspot Decrease May Affect Climate Change

8/26/2013 10:33:52 AM

Climate scientists say the sun may be entering a "grand solar minimum" of no sunspot activity, leading to studies on how that could affect global warming.

Solar physicists in the United States and Australia have concluded that a 50-year grand minimum in sunspot activity may reduce global average temperatures during the period by a few tenths of a degree Celsius. They think the warming trend would resume once solar activity returned to normal.

The flip of the sun's magnetic field in a few months will signal the peak of the current sunspot cycle, which has produced the fewest sunspots in at least 100 years, and perhaps the last 200 years.

Sunspots in ultraviolet. Photo by NASA Goddard Photo and Video

The grand solar minimum would be comparable to a 70-year period from the early 17th century into the early 18th century, when the sun produced no sunspots at all. This period, known as the Maunder Minimum, coincided with the Little Ice Age, when the climate in the Northern Hemisphere cooled significantly.

"What if we went into another Maunder Minimum? Would that actually stop global warming"? asked Gerald Meehl, a researcher at the National Center for Atmospheric Research in Boulder, Colo., and a lead researcher in the study.

"The short answer is no," he said. "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." The warming trend would resume in spite of the disruption.

Sunspots' magnetic fields have declined fairly steadily over 13 years.

"We still see a decrease in the sunspot magnetic fields," said Matt Penn, a researcher with the National Solar Observatory in Tucson, Ariz., and part of the study. "The results are consistent with what we presented in 2011. It seems the trend is continuing along that line."

Using a model that assumed a 50-year sunspot hiatus from 2020 to 2070, the team found that between 2026 and 2035, global average temperatures could increase 0.64 degrees Celsius assuming sunspots went into an extended hibernation, compared with 0.80 degrees Celsius with normal solar activity (Pete Spotts, Christian Science Monitor, Aug. 21).

Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500.

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