WASHINGTON Sunspot cycles -- those 11-year patterns when dark dots appear on the solar surface -- may be delayed or even go into "hibernation" for a while, a U.S. scientist said on Wednesday.
But contrary to some media reports, this does not mean a new Ice Age is coming, Frank Hill of the National Solar Observatory said in a telephone interview.
"We have not predicted a Little Ice Age," Hill said, speaking from an astronomical meeting in New Mexico. "We have predicted something going on with the Sun."
The appearance of sunspots helps predict solar storms that can interfere with satellite communications and power grids.
Hill and other scientists cited a missing jet stream, fading spots and slower activity near the Sun's poles as signs that our nearest star is heading into a rest period.
"This is highly unusual and unexpected," he said in a statement released on Tuesday. "But the fact that three completely different views of the Sun point in the same direction is a powerful indicator that the sunspot cycle may be going into hibernation."
That hibernation would not begin now, as the current sunspot cycle, the 24th, has recently passed its minimum. Hill and his colleagues pondered a slowdown in sunspot activity in the 25th cycle, expected sometime around 2019.
They also wondered whether this possible slowdown, or even a long cessation of sunspot activity, indicates an upcoming return of the Maunder Minimum, a 70-year sunspot drought seen from 1645-1715.
They had no answer as to whether this might be true, and said nothing about whether the Maunder Minimum -- named for astronomer E.H. Maunder -- was related to a long cold period in Europe and other parts of the Northern Hemisphere known as the Little Ice Age.
How strong a connection is there between a Little Ice Age and a Maunder Minimum? "Not as strong a connection as people would like to believe," Hill said by phone.
"The Little Ice Age actually lasted for hundreds of years, of which the Maunder Minimum was only a small segment ... My personal opinion is that there is only an anecdotal connection without a whole lot of scientific background behind it."
Several websites and blogs have argued that the potentially cooling influence of a lower level of sunspot activity could cancel out the warming caused by human activities that generate climate-warming greenhouse gases. Hill disputed this.
"In my opinion, it is a huge leap ... to an abrupt global cooling, since the connections between solar activity and climate are still very poorly understood," he said in an e-mail.
(Editing by Michele Gershberg and Cynthia Osterman)