[PPRAANet] Sunspot Hibernation?

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 Scientists predict rare 'hibernation' of sunspots
For years, scientists have been predicting the Sun would move into
 solar maximum, a period of intense ?
 by Kerry Sheridan ? Tue Jun 14, 5:38 pm ET

 WASHINGTON (AFP) ?For years, scientists have been predicting the Sun would 
by
 around 2012 move into solar maximum, a period of intense flares and sunspot
 activity, but lately a curious calm has suggested quite the opposite.
 According to three studies released in the United States on Tuesday, 
experts
 believe the familiar sunspot cycle may be shutting down and heading toward 
a
 pattern of inactivity unseen since the 17th century.
 The signs include a missing jet stream, fading spots, and slower activity 
near
 the poles, said experts from the National Solar Observatory and Air Force
 Research Laboratory.
 "This is highly unusual and unexpected," said Frank Hill, associate 
director of
 the NSO's Solar Synoptic Network, as the findings of the three studies were
 presented at the annual meeting of the American Astronomical Society's 
Solar
 Physics Division in Las Cruces, New Mexico.
"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."
 Solar activity tends to rise and fall every 11 years or so. The solar 
maximum
 and solar minimum each mark about half the interval of the magnetic pole
 reversal on the Sun, which happens every 22 years.
 Hill said the current cycle, number 24, "may be the last normal one for 
some
 time and the next one, cycle 25, may not happen for some time.
 "This is important because the solar cycle causes space weather which 
affects
 modern technology and may contribute to climate change," he told reporters.
 Experts are now probing whether this period of inactivity could be a second
 Maunder Minimum, which was a 70-year period when hardly any sunspots were
 observed between 1645-1715, a period known as the "Little Ice Age."
 "If we are right, this could be the last solar maximum we'll see for a few
 decades. That would affect everything from space exploration to Earth's
 climate," said Hill.
 Solar flares and eruptions can send highly charged particles hurtling 
toward
 Earth and interfere with satellite communications, GPS systems and even 
airline
 controls.
 Geomagnetic forces have been known to occasionally garble the world's 
modern
 gadgetry, and warnings were issued as recently as last week when a moderate
 solar flare sent a coronal mass ejection in the Earth's direction.
 The temperature change associated with any reduction in sunspot activity 
would
 likely be minimal and may not be enough to offset the impact of greenhouse 
gases
 on global warming, according to scientists who have published recent papers 
on
 the topic.
 "Recent solar 11-year cycles are associated empirically with changes in 
global
 surface temperature of 0.1 Celsius," said Judith Lean, a solar physicist 
with
 the US Naval Research Laboratory.
 If the cycle were to stop or slow down, the small fluctuation in 
temperature
 would do the same, eliminating the slightly cooler effect of a solar 
minimum
 compared to the warmer solar maximum. The phenomenon was witnessed during 
the
 descending phase of the last solar cycle.
 This "cancelled part of the greenhouse gas warming of the period 2000-2008,
 causing the net global surface temperature to remain approximately flat --  
and
 leading to the big debate of why the Earth hadn't (been) warming in the 
past
 decade," Lean, who was not involved in the three studies presented, said in 
an
 email to AFP.
 A study in the March 2010 issue of Geophysical Research Letters explored 
what
 effect an extended solar minimum might have, and found no more than a 0.3
 Celsius dip by 2100 compared to normal solar fluctuations.
 "A new Maunder-type solar activity minimum cannot offset the global warming
 caused by human greenhouse gas emissions," wrote authors Georg Feulner and
 Stefan Rahmstorf, noting that forecasts by the Intergovernmental Panel on
 Climate Change have found a range of 3.7 Celsius to 4.5 Celsius rise by 
this
 century's end compared to the latter half of the 20th century.
 "Moreover, any offset of global warming due to a grand minimum of solar 
activity
 would be merely a temporary effect, since the distinct solar minima during 
the
 last millennium typically lasted for only several decades or a century at 
most."