http://www.washingtonpost.com/news/morning-mix/wp/2015/07/14/news-about-an-imminentmini-ice-age-is-trending-but-its-not-true/?postshare=8611436921642317
News about an imminent ‘mini ice age’ is
trending — but it’s not true
By Sarah Kaplan July 14
Montage of images of solar activity between August 1991 and September 2001. New research says the sun is about to enter a
quiet period, but that doesn’t mean the Earth is going to cool off. (Yohkoh/ISAS/Lockheed-Martin/NAOJ/U. Tokyo/NASA)
“Scientists warn the sun will ‘go to sleep’ in 2030 and could cause
temperatures to plummet,” blared one headline from this weekend.
“Earth heading for ‘mini ice age’ within 15 years,” warned another.
By Sunday evening, news that the Earth could be headed for period of
bitter cold was trending on Facebook and whizzing across Twitter. The
story — which has been reported everywhere from conservative blogs to
theBritish press to the Weather Channel to the Huffington Post — was
based on arecent presentation at the Royal Astronomical Society’s
national meeting. Researchers studying sunspots found that solar
activity is due to decline dramatically in the next few decades, reaching
levels not seen since the 17th century, during a period known as the
Maunder minimum. Back then, the decline coincided with what’s called
the “Little Ice Age,” when Europe’s winters turned brutally cold, crops
failed and rivers froze over. Could another one be on its way?
Not quite.
Though University of Northumbria mathematics professor Valentina
Zharkova, who led the sunspot research, did find that the magnetic
waves that produce sunspots (which are associated with high levels of
solar activity) are expected to counteract one another in an unusual way
in the coming years, the press release about her research mentions
nothing about how that will affect the Earth’s climate. Zharkova never
even used the phrase “mini ice age.” Meanwhile,
several other recent studies of a possible solar minimum have concluded
that whatever climate effects the phenomenon may have will be dwarfed
by the warming caused by greenhouse gas emissions.
Besides, that “Little Ice Age” that occurred during the Maunder
minimum, it wasn’t so much a global ice age as a cold spell in Europe,
and it may have been caused more by clouds of ash from volcanic
eruptions than by fluctuations in solar activity.
(It’s also worth mentioning that Zharkova’s findings have not yet been
published in a peer-reviewed journal, so her conclusions haven’t been
vetted and refined.)
But those nuances were totally lost as stories about Zharkova’s research
made the rounds on social media and in the press. Instead, we got 300year-old engravings of Londoners cavorting on the frozen River Thames
accompanied by predictions of food shortages and brutal cold — plus
snarky tweets about not worrying about global warming anymore.
This isn’t the first time that a story about sunspots has turned into a
story about climate change skepticism. John Casey, president of the
Orlando-basedSpace and Science Research Corporation, which denies
that global temperatures are rising, has written two books on the threat
of impending “solar hibernation.” In 2011, when a series of studies
concluded that the sun was heading into a cycle of unusually low
activity, one headlinecheered “Global Warming Be Damned, We Might
Be Headed for a Mini Ice Age.”
For decades, scientists have known that solar activity fluctuates
according to a roughly 11-year cycle. Sunspots — (relatively) cool, dark
blotches on the sun’s surface — indicate areas of intense magnetic
activity. But recently sunspots have been weakening, as has the sun’s
magnetic field, leading scientists to conclude that the sun is heading into
an especially quiet cycle termed the “grand solar minimum”
The new research from Zharkova argues that the solar cycles are
regulated by not one but two magnetic waves fluctuating at slightly
different frequencies, and that the unusually low activity can be
explained by the waves getting far enough out of sync that
they effectively cancel one another out.
Even if the upcoming decline in solar activity turns out to be as
Zharkova’s suggests, scientists who study the sun say we can’t be sure
how it will affect Earth’s climate.
“We have some interesting hints that solar activity is associated with
climate, but we don’t understand the association,” Dean Pesnell, a NASA
scientist who worked on one of the 2011 studies about the grand
minimum, told National Geographic at the time.
Those studies that have found a correlation between solar activity and
global temperatures predict that the drop in temperatures associated
with a grand minimum will be much smaller than the warming that’s
predicted to occur due to greenhouse gas emissions: A 2010 study in the
journal Geophysical Letters predicted it could cause a global temperature
decrease of about 0.3 degrees Celsius by 2100 — not nearly enough to
offset the 1 to 5 degree increase anticipated from human-caused global
warming.
As for that image of Londoners frolicking at “frost fairs” on the frozenover Thames? Those had less to do with the activity of the sun than the
activities of humans. Historical climatologist George Adamson told the
BBC last year that the river used to freeze because of the architecture of
the old London Bridge, whose arches prevented salty sea water from
passing upriver and lowering its freezing point. The construction of a
new bridge in the 19th century, and other landscape changes that made
the river flow faster, brought an end to those festivals — less so than the
end of the Maunder minimum.
“I’d be surprised if it froze again to the extent where we’d be able to allow
large numbers of people on the Thames,” he said.