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Big volcanoes can wake up fast
By Alexandra Witze
Long-slumbering volcanoes can jolt to
life faster than students drinking Red
Bull, a new study suggests.
Studies of millennia-old rocks that
erupted at Santorini, Greece, show that
the chemical composition of the magma
changed just a few decades before the
volcano blew its top around 1600 B.C.
That blast came after 18,000 years of
“There’s kind of a rapid wake up,” says
Tim Druitt, a volcanologist at Blaise
Pascal University in Clermont-Ferrand,
France. Druitt and his colleagues describe
the awakening in the Feb. 2 Nature.
Santorini’s Bronze Age eruption is one
of the most famous in history. But what
exactly set the volcano off after such a
long quiet period has remained a mys-
tery. “A fundamental question that we
know very little about is what happens
to reactivate these systems,” says Druitt.
Viewed from an orbiting satellite, islands
can be seen encircling the caldera
left by the Santorini, Greece, volcano
that erupted around 1600 B.C.
Several cubic kilometers of magma
may have welled up from the depths,
then melted and mixed with other rocks
just below the surface and primed Santorini for its mammoth eruption. It’s still
not clear what may have caused more
magma to rise in the first place, says
David Pyle, a volcanologist at the University of Oxford in England.
Little Ice Age
began with bang
Frozen moss suggests
eruptions kicked off cold era
By Devin Powell
The Little Ice Age, a centuries-long cold
spell in Europe and elsewhere, began suddenly late in the 13th century, a new study
finds. A string of volcanic eruptions may
have set off this climate shift by belching
sunlight-reflecting particles that allowed
Arctic sea ice to reach epic proportions,
researchers report online January 31 in
Geophysical Research Letters.
“We’ve been able to identify the beginning of the Little Ice Age, something that’s
been very difficult to do in the past,” says
Gifford Miller, a paleoclimatologist at the
University of Colorado Boulder.
It has long been known that much
of the globe became chillier during the
Renaissance. By the 17th century, temperatures in the Northern Hemisphere
had fallen half a degree Celsius compared with medieval times.
To pin down when this climate
change began, Miller’s team traveled to
Baffin Island on the northern fringes
of Canada. Small glaciers in this region
tend to respond quickly to temperature changes. Carbon dating of moss
entombed in Baffin’s ice revealed two
sudden advances of the snow line that
killed off the vegetation: a cold spell that
started bet ween 1275 and 1300, followed
by another between 1430 and 1455.
Testing whether this chill extended
beyond Canada took the researchers to
the Langjökull glacier, the second larg-
est ice cap in Iceland. Layered sediments
from a nearby lake appeared progressively
thicker in the 14th century — exactly what
would be expected if the glacier expanded
and ground away the landscape.