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Wednesday, January 25, 2017 The Nugget Newspaper, Sisters, Oregon
Scientists study ancient ocean temperatures
By Mark Floyd
Correspondent
PHOTO PROVIDED
Martin Sexton plays Wednesday.
CONCERT: Show
launches festival’s
annual series
Continued from page 3
at concerts ranging from col-
laborating with John Mayer
to the jam scene work-
ing with Peter Frampton,
to the Newport Folk Fest,
Bonnaroo, and the New
Orleans Jazz Fest. Promotion
of the 2017 tour states:
“Remember that mix-tape
your friend made you way
back when — the one that’s
etched in your soul? Martin
Sexton’s new album, Mixtape
of the Open Road, is that
musical cross-country trip,
blazing through all territories
of style as you cruise through
time and place. This record is
a charm bracelet of 12 gems
all strung together with the
golden thread of what Rolling
Stone calls a “soul-marinated
voice.”
Tickets can be purchased
at www.sistersfolkfestival.
org/tickets or by calling
541-549-4979.
Series passes are $55 for
adults, $40 for youth 18 and
under. Tickets are also avail-
able for individual shows.
All shows are at Sisters High
School Auditorium at 7 p.m.
CORVALLIS — During
the last major interglacia-
tion period, when ice sheets
in Greenland and Antarc-
tica were smaller than today
resulting in a global sea level
that was 20 to 30 feet higher,
scientists believe ocean tem-
peratures were warmer than
at most times in the Earth’s
recent history.
However, those estimates
of ocean temperatures show
a high level of uncertainty,
making it difficult to accu-
rately project warming into
the future and its impacts on
sea level rise.
Now a team of scientists
has assembled data from
around the world in a com-
prehensive analysis of global
ocean temperatures during the
interglaciation period from
129,000 to 116,000 years ago.
The team found that global
average ocean temperatures
were roughly half a degree
(Celsius) warmer during that
period than during pre-indus-
trial times and nearly identi-
cal to the average temperature
over the last 20 years.
Results of the study,
which was supported by the
National Science Founda-
tion, appear this week in the
journal Science.
“Half a degree may not
sound like very much, but in
terms of average global ocean
temperature, it actually is
quite substantial,” said lead
author Jeremy Hoffman, who
led the work as a doctoral stu-
dent at Oregon State Univer-
sity, and is now a staff scien-
tist with the Science Museum
of Virginia. “The problem is
that computer models have
not been able to simulate this
amount of warming for the
last interglaciation. Because
these are the same models
used to project future temper-
atures, this suggests that they
may be missing important
processes that would result
in even warmer temperatures
than now considered.”
The last interglaciation
period was one of the warm-
est periods on Earth in the
last 800,000 years. A previ-
ous study by Oregon State
researchers — published in
Science — documented the
higher sea levels and scien-
tists have hypothesized that
warmer ocean temperatures
have been part of the process.
Peter Clark, an Oregon
State climate scientist and
co-author on the study, said
one reason for warmer tem-
peratures during the last inter-
glaciation, and the decline of
the Greenland ice sheet, was
a shift in Earth’s orbit around
the sun.
“Although carbon dioxide
levels then were comparable
to the pre-industrial era, solar
insolation in the northern
hemisphere during the sum-
mer was much higher,” said
Clark, who has the title of dis-
tinguished professor in OSU’s
College of Earth, Ocean, and
Atmospheric Sciences. “This
more intense solar insolation
contributed to the warmer
temperatures.”
The researchers believe the
melting of the Greenland ice
sheet weakened the Atlantic
Meridional Overturning Cir-
culation, or AMOC, a system
of currents that usually brings
warmer water from the tropics
to the south. As it weakened,
sea-surface temperatures rose
in the southern hemisphere,
also contributing to warmer
global temperatures.
“It was a double-
whammy,” Clark said. “Solar
insolation warmed the north-
ern hemisphere, a weakened
AMOC warmed the south.”
Earth’s orbit around the
sun is different today, result-
ing in less solar insolation.
The planet has warmed by
about one degree (Celsius)
since 1750 because of human
influence.
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