USGS: Arctic sea too warm for sea ice 3 million years ago

SST 3 million YA – click to enlarge 

There is increased evidence that the Arctic could face seasonally
ice-free conditions and much warmer temperatures in the future.

Scientists documented evidence that the Arctic Ocean and Nordic Seas
were too warm to support summer sea ice during the mid-Pliocene warm
period (3.3 to 3 million years ago). This period is characterized by
warm temperatures similar to those projected for the end of this
century, and is used as an analog to understand future conditions.

The U.S. Geological Survey found that summer sea-surface
temperatures in the Arctic were between 10 to 18°C (50 to 64°F)
during the mid-Pliocene, while current temperatures are around or below
0°C (32°F). 

Examining past climate conditions allows for a true understanding of
how Earth’s climate system really functions. USGS research on the
mid-Pliocene is the most comprehensive global reconstruction for any
warm period. This will help refine climate models, which currently
underestimate the rate of sea ice loss in the Arctic.

Loss of sea ice could have varied and extensive consequences, such
as contributions to continued Arctic warming, accelerated coastal
erosion due to increased wave activity, impacts to large predators
(polar bears and seals) that depend on sea ice cover, intensified
mid-latitude storm tracks and increased winter precipitation in western
and southern Europe, and less rainfall in the American west.

“In looking back 3 million years, we see a very different
pattern of heat distribution than today with much warmer waters in the
high latitudes,” said USGS scientist Marci Robinson. “The
lack of summer sea ice during the mid-Pliocene suggests that the
record-setting melting of Arctic sea ice over the past few years could
be an early warning of more significant changes to come.”

Global average surface temperatures during the mid-Pliocene were
about 3°C (5.5°F) greater than today and within the range
projected for the 21st century by the Intergovernmental Panel on
Climate Change.

Read the full article at http://micropress.org/stratigraphy/.

[ PDF is here http://micropress.org/stratigraphy/papers/Stratigraphy_6_4_265-275.pdf – Anthony ]

Scientists studied conditions during the mid-Pliocene by analyzing
fossils dated back to this time period. The USGS led this research
through the Pliocene Research, Interpretation and Synoptic Mapping
group. The primary collaborators in PRISM are Columbia University,
Brown University, University of Leeds, University of Bristol, the
British Geological Survey and the British Antarctic Survey. Learn more
about PRISM research.

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