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Research

Arctic Could Face Warmer and Ice-Free Conditions



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Mid-Pliocene versus modern sea-surface-temperature anomalies
Above: Mid-Pliocene versus modern sea-surface-temperature (SST) anomalies, based on the PRISM SST reconstruction. Yellow, orange, and red colors indicate areas where average sea-surface temperatures were warmer during the mid-Pliocene than today. These anomalies show little difference from modern temperatures near the equator, with increasingly warmer mid-Pliocene temperatures toward the pole. [larger version]

There is increased evidence that the Arctic could face seasonally ice-free conditions and much warmer temperatures in the future, according to a recent report by the U.S. Geological Survey (USGS).

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 was characterized by warm temperatures similar to those projected for the end of this century, and is used as an analog to understand future conditions. (See related article "New Discoveries About the Deep Ocean Could Improve Climate Projections," this issue.)

The USGS found that summer sea-surface temperatures in the Arctic ranged from 10 to 18°C (50 to 64°F) during the mid-Pliocene, whereas 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 has also produced the most comprehensive global reconstruction of climate conditions for any warm period prior to the last interglacial (approximately 125,000 years ago). This reconstruction will help refine climate models, which currently underestimate the actual 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 (for example, see Sound Waves story, "Erosion Doubles Along Part of Alaska's Arctic Coast — Cultural and Historical Sites Lost"), 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 and report author Marci Robinson. "The absence 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) warmer than today and within the range projected for the 21st century by the Intergovernmental Panel on Climate Change.

To learn more about USGS research on the mid-Pliocene, listen to a USGS CoreCast interview with Harry Dowsett and Marci Robinson, "Want Clues to Climate Change? Let's Look Back 3 Million Years…" (Episode 115) and read these related Sound Waves articles: "New Discoveries About the Deep Ocean Could Improve Climate Projections" (this issue) and "Getting Warmer? Prehistoric Climate Can Help Forecast Future Changes" (January/February 2009).

Technical articles on the subject include the recent report, "New quantitative evidence of extreme warmth in the Pliocene Arctic," published in the journal Stratigraphy (v. 6, no. 4, p. 265-275, http://micropress.org/stratigraphy/), and reports in Climate of the Past (v. 5, p. 769-783, http://www.clim-past.net/5/769/2009/cp-5-769-2009.html) and Nature Geoscience (December 6, 2009, http://dx.doi.org/10.1038/ngeo706).

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 (PRISM) group. The primary collaborators in PRISM are Columbia University, Brown University, the University of Leeds, the University of Bristol, the British Geological Survey, and the British Antarctic Survey. Learn more about PRISM research at http://geology.er.usgs.gov/eespteam/prism/.


Related Sound Waves Stories
New Discoveries About the Deep Ocean Could Improve Climate Projections
Jan. / Feb. 2010
Erosion Doubles Along Part of Alaska's Arctic Coast — Cultural and Historical Sites Lost
May 2009
Getting Warmer? Prehistoric Climate Can Help Forecast Future Changes
Jan. / Feb. 2009

Related Web Sites
Want Clues to Climate Change? Let's Look Back 3 Million Years…
USGS
Pliocene Research, Interpretation and Synoptic Mapping (PRISM)
USGS
New quantitative evidence of extreme warmth in the Pliocene Arctic
Stratigraphy
Pliocene three-dimensional global ocean temperature reconstruction
Climate of the Past
Earth system sensitivity inferred from Pliocene modelling and data
Nature Geoscience

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Fieldwork
cover story:
Measuring Tidal Flows in the Cape Cod Canal

Research Peace River Vulnerable to Running Dry

New Discoveries Could Improve Climate Projections

Arctic Could Face Warmer and Ice-Free Conditions

Meetings CCAA Miami Conference on the Caribbean and Central America

Tampa Bay Area Scientific Information Symposium

Antarctic Treaty Summit

SACNAS National Conference

Airborne Lidar Processing System (ALPS) Workshop

Awards Awards for USGS Publication on the Coral Reef of South Moloka‘i, Hawai‘i

Staff New USGS Director Visits Centers in California

Gaye Farris Retires from the USGS National Wetlands Research Center

Publications Jan. / Feb. 2010 Publications List


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