Press Releases

August 16, 2007
The Japan Agency for Marine-Earth Science and Technology
The Japan Aerospace Exploration Agency

The Recorded Minimum Arctic Sea Ice Extent
Further Shrinkage of the Sea Ice Extent is
Expected until Mid September


The Japan Agency for Marine-Earth Science and Technology (JAMSTEC, led by President Yasuhiro Kato) and the Japan Aerospace Exploration Agency (JAXA, led by President Keiji Tachikawa) identified Arctic sea ice extent has become the smallest value on the record on August 15 since satellite observations started in 1978, based on joint analysis of ocean/ atmosphere observation data and satellite sea ice data. Ice reduction normally continues until mid September, thus further shrinkage of the sea ice extent is expected. The observed feature significantly exceeded the projected model result in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), and yesterday, the sea ice extent has already reached the projected value of 2040 in the IPCC report about five weeks earlier than nominal date when the minimum sea ice extent is observed. Such anomalous difference tells us that the model may not precisely reflect the actual mechanisms in the Arctic Ocean.
(Fig.1: Reference picture of Arctic Sea Ice condition on August 6)


The following are findings as a result of analyses of observational data acquired by the Advanced Microwave Scanning Radiometer (AMSR-E)*1 and visible images. AMSR-E was developed and is operated by JAXA,

Since July this year, the daily minimum record of sea ice extent in the Arctic Ocean has been renewed every day.
Since the beginning of August, the shrinkage of sea ice extent has been accelerated by a low generated and lingering off Siberia.
On August 15, the total sea ice extent in the Arctic Ocean marked a new low.
If this rate of reduction continues, decreasing rate of the sea ice extent may significantly exceed the IPCC projection, and it may actually reach the forecasted values for 2040 to 2050 (Figure 2 and 3.)

Estimated causes

The following are estimated causes of accelerated sea ice reduction this year as a result of the comprehensive analysis of the observation data acquired by JAMSTEC, including observational data by vessals and drifting buoys (JCAD, POPS*2) and atmospheric data. (Please refer to Figure 4)

Sea ice reduction has been observed not only along the coast of Alaska but also along the Arctic Ocean coast of Canadian archipelago this year. Accordingly, the impact of friction from coastal areas is smaller than usual, thus sea ice tends to move in a large scale. This condition yields strengthening of large scale anticyclonic sea ice motion. Therefore, in the western part of the anticyclonic sea ice motion, the first year ice, which was just formed previous winter and therefore was not so thick, drifted northward beyond 80 oN.
As the first year ice spreading into the Arctic Ocean melted quickly and that facilitates the ocean water to absorb more sunshine, ocean warming and sea ice melting have accelerated.
More sea ice has been drifting toward the Atlantic Ocean from the Arctic Ocean, thus the sea ice extent in the Arctic Ocean has been decreasing.

You can find the latest image of the sea ice extent in the Arctic Ocean and past observational images on the website of the International Arctic Research Center (IARC, Alaska Fairbanks.) The image data is updated using the IARC-JAXA information system (IJIS), which JAXA places at the IARC.


The Advanced Microwave Scanning Radiometer (AMSR-E) is one of the onboard sensors of the American earth observation satellite Aqua, which was launched in May 2002. By observing weak radio frequencies emitted from Earth, the AMSR-E can measure sea ice, ocean temperature, water vapor, and precipitation, day and night regardless of weather conditions. The successor of the AMSR-E, the AMSR2 (which will be installed into the GCOM-W1 satellite) is under development and is scheduled for launch in Japan Fiscal Year 2011.

J-CAD (JAMSTEC Compact Arctic Drifter):

Drifting buoy deployed in the Arctic Ocean automatically observes water temperature, salinity and current to a water depth of 250m, as well as atmospheric temperature and air pressure at the Arctic sea ice area. It has been developed and operated by JAMSTEC from 2000 to 2005. Since 2006, the next-generation buoy "POPS" has been in operation.

POPS (Polar Ocean Profiling System):

The observation system that enabled multi-year observations of sea ice in the Arctic Ocean utilizing Algo Float. AlgoFloat is fixed to the cable hang from the platform which is installed to the sea ice. It moves vertical along with the cable between 10 to 1,000m water depth and monitor water temperature and salinity.

Related Links

JAMSTEC, Arctic Ocean Climate System Group, Institute of Observational Research for Global Change website

JAXA, Earth Observation and Research Center, AMSR-E Site


Dr. Koji Shimada, Group Leader
Arctic Ocean Climate System Group, Institute of Observational Research for Global Change
Mr. Tatsunosuke Tuzuku: email:
Manager, Research Promotion Office, IORGC
Mr. Shinji Oshima, email:
Manager, Planning Department, Press Office