Uncertainty informs decisions and drives science forward

The role of science is to assess evidence and show which of several possible answers has the most support. Remaining uncertainties indicate what to investigate next.

We all make choices that are based on incomplete information. It is helpful to know about uncertainties up front so that we can make informed decisions.

Navigating and collecting data in heavy ice was very uncertain for historic mariners.

We can plan for the future by studying the past.

Key findings from a 2011 report on the need for spatial tools for Arctic mapping and planning indicate that:

Marine resource management decisions are often made through processes that are not based explicitly on resource data … important weaknesses in current decision-making processes involve two issues that spatial tools can help address: public participation and the availability of data and information.

The most pressing management decisions revolve around climate change and the associated changes in environmental conditions coupled with increasing industrial development and consequent human uses of the ocean and near shore environments.

For the first time, you can simultaneously view multiple sources of historical sea ice data from the oceans surrounding northern Alaska. Choose a region and time of interest and inspect a map of data collected between the mid-1800s and today, to discover how ice extent and concentration have changed over time.

If you are a resident of a coastal community, someone who hunts or fishes in a marine environment, a member of the shipping or oil + gas industries, in the US Coast guard, a scientist, or otherwise interested in Arctic sea ice data and climate change, this atlas is for you.

Data considerations

These data represent “snapshots” in time, as well as historical trends in arctic sea ice cover and extent. They are not projections or predictions of future conditions. The atlas is not designed for forecasting or prediction, but can provide useful historical context for future planning efforts.

Factors that create uncertainty in these data

Data collection challenges. Collecting sea ice data has always been difficult and dangerous work. Historic interpretations of ice concentration differed from modern protocols. A wide variety of instrument calibrations and sensors (human observation, radar, satellites) has been used over time. All add up to data inconsistencies.

Data compilation choices. Compiling data involves choices: Which hard copy maps to digitize? How do we interpret this handwriting? How do we fill gaps in the data record? Which time scale is best to use? These choices lead to uncertainty.

Sources of sea ice data used in this Atlas

Data source descriptions

Arctic Climate System Study (ACSYS)  An activity of the World Climate Research Program. Includes digitized ice edge positions for the north Atlantic. ACSYS Ice edge information is irregular in time and space, and is most frequent in the 20th century. When available, ice edge data are provided monthly. The ACSYS study has expanded into the Climate and Cryosphere Project. Visit the ACSYS/CliC Historical Ice Chart Archive to access all data from this work.

Brian Hill Collection  Includes ice edge coordinates and accompanying maps of ice edge around Newfoundland, Grand Banks, and the Gulf of St. Lawrence, Canada. Information is monthly for winter months of most years.

Danish Meteorological Institute (DMI)  These charts provide observed and inferred sea ice extent for each summer month from 1893–1956. Additionally, Kelly et al. have digitized summer (May-Sept) ice edge information from DMI's monthly maps.

Arctic and Antarctic Research Institute (AARI)  Located in St. Petersburg, Russia, AARI produces sea ice charts for safety of navigation in the Eurasian Arctic and other operational and scientific purposes. Chart coverage focuses on the Northern Sea Route, although later charts extend into the central Arctic. Charts contain several categories of ice concentration.

NSIDC Bill Dehn Data Collection  Scanned versions of almost 7,000 ice charts donated to the National Snow and Ice Data Center (NSIDC) by the estate of Bill Dehn are available through a searchable interface. A subset of the charts have been digitized by the Alaska Center for Climate Assessment and Policy (ACCAP).

Walsh and Johnson/Navy-NOAA Joint Ice Center  Early version of pan-Arctic digital database of Arctic sea ice concentrations. Grids cover the pre-satellite (passive microwave) period and are synthesized from various sources. Resolution is 60 nautical miles in space and monthly in time. Described in: Walsh and Johnson, 1979, J. Phys. Oceanography, 9, 58–591.

Naval Oceanographic Office (NAVOCEANO)  Oversees the Naval Ice Center (NAVICE), which provides worldwide operational ice analyses for the US military and government agencies as well as allied nations. Sea ice maps for the Alaskan and Greenland sectors were compiled into yearbooks for the period 1953–1971. Hard copies of yearbooks are held by the National Snow and Ice Data Center (NSIDC). In 1972, ice charting was transitioned to the predecessor of the National Ice Center.

Japan Meteorological Agency  Monitors sea ice in the Sea of Okhotsk from November to July. Results of monitoring are published for public use.

Navy-NOAA Joint Ice Center Climatology  The National Ice Center began in 1976 as the Joint Ice Center in 1976, comprised of personnel from NOAA and the US Navy. In 1995, the Joint Ice Center became the National Ice Center as it expanded to include the US Coast Guard. Coast Guard aircraft, icebreakers, and Marine Safety Offices contribute valuable platforms for onsite aerial and ship observations, as well as accurate and timely ship and station reports. Ice charts dating back to 1972 are from predecessor organization. Hard-copy (paper) charts produced by analysts are subsequently scanned and digitized. Ice charts are based mainly on satellite imagery, supplemented by aircraft, ship and shore reports.

NSIDC Nimbus-7 SMMR Arctic Sea Ice Concentrations   The National Snow and Ice Data Center  (NSIDC) supports research into our world's frozen realms: the snow, ice, glaciers, frozen ground, and climate interactions that make up Earth's cryosphere. NSIDC manages and distributes scientific data, creates tools for data access, supports data users, performs scientific research, and educates the public about the cryosphere.