Data Stories for IPY

How Fast is Summer Sea Ice in the Arctic Retreating?

Following is an example of a Data Story which provides background information about the “who, what, where, when, how, and why” of a research effort, providing context for non-technical users as to how relevant data are collected and analyzed.

1) Related IPY Project: #94 - Development of a Comprehensive Data Products for Arctic Environmental Studies

5) What: (tools/technology) – Animations and related products based on sea ice index using data from DMSP and the prior NIMBUS 7 satellites which provide overview of the extent and changes of sea ice, but do not provide the total volume of ice or ice mass balance which require ice thickness information as well.

6) Where: (geo ref)- Arctic Ocean – sea level

7) Where: (teleconnections)- Impact on global climate system, but not direct impact on sea level rise.

8) When: (period of observations) October1978 (the beginning of continuous satellite monitoring of the polar regions) to the most recent month. September sea ice extent is used for comparison purposes because the lowest seasonal sea ice extent occurs around the Equinox, when daylight and darkness are equal (12 hours each) in every location. After the September Equinox, the Arctic sea ice begins to grow as the nights become longer, the daylight shorter. The growth of the sea ice continues through the winter months until the Spring Equinox, when the process is reversed as days become longer than nights and the sea ice begins to melt from the increased solar energy.

9) How: The images in the Sea Ice Index depict average ice conditions, estimated using satellite passive microwave data for the most recent month available. Data are collected by satellite sensors measure energy emitted by the ice in the microwave range of the electromagnetic spectrum. The amount of energy emitted by sea ice is distinctive from the energy one sees from the unfrozen ocean, which allows scientists to determine how much ice exists. Mathematical formulas, or algorithms, convert the data collected by the satellites into an estimate of sea ice concentration (percentage of a given area covered by ice), which are then used to create maps of the ice-covered areas. Daily data “fields” are used to create monthly averages, which are then used to determine the total hemispheric area covered by sea ice. The monthly data are compared with climatological averages and previous months to compute anomalies (how much above/below average) and trends (how much ice has increased or decreased over time).

10) Why: (importance) - In the Northern Hemisphere, sea ice reaches an annual minimum extent in September, and maximum extent in February or (usually) March, although there may be regional variations. Seasonal changes in Arctic sea ice extent and concentration have an impact on (1) the length of the shipping season, (2) wildlife, e.g., the ability of polar bears to hunt on the sea ice, (3) the culture of indigenous communities (e.g., hunting, transportation), and (4) myriad effects on the global climate system (e.g., since the amount of solar radiation captured by dark, open water is significantly different from the amount of heat radiated by white ice back to space).

The Sea Ice Index and related datasets are also important for developing and evaluating models of future projected changes in the Arctic seasonal sea ice cover. In addition to the seasonal changes, the Sea Ice Index and products help in examining longer-term changes trends. For example, the Arctic has lost over 1 million sq. km. of ice since 1979, which corresponds to an area about twice the size of the state of Texas. Current models predict the Arctic could be ice-free during at least some of the summer by 2040 or even earlier. Such a dramatic change in the surface would have major implications, not only on global climate, but also on such things as the length of shipping season, ability of polar bears to hunt on the sea ice, the oil industry, and especially the Inuit and other native communities that live on and near the ice.

Compiled by Mark S. McCaffrey, Revised February 18, 2008