The Sea Ice Index provides a quick look at Arctic- and Antarctic-wide changes in sea ice extent. It is a source for consistent, up-to-date sea ice area from November 1978 to the present. Monthly data and images are available via Sea Ice Index Web site (http://nsidc.org/data/seaice_index/index.html). The covered area includes the area near the pole not imaged by the sensor. It is assumed to be entirely ice covered with at least 15% concentration.