Sea-Ice Distribution in the Bering and Chukchi Seas: Information from Historical Whaleships’ Logbooks and Journals


  • Andrew R. Mahoney
  • John R. Bockstoce
  • Daniel B. Botkin
  • Hajo Eicken
  • Robert A. Nisbet



sea-ice extent, historical data, Arctic, Bering Sea, Chukchi Sea, Beaufort Sea


Satellite data have revealed dramatic losses of Northern Hemisphere sea ice since the end of the 1970s. To place these changes in a longer-term context, we draw on daily observations taken from logbooks and journals of whaling vessels cruising in the Bering and Chukchi seas to investigate sea-ice conditions in this region of the Arctic between 1850 and 1910. We compare these observations to sea-ice data from 1972 to 1982, which predate the majority of the recent changes and cover a period recognized as a relative maximum in recent Bering Sea ice extent. Records from May indicate that end-of-winter sea-ice extent in the Bering Sea during the mid 19th century closely resembled that in the 1972 – 82 data. However, the historical data reveal that sea ice was more extensive during summer, with the greatest difference occurring in July. This pattern indicates a later and more rapid seasonal retreat. These conclusions highlight the value of historical data, which we have far from exhausted in this study.