Community Connection: Ice Breakup in Three Alaskan Rivers

Cryosphere
This feature examines the timing of spring river ice breakup in three communities that have kept detailed records for more than 100 years.

This feature examines the timing of spring river ice breakup in three communities that have kept detailed records for more than 100 years.

Figures

Figure 1. Ice Breakup Dates for Three Alaskan Rivers, 1896-2024

Data sources: National Snow and Ice Data Center, 20244; Yukon River Breakup, 20245; Kuskokwim Ice Classic, 20246; National Weather Service, 20247
Web update: December 2024

Figure data (CSV) EPA source data (CSV)

This figure shows the date each year when ice breaks up at three locations: the town of Nenana on the Tanana River, Dawson City on the Yukon River, and Bethel on the Kuskokwim River. The annual data for each river have been plotted using a nine-year moving average.

Show the data behind this figure
Year Yukon River (days from January 1) Tanana River (days from January 1) Kuskokwim River (days from January 1)
1896 134.0000 NA NA
1897 134.0000 NA NA
1898 133.6667 NA NA
1899 133.5556 NA NA
1900 132.8889 NA NA
1901 131.7778 NA NA
1902 131.1111 NA NA
1903 130.7778 NA NA
1904 129.7778 NA NA
1905 130.1111 NA NA
1906 129.7778 NA NA
1907 129.3333 NA NA
1908 129.0000 NA NA
1909 129.6667 NA NA
1910 129.6667 NA NA
1911 128.7778 NA NA
1912 128.6667 NA NA
1913 129.4444 NA NA
1914 129.4444 NA NA
1915 129.4444 NA NA
1916 130.7778 NA NA
1917 131.0000 127.4000 NA
1918 131.0000 127.9111 NA
1919 131.0000 128.0889 NA
1920 131.6667 128.6000 NA
1921 132.2222 128.5556 NA
1922 130.8889 128.1111 NA
1923 131.1111 128.3333 NA
1924 131.0000 128.7778 131.4000
1925 129.6667 128.0000 131.6889
1926 129.4444 127.6667 132.3111
1927 129.1111 127.4444 132.7111
1928 128.3333 126.6667 132.8889
1929 128.3333 126.2222 131.5000
1930 127.5556 125.4444 129.1250
1931 129.0000 127.5556 131.3750
1932 128.2222 126.2222 133.2500
1933 128.2222 126.7778 134.2500
1934 128.7778 126.8889 132.8750
1935 129.0000 125.8889 132.2857
1936 127.6667 123.7778 129.4286
1937 127.3333 123.8889 128.4286
1938 127.0000 123.0000 128.8750
1939 127.0000 122.7778 130.3750
1940 125.8889 121.6667 130.2500
1941 127.0000 123.3333 130.8750
1942 126.8889 122.5556 131.5000
1943 126.5556 122.2222 133.2500
1944 126.6667 123.8889 133.8889
1945 128.2222 126.4444 137.2222
1946 129.3333 126.7778 138.5556
1947 129.5556 126.7778 138.0000
1948 130.7778 128.4444 139.4444
1949 130.6667 127.7778 138.6667
1950 130.2222 126.6667 137.0000
1951 130.6667 127.1111 136.3333
1952 130.5556 127.0000 136.1111
1953 130.1111 126.0000 134.7778
1954 129.1111 124.3333 133.2222
1955 129.6667 124.5556 133.5556
1956 129.3333 124.8889 134.8889
1957 128.8889 124.0000 131.7778
1958 130.1111 125.4444 134.2222
1959 129.3333 125.3333 134.7778
1960 131.1111 126.6667 136.5556
1961 132.2222 127.2222 136.7500
1962 132.4444 127.5556 139.8750
1963 133.3333 128.1111 139.2500
1964 132.7778 128.2222 138.5000
1965 132.7778 127.6667 136.8750
1966 133.0000 127.5556 138.2500
1967 132.5556 127.1111 137.7500
1968 133.3333 127.7778 139.2500
1969 131.0000 125.8889 136.6250
1970 130.1111 125.7778 135.5556
1971 129.8889 126.0000 134.0000
1972 129.2222 125.8889 135.4444
1973 128.8889 125.5556 136.3333
1974 129.0000 125.7778 136.6667
1975 128.0000 125.3333 135.7778
1976 127.4444 124.4444 134.1111
1977 127.0000 123.2222 132.3333
1978 127.5556 123.8889 132.7778
1979 126.5556 123.1111 133.2222
1980 126.5556 123.1111 132.7778
1981 127.6667 124.0000 133.4444
1982 128.2222 124.2222 132.4444
1983 128.5556 124.7778 133.4444
1984 128.5556 124.5556 134.3333
1985 127.6667 124.6667 134.5556
1986 126.7778 124.0000 134.3333
1987 125.3333 123.0000 133.2222
1988 126.2222 124.7778 134.7778
1989 125.1111 122.8889 133.4444
1990 123.4444 121.5556 131.4444
1991 122.1111 120.2222 130.5556
1992 122.0000 120.3333 129.6667
1993 122.2222 120.5556 128.5556
1994 122.7778 119.3333 128.0000
1995 123.6667 119.8889 129.3333
1996 124.3333 120.0000 129.6667
1997 124.2222 119.2222 128.6667
1998 125.6667 120.7778 130.0000
1999 126.3333 120.7778 129.4444
2000 126.8889 120.6667 129.1111
2001 125.8889 119.7778 129.0000
2002 126.6667 120.0000 131.3333
2003 126.6667 120.7778 131.0000
2004 126.3333 121.6667 130.5556
2005 126.0000 121.5556 130.3333
2006 125.1111 120.5556 130.4444
2007 124.5556 120.2222 130.1111
2008 124.0000 119.6667 131.6667
2009 125.1111 122.4444 134.5556
2010 125.4444 122.1111 133.7778
2011 124.6667 121.2222 131.6667
2012 123.5556 120.8889 130.3333
2013 123.3333 120.2222 129.4444
2014 123.8889 120.2222 128.6667
2015 123.1111 118.5556 124.7778
2016 122.7778 117.8889 124.0000
2017 123.2222 118.5556 122.8889
2018 122.3333 116.5556 120.2222
2019 123.1111 118.0000 122.2222
2020 122.5556 118.4444 122.7778
2021 123.7778 119.2444 124.7556
2022 124.0000 119.2667 125.0667
2023 123.6667 119.2889 125.8222
2024 125.0000 121.2000 128.8000

Key Points

  • The Tanana, Yukon, and Kuskokwim rivers all demonstrate long-term trends toward earlier ice breakup in the spring. The ice breakup dates for all three rivers have shifted earlier by seven to nine days over their respective periods of record.
  • At all three locations, the earliest breakup dates on record have occurred within the past six years.
  • Despite the overall trend toward earlier breakup, most of the recent breakup dates for the rivers are within the range of historical variation.

Background

Regions in the far north such as Alaska are warming more quickly than other parts of the world, and this pattern is expected to continue1,2 (see the Arctic Sea Ice indicator; for more information about regional temperature changes, see the U.S. and Global Temperature indicator). The Tanana, Yukon, and Kuskokwim rivers in Alaska provide a particularly noteworthy record of northern climate. For a century or more, local citizens have recorded the date when the ice on these rivers starts to move or break up each spring. In fact, some towns have annual competitions to guess when ice breakup will occur.

Since 1917, the Nenana Ice Classic competition on the Tanana River in central Alaska has paid several million dollars in winnings to the people who come closest to guessing the exact date and time of day when the river ice will break up. Similar traditions exist on the Kuskokwim River in Bethel, where breakup dates have been recorded since 1924, and in Dawson City on the Yukon River, just across the border in Canada, where breakup dates have been recorded since 1896.

River ice breakup is more than just a friendly competition, though. Ice breakup is an important time of transition for communities that rely on these relatively remote and free-flowing wild rivers for transportation, subsistence hunting and fishing, and other needs. In addition, early thawing can lead to severe ice movement, jamming, damage to infrastructure, and destructive floods.3

The data collected by these communities highlight how the river ice breakup dates in Nenana, Dawson City, and Bethel have changed over time. The towns all use the same method to measure the date and time of river ice breakup. Residents place a tripod on the ice in the center of the river. This tripod is attached by a cable to a clock on the shore. When the ice under the tripod breaks or starts to move, the tripod moves, pulling the cable and stopping the clock.

For this and other examples of community connections to observed climate-related changes, see the StoryMap at: https://storymaps.arcgis.com/stories/ebd8dcbb0b6048cd81caa6eb450b8974.

About the Data

Notes

Besides climate change, natural year-to-year variations and other factors, such as local development and land-use patterns, can influence ice breakup dates. The three locations featured here are relatively remote and undeveloped, so the ice breakup dates are more likely to reflect natural changes in weather and climate conditions. However, corresponding measurements of water conditions and air temperature are useful to help understand the connection between changes in river ice breakup and changes in climate. A recent comparison with satellite measurements of freeze/thaw conditions at ground level (basically a way of measuring surface temperature) showed a close correlation between regional temperature conditions and actual Tanana River breakup dates.8

Data Sources

Ice breakup dates for the Tanana River at Nenana, the Yukon River at Dawson City, and the Kuskokwim River at Bethel have been recorded and made publicly available as part of three long-running community competitions: the Nenana Ice Classic, the Yukon River Breakup, and the Kuskokwim Ice Classic. The data shown here and other information can be found online at: www.nenanaakiceclassic.com, https://nsidc.org/data/nsidc-0064/versions/2, www.yukonriverbreakup.com/statistics, http://iceclassic.org/historical-data, and additional sources linked from these websites. Ice breakup dates for these rivers are also archived by the National Snow and Ice Data Center at: https://nsidc.org/data/g01377/versions/1 and the National Weather Service at: www.weather.gov/aprfc/breakupDB.

Technical Documentation

References

  1. Marvel, K., Su, W., Delgado, R., Aarons, S., Chatterjee, A., Garcia, M. E., Hausfather, Z., Hayhoe, K., Hence, D. A., Jewett, E. B., Robel, A., Singh, D., Tripati, A., & Vose, R. S. (2023). Chapter 2: Climate trends. In USGCRP (U.S. Global Change Research Program), Fifth National Climate Assessment. https://doi.org/10.7930/NCA5.2023.CH2
  2. IPCC (Intergovernmental Panel on Climate Change). (2021). Climate change 2021—The physical science basis: Working Group I contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (V. Masson-Delmotte, P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, & B. Zhou, Eds.). Cambridge University Press. https://doi.org/10.1017/9781009157896
  3. Beltaos, S., & Burrell, B. C. (2003). Climatic change and river ice breakup. Canadian Journal of Civil Engineering, 30(1), 145–155. https://doi.org/10.1139/l02-042
  4. NSIDC (National Snow and Ice Data Center). (2024). Nenana Ice Classic: Tanana river ice annual breakup dates (NSIDC-0064; Version 2) [Data set]. NASA National Snow and Ice Data Center Distributed Active Archive Center. Retrieved November 15, 2024, from https://doi.org/10.5067/CAQ58H42LQY2
  5. Yukon River Breakup. (2024). Yukon River breakup. Retrieved November 15, 2024, from https://yukonriverbreakup.com
  6. Kuskokwim Ice Classic. (2024). Kuskokwim Ice Classic. Retrieved November 15, 2024, from http://iceclassic.org
  7. National Weather Service. (2024). Alaska-Pacific River Forecast Center: Break up database. Retrieved November 15, 2024, from www.weather.gov/aprfc/breakupDB
  8. Kim, Y., Kimball, J. S., Glassy, J., & Du, J. (2017). An extended global Earth system data record on daily landscape freeze–thaw status determined from satellite passive microwave remote sensing. Earth System Science Data, 9(1), 133–147. https://doi.org/10.5194/essd-9-133-2017

Text on this page is EPA’s own published wording (a U.S. Government work, not subject to domestic copyright), extracted from EPA’s published indicator page and verified paragraph by paragraph against the archived HTML. Data, chart code, and the full extraction pipeline are maintained in the alaskan-rivers repository, which this page reads its data from directly.

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