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| Ice Breakup in Two Alaskan Rivers |
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 Community Connection: Ice Breakup in
Two Alaskan Rivers
This feature examines the timing of spring river ice breakup
in two communities that have kept detailed records for more
than 100 years.
Key Points
The Tanana and Yukon rivers both demonstrate long-term
trends toward earlier ice breakup in the spring. The ice
breakup dates for both the Tanana and Yukon rivers have
shifted earlier by approximately seven days over their
respective periods of record.
The 2016 breakup date recorded at Dawson City was the
earliest on record.
Despite the overall trend toward earlier breakup, recent
breakup dates for both rivers are largely within the range
of historical variation. |
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Background
Regions in the far north 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 and Yukon
rivers in Alaska provide a particularly noteworthy record of
northern climate because, 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.
A similar tradition exists 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.
The data collected by these communities highlights how the
river ice breakup dates in Nenana and Dawson City have
changed over time. Both towns use the same method to measure
the exact 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. |
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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 two 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 would
be useful to help understand the connection between changes
in river ice breakup and changes in climate.
Data Sources
Ice breakup dates for the Tanana River at Nenana and the
Yukon River at Dawson City have been recorded and made
publicly available as part of two long-running, community
competitions: the Nenana Ice Classic and the Yukon River
Breakup. The data shown here and other information can be
found online at: www.nenanaakiceclassic.com and:
www.yukonriverbreakup.com/statistics. Data records of ice
breakup dates for these two rivers are also archived by the
National Snow and Ice Data Center at:
https://nsidc.org/data/lake_river_ice.
Technical Documentation
Download related technical information PDF |
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 Figure
1. Ice Breakup Dates for Two Alaskan Rivers,
1896–2016
This figure shows the date each year when ice breaks up at
two locations: the town of Nenana on the Tanana River and
Dawson City on the Yukon River.
Data sources: Nenana Ice Classic, 20164; Yukon River
Breakup, 20165 |
 Reference
Map
Reference map for figure 1 above. |
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EPA Page |
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This is the
EPA page for this topic. To see if the Trump
administration has changed the EPA page, simply click the
link and compare the information with this page. If you
notice changes were made to the EPA page, please post a
comment. Thanks. |
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Additional Climate Change Information |
Climate Change and Carbon Dioxide
(Beginner - Listening,
reading)
A video lesson to
help with your understanding of climate change
and carbon dioxide.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
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(Beginner - Listening,
reading)
A video lesson to
help with your understanding of carbon dioxide
and climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice. |
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spoken at 75% of normal speed.
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The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
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found that January temperatures in the Arctic reached a record high. |
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The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Most scientists agree that carbon-dioxide gas is partly to blame for climate
change: rising global temperatures. But capturing the CO2 gas released by power
stations is costly and difficult. |
Growth, Climate Change Threaten African Plants and
Animals
(Beginner - Listening,
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A video lesson to
help with your understanding of climate change.
The English is
spoken at 75% of normal speed.
Great English listening and reading practice.
Researchers believe Africa may lose as much as 30 percent of its animal and
plant species by the end of this century. |
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