The third in our series of science briefs and analyses, this report was prepared for The Pew Charitable Trusts U.S. Arctic Program by Andrew R. Mahoney and released in November of 2012.
The Chukchi and Beaufort seas lie north of Alaska and together contain the entire U.S. Arctic domain. Nominally, the two seas are separated by Point Barrow, the northernmost point of the North American mainland. Away from the coast, the boundary between the Chukchi and Beaufort seas is typically defined by the regional bathymetry. The Chukchi Sea is dominated by a broad, shallow shelf (the Chukchi Shelf) mostly less than 50 meters (160 feet) deep with shoals such as Hanna Shoal and Herald Shoal rising to around 20 m. Conversely, water shallower than 50 m in the Beaufort Sea occupies only a narrow strip less than 100 km from the coast. Most of the Beaufort Sea is greater than 1,000 m deep and is part of the Canada Basin. There are other geographic differences between the Chukchi and Beaufort seas, such as latitude and coastal confinement. These factors, along with the Chukchi’s connection to the Pacific Ocean, play a large role in defining the sea ice conditions in the two seas and how they might respond to ongoing changes in the Arctic climate.
Differences in geographic setting and bathymetry between the Chukchi and Beaufort seas lead to marked differences in the character of sea ice in these two regions. Due to its more southerly location and connection to the Pacific Ocean, the Chukchi Sea experiences a longer open water season than the Beaufort. In addition, due to the combination of a thinner ice pack and a coastline that offers the opportunity for open water creation under almost any drift direction, sea ice in the Chukchi Sea is more mobile and changeable than sea ice in the Beaufort. This is also reflected in the greater extent of landfast sea ice in the Beaufort Sea.
These differences represent important considerations for offshore activities in the U.S. Arctic domain. In particular, operational experience gained in one sea may not be directly applicable to the other. It is also important to recognize that the extent of our understanding of the sea ice environment for the Chukchi is different from the Beaufort. This is partly because there is a shorter history of commercial interest in the Chukchi Sea than the Beaufort Sea and therefore fewer baseline sea ice data are available. In addition, the Pacific sector of the Arctic is undergoing some of the most rapid environmental changes on Earth, which reduce the value of data from previous decades for planning and design purposes. However, Arctic stakeholders, including academics, industry executives, state and federal regulators, and local communities are rising to the challenge, and there is currently an unprecedented number of active observing programs in the region.
Chukchi and Beaufort Sea Bathymetry
Sea Ice Age Ice in Beaufort Chukchi Seas