Plan C: the St Lawrence Dam
1. Fully closing off Pacific waters from the Arctic by building a dam not at the very Bering Strait, the narrowest point, but instead further south in the Bering Sea, on the shallow plain of the continental shelf, connecting St Lawrence island to the mainland of Alaska and Siberia.
2. Optional, to increase benefits: diverting part of the lower Kuskokwim river flow, by digging an approximately 100 kilometre long canal, connecting this 9th largest river of the United States to the lower Yukon.
Effects
1. Temperature
Plan C will lead to a decrease in temperature in the Chuckchi (and the entire Arctic) similar to plan A, but perhaps even slightly greater, due to increased local albedo benefits, that in turn increase isolation.
2. Dynamics
Plan C will lead to a decrease in dynamics in the Chuckchi (and the entire Arctic) similar to plan A, with the difference that this effect will reach further south.
3. Salinity
Plan C will lead to a decrease in salinity in the Chuckchi (and the entire Arctic), because the only net water flow northward through the Bering Strait will originate in fluvial input, whereas all salt, oceanic inflow is blocked.
Plan C will also lead to the formation of a small basin in between the St Lawrence dam and the Bering Strait. Most likely the waters of this basin will become significantly sweeter over time, as it will be more or less ‘flushed’ by Yukon waters. It is therefore also likely this basin will easily freeze during winter months, and stay frozen to some point much further in spring than the present early unset of Bering and Chuckchi melting, creating the above mentioned albedo benefit. Although this effect will be local and small it does add dimension, literally, to the temperature border between the Pacific waters and the Chuckchi Sea.
Conclusion
Based upon the comparison of likely effects on three dominant factors influencing Arctic ice conditions plan C seems most potent.
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