One drastic proposal for for saving the Arctic ice is to dam the Bering strait. By limiting the heat and water flow in this would putatively preserve the ice. Besides being a very challenging engineering task, this would have other huge and likely unpredictable consequences. On the positive side, it would permit rail and perhaps road traffic between the US and Russia as well as supporting trans Arctic sale of Russian oil and gas, as well as other trade. The normal annual flow through the Bering strait is about 1 Sverdrup (10^6 m^3/s), or about the combined flow of every river in the world (or so I'm told*). So there could be hydroelectic potential too.
I am in no way condoning or endorsing this idea - it looks pretty damn dangerous.
*For comparison, the number one river, the Amazon, is about 20% of this, and the number 2, the Congo, is 4%. The biggest North American rivers, the Mississippi and the Saint Lawrence, are about 1.6% each.