Question: If Obama's top science advisor is warning of an Arctic free of ice year-round, why should we spend $3.2 billion for four new icebreakers?

Shell-Led Arctic Push Finds U.S. Shy in Icebreakers: Energy - Bloomberg

Without more icebreakers, the [Coast Guard] service will be “unable to accomplish its Arctic missions,” according to a report last year by the Homeland Security Department’s inspector general.
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Even as ice recedes, the Arctic remains a vast frozen area with hurricane-strength storms, below-freezing temperatures [Wait, what?  So you don't need CO2-warmed water to provide the energy required for hurricane-strength storms?] and large ice floes, making icebreakers critical.

“Even with the open sea lanes, the Arctic is immensely dangerous,” Peter Harrison, director of the school of policy studies at Queen’s University in Ontario, whose work focuses on the Arctic, said at a Brookings Institution conference on the subject last month. “If anyone thinks it’s like Lake Michigan in July and August, they are dreaming in Technicolor.”

Papp said the Coast Guard eventually would need three heavy-duty and three medium-duty icebreakers for the Arctic. It now has one medium-duty icebreaker and two heavy-duty ones dating from the 1970s, neither of which is currently operable. The service plans to repair one of them.

That means the U.S. would need to build four icebreakers -- two heavy-duty and two medium-duty -- with an estimated total cost of $3.2 billion, according to a Congressional Research Service report in April.

Obama’s Science Adviser Warns Of Ice Free Winters In The Arctic | Real Science

John Holdren is Paul Ehrlich’s lifetime scientific partner, and Obama’s top science adviser.

[Holdren] "…if you lose the summer sea ice, there are phenomena that could lead you not so very long thereafter to lose the winter sea ice as well."