Sailing in the Arctic and the Antarctic is no easy feat. To help scientific and other craft navigate these frozen waters, the U.S. Coast Guard employs a small fleet of icebreakers—powerful ships with reinforced hulls that clear the way for other vessels. This past spring the Coast Guard, which has not built a heavy polar vessel in four decades, took a preliminary but crucial step toward expanding its fleet by testing ship models at one of the world's largest ice-tank facilities, located in Canada. It hopes to start building the first new heavy icebreaker in 2020, with completion scheduled for 2023.

The Coast Guard now relies largely on just two vessels in the polar seas. The heavy ship Polar Star conducts the annual Operation Deep Freeze resupply run to McMurdo Station, the largest U.S. Antarctic research base. The Healy, a medium-size ship, has better scientific facilities and operates mostly in the Arctic. A Coast Guard without heavy icebreakers would face huge challenges in performing search-and-rescue missions, responding to oil spills, protecting U.S. fisheries or supporting navy operations in the polar oceans.

In the Coast Guard's spring tests, small-scale models navigated an ice sheet as long as one-and-a-half Olympic-sized swimming pools at the National Research Council's ice-tank test facility in Newfoundland to measure various designs' resistance, power and maneuverability (shown below). The ice-tank trials were intended to evaluate potential heavy polar icebreaker designs for the future fleet, says Alana Miller, a Coast Guard representative. The most promising performers will set the design standards for building the full-size ships. Ultimately the Coast Guard aims to grow its fleet to include three heavy and three medium icebreakers.

Credit: Courtesy of National Research Council of Canada

The current U.S. vessels have mainly been used to support scientific research. But mission priorities will likely shift as a warming climate opens Arctic waters to more tourism, shipping and commercial fishing. And energy companies may once again look to tap Arctic oil and gas reserves if prices rise and drilling rights can be secured.

Melting sea ice does not automatically mean smooth sailing, however. Vessels would still encounter plenty of dangerous conditions, according to a 2017 report by the nonprofit Council on Foreign Relations. Researchers still need icebreaking capability to study global warming's effects on polar environments—and climate change will sharpen this need well beyond scientific missions. “Going forward, the Coast Guard will likely need to be able to conduct a similar set of missions in the Arctic [as] they conduct in the lower-48 states, [such as] fisheries enforcement, search and rescue, and law enforcement,” says marine scientist Robert Campbell, chair of the Arctic Icebreaker Coordinating Committee at the University–National Oceanographic Laboratory System.

“I don't see how, without an increase in the number of icebreakers, we will be able to maintain a significant presence in the Arctic,” Campbell says. “We will by default have to cede leadership on issues in the Arctic—including those that pertain to security—to other nations.”

In fact, some experts and members of Congress have warned of an “icebreaker gap,” noting that Russia has more than 40 such vessels. But this argument is somewhat misleading because Russia's navy and economy depend more on Arctic routes than the U.S.'s do, says Andreas Kuersten, a law clerk at the U.S. Court of Appeals for the Armed Forces. Still, Kuersten agrees that the U.S. needs new ships: “If someone gets stuck or if someone needs something delivered, [they] don't want to have to call up Russia to steam across the ocean.”

Funding for icebreakers has “fallen between bureaucratic cracks” in past years, says public policy expert Sherri Goodman, a senior fellow at the Woodrow Wilson International Center for Scholars and a member of the Arctic Task Force at the Council on Foreign Relations. She says that the Coast Guard has shouldered the burden of building new vessels while government defense spending increases have gone elsewhere. But the icebreaker-acquisition program began grinding forward during the Obama administration and has requested a major funding boost in the fiscal year 2017 budget.

For its current missions the U.S. National Science Foundation charters private research ships such as the Nathaniel B. Palmer, which can crunch through three feet of ice at three nautical miles per hour. But such vessels are no match for the Coast Guard's—the Healy can breach ice that is eight feet thick by backing up and ramming it, and the Polar Star can smash through 21 feet of ice with the same “back and ram” technique. Future icebreakers will also need this ability.

An expanded fleet of six vessels means off-duty ships would have time for maintenance in port, Goodman says. That backup also means rescue capability if a lone icebreaker runs into trouble. As the planet warms and more ships enter Arctic and Antarctic waters, the Coast Guard hopes to finally break the deep freeze on new icebreakers and lead the way.