GWEN IFILL: Next, we head north to the Arctic Sea.
Thanks to climate change, there are now new waters to discover there. Melting ice has opened new routes for ships, and raised concerns about safety for maritime traffic in uncharted territory.
NewsHour’s April Brown reports part two of our series, Arctic Thaw.
APRIL BROWN: The vivid blue glaciers in Prince William Sound captivate tourists from all over the world. But they are slowly shrinking.
CODY HANNA, Klondike Express Captain: We're back here, you know, about five months out of the year every day, so we're watching these glaciers break off, move back, and we're seeing the change daily.
APRIL BROWN: Cody Hanna captains the Klondike Express tour boat. He says the melting glaciers create more navigable water.
CODY HANNA: Barry Glacier probably being one of the fastest-receding glaciers here in the Sound, and I believe, from what I have been told and the pictures I have seen of 2003 until now, we're over a mile back. That's a lot of water.
APRIL BROWN: Off the North Slope of Alaska, rapid ice melting is even more pronounced. Parts of the Arctic Ocean often look like this in the summer, ice-free.
James Overland is an oceanographer with NOAA, the National Oceanic and Atmospheric Administration. He's spent decades looking at the Arctic Sea ice trends.
JAMES OVERLAND, National Oceanic and Atmospheric Administration: It's a scary proposition that things are happening a lot faster than we thought even a few years ago.
APRIL BROWN: Last year, the Arctic summer sea ice extent was at a record low, shrinking significantly over the past decade and covering only about half the area it did in the early 1990s.
JAMES OVERLAND: The real scary thing that we're focusing on now is, it's not just the extent, but it's the thickness of the ice, and that's been going down dramatically.
APRIL BROWN: According to Overland, three-fourths of the volume of Arctic Sea ice have been lost since the 1980s. And while it's destroyed a lot of habitat for animals like the polar bear and walrus, it's opened the door for many businesses.
JAMES OVERLAND: Shell Oil was beginning to explore for oil in the Alaskan Arctic, and cruise ships.
APRIL BROWN: And just like his fellow mariners further north, Captain Hanna has no way to know if it's safe to sail in the open water the melting ice leaves behind.
He relies on detailed charts from NOAA, and has been talking with one of its representatives about updates that will let him know how close he can take his passengers to the glaciers that remain.
CODY HANNA: It definitely cannot be underestimated how important having these charts is. Obviously, someone came out here first. Someone explored. Someone probably bumped a few rocks, not something we want to do in our day and age, with the sophistication they have on the charts.
APRIL BROWN: Just off the shores of Alaska, a small survey boat is gathering the kind of data that eventually leads to the creation of charts Hanna and other mariners rely on. The scientists on board are painting the sea floor with sonar, going back and forth over a designated area, as if mowing a lawn. Slowly, hydrographic survey technician Barry Jackson sees something big.
BARRY JACKSON, Hydrographic Senior Survey Technician: I see there is an obvious object that is coming into view here. You can see the mast and the superstructure in there.
APRIL BROWN: After the information is thoroughly processed, it becomes clearer this is the outline of a shipwreck.
Previously unknown potential threats like this one are exactly what Jackson and Lieutenant Meghan McGovern are looking for.
WOMAN: We're part of the Department of Commerce, so we're here to make sure that commerce is safe, that they can navigate these waters. Alaska is very heavily trafficked with, you know, big ships, small ships, fishing boats all kinds of traffic that moves through here. And our job is to find the rocks and the shipwrecks and any other hazards that are there, so that so that those vessels don't run into anything.
APRIL BROWN: The small survey boat Jackson and McGovern are working on was launched from the NOAA Ship Rainier. Its captain is Commander Rick Brennan.
CMDR. RICK BRENNAN, National Oceanic and Atmospheric Administration: I think the surface of mars has been mapped better than our oceans have been.
APRIL BROWN: Brennan's ship and crew have spent the summer charting the popular fishing area off Alaska's Shumagin Islands, where the Rainier itself can mow a kilometer-wide path with sonar. Its summer cruise, as it's known, is part of a larger NOAA effort to get more information about the vast waters around the state, especially those in higher latitudes, where, if current trends continue, more ships are heading.
According to government figures, the number of vessels transiting through the Arctic has more than doubled since 2008, from about 120 to 250 last year, with tankers, cargo ships, and tugs leading the way. But there is sometimes little or no information to insure a safe passage, particularly in the Arctic Circle.
In many places, only rudimentary depth measurements exist, some dating back to the 1700s, when the British navy's Captain James Cook sailed around Alaska.
RICK BRENNAN: Well, as you proceed north from the Alaska Peninsula, and you start proceeding up towards Barrow and Prudhoe, it just -- the soundings or those measurements that we have of the -- you know, of how deep the water is just continue to get less and less and less, because those areas had never been mapped because they were covered with ice.
APRIL BROWN: And it's one of the reasons the Rainier's sister ship, the Fairweather, surveyed a path through the Arctic last summer, sailing north from the Aleutian Islands up the west coast of Alaska, through the Bering Strait, and into the waters off Alaska's North Slope, through the Chukchi, past Barrow, and into the Beaufort Sea beyond Prudhoe Bay.
As Arctic Sea ice continues to melt and human activity in the area grows, so, too, does the pressure on the Coast Guard. Its operations, both land and sea, are based here in Kodiak.
MAN: When that ice recedes, then the vessels are going to increase.
APRIL BROWN: And if something does go wrong in the roughly 500,000 square miles of water around the state, the Coast Guard is the agency that responds.
Commander Mark Vislay is the Kodiak Air Station's operations officer.
CMDR. MARK VISLAY, U.S. Coast Guard: One of our primary responsibilities is to ensure the safe and -- the security and safe operations of maritime traffic, search-and-rescue response to the distressed mariners.
APRIL BROWN: But the Coast Guard is also tasked with environmental protection and responding to potential disasters. In January, not far from the Kodiak base, the Royal Dutch/Shell rig Kulluk, which had been drilling off Alaska's North Slope, ran aground during a violent storm while being towed south.
The agency prepared for the possibility that thousands of gallons of diesel fuel and other fluids could leak out of the stranded rig. That didn't happen. But with an expanding area to cover and more vessels going through, Vislay admits the Coast Guard is being stretched.
MARK VISLAY: We can manage the risk, if you will, but we definitely are short of what we need to cover this entire area of responsibility up here in Alaska.
APRIL BROWN: All three members of Alaska's congressional delegation in Washington have long been calling for more general infrastructure and Coast Guard resources.
Democrat Mark Begich says it's been an uphill battle, but that lawmakers are slowly coming around.
SEN. MARK BEGICH, D-Alaska: When I came here five years ago, I'm not sure people really understood that there was an Arctic Ocean, to be very frank with you. And so having that discussion about the impacts of what's going on, on there, it's not a question if the Arctic will be developed. It's happening. The question is, how do we manage it?
APRIL BROWN: Meanwhile, the Coast Guard established a temporary forward operating base in the Arctic near the Bering Strait this summer. Last year, 480 vessels sailed through the 58-mile-wide passage between the U.S. and Russia. That's more than twice as many as in 2008.