One of the ships researchers use to crunch through the icy waters of the Arctic Ocean is the U.S. Coast Guard Cutter Healy. Equipped with four 10,000-horsepower diesel engines, it rams ice under its sloping hull, which is reinforced with 2-inch-thick steel plates.

Two other icebreakers, Polar Star and Polar Sea, support scientific missions mainly in Antarctica. Each ship can carry two Coast Guard helicopters and has multiple internal laboratories and room for more portable science laboratories on deck, according to the National Science Foundation, which funds much of the polar research conducted on the ships, and helps fund the NewsHour's Science Unit.

Federal agencies and other institutions use these floating labs. In the summer of 2007, the USCGC Healy completed the third in a series of Arctic floor mapping missions, conducted by the National Oceanic and Atmospheric Administration and the Joint Hydrographic Center at the University of New Hampshire in Durham.

Scientists are charting the seafloor in the remote northern Chukchi Cap to try to add it to the part of the continental shelf the United States controls, extending its rights to the oil and gas resources there. Any additions have to meet certain geologic criteria under the U.N. Convention on Law of the Sea. The data gleaned during the cruises also help researchers better understand fisheries' habitats and improve climate models, according to NOAA.

"What struck us this year was how little ice there was and how broken up it was," said the mission's chief scientist, Larry Mayer of UNH, adding that the general consensus is that global warming is a major contributor.

The icebreakers are equipped with multibeam sonar, which bounces acoustic signals off the seafloor to map geologic features such as pockmarks that indicate the release of gas from the sediment. The system works best in a quiet environment, rather than a noisy icebreaker, but the researchers make do, Mayer said.

The team's next Arctic floor mapping mission is planned for 2008.

-- By Larisa Epatko, Online NewsHour