U.S. Navy should begin to strengthen capabilities in the Arctic, prepare for more frequent humanitarian missions, and analyze potential vulnerabilities of seaside bases and facilities, in response to effects of climate change, said a report issued Thursday by the National Research Council.

Although the ultimate consequences of future climate change remain uncertain, many effects such as melting sea ice in the Arctic and rising sea levels are already under way and require U.S. naval monitoring and action, warned the report, which was sponsored by the U.S. Department of the Navy.

"Even the most moderate predicted trends in climate change will present new national security challenges for the U.S. Navy, Marine Corps, and Coast Guard," said retired navy admiral Frank Bowman, co-chair of the committee that wrote the report. "Naval forces need to monitor more closely and start preparing now for projected challenges climate change will present in the future."

Summer sea ice in the Arctic is declining at an estimated rate of 10 percent per decade or more, and Arctic Ocean sea lanes could be open as early as the summer of 2030. U.S. security challenges are growing as shipping, oil and gas exploration, and other activities increase in the region, the report says. To protect U.S. interests, the country's naval forces need to fund a strong, consistent effort to increase Arctic operations and cold weather training programs.

In addition, for Arctic national security operations, the U.S. Coast Guard should have operational control of the nation's three icebreakers, rather than the National Science Foundation. The report reiterates a previous Research Council report that says the icebreakers, which should provide access to many sites throughout the year, are old, obsolete, and underfunded. The Coast Guard should have the authority to determine future icebreaker requirements.

The report noted that Naval forces will also need to meet growing demands for humanitarian assistance and disaster relief efforts in response to a range of predicted crises created by climate change, including floods, droughts, intense storms, and geopolitical unrest. Of particular concern is the future of U.S. Navy hospital ships to provide evacuation services and trauma care.

The Navy and Marine Corps should retain the medical capability of the current two-ship hospital fleet at a minimum and also consider other options such as contracting with private ships to meet growing demands. In the near term, the report says, the Navy need not specifically fund new capabilities to deal with projected climate change but instead modify existing structures and forces as demands become more clear.

The report notes that rising sea levels accompanied by stronger, more frequent storm surges could leave U.S. naval installations vulnerable. An estimated 100 billion U.S. dollars worth of Navy installations would be at risk from sea-level rise of 1 meter or more. The Navy, Marine Corps, and Coast Guard should work together to ensure that a coordinated analysis addresses vulnerabilities of shore-based facilities to the consequences of climate change.