Dan Cohen AUTHOR Military installations on the East and Gulf coasts are extremely vulnerable to the impacts of climate change, with rising sea levels expected to threaten increasing amounts of coastal land over the coming decades, according to an analysis by the Union of Concerned Scientists released Wednesday.Coastal installations will experience more extensive tidal flooding and when hurricanes strike, deeper and more extensive storm surge flooding, the study concluded.“We’re now at the front end of the changes that will occur, with some installations already dealing with flooding during extreme high tides,” said Erika Spanger-Siegfried, lead author of the report. “Depending on how fast sea level rises in the second half of this century, tidal flooding will become a daily occurrence in some areas; that is, those places become part of the tidal zone as opposed to useable land.”Sea level increases — already up 8 inches globally since 1880 — are the product of rising temperatures and ice melt primarily caused by global warming. The East and Gulf coasts experience some of the fastest rates of sea level rise, according to the National Oceanic and Atmospheric Administration.By 2050, half of the 18 installations the study evaluated would experience 270 or more flood events per year — up from just 10 events per year today — under an intermediate sea level-rise scenario. Under the highest scenario, those installations likely would experience daily floods.Four sites — Naval Air Station Key West, Fla.; Naval Station Mayport, Fla.; Fort Eustis at Joint Base Langley-Eustis, Va.; and Marine Corps Recruit Depot Parris Island, S.C. — stand to lose one-fifth or more of their land by 2050 due to daily high-tide flooding under the highest sea level-rise scenario.“In 2070, all but a few [of 18 installations studied] are projected to see flooding once or twice every day. Shockingly, these aren’t even the worst-case scenarios,” said co-author and lead analyst Kristy Dahl.DOD has been addressing the problem in recent years. At Langley AFB, Va., for example, the Air Force has constructed a shoreline seawall and door dams to protect some of its buildings, and it has installed a pump system to remove flood waters.“But there’s a big gap between what’s being done and what’s needed,” said Spanger-Siegfried.Installations should plan collaboratively with surrounding communities to counter the impact of rising seas on housing, transportation systems and critical infrastructure on and off installations, the report recommended.Individual installations also will need more detailed analyses of how rising seas will affect their infrastructure, as well as additional resources to adapt to the changing conditions, according to the study.