The strongest winter nor’easters striking the U.S. East Coast are intensifying as ocean temperatures rise, according to peer-reviewed research published this week in the Proceedings of the National Academy of Sciences. The study, led by University of Pennsylvania climatologist Michael Mann, combed through 85 years of reanalysis data and identified 900 storms that met strict criteria for duration, track and central pressure. While the overall number of nor’easters has declined since 1940, the team found that maximum sustained wind speeds in the most powerful events have climbed about 6 percent, a gain that translates to a roughly 20 percent increase in destructive potential. Associated precipitation—rain or snow—has risen close to 10 percent. Warmer Atlantic surface waters supply additional moisture and energy, allowing the biggest systems to reach higher intensities, the authors said. The trend heightens flood and blizzard risks for densely populated coastal corridors from Washington to Boston, where individual nor’easters already cause an estimated $5 billion to $10 billion in damage. Mann warned that current coastal-hazard assessments often overlook the growing punch of these winter storms, leaving infrastructure and emergency-planning models out of step with emerging climate realities. The findings arrive as federal climate-risk tools are being scaled back. The National Centers for Environmental Information stopped updating its long-running billion-dollar disaster database in May, and administration officials this week suspended development of a model used to predict extreme rainfall frequency. Researchers say those decisions, coupled with the increasing severity of nor’easters, could hinder efforts to fortify communities against future storms.