Evaluate the cost-effectiveness, ecological impacts, and social equity implications of managed retreat versus hard seawall construction as strategies for urban coastal flood risk management in New York City under RCP4.5 and RCP8.5 sea-level rise projections for 2050–2100. Using scenario data, quantify lifecycle costs (e.g., NPV), compare ecosystem service losses/gains and habitat impacts, assess distributional effects on vulnerable communities and displacement risks, analyze adaptive capacity and co-benefits, and synthesize uncertainty to justify a preferred strategy or hybrid alternative with recommended policy measures.