Marine protected areas (MPAs) are central to global biodiversity policy, however, most MPAs were 19 designed around relatively fixed species distributions and historical habitat conditions. Accelerating 20 ocean warming, deoxygenation, and habitat redistribution now challenge this static model. Here, we 21 combined global climate diagnostics, long-term coastal observations, species-distribution modelling, 22 and MPA assessments to evaluate whether existing conservation systems remain aligned with 23 climate-sensitive habitats. We showed that coastal waters are global convergence zones where 24 accelerated warming, dense human populations, and high marine biodiversity overlap. In four sentinel 25 bays (the Baltic Sea, Chesapeake Bay, Greater Bay Area, and San Francisco Bay), we found that 26 substantial reductions in local nutrient loads and CO2 emissions coincided with continued ecological 27 deterioration, including a hypoxia expansion of 21% to 200% and fish biomass-index declines of 37% 28 to 80%. Structural equation modelling of the Greater Bay Area identified oxygen depletion as a major 29 pathway linking climate-driven environmental change to reduced fish richness. Species-distribution 30 models showed that core habitats for representative flagship species contracted by approximately 40% 31 to 65% between the years 2000 and 2020, and habitat centroids shifted away from existing protected-32 area coverage. Globally, we saw that MPA climate pressure exposure would intensify under SSP2-33 4.5, with high-pressure grid cells increasing from 5% to 15% by 2050 and low-pressure cells declining 34 from 50% to 7%. We translated these patterns into a climate-sensitive diagnostic framework based 35 on climate pressure exposure, core habitat overlap, and redistribution alignment, distinguishing 36 functionally mismatched, exposed-but-important, transition-zone, and climate-refugia MPAs. Our 37 findings indicated that 30×30 and the BBNJ Agreement must move beyond static area-based targets 38 towards climate-adaptive conservation.