In my introductory chapter, I reviewed how coastal biodiversity may respond to sea level rise (SLR), including potential expansions, shifts, contractions, or extirpations. Using a trait-based framework, I identified characteristics that may make species more or less vulnerable to SLR. Coastal waterbirds emerged as key indicators for future research due to their high vulnerability to habitat loss. Chapter 1 presents a regional assessment of SLR impacts in Northwest Mexico—one of the most important areas for waterbirds along the Pacific Flyway. Using the red knot (Calidris canutus roselaari) as a model species, I found that 55% of current wetland habitat could be permanently submerged by 2050, while remaining high-quality habitat may lose 20% of its suitability. These changes could accelerate red knot declines and affect many other species. Chapters 2, 3, and 4 explore how sea level rise affects all aspects of the waterbird life cycle—breeding, feeding, and roosting—revealing vulnerabilities across each essential stage. Chapter 2 focuses on the breeding impacts of SLR for two threatened beach-nesting birds in Ensenada, Mexico: the Least Tern (Sternula antillarum) and Snowy Plover (Anarhynchus nivosus). Tidal flooding already causes 18% of nest failures. However, nests on berms—elevated sand platforms—had 76% higher survival, suggesting berms are a key feature to mitigate flood risk. In Chapter 3, I evaluated how long-term SLR could impact foraging habitats in Guerrero Negro Lagoon for a 28-species waterbird community. By 2100, red knots may lose 43% of their low-tide foraging habitat and experience 86% less foraging time. Thirteen small-bodied species are projected to be affected a decade earlier than larger species, indicating cascading community-wide effects. Chapter 4 documents a novel strategy used by waterbirds during spring tides: ephemeral roosts on floating rafts of dead seagrass. These small rafts supported up to 60 birds/m² and 25 species, representing key roost habitats during high tides—a proxy for SLR. Their effectiveness suggests potential for nature-based solutions to mitigate roosting habitat loss. Overall, my dissertation underscores the urgent need to plan for both immediate and long-term impacts of SLR, with species-specific insights and nature-based solutions critical for conserving vulnerable coastal bird populations.