evidence: In 2021, the IPCC concluded with high confidence that global mean sea level is rising at rates unprecedented in at least the last 3,000 years due to human-induced global warming. This technical brief provides a summary of the latest science on sea-level rise and its present-day and projected impacts — including coastal flooding — at a global and regional level, with a focus on major coastal cities in the Group of Twenty (G20) countries and the Pacific Small Island Developing States. The findings demonstrate that sea-level rise is affecting the lives and livelihoods of coastal communities and low-lying island nations around the world today, and it is accelerating. The climate actions and decisions taken by political leaders and policymakers in the coming months and years will determine how devastating these impacts become and how quickly they worsen.