This chapter assesses past and future contributions to global, regional, and extreme sea level changes, associated risks to low-lying islands, coasts, cities, and settlements, and response options and pathways to resilience and sustainable development along the coast. It follows the risk framework of the IPCC Fifth Assessment Report (AR5), assessing risk in terms of hazard, exposure, and vulnerability. The chapter is structured into four main sections: the physical basis for sea level change and associated hazards, exposure, vulnerability, impacts, and risk related to sea level rise, responses to sea level rise, and governance challenges and ways forward. Global mean sea level (GMSL) is rising and accelerating, with the dominant source of GMSL rise being the loss of ice from glaciers and ice sheets. GMSL has increased from 1.4 mm yr⁻¹ over 1901–1990 to 3.6 mm yr⁻¹ over 2006–2015. The dominant cause of GMSL rise since 1970 is anthropogenic forcing. Past climate states warmer than pre-industrial, such as the Last Interglacial and mid-Pliocene Warm Period, had significantly higher sea levels, but the exact magnitude is uncertain. Non-climatic anthropogenic drivers, including subsidence and demographic trends, have increased exposure and vulnerability to sea level rise (SLR) and extreme sea level (ESL) events. Coastal ecosystems are already impacted by SLR and other climate-related changes, but their ability to adapt is being compromised by human activities. Coastal risk is dynamic and increasing due to changes in infrastructure, livelihoods, agriculture, and habitability. A diversity of adaptation responses have been implemented, including hard coastal protection measures, ecosystem-based adaptation, and retreat. Future SLR is projected to be faster under all scenarios, with GMSL rising between 0.43 m and 0.84 m by 2100 under RCP2.6 and RCP8.5. Beyond 2100, sea level will continue to rise for centuries due to deep ocean heat uptake and mass loss of ice sheets. Under RCP8.5, estimates for 2100 are higher and the uncertainty range larger than in AR5. Antarctica could contribute up to 28 cm of SLR by the end of the century. SLR is not globally uniform and varies regionally. Thermal expansion, ocean dynamics, and land ice loss contribute to regional departures of about ±30% around GMSL rise. Subsidence caused by human activities is the most important cause of relative sea level rise in many delta regions. ESL events that are historically rare will become common by 2100 under all RCPs. Low-emission scenarios reduce but do not eliminate risk to low-lying coasts and islands. Non-climaticThis chapter assesses past and future contributions to global, regional, and extreme sea level changes, associated risks to low-lying islands, coasts, cities, and settlements, and response options and pathways to resilience and sustainable development along the coast. It follows the risk framework of the IPCC Fifth Assessment Report (AR5), assessing risk in terms of hazard, exposure, and vulnerability. The chapter is structured into four main sections: the physical basis for sea level change and associated hazards, exposure, vulnerability, impacts, and risk related to sea level rise, responses to sea level rise, and governance challenges and ways forward. Global mean sea level (GMSL) is rising and accelerating, with the dominant source of GMSL rise being the loss of ice from glaciers and ice sheets. GMSL has increased from 1.4 mm yr⁻¹ over 1901–1990 to 3.6 mm yr⁻¹ over 2006–2015. The dominant cause of GMSL rise since 1970 is anthropogenic forcing. Past climate states warmer than pre-industrial, such as the Last Interglacial and mid-Pliocene Warm Period, had significantly higher sea levels, but the exact magnitude is uncertain. Non-climatic anthropogenic drivers, including subsidence and demographic trends, have increased exposure and vulnerability to sea level rise (SLR) and extreme sea level (ESL) events. Coastal ecosystems are already impacted by SLR and other climate-related changes, but their ability to adapt is being compromised by human activities. Coastal risk is dynamic and increasing due to changes in infrastructure, livelihoods, agriculture, and habitability. A diversity of adaptation responses have been implemented, including hard coastal protection measures, ecosystem-based adaptation, and retreat. Future SLR is projected to be faster under all scenarios, with GMSL rising between 0.43 m and 0.84 m by 2100 under RCP2.6 and RCP8.5. Beyond 2100, sea level will continue to rise for centuries due to deep ocean heat uptake and mass loss of ice sheets. Under RCP8.5, estimates for 2100 are higher and the uncertainty range larger than in AR5. Antarctica could contribute up to 28 cm of SLR by the end of the century. SLR is not globally uniform and varies regionally. Thermal expansion, ocean dynamics, and land ice loss contribute to regional departures of about ±30% around GMSL rise. Subsidence caused by human activities is the most important cause of relative sea level rise in many delta regions. ESL events that are historically rare will become common by 2100 under all RCPs. Low-emission scenarios reduce but do not eliminate risk to low-lying coasts and islands. Non-climatic