structural:expansion, structural:reformatting, information:classification
Recent changes

Between 1901 and 2018, the average global sea level rise was 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This is faster than the sea level has risen over the past 3,000 years, if not longer. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise, with another 42% resulting from thermal expansion of water.

Sea level rise lags behind changes in the Earth 's temperature, and sea level rise will therefore continue to accelerate between now and 2050 in response to warming that has already happened. What happens after that depends on human greenhouse gas emissions. Sea level rise would slow between 2050 and 2100 if there are very deep cuts in emissions. It could then reach slightly over 30 cm (1 ft) from now by 2100. With high emissions it would accelerate. It could rise by 1.01 m (3 + 1 ⁄ 3 ft) or even 1.6 m (5 + 1 ⁄ 3 ft) by then. In the long run, sea level rise would amount to 2–3 m (7–10 ft) over the next 2000 years if warming amounts to 1.5 °C (2.7 °F). It would be 19–22 metres (62–72 ft) if warming peaks at 5 °C (9.0 °F).

Rising seas affect every coastal and island population on Earth. This can be through flooding, higher storm surges, king tides, and tsunamis. There are many knock-on effects. They lead to loss of coastal ecosystems like mangroves. Crop yields may reduce because of increasing salt levels in irrigation water. Damage to ports disrupts sea trade. The sea level rise projected by 2050 will expose places currently inhabited by tens of millions of people to annual flooding. Without a sharp reduction in greenhouse gas emissions, this may increase to hundreds of millions in the latter decades of the century. Areas not directly exposed to rising sea levels could be vulnerable to large-scale migration and economic disruption.

Local factors like tidal range or land subsidence will greatly affect the severity of impacts. There is also the varying resilience and adaptive capacity of ecosystems and countries which will result in more or less pronounced impacts. For instance, sea level rise in the United States (particularly along the US East Coast) is likely to be 2 to 3 times greater than the global average by the end of the century. Yet, of the 20 countries with the greatest exposure to sea level rise, 12 are in Asia, including Indonesia, Bangladesh and the Philippines. The greatest impact on human populations in the near term will occur in the low-lying Caribbean and Pacific islands. Sea level rise will make many of them uninhabitable later this century.