IPCC estimates that, between 1901 and 2010, sea levels have risen about 20 cm worldwide, with strong local disparities. Since the 1990s this trend has accelerated dramatically, with an annual average rate of 3.2 mm. The IPCC estimates that, at current emissions level, average sea level rise will be 24-30 cm by 2065 and 40-36 cm by 2100. Even if emissions were stopped today, the impacts would continue to be felt for centuries.
The immediate causes of the sea-level rise are both ice melting and water thermal expansion, due to global warming. Many coastal areas are at risk of erosion, flood and salinisation of the groundwater. At least eight small islands in the Pacific Ocean have already disappeared, maybe more. An analysis by Climate Central found that, at current emission levels, by the end of the century up to 650 million people could live in land below the sea level or regularly flooded. Among the most vulnerable areas there are poor and densely populated countries, especially in Asia, such as Bangladesh, and the small Pacific islands. Eight of the world’s 10 largest cities are near a coast, according to the U.S. Atlas of the Oceans, and thus are potentially at risk.