Explainer: How sea level rise poses an ‘existential threat’ to humans, heritage and nature

For millions of people around the world, rising sea levels are already reshaping economies, livelihoods and cultures.

The world’s oceans are currently rising at a faster rate than at any time in at least the past three millennia, with human influence the “ dominant cause ” of sea level rise since at least 1970.

At the UN general assembly in New York this week, world leaders are set to adopt a high-level declaration on the “existential threats” posed by sea level rise.

The declaration notes: “Sea level rise is not a distant scenario, but a real and lived experience for many.”

On average, global sea levels rose by 20 centimetres (cm) between 1901 and 2018.

This is due to both the melting of glaciers and ice sheets and the expansion of seawater as it warms, as well as changes in land-water storage .