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Sea level rise, explained

Oceans are rising around the world, causing dangerous flooding. Why is this happening, and what can we do to stem the tide?

By Christina Nunez
PUBLISHED
Climate change / sea-level rise in Kiribati
Families from Kiribati’s outer atolls are flocking to South Tarawa for jobs, education, and health care, swelling the population to more than 50,000. Newcomers are often forced to live in marginal areas prone to flooding by high tides.

As humans continue to pour greenhouse gases into the atmosphere, oceans have tempered the effect. The world's seas have absorbed more than 90 percent of the heat from these gases, but it’s taking a toll on our oceans: 2018 set a new record for ocean heating.

Many people think of global warming and climate changeas synonyms, but scientists prefer to use “climate change” when describing the complex shifts now affecting our planet’s weather and climate systems.

Rising seas is one of those climate change effects. Average sea levels have swelled over 8 inches (about 23 cm) since 1880 , with about three of those inches gained in the last 25 years.Every year, the sea rises another .13 inches (3.2 mm ).

The change in sea levels is linked to three primary factors, all induced by ongoing global climate change:

    Thermal expansion: When water heats up, it expands. About half of the sea-level rise over the past 25 years is attributable to warmer oceans simply occupying more space. Melting glaciers: Large ice formations such as mountain glaciers naturally melt a bit...
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