Imagine your favourite sunny beach. Anywhere will do. You look out and see the ocean stretching to the horizon. To a glaciologist, that view is not just water; it’s melted ice.

Our new study shows that the best case sea-level rise scenarios may now be out of reach.

Around 20,000 years ago, during the most recent ice age, the Earth was about 5°C cooler than today. Vast ice sheets, comparable in scale to Greenland and Antarctica, covered Canada, northern Europe, and other regions. Those ice sheets formed as water evaporated from the oceans, fell as snow, and accumulated year after year on land.

Locked away as ice, that water was removed from the ocean, lowering sea level by around 130m and reshaping the planet’s coastlines. You could have walked from Britain to mainland Europe or from Siberia to North America as much of today’s continental shelf was dry land.

Between 20,000 and 10,000 years ago, global temperatures increased and those ice sheets melted. Sea level rose, flooding coastal plains and river valleys, and leading to modern coastlines. The lesson from Earth’s recent history is simple: When global temperature changes, sea level changes, and coastlines change with it.

Sea level rise has three main causes. First, as the........

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