By Will McCarry
July 10, 2025
5 things you didn’t know about sea-level rise
4 min
But there’s more to this story than you might realize. Here are a few facts about sea-level rise that you might not know.
1. It’s not just the melting ice.
So yes, melting ice matters. But the oceans themselves are also swelling with heat.
2. Seas aren’t rising at the same pace around the world.
It might seem like all the oceans would rise evenly — after all, they’re connected like one giant bathtub.
Of course, your bathtub probably doesn’t have shifting currents and stormy weather, which influence how ocean water moves — and where it ends up.
Earth’s mass isn’t spread out evenly. Big features — like mountain ranges, dense rock and especially ice sheets — create stronger gravitational pulls. Ice sheets, in particular, are so heavy they actually draw ocean water toward them, raising sea levels in nearby regions.
But when those ice sheets melt, they lose mass — and their gravitational pull weakens. The water that was once drawn in starts to move away. Ironically, this means places close to melting ice, like Greenland or Antarctica, may see sea levels drop — while places farther away, like the U.S. East Coast, end up with more of that water and higher seas.
3. Some islands are in trouble — but not for the reason you might think.
But as seas rise, they push up the salty water beneath the island, squeezing and flooding this fragile lens. Saltwater can seep into wells or break through the surface, making the island’s water too salty to drink.
4. Seas could rise too fast for mangrove forests to keep up.
Mangrove forests are tough. They thrive where few trees can — right at the ocean’s edge, rooted in salty water and soft mud. They buffer coastlines from storms, shelter marine life and store massive amounts of carbon in their tangled roots.
But even mangroves can’t take everything the sea throws at them.
Without space to move or time to grow, even these salt-tolerant survivors may be overwhelmed.
5. We can’t stop sea-level rise entirely — but we can shape what happens next.
But what we do today still matters. Cutting emissions, protecting coastal ecosystems like mangroves, and giving communities time and resources to adapt can mean the difference between manageable impacts — and devastating ones.
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