For years, scientists thought Antarctica was the main source of meltwater that flooded the planet's oceans after the last ice age. But new research has flipped that story, and it has major implications for today's rising seas.

What's happening?

A new study led by Tulane University revealed that melting ice sheets in North America added more than 30 feet to global sea levels between 9,000 and 8,000 years ago, a massive shift that dramatically reshaped the world's coastlines.

"[This] requires a major revision of the ice melt history during this critical time," said geology professor Torbjörn Törnqvist, one of the study's authors, in a statement. "The amount of freshwater that entered the North Atlantic Ocean was much larger than previously believed, which has several implications."

By studying ancient marshes sediments buried in the modern-day New Orleans area and comparing them to global sea-level data, the team found that North American ice, not Antarctic ice, was the main driver of this melt surge, as Tulane's summary detailed.

The finding adds new urgency to modern concerns. Scientists warn that the same process, only now fueled by human-caused overheating, is accelerating again today.

Why is this phenomenon concerning?

The researchers' discovery points to the North Atlantic's fragile balance. When that much freshwater enters the ocean, it can disrupt a key system of ocean currents known as the Atlantic Meridional Overturning Circulation.

The AMOC helps regulate weather patterns across the Northern Hemisphere. If it weakens, the impacts could be severe — potentially including harsher winters in Europe and faster-rising seas along the U.S. East Coast.

And the ice melt warnings don't stop there. In Svalbard, researchers observed the archipelago over just six weeks lose 1% of its ice cover — reportedly about 62 gigatons or enough to raise global sea levels by 0.16 millimeters.

And, in Antarctica, this summer saw the second-lowest ice coverage in recorded history, with missing ice equal to about the size of Pakistan.

Together, these findings paint a picture of a rapidly changing Earth, one in which ancient melt patterns offer clues to a dangerously familiar future.

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What's being done about melting ice?

While we can't stop ancient ice from melting, we can slow the warming that's accelerating today's sea-level rise. 

One top priority is transitioning from dirty energy to cleaner, more affordable sources like solar and wind power.

In addition, we can do something that's perhaps even more powerful: stay informed. By keeping up with the critical climate issues that shape our environment, we can make eco-conscious daily choices, back climate-friendly businesses and organizations, and allow our knowledge to guide us when it comes time to head to the polling booths.

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