Two Greenland Glaciers Sitting Right Beside Each Other Are Melting at Radically Different Speeds

Sunday, 24 June 2018 - 4:03PM
Earth
NASA
Sunday, 24 June 2018 - 4:03PM
Two Greenland Glaciers Sitting Right Beside Each Other Are Melting at Radically Different Speeds
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NASA
Much like other glaciers around Earth's two poles, the Inglefield Gulf in northwest Greenland is melting and gradually contributing to the planet's rising sea level.

But there are some confusing aspects to these particular glaciers that scientists didn't initially understand: two large chunks of ice in the gulf, called the Tracy and Heilprin glaciers, are melting at dramatically opposing speeds despite being side by side with each other. It took a five year investigation of how the warming oceans are impacting Greenland, but NASA thinks they've finally figured out what's going on.

These particular glaciers have been melting down for a long time, and have been recorded flowing water into the gulf since 1892. In the approximately 125 years since then, the Heilprin glacier has shrunk by only 2.5 miles (4 kilometers) while Tracy is now 9.5 miles (15 kilometers) farther upstream than it used to be. Again, they're close together and there's no visible reason why they're acting so differently.



NASA runs a campaign called Oceans Melting Greenland (OMG, ignore the silly acronym), which specifically looks for evidence that ocean water is running underneath Greenland ice and melting it down from below. So when it happened to pick up plumes of water running underneath the glaciers, it was the perfect tool to examine this, and it dispatched a boat into the gulf back in 2016 to collect data.

As it happens, these plumes of water were precisely the culprit - the plume beneath Tracy was much warmer than the cold plume beneath Heilprin, explaining why Tracy has lost nearly four times as much ice over the years. Of course, now the next question is simple: what on Earth is causing such radically different streams of water to run underneath these two neighbors?

That can be explained by data NASA took even earlier, with their Operation IceBridge project that maps out icy regions of the planet. It had detected about a decade ago that the Tracy glacier extends much farther underground, reaching down 2,000 feet (610 meters) to the bedrock below. Meanwhile, Heilprin goes only half as deep at 1,100 feet (350 meters).




Because of this, Tracy has better access to the warmer waters that run deeper underground. And when its ice melts, it causes even more damage as the melting water pulls in more of the underground water and forms a plume. Heilprin might be a larger glacier than Tracy, but it's touched by much cooler waters and doesn't melt as quickly.

The results from OMG were just published in the journal Oceanography, but the campaign's other investigations will continue through 2020. Greenland may not be as massive as your nearby Mercator projection would suggestion, but it's still a large country full of melting ice, and we'll need to understand that in the coming years as climate change continues and sea levels rise.
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