Glaciologist Kristin Poinar explores the mysterious world beneath Greenland’s massive ice sheet - a story of hidden water, ancient landscapes, and rapid climate change.

Using ice-penetrating radar, scientists have uncovered vast networks of subglacial lakes and rivers flowing beneath nearly two miles of ice. These meltwater systems act like natural lubricants, allowing the ice to slide more quickly toward the ocean. As the ice flows faster, more of it breaks off and melts into the sea, contributing to rising sea levels.

But what surprised scientists even more was the discovery of a massive canyon carved by ancient rivers long before Greenland was covered in ice. This canyon stretches more than 750 kilometers and plunges nearly a mile deep. It still plays an active role today by guiding water beneath the ice and influencing how fast it moves.

These discoveries show that Greenland’s ice sheet is not a solid, frozen block. It is alive and in motion. When warmer summers produce more surface meltwater, that water drains through crevasses and reaches the bottom. There, it joins the hidden river system and accelerates the ice flow.

Poinar explains that this interaction between surface melt and subglacial water systems was not fully accounted for in earlier climate models. As a result, we may have underestimated how quickly Greenland’s ice could disappear and how much it could raise sea levels.

She ends her talk with a warning and a call to action. The ice sheet is more dynamic and vulnerable than we thought. Understanding what lies beneath it is essential for predicting sea level rise and preparing for the future of our planet.

What is under Greenland’s ice is no longer hidden and what we learn from it may shape our response to climate change for decades to come.

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