As Earth's climate warms, glaciers are retreating. This is evident all around the world . Glacial retreat isn't always a peaceful process and can significantly effect the landscape. Our fleet of Earth-observing satellites bears witness to these changes.

In 2025, the retreating South Sawyer Glacier in Alaska's Tracy Arm, a fjord near Juneau, triggered a large landslide. As the debris from the landslide smashed into the water, it created a megatsunami that swept down the fjord into the ocean. On its way down, it reached a maximum height of 481 m (1,578 ft), the second highest tsunami known to humans.

A team of scientists led by Dan Shugar, a geomorphologist at the University of Calgary in Canada, reconstructed the tsunami and published their results in Science. It's titled " A 481-meter-high landslide-tsunami in a cruise ship–frequented Alaska fjord.…