Alaska’s expanding glacier lakes signal both risk and new beginnings

As glaciers in the Saint Elias Mountains of southeast Alaska¹ retreat under a warming climate, hundreds of glacial lakes are expanding at an accelerating pace. Scientists project that these lakes could quadruple in size over the next one to two centuries, fundamentally reshaping the region’s landscape. This expansion is driven in part by the lakes themselves. Because water absorbs more heat than ice or land, glaciers that disappear in lakes melt faster, creating a feedback loop of retreat and growth. Since 1986, glacial lakes in southeast Alaska have already expanded by about 60 percent, covering roughly 1,300 square kilometers. Researchers estimate they could eventually reach 5,500 square kilometers. 

While glacier loss is often framed as purely negative, these lakes bring ecological benefits. As meltwater settles in lakes, sediment drops out and water warms slightly before flowing downstream. This stabilizes river channels and creates more hospitable environments for vegetation and wildlife. In particular, salmon populations would benefit, with thousands of kilometers of river habitat becoming more suitable for reproduction. However, the transformation is not without danger. Expanding lakes can trigger flooding, alter river courses, and destabilize surrounding terrain. In some Alaskan communities, annual outburst floods already pose serious risks. Ultimately, Alaska’s growing glacier lakes illustrate how climate change is not only erasing ice, but also creating entirely new ecosystems, bringing both opportunity and upheaval. 

¹ https://www.sciencenews.org/article/glacier-lakes-alaska-growing-climate

This article was adapted from Science News’ Lakes are growing in Alaska. That’s not entirely a bad thing by Douglas Fox.

Fox, Douglas. “Lakes are growing in Alaska. That’s not entirely a bad thing.” Science News, March 9, 2026. https://www.sciencenews.org/article/glacier-lakes-alaska-growing-climate.