The St. Elias Mountains in southeast Alaska are witnessing a significant transformation as over 100 glacial lakes expand rapidly. As glaciers continue to retreat, these lakes are projected to quadruple in size over the next century or two, according to a recent study published in the Proceedings of the National Academy of Sciences. This change is set to reshape landscapes, create modern habitats for salmon, and potentially alter the course of major rivers in the region.
“We are seeing the great age of ice retreat in Alaska,” remarked Daniel McGrath, a glaciologist at Colorado State University in Fort Collins. “These glaciers are just peeling back from the landscape,” revealing deep grooves carved into the Earth where new lakes are forming.
As the glaciers melt at an alarming rate, This proves critical to understand the implications of these growing lakes. “Understanding where these lakes are going to emerge is important,” stated Eran Hood, a glacial hydrologist at the University of Alaska Southeast in Juneau, “because it changes the whole nature of the downstream ecosystem.”
The Expanding Lakes of Southeast Alaska
Currently, the St. Elias Mountains lose approximately 60 cubic kilometers of ice each year. Glacial lakes in this region have already expanded by 60 percent since 1986, covering a combined area of around 1,300 square kilometers. Researchers speculate that the lakes will continue to grow, potentially reaching 5,500 square kilometers, an area comparable to Delaware.
To investigate the extent of this expansion, McGrath and his team combined satellite imagery with estimates of ice thickness, uncovering approximately 4,200 square kilometers of glacier-covered grooves adjacent to existing lakes. As the glaciers retreat, these grooves will likely fill with water, contributing to the rapid expansion of the lakes.
Impacts on River Systems
Notably, changes in lake size and glacier retreat could significantly impact river systems. For instance, Alaska’s Grand Plateau Glacier is set to retreat further from Alsek Lake, causing Alsek Lake and Grand Plateau Lake to merge, which may provide the Alsek River with a new, more direct route to the ocean. This shift could alter the river’s course by as much as 25 kilometers.
As lakes grow, they provide a more stable habitat for fish populations. Unlike the cold, rocky floodplains created by glaciers terminating on land, lakes allow meltwater to warm and settle before flowing into rivers. This stabilization can reduce sediment transport and result in more hospitable environments for fish, including salmon.
Research by Jonathan Moore, an aquatic ecologist at Simon Fraser University, indicates that as glacial lakes expanded over nearly four decades, downstream river channels stabilized, allowing vegetation like willows and bushes to flourish across floodplains. “It creates salmon habitat,” Hood explained, highlighting the potential for glacial retreat to improve conditions for salmon species, particularly the commercially important sockeye salmon.
Environmental Challenges Ahead
Despite these positive outcomes, the transformation of ecosystems due to expanding lakes is not without challenges. Moore cautions that such changes could be violent and dangerous. For example, Juneau residents experience annual flash floods from a lake dammed by the nearby Mendenhall Glacier, necessitating the construction of protective levees.
As the lakes and rivers continue to evolve, communities will need to adapt to the new environmental dynamics. This includes preparing for potential flooding and understanding the broader ecological impacts of shifting habitats on local wildlife.
Looking Forward
By the end of this century, researchers anticipate that all of the glacial lakes in the St. Elias region will be fully developed. As these lakes fill with water from retreating glaciers, the surrounding landscapes will continue to morph, creating both opportunities and challenges for local ecosystems and communities. Understanding these changes is crucial for effective conservation and management strategies in the face of climate change.
As we monitor these developments, it is essential to continue sharing knowledge and fostering dialogue about the implications of glacial retreat and lake expansion in Alaska. What do you think about the transformation taking place? Share your thoughts and insights in the comments below.
Disclaimer: This article is for informational purposes only and does not constitute professional advice.
