Warmer Winters May Bring Major Ecological Changes To Northern Lakes, Study Warns

With rising temperatures, winters are getting shorter and warmer. Ice is melting rapidly, even in the world's coldest, snowiest regions. A new scientific study has found that lakes in northern regions, like the Arctic, could face the worst impacts as ice covers them for less time each year. The study published in Ecology Letters, was led by Ted Ozersky, a biologist at the University of Minnesota Duluth, along with researchers from Norway and Canada. The research focused on what happens to lakes during winter, especially those in far northern areas.

What Happens When Lakes Don't Freeze Like They Used To?

Scientists found that lakes closer to the poles are more susceptible to winter changes than lakes in more temperate (warmer) regions. That's because of how sunlight interacts with ice and snow.

At higher latitudes, a large part of the year's sunlight arrives during the time when lakes are still frozen. For example:

. Near the Arctic Circle (75°N), more than half of the annual sunlight hits the Earth while lakes are still covered in ice.

. Farther south (45°N), like in parts of the US or southern Canada, that number drops to about 25%.

These changes can have significant effects. Sunlight is critical for life in lakes for the sustenance of tiny plants that form the base of the food web. So, less ice or thinner ice in northern lakes means more light can enter the water that can boost productivity. However, more snow on the ice can block that light, reducing productivity. The balance is delicate.

Amanda Poste, a co-author of the study, explained that under these conditions, life under ice can still be very active. In fact, during long daylight periods in spring and early summer, the lake's food chain can be fuelled by under-ice plant growth. However, climate change is altering this pattern.

In some areas, increasing snow may block more light and reduce under-ice productivity. In others, faster ice melt during long daylight periods could actually increase plant growth. The result: big, unpredictable changes to the lake ecosystems.

Key Takeaways from the Study:

. High-latitude lakes are much more sensitive to changes in snow and ice than warmer regions.

. Climate change is creating new conditions in these regions that could change how much life these lakes support.

. These changes may lead to major shifts in productivity, food chains, and the timing of biological events like algae blooms or fish spawning.

Why This Matters

Researchers argue that what happens under the ice can have long-lasting impacts on the northern lakes. The researchers are now collaborating with dozens of other scientists worldwide to collect real-world data from lakes in winter. Climate change is a big challenge and understanding these shifts is key to protecting lake ecosystems and the communities that depend on them, now and in the future.

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