Scientists sound the alarm after discovering drastic changes in once-pristine lakes: 'Across a tipping point'

Authors of a new study worry that climate change and extreme weather conditions have pushed some of Greenland's pristine lakes "across a tipping point."

What's happening?

In the study, published in the journal Proceedings of the National Academy of Sciences, researchers monitored the changes to Arctic lakes in Greenland over the course of 10 years. In particular, they looked at what happened after the fall of 2022, a season that brought record heat and rainfall to the area via atmospheric rivers.

Less than a year after these extreme weather conditions, influenced by our changing climate, the lakes transformed from their standard "blue" (highly transparent) to "brown." As they browned, light penetration was reduced by 50%.

This "brownification" of the lakes, which occurred in less than 12 months, typically takes hundreds, if not thousands, of years to occur.

Since many lake species, especially algae, are dependent on light as a resource, brownification can seriously alter lake ecosystems. Many of these species are involved in the carbon cycle.

"As a result, lakes shifted from being summer carbon sinks to sources, with a >350% increase in carbon dioxide flux from lakes to the atmosphere," researchers wrote. Basically, once these lakes browned, they were way less helpful in storing planet-warming carbon.

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Why is this important?

If the lakes stop trapping these gases and instead start pumping carbon dioxide into the atmosphere, it could have catastrophic effects in the fight against global warming. This study shows how fine that line may be — at least for freshwater lakes in Arctic environments.

"Arctic lakes lie at a sensitive threshold for shifts in metabolic balance," the study's authors wrote. "As the responses between climate, terrestrial–aquatic linkages, and carbon dynamics are tightly coupled, climate-driven shifts in hydrologic connectivity of lakes will propagate changing [greenhouse gas] emissions."

The next step for researchers is to continue monitoring the area to see if any or all of the lakes revert back to becoming carbon sponges.

What can I do?

As individuals, we can take everyday actions to help slow climate change. Whether it's studying the key issues, speaking up for our planet, switching to high-efficiency appliances, or vacationing responsibly, there are plenty of ways to make an impact.