Scientists discover concerning phenomenon that might disrupt vital food chains: 'Could have long-term implications'

Geoscientists have discovered that retreating glaciers may be delivering fewer nutrients to the ocean, disrupting the balance of vulnerable marine ecosystems. 

What's happening?

As reported by UC San Diego Today, a recent study on Alaskan glaciers found that meltwater from a rapidly retreating glacier contained lower concentrations of essential micronutrients such as iron and manganese. This was likely due to meltwater spending more time interacting with rock, which may alter the mineral content before it reaches the sea.

First published in Nature Communications, the study was led by researchers from the Scripps Institution of Oceanography at the University of California, San Diego. The researchers analyzed sediments from two fjords located in Southcentral Alaska. 

They found that the movement of tidewater glaciers, particularly when they advance or retreat, greatly affects how much sediment enters fjords and changes their chemistry. Any reduction of micronutrients could negatively impact phytoplankton, potentially affecting fisheries and other marine life.

Why is advanced glacier retreat important?

"If we can duplicate these findings elsewhere, the impacts go beyond our scientific understanding of glaciers," said Sarah Aarons, a geoscience researcher at Scripps and co-author of the study, per UC San Diego Today. "This could impact the productivity of really significant marine ecosystems, which could have long-term implications for the health of major fisheries."

Phytoplankton are widely considered to be the foundation of marine ecosystems, serving as the base of the food web. If phytoplankton are unable to absorb the life-sustaining nutrients, countless marine species could eventually face potential extinction.  

Phytoplankton also produce about half of the world's oxygen through photosynthesis. Without the vital nutrients that keep these organisms healthy, the planet could experience unforeseen side effects. This includes the loss of one of the most valuable carbon sinks, making the ocean far less effective at absorbing carbon dioxide, which is likely to worsen global temperatures. 

What's being done about glacier retreat?

"The longer you have water in contact with rock or sediments, the more chemical breakdown or weathering takes place," added Aarons, per UC San Diego Today. "So a retreating glacier might be sending more sediment to the ocean but with lower concentrations of bioavailable nutrients like iron because more weathering is occurring."

Rising global temperatures remains one of the driving forces behind glacier retreat. If human-caused carbon pollution continues to reach record-setting numbers, temperatures across the planet will continue to rise, leading to increased risks of more prevalent extreme storms and devastating droughts.  

For now, countries are attempting to combat rising global temperatures by enacting policies to reduce our reliance on planet-heating fossil fuels and promote the transition to renewable energy resources. As governments across the globe react to shifting climate conditions, scientists continue to emphasize the importance of research efforts.  

"We see very clear geochemical differences between these two glacier systems that we link to their state of retreat," said Kiefer Forsch, the study's lead author, per UC San Diego Today. "However, this is a snapshot of two glaciers in one region. Understanding whether these patterns hold across glaciers elsewhere in the world with different bedrock types and stages of retreat will require more research." 

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