Retreating Glaciers Starve Oceans

Photo courtesy Wikimedia Commons


Just when I thought I couldn’t be surprised by yet another falling domino in the cascade of negative effects from global climate changejolt. A study  of Alaskan glaciers in the prestigious journal Nature finds that as glacial ice disappears, so does high-quality food from the marine foodweb.

Here’s how it works:

  • As they flow into the sea, glaciers fringing the Gulf of Alaska export dissolved organic matter left over from extinct forests overrun by ice.
  • The surprise is that this organic matter turns out to be super biologically active (read: nutrient-rich), above and beyond what’s found in nonglacial rivers.
  • The second surprise is that this particular brand of dissolved organic matter does not decreases in quality as it ages (like most such particulate).
  • Instead, this 4,000-year-old stuff turns out to be super nutritious, with up to 66 percent of it rapidly metabolized by tiny marine microbes, instantaneously becoming part of the living biomass and supporting the greater marine foodweb.

The problem is that Alaskan glaciers are receding and disappearing in a warmer world. Therefore the input of this valuable food source is disappearing. What’s at stake? Well, the glacial-fed rivers fringing the Gulf of Alaska discharge as much water as the Mississippi River into a marine system harboring the most productive salmon fishery in the world. For starters.

Poof. We figure it out and then it’s gone. Another example of what I’m beginning to think of as the twisted quantum observer effect.
 

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  • Julia Whitty is the environmental correspondent for Mother Jones. Her latest book is Deep Blue Home: An Intimate Ecology of Our Wild Ocean. For more of her stories, click here.