Cynthia Barnett is an environmental journalist who has covered water and climate stories worldwide.
Her latest book, The Sound of the Sea: Seashells and the Fate of the Oceans, is a cultural and natural history of seashells and the mollusks that make them. These creatures have been on Earth much longer than people and have helped shape our world.
WUSF’s Cathy Carter recently spoke with Barnett about what seashells have to tell us about the oceans.
Cynthia, one of the things you say about seashells is that people really love them for their beautiful exteriors. But we don't give an awful lot of thought to the life inside of them.
That's right. These are amazing animals. And I came to think of seashells and their makers as a good metaphor for how we view the ocean itself, right? We see the ocean as this beautiful backdrop of life rather than the very source of life. And I think the ocean is so large and beautiful that it's hard to grasp what's happening beneath the waves, particularly when it comes to something invisible, like ocean acidification.
Yes, so what do seashells tell us about our changing oceans?
So, seashells are beginning to send us signals about the acidifying warming seas, the oceans have absorbed nearly a third of the extra carbon dioxide that humans have pumped into the atmosphere. And they've absorbed more than 90% of the additional heat that has been rising with those carbon emissions. Already, some parts of the oceans have become too warm for mollusks. And when it comes to the shells themselves, mollusks use minerals in the surrounding seawater to build their shells, primarily calcium carbonate. And those extra carbon emissions have made it difficult for mollusks to take up carbonate in the sea around them. It has made it more difficult for mollusks to build their shells.
So, it sounds like seashells are offering some kind of warning sign.
Yes, I came to think of seashells and their makers as the world's great fact checkers. There's a terrific paleobiologist at the University of South Florida in Tampa, who was a great help with the book. His name is Greg Herbert and he does some fascinating analysis offshore in the Gulf. He compares shells that are there now compared with say 50 years ago, and his research is showing that there really aren't the number of marine mollusks that there were in mid-century America. So, it's not just climate change, or just overharvesting or just toxic algae, it really is the way we're living and our myriad impacts to the oceans.
So, given what we know about the oceans and the stresses that seashells are facing, is it still okay to pick up a seashell on the beach?
I think that's a great question. And I think that it says so much about our changing world that you know, sometimes you feel guilty, even really enjoying things that you used to enjoy as a kid. Even like eating seafood for me has become much more fraught. And now I make really different choices about seafood because of what I know about the sea. I think it's the same with collecting seashells. But I still think it's very important to experience the joy of picking up a shell and particularly a child picking up a shell. And it's actually more sustainable to find your own empty shell along the beach than to buy a tropical seashell in a seashell shop, which may have imported that shell from Indonesia or another place where that animal is endangered. So, I think picking up a local shell is a fine thing to do and a wonderful memory of the beach.
Cynthia Barnett will discuss and sign The Sound of the Sea at 4 p.m. July 11 at Tampa Bay Watch, 3000 Pinellas Bayway S, Tierra Verde, and will appear virtually, in conversation with historian Jack Davis, at Tombolo Books in St. Petersburg at 6:30 p.m. July 20.
