January 1, 2018

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Mass Extinction in Earth’s Oceans Could Begin by 2100

By Mark Fischetti & Jen Christiansen

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The amount of carbon in our planet's oceans has varied slowly over the ages. But 31 times in the past 542 million years the carbon level has deviated either much more than normal or much faster than usual (dots in main graph). Each of the five great mass extinctions occurred during the same time as the most extreme carbon events (pink dots). In each case, more than 75 percent of marine animal species vanished. Earth may enter a similar danger zone soon. In 1850 the modern oceans contained about 38,000 gigatons of carbon, and a new study by geophysics professor Daniel H. Rothman of the Massachusetts Institute of Technology indicates that if 310 gigatons or more are added, the deviation will again become acute. Humans have already contributed about 155 gigatons since then, and the world is on course to reach 400 gigatons by 2100 (small graph). Does that raise the chance for a mass extinction? “Yes, by a lot,” Rothman says.

Credit: Jen Christiansen; Source: “Thresholds of Catastrophe in the Earth System,” by Daniel H. Rothman, in Science Advances, Vol. 3, No. 9, Article No. E1700906; September 20, 2017

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Mark Fischetti was a senior editor at Scientific American for nearly 20 years and covered sustainability issues, including climate, environment, energy, and more. He assigned and edited feature articles and news by journalists and scientists and also wrote in those formats. He was founding managing editor of two spin-off magazines: Scientific American Mind and Scientific American Earth 3.0. His 2001 article “Drowning New Orleans” predicted the widespread disaster that a storm like Hurricane Katrina would impose on the city. Fischetti has written as a freelancer for the New York Times, Sports Illustrated, Smithsonian and many other outlets. He co-authored the book Weaving the Web with Tim Berners-Lee, inventor of the World Wide Web, which tells the real story of how the Web was created. He also co-authored The New Killer Diseases with microbiologist Elinor Levy. Fischetti has a physics degree and has twice served as Attaway Fellow in Civic Culture at Centenary College of Louisiana, which awarded him an honorary doctorate. In 2021 he received the American Geophysical Union’s Robert C. Cowen Award for Sustained Achievement in Science Journalism. He has appeared on NBC’s Meet the Press, CNN, the History Channel, NPR News and many radio stations.

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Jen Christiansen is acting chief of design and senior graphics editor at Scientific American, where she art directs and produces illustrated explanatory diagrams and data visualizations. She is also author of the book Building Science Graphics: An Illustrated Guide to Communicating Science through Diagrams and Visualizations (CRC Press). In 1996 she began her publishing career in New York City at Scientific American. Subsequently she moved to Washington, D.C., to join the staff of National Geographic (first as an assistant art director–researcher hybrid and then as a designer), spent four years as a freelance science communicator and returned to Scientific American in 2007. Christiansen presents and writes on topics ranging from reconciling her love for art and science to her quest to learn more about the pulsar chart on the cover of Joy Division’s album Unknown Pleasures. She holds a graduate certificate in science communication from the University of California, Santa Cruz, and a B.A. in geology and studio art from Smith College. Follow Christiansen on Bluesky @jenchristiansen.com

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Scientific American Magazine Vol 318 Issue 1This article was published with the title “Killer Seas” in Scientific American Magazine Vol. 318 No. 1 (), p. 80
doi:10.1038/scientificamerican0118-80
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