mass extinction
noun
plural mass extinctions
: an event in which many living species on Earth experience rapid extinction rates during a relatively short period of geologic time
Unless climate change is curbed, Earth's oceans could see a mass extinction of marine life unlike anything the planet has seen for millions of years …—
Doyle Rice
Doyle Rice[Paleobiologist Anthony] Barnosky calculates that humans are now creating a mass extinction. … As many as 30% of all species may be lost over the next four decades, conservationists estimate.—Gaia Vince
Gaia Vince
specifically
: a rare event in which seventy-five percent or more of all living species on Earth die out within a relatively short period of geologic time and that is usually associated with catastrophic natural phenomena (such as volcanic eruptions or asteroid impacts)
… the most recent of five events in Earth's history that scientists consider mass extinctions, defined by paleontologists as events where more than 75 percent of species vanish within a geologically short period of time, typically less than two million years. —Katarina Zimmer
Katarina Zimmer About 252 million years ago, the vast majority of species on Earth were killed off in the "Great Dying," the worst mass extinction in our planet's history. Up to 96% of all marine species and 70% of land animals were killed off during this event … —Peter Kotecki
Peter Kotecki We are still far from meeting the requirements that paleontologists set for a "mass extinction event" (loss of 75 percent of species globally). However, in geologic time, we are moving towards that reality. —Gabe Allen
Gabe Allen The Triassic mass extinction event took place 200 million years ago, eliminating about 80% of Earth's species, including many types of dinosaurs. —Tammana Begum
Tammana Begum Examples of mass extinction in a Sentence
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Throughout Earth’s history, the planet has been struck by multiple asteroids, some so large, like the Chicxulub Impactor, that Earth’s climate was altered to the point of a mass extinction event.
—Monica Cull, Discover Magazine, 10 July 2025
That’s surprising, because animals that survive mass extinction events tend to reproduce quickly, as Nathan Lo, an evolutionary biologist at the University of Sydney who was not involved with the research, tells New Scientist.
—Sarah Kuta, Smithsonian Magazine, 25 June 2025
This realization led Wright and his coauthors to connect the cosmic phenomenon with mass extinctions on Earth.
—Katie Hunt, CNN, 20 Mar. 2025
The results confirmed their hypothesis, showing that the loss of vegetation during the mass extinction event significantly reduced the planet’s ability to store carbon, meaning very high levels remained in the atmosphere.
—Laura Paddison, CNN Money, 2 July 2025
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Monica Cull, Discover Magazine, 10 July 2025
That’s surprising, because animals that survive mass extinction events tend to reproduce quickly, as Nathan Lo, an evolutionary biologist at the University of Sydney who was not involved with the research, tells New Scientist.
—Sarah Kuta, Smithsonian Magazine, 25 June 2025
This realization led Wright and his coauthors to connect the cosmic phenomenon with mass extinctions on Earth.
—Katie Hunt, CNN, 20 Mar. 2025
The results confirmed their hypothesis, showing that the loss of vegetation during the mass extinction event significantly reduced the planet’s ability to store carbon, meaning very high levels remained in the atmosphere.
—Laura Paddison, CNN Money, 2 July 2025
See All Example Sentences for mass extinction
Cite this Entry
“Mass extinction.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/mass%20extinction. Accessed 23 Jul. 2025.
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