Ancient Mass Extinctions Hint at Possible Ocean Future
After dramatic oceanic extinctions 250 million and 200 million years ago, the global carbon cycle turned chaotic. Earth’s biogeochemistry went boom and bust for millions of years thereafter, as if some regulating mechanism were lost — which is exactly what happened.
“People talk about saving biodiversity, and isn’t it good to have a variety of all these creatures. But the reason it matters is because ecosystem function is itself dependent on diversity in the face of normal environmental changes,” said geologist Jessica Whiteside of Brown University. “Lower diversity too much, and the system will lose its resiliency. It will become a slave to otherwise minor environmental changes.”Scientists say that another mass extinction is now underway, with extinction rates an order of magnitude higher than normal, both on land and at sea. Studies like Whiteside’s suggest what the extinction’s consequences could be — not just for people, on a scale of decades or centuries, but for how the planet will work, millions of years in the future.Well... fiddlesticks.Even though contemporary time is just a blink in geological terms, the findings still have modern relevance, said Whiteside. One might see, at a far smaller scale, similar patterns in regions like the Sea of Japan or off the coast of North Carolina, where overfishing and pollution have produced stripped-down ecosystems devoid of the large predators needed to maintain the rich food webs crucial to a stable carbon cycle.
“What’s wonderful about looking at the past is the long lens of geological history,” said Whiteside. “There is evidence that food web collapse is starting to occur in some marine ecosystems. It will take a long time for systems to recover.”