While scientists are aware that climate change is and will have effects around the globe, the ocean depths can be particularly difficult to study. To what degree are they damaged, and over how long do the changes take effect? Now, researchers from UC Davis have found that while just decades of climate change can have a profound effect on sea ecosystems, correcting those changes can take thousands of years.
“These past events show us how sensitive ecosystems are to changes in Earth’s climate — it commits us to thousands of years of recovery,” said Sarah Moffitt, a scientist from UC Davis Bodega Marine Laboratory and Coastal and Marine Sciences Institute. “It shows us what we’re doing now is a long-term shift — there’s not a recovery we have to look forward to in my lifetime or my grandchildren’s lifetime. It’s a gritty reality we need to face as scientists and people who care about the natural world and who make decisions about the natural world.”
The “events” Moffitt’s referring to is the deoxygenation of sea water brought on by climate change. For her study, Moffitt examined a core of seafloor that spans a period from 3,400 to 16,100 years ago – back to the earliest known record of disturbance and recovery of seafloor ecosystem biodiversity. Included in the sediment sample were over 5,000 invertebrate fossils.
“After the initial sampling at sea, I took the entire core, which was about 30 feet long,” Moffitt said. “I cut it up like a cake, and I sampled the whole thing. Because of that, I had the whole record.”
At the time captured in the sample, the planet was in a period of deglaciation (the melting of glaciers) due to rapid global warming. Over time, Moffitt could observe the ecological response to lowering levels of oxygen: The fossil record is initially diverse, then eventually thins out to contain almost none at all as the oceans got warmer and less oxygenated. It took several thousand years before the ocean life was able to recover.
It’s not good news for climate change crusaders, who insist that a rapid and abrupt change in course is necessary to prevent a catastrophic event like the one depicted in Moffitt’s sample. That may be true, in a technical sense, but as Moffitt stated, changes won’t happen overnight. While earlier recovery estimates by scientists were in the 100-year range, it’s now obvious that it may be several thousand years, in some cases.