Oceans could take thousands of years to recover from climate change, study says
Decades of climate change have taken a toll on ocean ecosystems 鈥� and it could take millennia for them to bounce back, according to new research.
At the UC Davis Bodega Marine Laboratory, Sarah Moffitt examines fossils within a marine sediment core.
Joe Proudman, UC Davis
It only took us an existential moment to damage them, but they won鈥檛 be fixed in our lifetime.
Researchers say ocean ecosystems have taken a hit from climate change 鈥� and that it could be thousands of years, not hundreds, before they recover. By analyzing layers of fossilized ocean fauna, scientists from UC Davis鈥� Bodega Marine Laboratory and Coastal and Marine Sciences Institute were able to make out correlations between abrupt climate change and disturbances in ocean biodiversity. Their was published yesterday in the聽Proceedings of the National Academy of Sciences.
Biologically diverse seafloors can lose large amounts of dissolved oxygen as a result of climate change. The process 鈥� called deoxygenation 鈥� can disrupt the biodiversity of ocean ecosystems. But previous studies did not quantify these disturbances and recoveries in relation to sudden climate change. Led by Sarah Moffitt, a UC Davis research team began by extracting a huge fossil core from the ocean floor off Santa Barbara.
鈥淎fter the initial sampling at sea, I took the entire core, which was about 30 feet long,鈥� Dr. Moffitt said in a statement. 鈥淚 cut it up like a cake, and I sampled the whole thing. Because of that, I had the whole record.鈥�
The core contained fossil evidence from a period spanning 16,100 to 3,400 years ago. In that time, Moffitt noticed repeating patterns. Diverse seafloor ecosystems would experience deoxygenation coinciding with warming periods, and rapid loss of diversity would follow. In low-oxygen periods, fossil evidence was minimal. Even minor drops in oxygen levels appeared to curtail undersea life. And while the warming events seemed to last hundreds of years聽鈥� possibly only decades聽鈥� it took ecosystems thousands of years to bounce back.聽
And it鈥檚 not all in the past 鈥� Moffitt says these deoxygenation events should viewed as analogues to the present.
鈥淭hese past events show us how sensitive ecosystems are to changes in Earth鈥檚 climate 鈥� it commits us to thousands of years of recovery,鈥� Moffitt said in a statement. 鈥淚t shows us what we鈥檙e doing now is a long-term shift 鈥� there鈥檚 not a recovery we have to look forward to in my lifetime or my grandchildren's lifetime. It鈥檚 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.鈥�