A critical measure of the ocean’s health suggests that the world’s marine systems are in greater peril than scientists had previously realized and that parts of the ocean have already reached dangerous tipping points.
A study, published Monday in the journal Global Change Biology, found that ocean acidification—the process in which the world’s oceans absorb excess carbon dioxide from the atmosphere, becoming more acidic—crossed a “planetary boundary” five years ago.
“A lot of people think it’s not so bad,” said Nina Bednaršek, one of the study’s authors and a senior researcher at Oregon State University. “But what we’re showing is that all of the changes that were projected, and even more so, are already happening—in all corners of the world, from the most pristine to the little corner you care about. We have not changed just one bay, we have changed the whole ocean on a global level.”
The new study, also authored by researchers at the UK’s Plymouth Marine Laboratory and the National Oceanic and Atmospheric Administration (NOAA), finds that by 2020 the world’s oceans were already very close to the “danger zone” for ocean acidity, and in some regions had already crossed into it.
Scientists had determined that ocean acidification enters this danger zone or crosses this planetary boundary when the amount of calcium carbonate—which allows marine organisms to develop shells—is less than 20 percent compared to pre-industrial levels. The new report puts the figure at about 17 percent.
“Ocean acidification isn’t just an environmental crisis, it’s a ticking time bomb for marine ecosystems and coastal economies,” said Steve Widdicombe, director of science at the Plymouth lab, in a press release. “As our seas increase in acidity, we’re witnessing the loss of critical habitats that countless marine species depend on and this, in turn, has major societal and economic implications.”
Scientists have determined that there are nine planetary boundaries that, once breached, risk humans’ abilities to live and thrive. One of these is climate change itself, which scientists have said is already beyond humanity’s “safe operating space” because of the continued emissions of heat-trapping gases. Another is ocean acidification, also caused by burning fossil fuels.
