'Ticking Time Bomb' of Ocean Acidification Has Already Crossed Planetary Boundary, Threatening Marine Ecosystems: Study
On the first day of the United Nations Ocean Conference in Nice, France, the findings of a new study have revealed that ocean acidification (OA) — which damages ecosystems like coral reefs — is not only getting worse, but crossed its “planetary boundary” roughly five years ago. The findings came as a surprise, as scientists in a report published last year said OA was “approaching a critical threshold,” but had not yet crossed the boundary. The nine defined planetary boundaries in which Earth can operate safely include climate change, freshwater use and OA. “OA is the term given to the long-term shift of marine carbonate chemistry resulting primarily from the uptake of carbon dioxide (CO2) by the oceans, leading to an increase in ocean acidity and a decrease in carbonate ion (CO32−
concentration,” the authors of the study wrote. “OA can severely affect marine organisms through its direct impact on physiology, growth, survival and reproduction.”
The researchers pointed out that ocean conditions vary widely across the world, with OA levels in tropical regions over two times as high as in polar regions. “Looking across different areas of the world, the polar regions show the biggest changes in ocean acidification at the surface. Meanwhile, in deeper waters, the largest changes are happening in areas just outside the poles and in the upwelling regions along the west coast of North America and near the equator,” said lead author of the report Helen Findlay, a professor at the United Kingdom’s Plymouth Marine Laboratory (PML) and chair of the North-East Atlantic Ocean Acidification Hub, in a press release from PML.
The study, led by PML, the National Oceanic and Atmospheric Administration in the United States and Oregon State University’s Cooperative Institute for Marine Resources Studies (CIMERS), said OA’s threat to marine ecosystems globally is much more widespread than previously believed. The research team used the most recent chemical and physical measurements of the upper ocean, along with studies of marine life and advanced computer models to conclude that by 2020, average ocean conditions globally were already very near — and in some regions had already surpassed — the OA “danger zone.”
“Most ocean life doesn’t just live at the surface – the waters below are home to many more different types of plants and animals. Since these deeper waters are changing so much, the impacts of ocean acidification could be far worse than we thought. This has huge implications for important underwater ecosystems like tropical and even deep-sea coral reefs that provide essential habitats and nursing refuge for many species, in addition to the impacts being felt on bottom-dwelling creatures like crabs, sea stars, and other shellfish such as mussels and oysters,” Findlay explained.
https://www.ecowatch.com/ocean-acidification-planetary-boundary.html