Photo of shells by Anthony
A crisis breaching planetary boundaries
A groundbreaking study by researchers from the Plymouth Marine Laboratory, NOAA, and Oregon State University has found that ocean acidification—driven by escalating CO₂ absorption—has crossed a key “planetary boundary.” By 2020, acidification levels in approximately 60% of the ocean at depths near 200 m had exceeded what scientists deem safe. This damage reaches far below the surface, threatening deep-sea corals, pteropods, oysters, mussels, and a host of other marine organisms essential to the ocean food web.
The “Evil Twin” of climate crisis
Dubbed the “evil twin” of climate change, ocean acidification is often overlooked. Professor Steve Widdicombe of PML, co-chair of the Global Ocean Acidification Observing Network, emphasised that acidification isn’t just an environmental issue—it’s “a ticking timebomb for marine ecosystems and coastal economies.”
The damage is already observable, for example, ocean acidification has caused near-collapse of oyster hatcheries in North-West America by preventing juvenile oysters from building shells.
The study marks a concerning milestone—acidification has now joined other breached planetary boundaries such as climate change, biodiversity loss, and nutrient cycles.
Voices from the front line
Professor Helen Findlay warned that deeper ocean ecosystems may suffer greater impacts than previously anticipated.
“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.”
Jessie Turner, Director of the Ocean Acidification Alliance, urged policymakers to elevate acidification on par with climate and biodiversity, saying, “we are running out of time and what we do – or fail to do – now is already determining our future.”
Meanwhile PML’s Professor Steve Widdicombe has warned that the impacts will be felt in very real terms: “from the coral reefs that support tourism to the shellfish industries that sustain coastal communities, we’re gambling with both biodiversity and billions in economic value every day that action is delayed.”
Spotlight at UN Ocean Conference
The study arrives just as global leaders gather at the UN Ocean Conference in Nice. With acidification now quantified as a planetary boundary crisis, there will be pressure for the conference to prioritise CO₂ reduction and protective measures for vulnerable marine areas and species.