Ocean acidification close to critical threshold, say scientists, posing threat to marine ecosystems and global liveability

Industrial civilisation is close to breaching a seventh planetary boundary, and may already have crossed it, according to scientists who have compiled the latest report on the state of the world’s life-support systems.

“Ocean acidification is approaching a critical threshold”, particularly in higher-latitude regions, says the latest report on planetary boundaries. “The growing acidification poses an increasing threat to marine ecosystems.”

At a briefing outlining the findings, Levke Caesar, a climate physicist at PIK and co-author of the report, said there were two reasons the levels of ocean acidification were concerning.

“One is [that] the indicator for ocean acidification, which is the current aragonite separation state, while still being in the safe operating space, is approaching the threshold of transgressing the safe boundary,” Caesar said.

“The second is that there are actually several new studies that were published over the last years that indicate that even these current conditions may already be problematic for a variety of marine organisms, suggesting a need [to] re-evaluate which levels can actually be called safe.”

Ocean acidification was getting worse globally, with the effects most pronounced in the Southern Ocean and the Arctic Ocean, she added.

As a consequence of global warming and human-induced climate
change, the thawing of permafrost not only contributes to global
greenhouse gas (GHG) emissions and warming, but also poses
substantial risks to both local ecosystems and human communities in
affected regions

Considering the cold winters and short, cool summers, the presence
of permafrost affects the availability of arable land and the growing
season for crops, making agriculture challenging. While climatedriven northward expansion of agriculture increasingly provides
new food sources, little is known about the effectiveness, feasibility
and risks in cultivation-permafrost interactions.

Thawing permafrost also releases contaminants, including
mercury, into the environment. This negatively
impacts water quality in Arctic rivers and lakes, leading to potential
risks to human health through contaminated food chains and drinking
water sources.

Beyond its ecological consequences, permafrost thaw has significant
implications for the infrastructure built on permafrost soil. As the
ground becomes unstable, buildings, roads, pipelines, water facilities,
and communication systems are damaged and hazardous substances mobilised

Up to 80 per cent of infrastructure elements
show substantial infrastructure damage and 70 per cent of current
infrastructure in the permafrost domain is in areas with high potential
for thaw by 2050