By R. Mark Leckie , Science.  Excerpt: Foraminifera inhabit coastal and deep-sea marine environments. These microscopic, single-celled organisms are widely used as proxies for relative age determination and reconstructing past climates. The ratio of calcium isotopes ( 44 Ca/ 40 Ca) in their calcium carbonate shells depends on the amount of carbon dioxide (CO 2 ) and carbonate saturation in seawater at the time of the shells’ formation. ...Chen et al. ( 1 ) report geochemical evidence that a rise in atmospheric CO 2 concentration and ocean acidification at the end of the Aptian Stage [~113 million years ago (Ma)] may have caused the largest extinction of planktic foraminifera of the Cretaceous Period (146 to 66 Ma)..., which is second only to the extinction event at the end of the Cretaceous Period (66 Ma).... The findings could be important for understanding potential effects of present-day increases in atmospheric CO 2 levels on marine organisms....  Full article at https:...

By EurekAlert!  Excerpt: An ongoing research project exploring the effects of rising levels of oceanic CO 2 on squid neurology reveals that exposure to future levels of ocean acidification could shrink their brain volume by around 50%. This severe brain shrinkage appears to be most pronounced in the areas that interpret visual information, correlating with significant reductions in normal feeding behaviours and suggesting serious consequences for the future of squid and other cephalopods. ...To investigate the effects of future ocean acidification on the squid neurology, ...Dr Allen and project lead Dr Yung-Che Tseng ...at Academia Sinica’s Marine Research Station reared the squid in one of two parallel water tanks: one representing the modern oceans (pH 8.2) and one representing the oceans in the year 2100 under a predicted climate change scenario (pH 7.8). After 90 days, the squid were removed and their heads were preserved for visual analysis with diffusion magnetic resonance i...

By Science Advisor.  Excerpt: Researchers have declared  southern Florida’s  Acropora  coral colonies functionally extinct . The death knell for two reef-building species, elkhorn and staghorn, was the 2023 marine heatwave that brought temperatures above 31°C for almost 6 weeks. The event was the ninth mass coral mortality event for the region since 1987. “ This ecosystem is forever transformed ,” lead author Ross Cunning told  Nature . Conservation for these species “needs to fundamentally change.” Acropora  have made Florida and the Caribbean their home for the past 250,000 to 500,000 years. During the heatwave, they bleached in 98% to 100% of their southern Florida range, a process whereby the corals lose the symbiotic algae that feed them and give them color. Previously, scientists had attempted to reintroduce the corals in areas where they had declined. But with the reintroduced organisms now dead, the authors say that efforts must turn to breeding mor...

By Paul Voosen , Science.  Excerpt: Acoustic technique could make it easier to monitor threat to marine life stemming from rising carbon emissions. ...The ocean is a noisy place. Ship propellers and whale songs reverberate at the lowest pitches, while at higher tones dolphins click and shrimp snap their claws. Between these frequencies are the sounds of the churning sea itself, generated as waves, wind, and rain roil its surface. Researchers have now used this ambient noise to probe the rising acidity of the ocean. The acoustic technique,  published  last week in the  Journal of Geophysical Research: Oceans , could make it easier to measure this key parameter of ocean health across vast distances rather than relying on point measurements....  Full article at https://www.science.org/content/article/ambient-noise-can-track-dangerous-ocean-acidification . 

By Jim Robbins , The New York Times.  Excerpt: Eighteen years ago, farmed oyster larvae began disappearing in mass die-offs, mystifying hatchery managers in the Pacific Northwest and threatening a thriving part of the region’s economy. Up to 90 percent of the farmed Pacific oysters — the backbone of the industry — were being wiped out. Businesses like Taylor Shellfish Farms, the country’s largest grower now run by the fifth generation of the Taylor family, stood at the brink of catastrophe. ...The culprit turned out to be an increasingly acidic ocean, and research efforts to solve the mystery have propelled Washington State to the forefront of the world’s efforts to understand and offset the shifting chemical composition of the seas. Now, the global race against ocean acidification is intensifying as carbon dioxide levels in the seas increase. A recent study  found that the world’s oceans crossed a “planetary boundary”  in 2020, and warned that things were worse than prev...

By Kimberly Hatfield , Eos/AGU.  Excerpt: Scientists constructed a 100-year history of acidity in the Gulf of Maine. They expected coastal variability but were surprised by what they didn’t find: a strong anthropogenic signal. ...Using ocean chemistry recorded in algae, researchers have now constructed a nearly 100-year history of acidity (pH) in the region. The  analysis, published in  Scientific Reports , shows that ocean acidification, seen around the world, has been delayed in the gulf....  Full article at https://eos.org/articles/warming-gulf-of-maine-buffers-ocean-acidification-for-now . 

By Science.  Excerpt: As human activities continue to pump carbon dioxide into the atmosphere, more and more of the stuff gets absorbed into Earth’s oceans, where it reacts with seawater to form carbonic acid. When this weak acid dissociates into ions of hydrogen and bicarbonate, it drives down the ocean’s overall pH, which is typically slightly basic. This acidification—sometimes referred to as climate change’s “evil twin”—can wreak havoc on marine life, for example by interfering with the mineralization process that corals, oysters, and other organisms use to build and maintain their skeletons and shells. A 2014 video released by the National Oceanic and Atmospheric Association’s Pacific Marine Environmental Laboratory (NOAA PMEL), for instance, shows a marine snail called a pteropod  struggling to swim, its shell having been partially dissolved by acidic waters . In 2009, a group of researchers led by Swedish climate scientist Johan Rockström developed what is known as the ...

By Noam S. Vogt-Vincent et al.  Abstract: Past coral range expansions suggest that high-latitude environments may serve as refugia, potentially buffering coral biodiversity loss due to climate change. We explore this possibility for corals globally, .... Our simulations suggest that there is a mismatch between the timescales of coral reef decline and range expansion under future predicted climate change. Whereas the most severe declines in coral cover will likely occur within 40 to 80 years, large-scale coral reef expansion requires centuries. The absence of large-scale coral refugia in the face of rapid anthropogenic climate change emphasizes the urgent need to reduce greenhouse gas emissions and mitigate nonthermal stressors for corals, both in the tropics and in higher latitudes....  Full article at https://www.science.org/doi/10.1126/sciadv.adr2545 . 

By Elise Cutts , Science.  Excerpt: VIENNA—  Climate change is causing the oceans to get warmer and more acidic, making it harder for corals to build and maintain their mineral skeletons. Eventually, reefs will literally start to dissolve. It’s a grim fate, but one with a surprising silver lining. Research presented this week here at a conference of the European Geophysical Union shows  dissolving reefs will slow climate change , by boosting the oceans’ ability to soak up carbon dioxide (CO 2 ) out of the atmosphere. By the end of the century, the oceans could be absorbing up to 400 megatons of additional carbon per year. That’s more than the annual emissions of Australia or the United Kingdom. No one had actually calculated the magnitude of this “feedback” before, and it’s big enough that climate models need to account for it, says Jens Daniel Müller, a biogeochemist at ETH Zürich who wasn’t involved in the work. “Often we focus more on positive feedbacks, where the proc...

By Sebastiaan J. van de Velde et al, Science.  Excerpt: Fishers for bottom-loving species like flounder sometimes use a controversial method called bottom trawling, dragging nets along the seafloor to scoop the animals up. Critics point out that this dragging can kill sensitive animals like turtles and marine mammals, plus it causes extensive damage to the delicate habitats on the seabed. Now, they have another reason to gripe about the practice:  It worsens climate change . Researchers had already found that the act of stirring up sediment brings organic matter to the surface, where  microbes can digest it and release its carbon into the atmosphere . The team behind a new paper wanted to quantify other effects, including how stirring up sediment affects water chemistry. Sure enough, they found that messing with the seabed introduces more oxygen and acidifies the water, which in turn decreases its ability to dissolve carbon dioxide. ...trawling could be reduced with...

By Muhammed Fatih Sert et al, JGR Biogeosciences.  [Great example of the complexity of global systems!] Plain language summary: Cold seeps are geological features that release methane from the seabed to the water column. In oxygenated sea water column, seeping methane is consumed by specialized microbes that convert it into carbon dioxide. Although the increase in carbon dioxide can lead to ocean acidification, cold seeps are often found in the Hola trough of Northern Norway near cold-water corals (CWCs), which are vulnerable to changes in ocean acidity. This raises questions about how these features coexist in the same marine ecosystem and how they impact each other. We investigated the carbon exchange between cold seeps and CWCs by analyzing seawater samples. Our data on nutrients, organic matter, and microbial compositions implied cooccurring carbon processes such as methane oxidation and organic matter synthesis. Notably, cold seeps might support CWCs by producing dissolved or...

By Robert F. Service , Science.  Excerpt: The carbon dioxide (CO 2 ) spewing from human activities is not only changing Earth’s atmosphere, it’s also rapidly acidifying the planet’s oceans. In 50 years, that acidification could reduce the oceans’ ability to absorb CO 2  by 10% as it takes a toll on phytoplankton, microscopic single-cell organisms that feed on the gas through the process of photosynthesis, a new study suggests. Reported this week in the Proceedings of the National Academy of Sciences,  the effect could in turn cause atmospheric CO 2  to build up faster  and accelerate warming of the global climate....  Full article at https://www.science.org/content/article/more-carbon-dioxide-oceans-could-harm-carbon-eating-microbes-speed-climate-change .

By Warren Cornwall , Science.  Excerpt: Geoengineering study that would disperse alkaline chemicals off Cape Cod draws environmental opposition. Adam Subhas ...has spent much of his career as a chemical oceanographer at Woods Hole Oceanographic Institution (WHOI), quietly studying how seawater can naturally offset global warming by absorbing carbon dioxide (CO 2 ). Now, Subhas has been thrust into a heated public debate. Next month he and his colleagues want to dump tons of caustic chemicals off the coast of Massachusetts to see whether they can boost the ocean’s uptake of CO 2 . They’re seeking what would be the first-ever regulatory approval for such a study from the U.S. Environmental Protection Agency (EPA). But some nearby residents and environmental groups, worried about safety, have pressed EPA to delay or halt the study. “It’s been a new journey to interact with reporters and the public and everyone at this level and at this intensity,” Subhas says. ...The natural alkalinit...

By Sarah Stanley , Eos/AGU.  Excerpt: Marine life ...depends on the right combination of water temperature, acidity, and oxygen levels, so creatures such as fish and plankton can be  hard hit  by large regional fluctuations in any of these parameters. When two, or even all three, are off-kilter, the environment can become uninhabitable for many species. Because climate change has generally been  heating the ocean ,  boosting its acidity , and  lowering its oxygen levels , concerns over these regional multithreat events—known as column-compound extremes—are growing. Now,  Wong et al.  report that since the early 1960s, column-compound extremes have been intensifying: growing larger in volume, lasting longer, and occurring more often. ...The analysis suggests that triple column-compound extremes—events involving the convergence of extreme temperatures, high acidity, and low oxygen levels—occupied 39 times more ocean volume, lasted 3 times longer, an...

https://www.science.org/content/article/startups-aim-curb-climate-change-pulling-carbon-dioxide-ocean-not-air By ROBERT F. SERVICE , Science.  Excerpt: ...one long gray barge docked at the [Port of Los Angeles] is doing its part to combat climate change. On the barge, which belongs to Captura, a Los Angeles–based startup, is a system of pipes, pumps, and containers that ingests seawater and sucks out CO 2 , which can be used to make plastics and fuels or buried. The decarbonated seawater is returned to the ocean, where it absorbs more CO 2  from the atmosphere, in a small strike against the inexorable rise of the greenhouse gas. After a yearlong experiment with the barge, which is designed to capture 100 tons of CO 2  per year, Captura is planning to open a 1000-ton-per-year facility later this year in Norway that will bury the captured CO 2  in rock formations under the North Sea. Equatic, another Los Angeles–based startup, is launching an even larger 3650-ton-per-y...

https://edition.cnn.com/2024/03/07/australia/mass-coral-bleaching-event-great-barrier-reef-intl-hnk-scn/index.html By Helen Regan , CNN.  Excerpt: Australia’s Great Barrier Reef is suffering another  mass bleaching event , the reef’s managers confirmed Friday, the result of soaring ocean temperatures caused by the global climate crisis and amplified by  El Niño . This is the seventh mass bleaching event to hit the vast, ecologically important but fragile site and the fifth in only eight years.... 

https://www.theguardian.com/environment/2024/feb/09/atlantic-ocean-circulation-nearing-devastating-tipping-point-study-finds By Jonathan Watts , The Guardian.  Excerpt: ...researchers developed an early warning indicator for the breakdown of the Atlantic meridional overturning circulation (Amoc), a vast system of ocean currents that is a key component in global climate regulation. They found Amoc is already on track towards an abrupt shift, which has not happened for more than 10,000 years and would have dire implications for large parts of the world. Amoc, which encompasses part of the Gulf Stream and other powerful currents, is a marine conveyer belt that carries heat, carbon and nutrients from the tropics towards the Arctic Circle,  where it cools and sinks into the deep ocean . This churning helps to distribute energy around the Earth and modulates the impact of human-caused global heating. But the system is  being eroded by the faster-than-expected melt-off of Greenl...

https://www.science.org/content/article/after-mass-coral-die-off-florida-scientists-rethink-plan-to-save-ailing-reefs By WARREN CORNWALL , Science.  Excerpt: Four years ago, the U.S. National Oceanic and Atmospheric Administration (NOAA) unveiled a $100 million coral moonshot. Over 2 decades, nearly half a million hand-reared coral colonies would be planted on seven ailing reefs in southern Florida, in a bid to revive them. ...Today, the project looks as ailing as the coral it was meant to save. A record-breaking underwater heat wave that swept the Caribbean and southern Florida in 2023 killed most of the transplanted colonies....

https://www.theguardian.com/environment/2023/sep/13/earth-well-outside-safe-operating-space-for-humanity-scientists-find By Damian Carrington , The Guardian.  Excerpt: ...planetary boundaries are the limits of key global systems – such as climate, water and wildlife diversity – beyond which their ability to maintain a healthy planet is in danger of failing. ...Six boundaries have been passed and two are judged to be close to being broken: air pollution and ocean acidification. The one boundary that is not threatened is atmospheric ozone, after action to phase out destructive chemicals in recent decades led to the ozone hole shrinking. ...The planetary boundaries are not irreversible tipping points.... Instead, they are points after which the risks of fundamental changes in the Earth’s physical, biological and chemical life support systems rise significantly. ...Prof Johan Rockström...said: “...But what worries us, even more, is the rising signs of dwindling planetary resilience.” ...

https://eos.org/opinions/the-science-we-need-to-assess-marine-carbon-dioxide-removal By Jaime B. Palter ,   Jessica Cross ,   Matthew C. Long ,   Patrick A. Rafter  and   Clare E. Reimers , Eos/AGU. Excerpt: As companies begin selling credits for marine carbon dioxide removal in largely unregulated marketplaces, scientists must develop standards for assessing the effectiveness of removal methods. ...Three categories of mCDR [marine CO 2  removal] approaches— ocean iron fertilization ,  artificial upwelling , and  seaweed cultivation —aim to stimulate  primary productivity  at the ocean’s surface with the expectation that some of the additional biomass produced will sink into and remain in the deep ocean. In contrast,  ocean alkalinity enhancement  (OAE) involves intentionally dispersing alkaline materials such as lime on the ocean’s surface to shift the chemical equilibrium of the seawater carbon syste...