Lennart Bach

Evaluating ocean alkalinity enhancement for carbon dioxide removal: evidence from a one-year saltmarsh field experiment Abstract. Ocean alkalinity enhancement is a promising carbon dioxide removal (CDR) strategy aimed at reducing atmospheric carbon dioxide (CO2) concentrations. To evaluate its effectiveness and potenti...

Interesting study by colleagues in Portugal.

Evaluating ocean alkalinity enhancement for carbon dioxide removal: evidence from a one-year saltmarsh field experiment
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egusphere.copernicus.org/preprints/20...

Persistent eastern equatorial Pacific Ocean upwelling since the warm Pliocene Upwelling generates a nutrient-rich “cold tongue” in the eastern equatorial Pacific Ocean (EEP), with impacts on global climate, oceanic biological productivity, and the carbon cycle. The cold tongue ...

Today, we published a study long in the making on how upper and subsurface tropical Pacific waters responded (and maybe will adjust) to warmer global climate. Here’s the story of how we got here after 15 years. many authors but shout out @jfarmersalmanac.bsky.social
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www.science.org/doi/10.1126/...

🌟 Postdoc Opportunity in Marine Biogeochemistry at CNRS-CEREGE!

🚢 Are you a passionate researcher ready to tackle climate change? Dive into the ERC-funded Deep-C project in Aix-en-Provence, France!

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Frontiers | Regional ocean biogeochemical modeling challenges for predicting the effectiveness of marine carbon dioxide removal Effectively scaling diverse marine carbon dioxide removal (mCDR) technologies from pilot-scale demonstrations to industrial-scale deployments requires a quan...

New mCDR papers this month:

www.frontiersin.org/journals/cli...

www.frontiersin.org/journals/env...

Thanks again to @aaronferderer.bsky.social for going through this massive effort. I think this dataset is a noticeable step forward when it comes to mechanistically understanding phytoplankton responses to carbonate chemistry. More of that in the future!
Well done mate 🍻

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To explore the data yourself use the tool below. Hopefully, journals find a way to include such tools at least in the online versions of the article. It can be very powerful to understand a dataset and make further use of it for your own research 🌊

a-ferderer.github.io/Interactive_...

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And OA?

Increased H+ (reduced pH) associated with OA reduces growth rate in all species, but differently between them. Some are very resilient, whereas others are more sensitive. OA would not "kill all diatoms" but may change their species composition (with implications for food webs).

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How does this inform OAE?

OAE aims to store atmospheric CO2 as bicarbonate (HCO3-) in the ocean. No effect of HCO3- on growth suggests limited effect of this intentional storage. However, OAE can unintentionally cause a transient decrease of CO2 and H+, thereby briefly reducing diatom growth.🌊

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Key finding 3:

The concentration of bicarbonate (HCO3-), had no discernable effect on growth of any of the 5 diatom species. This is remarkable, considering that HCO3- was shown to be a predominant C source for photosynthesis.

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Key finding 2:

While the response pattern to changing carbonate chemistry was identical between species (see finding 1), their sensitivities to CO2 and H+ concentration varied widely. Thus, different species have different carbonate chemistry niches, some being specialists, others generalists.🌊

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Key finding 1:

Diatom responses to carbonate chemistry are mostly (almost entirely) driven by changes in CO2 and H+ concentration (H+ = pH). Across a large gradient, diatom growth increases with increasing CO2, while decreasing with increasing H+.
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Carbonate chemistry fitness landscapes inform diatom resilience to future perturbations Diatom growth rates are determined by concentrations of CO2 and H+ across broad carbonate chemistry landscapes.

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This study led by @aaronferderer.bsky.social tested how 5 diatom species respond to broad ranges of seawater carbonate conditions. Goal was to determine carbonate chemistry niches and to inform Ocean Alkalinity Enhancement (OAE) and Ocean Acidification (OA)

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www.science.org/doi/10.1126/...

I was confused as well. My reading is that the whole ecosystem including phytoplankton ingestion, defacation, burial... makes it net negative.
As usual, the question is what is the carbon budget in the absence of the oyster farm.

Congrats Jens!

Finally a topic where the "moral hazard" argument may be more relevant than for CDR.

Our new paper with Mengyang Zhou, Elizabeth Yankovsky, and Dustin Carroll is out as a preprint: egusphere.copernicus.org/preprints/20... "Substantial inter-model variation in OAE efficiency between the CESM2/MARBL and ECCO-Darwin ocean biogeochemistry models"

Agree, references would have helped.

Roundup: Unobligated but Not Unnoticed: OMB Pulls Back NOAA Funds August 12-26, 2025

A disaster for ocean and climate research is unfolding before our eyes. #NOAA 🌊
"The White House Office of Management and Budget is pulling back $239 million in funds Congress already provided. The biggest hits fall on climate and ocean research."
oceanpolicy.substack.com/p/roundup-un...

Yes, it is not on solid foot

Quick state of play on Ocean Alkalinity Enhancement (OAE): where the science stands, what recent trials show, and why it warrants careful, scaled testing. 🧵

Iron Fertilizer versus Antacids for the Ocean Which approach could end the climate crisis?

There is frustration with ocean iron fertilisation research/funding, which increasingly tranlates in attempts to argue against other CO2 removal pathways (here, alkalinity enhancement). This appears desparate rather than convincing/helpful. 🌊

climaterestoration.substack.com/p/iron-ferti...

Frontier buyers sign $31M deal with Planetary to advance ocean alkalinity enhancement Frontier has facilitated offtake agreements with Planetary, a company that removes atmospheric CO₂ and reduces local ocean acidity by adding dissolved alkaline minerals to seawater.

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frontierclimate.com/writing/plan...

YouTube video by Netflix The Platform | Main Trailer | Netflix

An excellent educational movie on the biological carbon pump.
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www.youtube.com/watch?v=Rlfo...

🌊📄 The Sabin Center published a new #report, International Legal Guidelines for Marine Carbon Dioxide Removal Governance under the London Convention and London Protocol.
Read here: scholarship.law.columbia.edu/sabin_climat...

#FridayReads

Is linked in a better source for information than bluesky? I feel I am missing quite some interesting things on bluesky

… a few more days to submit your abstract to this wonderful session 🙃 on mCDR 😉 at OSM26

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Biogeochemical and Ecological Insights for Evaluation of Marine Carbon Dioxide Removal (mCDR)
agu.confex.com/agu/osm26/pr...

"Therefore, we recommend that ecosystem restoration is pursued primarily for restoring biodiversity, supporting livelihoods and resilience of ecosystem services"

Earth’s silicate weathering continuum - Nature Geoscience Chemical weathering of silicate rocks occurs along a continuum from terrestrial to marine environments.

Two years ago, brilliant Utrecht University PhD student Gerrit Müller organized a workshop about the role of weathering in the CO2 cycle. He invited scientists from all over to debate the different parts of the cycle, and merged it jnto this review paper, published today in Nature Geoscience!

Plankton do not care: Minimal effects of ocean liming on plankton growth and grazing in the Eastern Mediterranean Increasing CO2 emissions have led to the development of CO2 removal strategies to counteract ocean acidification. Among these, ocean alkalinity enhancement techniques, particularly ocean liming, may ...

Top marks to Traboni et al. for the beautifully succinct - and stupendously blunt - title for their paper (... which is pretty great too) ... 🌊
aslopubs.onlinelibrary.wiley.com/doi/10.1002/...

In a new #RETAKE study, CDRmare expert Jessica Strefler & team have investigated the potential contribution of Ocean Liming to the Paris climate target from a systemic, techno-economic perspective using the global energy-economy-climate model REMIND. #OAE #mCDR iopscience.iop.org/article/10.1...