Lennart Bach

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...

Trump’s budget takes aim at gold standard measurement of atmospheric carbon dioxide OPINION: “President Trump, a renowned climate change denier, has shown repeatedly that he has no use for scientific data that disproves his preconceived assumptions,” David Ho writes.

I wrote about the Keeling Curve — our most iconic CO₂ time series — for @sfchronicle.com.

"The Keeling Curve is valuable to science, but it is also a treasure that belongs to humanity as the most poignant indication of our impact on the environment and as a testament to our ability to document it."

Antarctic Dense Water Formation Sensitivity to Ocean Surface Cell Thickness The ability of ocean models with depth coordinates to form Antarctic Dense Shelf Water (DSW) depends on their surface vertical resolution Deeper surface cells shift the direction of surface Ekman...

We figured out a cheap-ish way to make ocean models create Dense Shelf Waters (DSW) on the surface of the Antarctic continental shelf! How?
Fast answer: Ocean surface cells thinner than 1 m!
Long answer on the paper: dx.doi.org/10.1029/2024...
----
More info in the thread

A 48-hour flask test that predicts 700-day carbon removal outcomes? Sounds too good to be true, but in our lab, it’s working.

In our 2023/24 greenhouse study, we tested 400 rock-soil combos for enhanced weathering. Some worked brilliantly. Others completely flopped.

World’s highest court issues groundbreaking ruling for climate action. Here’s what it means for Australia The landmark ruling means Australia must reduce emissions in line with the best science, and regulate the fossil fuel industry to prevent further harm.

Australia sided with the fossil fuel states and the ICJ shot down their arguments. Australia has long ignored its exported scope 3 emissions. Now countries (including Aus) must increase their NDC to meet the Paris agreement targets. Well done Vanuatu law students on this court case. 🎉

🌊Celebrating 10th SOLAS Summer School!
Join us in Tamandaré, Brazil (9–27 March 2026) for an immersive 3-week programme exploring air-sea interactions & climate science under SOLAS3.0!
🔗 Apply by 31 August 2025: docs.google.com/forms/d/e/1F...
More info: www.solas-int.org/events/solas...

Figure 4(a) Effective radiative forcing (ERF) statistics across AR6 scenario database subsets as categorised by AR6WGIII using MAGICC for CO2, CH4, F-gases, and aerosols at different points in time for three climate emulators. Kikstra, J. S., Nicholls, Z. R. J., Smith, C. J., Lewis, J., Lamboll, R. D., Byers, E., Sandstad, M., Meinshausen, M., Gidden, M. J., Rogelj, J., Kriegler, E., Peters, G. P., Fuglestvedt, J. S., Skeie, R. B., Samset, B. H., Wienpahl, L., van Vuuren, D. P., van der Wijst, K.-I., Al Khourdajie, A., Forster, P. M., Reisinger, A., Schaeffer, R., and Riahi, K.: The IPCC Sixth Assessment Report WGIII climate assessment of mitigation pathways: from emissions to global temperatures, Geosci. Model Dev., 15, 9075–9109, https://doi.org/10.5194/gmd-15-9075-2022, 2022.

It is CO2 radiative forcing that poses the largest end-of-century climate threat, because CO2 accumulates in the atmosphere.

[C1-C4 are lower, and C5-C8 higher, IPCC temperature scenarios; ERF is effective radiative forcing.]

Nice paper.

gmd.copernicus.org/articles/15/...
@kikstra.bsky.social

3) The moderate plankton community shifts observed at the profound pH excursions were not deemed concerning because (a) in a real OAE setting this pH excursion would quickly be mitigated through dilution and CO2 influx and (b) the CO2 removal benefits of 500 umol/kg alk additions would be large. 🌊

2) The onset of a phytoplankton bloom was delayed by 2 days in the case when alkalinity additions (500 umol/kg, i.e. substantial!) were NOT matched with immediate CO2 influx (i.e. pH excursions were profound). This was likely because a re-shuffle in the diatom community before the bloom commenced. 🌊

1) No taxonomic shifts could be detected when alkalinity additions (500 umol/kg, i.e. substantial!) are matched with immediate CO2 influx (i.e. pH excursions are minimal). Thus, the extra CO2 stored as bicarbonate in seawater did not negatively or positively affect the community.
🌊

Winners and losers under hydroxide‐based ocean alkalinity enhancement in a Tasmanian plankton community Ocean alkalinity enhancement (OAE) is an emerging carbon dioxide CO2 removal approach for climate change mitigation and can be implemented with various alkaline materials that convert dissolved CO2 i...

Ocean Alkalinity Enhancement (OAE) is a marine CO2 removal method that uses alkaline material to increase the storage capacity for anthropogenic CO2 in seawater.
Kiyas investigated how hydroxide (NaOH) induces taxonomic shifts in plankton. She found: 👇 🌊

onlinelibrary.wiley.com/doi/10.1111/...

Thanks Zeke for constantly synthesizing all this information and keeping us up to date. Please keep doing what you are doing.

The great acceleration debate Why the consilience of evidence points toward acceleration

Is global warming accelerating? Over at The Climate Brink I argue that the consilience of evidence from surface temperatures, climate models, forcing changes, ocean heat content, and earth energy imbalance all point toward yes: www.theclimatebrink....

Will this be a CO2 source because CaCO3 is deliberately precipitated and alkalinity is not replenished? 🤔

Possibly a net source of CO2 when the organics are respired and the solid carbonates remain.

Earth is trapping much more heat than climate models forecast – and the rate has doubled in 20 years

Real world measurements of how much extra heat the Earth is trapping are well beyond most climate models. That’s a real problem.

How wonderful! Congratulations Matt, much deserved!

At #OOSC in Nice this week & am constantly hearing people say there is a global moratorium on #mCDR (or some specific approach like ocean fertilization). I heard the same last week at the Liege colloquium. It’s simply wrong. 🧵

Indicators of Global Climate Change 2024: annual update of key indicators of the state of the climate system and human influence Abstract. In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. Here we compile monitoring datasets (published at https://doi.org/10.5281/zenodo.15639576; Smith et al., 2025a) to produce updated estimates for key indicators of the state of the climate system: net emissions of greenhouse gases and short-lived climate forcers, greenhouse gas concentrations, radiative forcing, the Earth's energy imbalance, surface temperature changes, warming attributed to human activities, the remaining carbon budget, and estimates of global temperature extremes. This year, we additionally include indicators for sea-level rise and land precipitation change. We follow methods as closely as possible to those used in the IPCC Sixth Assessment Report (AR6) Working Group One report. The indicators show that human activities are increasing the Earth's energy imbalance and driving faster sea-level rise compared to the AR6 assessment. For the 2015–2024 decade average, observed warming relative to 1850–1900 was 1.24 [1.11 to 1.35] °C, of which 1.22 [1.0 to 1.5] °C was human-induced. The 2024-observed best estimate of global surface temperature (1.52 °C) is well above the best estimate of human-caused warming (1.36 °C). However, the 2024 observed warming can still be regarded as a typical year, considering the human-induced warming level and the state of internal variability associated with the phase of El Niño and Atlantic variability. Human-induced warming has been increasing at a rate that is unprecedented in the instrumental record, reaching 0.27 [0.2–0.4] °C per decade over 2015–2024. This high rate of warming is caused by a combination of greenhouse gas emissions being at an all-time high of 53.6±5.2 Gt CO2e yr−1 over the last decade (2014–2023), as well as reductions in the strength of aerosol cooling. Despite this, there is evidence that the rate of increase in CO2 emissions over the last decade has slowed compared to the 2000s, and depending on societal choices, a continued series of these annual updates over the critical 2020s decade could track decreases or increases in the rate of the climatic changes presented here.

Our new paper updating key metrics in the IPCC is now out, and the news is grim:

⬆️ Human induced warming now at 1.36C
⬆️ Rate of warming now 0.27C / decade
⬆️ Sharp increase in Earth's energy imbalance
⬇️ Remaining 1.5C carbon budget only 130 GtCO2

essd.copernicus.org/...

The CDR potential of olivine-based enhanced rock weathering in marine systems: a case study for the coastal zone of France - IOPscience The CDR potential of olivine-based enhanced rock weathering in marine systems: a case study for the coastal zone of France, Geerts, Luna J J, Hylén, Astrid, Meysman, Filip J R

We just published our open access paper on marine enhanced rock weathering, applied to the coastal zone of France!
iopscience.iop.org/article/10.1...

My co-chair François Houllier and I are delighted with this resounding success, after 2 years of preparation and many hurdles to overcome.

The recommendations will be presented to Heads of State and Governments tomorrow, the day before #UNOC starts.

#OOSC #ScienceForTheOcean

Congratulations for pulling this off, well done!

Principles for responsible and effective marine carbon dioxide removal development and governance - Ocean Panel Launched on June 4, 2025, at the One Ocean Science Congress in Nice, France, ahead of the United Nations Ocean Conference, this Blue Paper was

New report released today on marine carbon dioxide removal #OOSC
covering scientific, MRV, environmental, social & governance issues and role of governments in responsible #mCDR R&D 🌊
High Level Panel for a Sustainable Ocean Economy & WRI

oceanpanel.org/publication/...

This is not the actual cover of Nature, just shown here for illustrative purposes. We did submit this figure for consideration for their cover. Print run in two weeks, we'll know by then if it gets used.

Out today in Nature, our paper on the drivers of the record 2023 summer heating of the North Atlantic. Temperatures warmed to record levels in just a few months. The impacts on climate & ecosystems were severe. A thread on how this work came about and what we found.👇👇🧵 www.nature.com/articles/s41...

Thanks to all of the organisers for the excellent event 👍👍👍

Extra benefits from carbon tax? The whole would need some sort of collective financing and these could be distributed according to community-specific activities

These insights should be considered for the potential implementation of marine CO2 removal, e.g. via ocean alkalinity enhancement (OAE). OAE will be implemented in communities. Would be great if these could benefit (monetarily and beyond), instead of primarily individuals.

Agreed, 👎 shellfish farming for permanent CO2 storage in carbonate shells 😇

No compromise in efficiency from the co-application of a marine and a terrestrial CDR method - Nature Communications This study shows that combining land- and ocean-based Carbon Dioxide Removal methods does not compromise their effectiveness. This offers flexibility in designing diverse, sustainable mitigation strat...

“We show that global carbon flux responses scale linearly when different CDR methods are scaled up and/or combined, which suggests that the efficiency of CDR is insensitive to both the amount of CDR and the CDR portfolio composition.” 🌊🧪

Few moments ago, after a very long day, Robert said: "It ended as well as it started".
Photos are depicting how it started: The morning seawater sampling for our #OAEPIIP experiment!
Follow for more updates... #cocco-channel #hrzz 🌊

Professor Philip Boyd said he is "honoured to be elected to the Fellowship of the Royal Society, and especially proud of this recognition for our important work to better understand the interactions between ocean biogeochemistry, Earth's carbon cycle, and climate".

Prof Boyd led the SOLACE voyage in 2020/2021, which set out to capture a detailed picture of how plant life in the Southern Ocean helps remove carbon dioxide from the Earth’s atmosphere. Image: Robert Strzepek AAPP

Huge congrats to our oceanographer Prof Philip Boyd who's been recognised for his ocean science leadership. He is among over 90 outstanding researchers from across the world who've been elected to the prestigious Fellowship of The Royal Society, UK’s nat'l academy of sciences: tinyurl.com/35dushm4