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Tom Chalk

@chalkyoceans.bsky.social

1.1K followers 271 following 65 posts

Dr Chalk, destined to be a researcher of carbonates. CO2, & ocean-climate links, resident isotope geochemist @exoceanlab.bsky.social, @cerege.bsky.social, France. Equalist, technologist, environmentalist. #climatevegan 🌱. 🇬🇧🤝🇲🇫. 🏳️‍🌈 but always with the 🏳️‍⚧️.

Posts Replies Media

Tom Chalk @chalkyoceans.bsky.social · 02/03/2026

Watch this space for more #foraminifera, #CO2, and of course... more lego scientists @exoceanlab.bsky.social.

Part of the #legolab team, lego Jaime and lego Tom start looking at some new lego sediment core. They are surrounded by the tools of their trade; a giant 3D printed foram and lego mass spectrometer.

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Tom Chalk @chalkyoceans.bsky.social · 17/12/2025

Net accident you say? Ooops, this net came back looking like it had been mauled by a shark, and I think... Maybe it had. A good, but expensive(!) sample. Sorry @tdegaridel.bsky.social!

Look carefully! Fish carefully! A picture of a totally trashed plankton net and the legs of two very tired scientists.

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Tom Chalk @chalkyoceans.bsky.social · 10/12/2025

There's still much more to come from our trip to Bermuda with @juliemeilland.bsky.social, @thefosterlab.bsky.social and @case4climate.bsky.social. Whilst there, we were all tortured with video interviews... Here's a taster!

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Tom Chalk @chalkyoceans.bsky.social · 04/12/2025

Here comes the final boss: porewater microprofiles, using our favourite tools, pH and oxygen microsensors, made of glass and pure anxiety. Every time one snaps, we just sigh, call our finance manager, and prepare our next monthly order from @unisense.bsky.social. Thanks for the tiny sensors!

A jar of deep sea mud sitting on a height adjustable stand. It has microprobes to measure oxygen (respiration, photosynthesis) and pH (dissolution, precipitation, also respiration etc...) at tiny intervals to see what is going on right at the grain interface.

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Tom Chalk @chalkyoceans.bsky.social · 04/12/2025

Once the cores make it back to our lab, it’s time to get our hands dirty: we slice them like a very unappetizing cake, a couple of cms at a time. If we can, outside of the lab to keep it clean inside. All of that just to rebuild the sediment as it looked on the seabed.

Marine and Olivier cutting the core into slices, at the top it can be really liquid and gooey, so we keep it vertically, but lower down it can be almost like a rock. Despite the complaining from Olivier both of them are remarkably mud-free!

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Tom Chalk @chalkyoceans.bsky.social · 04/12/2025

#exoCeanadvent Day 4: At exoCean we also investigate what happens to calcifiers who mysteriously die (answer: a lot happens). For that we must go at sea and collect evidence, just like CSI but with more seasickness pills, same sunglasses.

Tom holding a surface interface core, like a proud father. The core includes the top layer of mud, with the bottom layer of ocean, including all the creatures living there (and more importantly for Tom, the ones long dead too).

Disclaimer: Tom does not get seasick.

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Tom Chalk @chalkyoceans.bsky.social · 09/10/2025

Thank you to everyone who came to our workshops & @pages-ipo.bsky.social meeting, contributed to the special issue, the community at large who use our CO2 reconstructions, and of course our funders @erc.europa.eu , @ukri.org, @dfg.de and @leverhulme.ac.uk! pastglobalchanges.org/publications...

Snap-shot of all the happy faces at the hybrid PAGES workshop which took place in Bergen, 2022.

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Tom Chalk @chalkyoceans.bsky.social · 09/10/2025

We look at the history and future of d11B-CO2 reconstructions, as well as their major limitations throughout the last 70 million years. I hope this will be a great resource for boron people new and not new, students and not students! Reach out if you want to know more.

A figure showing the relative importance of different error sources through time which impact the d11B-CO2 proxy. In general the most important are: analytical, disequilibrium, sea water isotope composition and species calibration.

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Tom Chalk @chalkyoceans.bsky.social · 02/10/2025

He doesn't just do the lab either, he's happy to brave the waves and come help us sample in the field. Go Maxime! (Here in the middle of the Atlantic, May 25)

@chalkyoceans and Maxime on a boat fishing forams.

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Tom Chalk @chalkyoceans.bsky.social · 04/09/2025

Future (and past) @climatecerege.bsky.social superstar @antacl.bsky.social giving her #ICP15 talk now. Modelling the Indian monsoon in the Miocene, and some important praise to the organisers for their diverse programme of speakers. Bravo!

Anta delivering her #ICP15 talk in Bengaluru.

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Tom Chalk @chalkyoceans.bsky.social · 01/06/2025

It's #pride month, and whilst I'm still in Bermuda, far away from my regular life I'm reflecting on the world for LGBTQ+ folk, which seems to have gotten just a little bit worse this year... But we're not going away, and not giving up on making things better. 🏳️‍🌈🏳️‍⚧️

Ooops, a foot pic. Sporting Bermuda pride sock.

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Tom Chalk @chalkyoceans.bsky.social · 20/05/2025

Fieldwork needs fieldwork hair, and like this the forams can't see me coming in the turquoise waters around Bermuda. 🧜🏼‍♂️

Me on the beach, trying to match my hair to the (sub) tropical waters.

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Tom Chalk @chalkyoceans.bsky.social · 14/11/2024

We also project conditions into the next century. Contrary to some people's (my, not Sonia) initial thoughts, that high latitudes are the most vulnerable to climate change, it is foraminifera in low latitudes which will move outside of known foraminifera thermal and saturation niches first.

Four plots showing low to high latitude foraminifera and their current temperature and calcite saturation niches. We project how these niches will change with climate under a "best case" scenario (SSP2-4.5) over the next century. Whilst high latitude niches change, they are still within the tolerances of modern foraminifera, however, in low latitudes temperature-saturation conditions are unlike anything currently experiences by planktic foraminifera in the modern ocean, putting them at risk of regional extinction.

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