Tom Chalk
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 🏳️⚧️.
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- Reposted by Tom Chalk#exocean advent calendar day 24! Today we thought it was a good fit to show an image/talk about “conception”… One of the thing we (try to) do best at ExoCean is planktonic foraminifera reproduction. Here two immaculate mummies… 😏 We would like to wish you all a beautiful Christmas Eve!
- Reposted by Tom Chalk#exoCeanadvent Day 23: at exoCean we also look at some old questions: in the late 1800s, during the HMS Challenger expedition, they discovered that you can have a constant rain of shells from above, and still end up with a seafloor that looks like the carbonate budget never existed. Why? Pressure. 🌊
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- Reposted by Tom Chalk#exoCeanadvent Day 22: Winding down for the holidays often means one thing... more mass spectrometry time is available! With our friends in @cerege.bsky.social's #ENVITOP facility, we're making use! Thanks to their equipment we're working on measuring elemental compositions down to the nano-gramme!
- Reposted by Tom Chalk#exocean advent calendar Day 21! The strongest link between all of us is our love for the ocean. Leaving Marseille with a magnificent sunrise reminds us each time we go out how lucky we are to do what we love for a living! We already have our ship time for the first 6 months of 2026 - exciting!
- Here's to #2026! Please don't hold us to any of these...
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- Reposted by Tom Chalk#exoCeanadvent Day 19: Friday edition: today’s post is about the peacocks at CEREGE, because it’s Friday and our brains are in weekend mode. They wander around like they own the campus, scream for no reason, and block paths with absolute confidence. Honestly, goals. 🦚
- Essential reading for those interested in going carbon negative 👀. See what @sulpis.bsky.social does for a living and how it connects to @exoceanlab.bsky.social here!
- Read the European Marine Board report here: 📘👀 www.marineboard.eu/publications...
- Reposted by Tom ChalkRead the European Marine Board report here: 📘👀 www.marineboard.eu/publications...
- 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!
- #exoCeanadvent Day 17: Net accident, happy outcome. Ex-lab member Laura caught this phronima (monster in a barrel) “by mistake”, so we adopted it - alive - in a lab aquarium. One haul turned into days of behaviour notes.
- Reposted by Tom Chalk#exoCeanadvent Day 16: We're getting closer to the holidays, but we don't stop yet. @erc.europa.eu postdoc @jysuarezibarra.bsky.social was out today presenting his work @maxplanck.de in Mainz. @soniachaabane.bsky.social is also visiting to chat with colleagues.
- Reposted by Tom Chalk#exoCeanadvent Day 15: Some plankton are tiny [citation needed?], and for those we need ways to measure tiny (this is a theme you'll hear us talking about a lot). Sometimes just holding samples in place can be hard.... enter the #Cryostage! ❄️
- Reposted by Tom Chalk#exoCeanadvent Day 14 Footprint reduction: we do lab-based ocean science because we genuinely love it, but also because lab experiments can replace lots of field trips. More control, more insight, and in part, fewer emissions. Bonus: dissolving old sediment cores neutralizes a bit of CO2. 😇
- Reposted by Tom Chalk#exoCeanadvent Day 13: Time Machine. Travel back in time with us 6 million years. Part of the reason for our work @exoceanlab.bsky.social is to better understand the past through observing the modern, but sometimes you just need some ancient mud..@chalkyoceans.bsky.social recently went to get some!
- Reposted by Tom Chalk#exoCeanadvent Day 12: End-of-year celebration - raclette edition. On the agenda for this team meeting: cheese, cheese, cheese, goals for next year: even more cheese. We’ve officially reached our melting point. 🧀
- Reposted by Tom Chalk#exoCeanadvent Day 11: Science makes you do strange things. Meet @astridhylen.bsky.social, a postdoc working with carbonate dissolution in coastal sediments. She recently found herself in the middle of a salt marsh, stirring one of the ponds with a (clean) toilet brush taped to a curtain rod.
- 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!
- #exoCeanadvent Day 10: As winter creeps into Provence we remember warmer days from our fieldwork in Bermuda. We stayed with the lovely folk at @biosstation.bsky.social, like @blancobercial.bsky.social who helped us to look for different foraminifera to catch, than our usual Mediterranean stuff.
- 100% recommend for fieldwork. See @maxime-felix.bsky.social for details on availability.
- Reposted by Tom Chalk#exoCeanadvent Day 9: Meet Maxime (again). At @exoceanlab.bsky.social and @climatecerege.bsky.social Maxime has been conducting several experiments focusing on the culture of marine organisms. One project involved culturing foraminifera in the presence of olivine (Mg,Fe)2SiO4, an igneous mineral.
- One of many super cool projects started or starting in @exoceanlab.bsky.social. Keep it up Katoo!
- #exoCeanadvent Day 8: Meet Katoo Declerk's Erasmus+ work. During her internship Katoo is investigating recently dead foraminifera (handily available in our lab!) Forams typically sink to the ocean floor soon after death, but partial or total dissolution can occur before getting there.
- Reposted by Tom Chalk#exoCeanadvent Day 6: To study the deepest ocean trenches, we’re building reactors that make our lab behave like the deep ocean. Funded by @erc.europa.eu #Deep-C, they will hold cold seawater at ~1000 bar (10km water) so we* watch pressure shape chemistry and biology 🔬🌊 *mostly @sulpis.bsky.social
- Reposted by Tom Chalk#exoCeanadvent Day 4: Why did we set up this lab? Part I. What is going to happen to climate as CO2 levels go up? @chalkyoceans.bsky.social and @erc.europa.eu project #ForCry look at CO2 in the past to better understand climate sensitivity. Part of this is making better past CO2 reconstructions.
- Find this data, and more - in the fantastic paper by Elwyn de la Vega. Boron isotope CO2 reconstructions in the Pleistocene have come a long way... but we still have more to come. Watch this space with @mudwaterclimate.bsky.social and many others! cp.copernicus.org/articles/19/...
- #Boron isotopes (a fancy chemical measurement from tiny shells, like these shown below) can be used to reconstruct CO2, just like the ice cores can in the past (also shown below). A little less precise, but show great potential, especially if we can work out how they work in laboratory conditions.
- It might have been 10 years @whoi.edu, but I still wear your hoodie at sea. Thanks for helping me know what to do when I'm there.
- #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.
- #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.
- 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.
- 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!
- For reference this is @juliemeilland.bsky.social's exact face every time she gets to play with living foraminifera. #foramwizard.
- #exoCeanadvent Day 3: An important part of creating a lab is to be able to plan things in miniature, for this we use #Lego versions of our team, they tend to be a bit cheaper for testing. You may spot some of @chalkyoceans.bsky.social's not so secret wishlist in the background (#nu-instruments).
- Feel so lucky to be a part of this team. It is a geochemist's dream to have foraminifera growing right on site. 🐚🌡️⚡🔬
- Together with @juliemeilland.bsky.social, we have perfected the task of bringing plankton back to the lab alive — more on that later in the month. When it is sunny and flat, even a rare @tdegaridel.bsky.social can be spotted offshore.
- Reposted by Tom ChalkDay 2 of #exoCeanadvent: Come with us to sea (you can also be a land based participant). As an 'inland' ocean lab, we don't quite have the sea on our doorstep, but that doesn't mean we can't bring it to us! We're based just 30–60 minutes from boats out of Marseille and Toulon.
- Reposted by Tom ChalkWelcome to the exoCean advent calendar! To get us through the wintery month of December we'll be telling you one thing about our lab everyday this month. (Until the 24th). Stay tuned! Today we unveil our new lab #logo and #website, it's a new era for #exoCean! exocean.academicwebsite.com
- So excited to see how this revolutionises foraminifera work. Well done and deserved @juliemeilland.bsky.social, but not sure I can ever forgive you for getting me into the "living stuff" !!
- @juliemeilland.bsky.social won this year’s Alan Higgins Award! We cite: « her pioneering work on planktonic foraminifera - including the first multi-generational lab cultures - has transformed how we study and apply these vital microfossils. » Yay!
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- Just realised that this is as close to an "M2-M2" project as you are likely to get. Explore the aftermath of one of the most interesting features of the Pliocene, MIS M2 during your M2 internship! www.sciencedirect.com/science/arti...
- Are you looking for a master's internship (5-6 months)? Constraining tropical planktonic foraminifera depth habitats in a (past) high-CO2 world 🥵🌎 Come to @climatecerege.bsky.social, south of France☀️🇫🇷 Deadline: 15 Nov 2025. Start: Jan-Mar 2026. More info👇 nuage.osupytheas.fr/s/fdAEGQXkwA...
- Reposted by Tom ChalkAre you looking for a master's internship (5-6 months)? Constraining tropical planktonic foraminifera depth habitats in a (past) high-CO2 world 🥵🌎 Come to @climatecerege.bsky.social, south of France☀️🇫🇷 Deadline: 15 Nov 2025. Start: Jan-Mar 2026. More info👇 nuage.osupytheas.fr/s/fdAEGQXkwA...
- Wonder what carbon was doing in the oceans before humans were around to see? We'll use the chemistry of tiny shells on the seafloor to find out how carbon moved between the ocean and atmosphere over 1 million years ago. Come work with us in 2026 for your M2 internship @climatecerege.bsky.social.
- Are you looking for a master's internship (5-6 months)? Early Pleistocene deep ocean carbon storage in the Caribbean Sea 🌎🌊 Come to @climatecerege.bsky.social, south of France☀️🇫🇷 Deadline: 30 Nov 2025. Start: Jan-Feb 2026. More info👇 nuage.osupytheas.fr/s/AF4qYHA4CQ...
- You'll be based in Aix-en-Provence and using mass spectrometry (firing atoms really fast to learn what they are) to better understand past climate. We'll look at the changing ocean chemistry of the Pleistocene. With Matthieu Buisson, @jysuarezibarra.bsky.social , me and others...
- ... you'll learn how to identify and separate tiny shells from old sediments, before analysing their chemistry in the lab. email: buisson@cerege.fr and chalk@cerege.fr for more information or to apply (CV + cover letter). nuage.osupytheas.fr/s/AF4qYHA4CQ...
- Interested in improving our knowledge of climate by looking into the past? In the Pliocene the earth was hotter than today, but carbon dioxide was "about the same". Come work with us in 2026 looking at where this crucial information comes from, and how to make it better during an M2 internship.
- Are you looking for a master's internship (5-6 months)? Constraining tropical planktonic foraminifera depth habitats in a (past) high-CO2 world 🥵🌎 Come to @climatecerege.bsky.social, south of France☀️🇫🇷 Deadline: 15 Nov 2025. Start: Jan-Mar 2026. More info👇 nuage.osupytheas.fr/s/fdAEGQXkwA...
- You'll be based at @climatecerege.bsky.social in Aix-en-Provence and looking at tiny fossil seashells called foraminifera. These shells lock away the ocean's chemistry and can be used as a Time Machine to explore past climate. With @jysuarezibarra.bsky.social, me and others you'll explore...
- how evolution impacts the fossil record and our climate data from the all-important mid-Pliocene interval (~3.2 million years ago). email: suarez@cerege.fr and chalk@cerege.fr for more information or to apply (CV + cover letter). nuage.osupytheas.fr/s/fdAEGQXkwA...
- New paper(s) alert! Check out @agu.org Palaeoceanography & Paleoclimate. Including our piece on best practices going forward for d11B-CO2 reconstructions. agupubs.onlinelibrary.wiley.com/doi/10.1029/... including @case4climate.bsky.social, @michaelhenehan.bsky.social,... @eleniwater.bsky.social.
- 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.
- Also check out the whole special issue, there are some really great papers inside... agupubs.onlinelibrary.wiley.com/doi/toc/10.1...
- 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...
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- Reposted by Tom ChalkStill time to apply:
- 📢We're hiring!📢 We have a permanent Lecturer in Earth Sciences position available in @OU_EEE @OpenUniversity £47,389 to £56,535 Closing Date: 20 October 2025* We are a friendly, research intensive school with supportive colleagues and great labs. jobs.open.ac.uk/job/Lecturer...
- Reposted by Tom ChalkThe lab keeps evolving and we are THRILLED! More equipment is about to arrive, some more is planned, and we feel super excited about our different projects. Also really… what a view when the doors are open, one can even see the emblematic « sainte victoire » behind the trees!
- Reposted by Tom ChalkSlowly but surely the lab we had in our heads with @sulpis.bsky.social and @chalkyoceans.bsky.social is coming to life. High pressure incubators are about to come, more microscopy equipments… Such a nice adventure has started!
- Reposted by Tom Chalk#Lecturer position in #EarthSciences 👇🏼@openuniversity.bsky.social Please apply, if interested 🙏🏼 Closing Date: 20 October 2025 Contract Type: #Permanent Fixed Term Contract/End Date: Not Applicable jobs.open.ac.uk/job/Lecturer...
- Come work in our lab! All the usual awesome things apply about doing exciting science, plus this one might save the world! @sulpis.bsky.social hiring a 2 year position to observe and model deep ocean processes using high-pressure reactors. *Goes to gather a bunch of forams to be dissolved* 😅
- Reposted by Tom ChalkSediments dissolving on the seafloor can act as a long term sink for carbon dioxide emissions. We're bringing it to the lab, deep sea research from the comfort of Southern France! Postdoctoral position for 2 years available working with @sulpis.bsky.social in the @exoceanlab.bsky.social.
- Nice comparison of foram-coating derived and sediment derived #Ndisotopes in the Mediterranean from Kazuyo Tachikawa and others @climatecerege.bsky.social and @cerege.bsky.social. Small cautionary tale for unrestricted use (of sediment), but normally it works! www.sciencedirect.com/science/arti...
- 👏🏼
- Watch this space for so much new exciting science from the new influx of Ceregiens. @cerege.bsky.social
- Day 4, #ICP15, next up @antacl.bsky.social talking about long term evolution of South Asian Summer Monsoon. Congratulations to @antacl.bsky.social for starting her new position soon 🥳 @climatecerege.bsky.social @cerege.bsky.social
- Reposted by Tom ChalkDay 4, #ICP15, next up @antacl.bsky.social talking about long term evolution of South Asian Summer Monsoon. Congratulations to @antacl.bsky.social for starting her new position soon 🥳 @climatecerege.bsky.social @cerege.bsky.social
- 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!
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- Thank you so much for the invitation #ICP15. Diversity makes us stronger, and the data shows it! ⏩🏳️🌈
- Lovely to hear from @chalkyoceans.bsky.social about need for #diversity (of careers, people, methods and minds) that underpins our working 🙏🏼 #ICP15
- Reposted by Tom ChalkNext up @chalkyoceans.bsky.social improving Neogene CO2 reconstructions - proxies, calibrations, morphotypes and much more.. 🙏🏼
- Reposted by Tom ChalkA new paper from our team, and the opportunity to introduce Jaime Suarez @jysuarezibarra.bsky.social , postdoc in our micropaleontology group!
- 🚨New paper alert🚨 Using the mean and 95th percentile of cross-sectional area measurements, we documented ecological and taphonomic imprints on the test size variation of planktonic foraminifera. @soniachaabane.bsky.social @chalkyoceans.bsky.social @tdegaridel.bsky.social doi.org/10.61551/gsj...
- Reposted by Tom Chalk✨ Honored to witness the inauguration of the BISSAP lab at UCAD — a new lab for ecosystem monitoring in Senegal! 🌍🔬 Huge congratulations to everyone involved! @climatecerege.bsky.social @ird-fr.bsky.social #ScienceForAll #UCAD #IRD #Biodiversity #Africa #BISSAP www.ird.fr/inauguration...
- Reposted by Tom Chalk🚨New paper alert🚨 Using the mean and 95th percentile of cross-sectional area measurements, we documented ecological and taphonomic imprints on the test size variation of planktonic foraminifera. @soniachaabane.bsky.social @chalkyoceans.bsky.social @tdegaridel.bsky.social doi.org/10.61551/gsj...
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- Reposted by Tom Chalk🏅 Congratulations to Isabelle Basile-Doelsch, Research Director at INRAE/CEREGE, for winning an @erc.europa.eu Advanced Grant for her NanoCLICS project. Learn more about her project: www.cerege.fr/en/nanoclick...
- Reposted by Tom ChalkNew job alert! We just opened a tenure-track Junior professor Chair at @cerege.bsky.social focused on the study of the critical zone in the Mediterranean and intertropical Africa. More info on the IRD website here: en.ird.fr/tenure-track... Contact me if you are interested!
- 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. 🏳️🌈🏳️⚧️
- Reposted by Tom ChalkMass Spec xkcd.com/3094/
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- Fieldwork needs fieldwork hair, and like this the forams can't see me coming in the turquoise waters around Bermuda. 🧜🏼♂️
- We're away from our lovely light and temperature controlled incubators @exoceanlab.bsky.social, but that doesn't mean we can't keep our plankton happy. @biosstation.bsky.social water baths to the rescue. If you've ever wondered what culturing for trace isotope systems looks like, it's this! #d11B
- Reposted by Tom ChalkBack in France, exoCean is still working hard... 🐚✨ A tiny miracle in the lab! For the first time in our team’s history, we’ve successfully harvested pteropod egg sacs and captured the moment of their eclosion on film.
- Reposted by Tom ChalkExcited to have hundreds of baby Forams in the lab after the first towing - different species - different behaviors! @exoceanlab.bsky.social @chalkyoceans.bsky.social
- ExoCean is in #Bermuda! Or at least most of it is (sorry @sulpis.bsky.social). We're here looking for foraminifera to grow in the lab, and sediments to observe how they will react to ocean change.
- Reposted by Tom ChalkWe then collect the live plankton and try to keep them alive long enough to get to the lab. There we can look at how they respond to different conditions in a controlled setting. (And if you know @chalkyoceans.bsky.social, you know there will be boron involved).
- Thank you @biosstation.bsky.social for hosting us. We're so excited to be here!
- ExoCean is in #Bermuda! Or at least most of it is (sorry @sulpis.bsky.social). We're here looking for foraminifera to grow in the lab, and sediments to observe how they will react to ocean change.
- Reposted by Tom ChalkTom Chalk, an isotope geochemist (interested in the tiny variations in mass of chemical elements), specialising in boron, the 5th element. I am the Principal Investigator of the ERC project ForCry and CNRS researcher, interested in the natural history and unnatural future of Earth’s climate.
- Find out what we're doing at @climatecerege.bsky.social and further abroad here. Follow our lab group @exoceanlab.bsky.social here for more. So happy to be in the same place as @juliemeilland.bsky.social and @sulpis.bsky.social to science!
- 🚨Hello world!🚨We'd like to introduce you to our new laboratory for "experimental ocean science", ExoCean (C is for carbon). We are three researchers teaming up to work on culturing, dissolving, & measuring marine samples. @juliemeilland.bsky.social, @sulpis.bsky.social & @chalkyoceans.bsky.social.
- Reposted by Tom ChalkInterested in doing a PhD with living planktonic foraminifera? Come work with us! Check our PhD subject and get in touch! @tdegaridel.bsky.social
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- Reposted by Tom Chalk📢 Today, CEREGE and other research laboratories from the Technopole de l’Arbois mobilized for research and academic freedom as part of the #StandUpForScience movement. Together, let’s defend free and independent science!
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- Can we (and by we I mean foraminifera) migrate our way out of the climate crisis? It doesn't look like it. Massive study by @soniachaabane.bsky.social with @tdegaridel.bsky.social, @juliemeilland.bsky.social, @sulpis.bsky.social, me and others! www.nature.com/articles/s41...
- Using the FORCIS database and almost 200,000 samples over the past century we look at depth habitats, and zonal distributions of foraminifera, an important plankton group (and palaeoclimate proxy). Despite movements in depth, long, & lat many species are declining in abundance in the modern oceans.
- 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.
- This paper highlights how even under relatively modest climate change (i.e. we are NOT on track for our "best case scenario" used here), planktonic foraminifera may suffer extreme contractions in their liveable environments. As organisms low in the food-chain, this could have dire knock-on impacts.
- Reposted by Tom Chalk🌊📉 New Paper Alert! "Migrating is Not Enough for Modern Planktonic Foraminifera in a Changing Ocean" published Open Access in Nature🧵👇 Me & @tdegaridel.bsky.social @juliemeilland.bsky.social @sulpis.bsky.social @chalkyoceans.bsky.social and others www.nature.com/articles/s41...
