Also published yesterday in Nature : Emerging climate impact on carbon sinks in a consolidated carbon budget.
www.nature.com/articles/s41...
(might not be open access sorry)

Lol’ed at this earlier. Unfortunately adding zeroes means the proxy will fall apart because most of the excess 230Th will have decayed away by 300 ka 🤦‍♂️🤷‍♂️

TY Evan! All credit to Alex Phillips here - we had a rough idea and she turned it into a beautiful illustration. Definitely worth pinging her if youre ever looking for technical grapgic design help - bren.ucsb.edu/people/alexa...

Agree 100%. Send me an email and I’ll send you a pdf (I’m not hard to find).

Great idea, prob going to need some new materials… I’d be skeptical about the lipid preservation in these 31-year old cores!

Excited to see this, Shannon!!

Frankie & I are extending these paired sea-ice and N cycling proxies to last interglacial. In the interim, I think it's truly open season on the Arctic now. The last 30 kyr chronologies are robust & ready for the full spectrum of new paleo proxies. Reach out if you need materials to test! (8/8)

In the Materials and methods, we evaluate the primary age concerns for the Arctic (hiatuses, authigenic calcite) and rule out both. Foram-bound N isotopes are an exceedingly important tool for clarifying the age of Arctic sediments, and thereby allowing the application of tools like 230Th_xs (7/n)

Using one of the flux proxies, excess 230Th, requires strong constraints on sediment ages. This has been a problem in the Arctic for some time. If you're interested in this question, check out the Materials and methods: (6/n)

www.science.org/doi/suppl/10...

The power of this approach is it doesn't require any fossils or biomarkers: it's a completely abiotic proxy of relative sea-ice extent. And it should be applicable anywhere in the Arctic Basin (or even Antarctic?) in sediment cores > 1000 m water depth (5/n).

The results are much as you might expect for the late Pleistocene, but had not been proven for the central Arctic: significant ice cover during the Last Glacial Maximum, ice breakup during the deglaciation, likely seasonal ice cover during the early Holocene. (4/n)

Frankie Pavia's idea here was simple yet profound: If you have two constant-flux proxies, 3He and excess 230Th, they should be coupled unless their inputs are cut off. But 3He, which comes from outer space, would be blocked by sea-ice cover. We tested this by applying it to Arctic sediments (3/n)

Currently the featured paper at science.org, and covered by @nytimes.com: www.nytimes.com/2025/11/06/climate/arctic-sea-ice-cosmic-dust.html (pretty epic!) (2/n)