Our GDGT Cookbook paper is out now in Biogeosciences! @egubg.bsky.social

Thx Peter Bijl and @kasiasliwinska.bsky.social in spearheading on this. Hope it will help people who study #TEX86 for a bit!

Proudly present Figs 1 and 4 that I made for the paper 😎

Great pleasure working with y'all!

We are pleased to have @cavemangriff.bsky.social and Sam Bova as invited speakers for our 4th #PaleoSEA session at #AGU25.

Last week to submit abstract: tinyurl.com/paleoSEA2025
AGU Student Travel Grant: www.agu.org/honors/fmstg

Calling all (paleo)climate thinkers, data wranglers, and storytellers of the Earth system! Join us for our 4th #PaleoSEA PP030 – Southeast Asia and the Indo-Pacific: Past, Present, and Future Climate and Environment at #AGU Fall Meeting 2025 in New Orleans, Louisiana. (1/2)

@syiwang.bsky.social

#Temporal changes of GDGT-2/-3 over the past 190 million years suggest that ecology of ammonia-oxidizing #archaea (#AOA) changes with Earth's past #climates and #oceans.

Today's deep AOA were suppressed in global oceans during #greenhouse climates!!

(7/10)

Here's what we found:
1) Hot spring #archaea show #thermal pattern in both cultures and env. samples.
2) #SPM and #coretops are grouped into #shallow and #deep samples using #pycnocline. Shallow = thermal. Deep = #nonthermal.
3) Paleo-lipids show patterns change thru time!!

(6/10)

2 patterns to look for here:

1) Samples with #TEX86 should show low GDGT-2/-3 (more GDGT-3 at higher T). This is our expected #thermal pattern.

2) The opposite occurs with core-top sediments. We called this #nonthermal pattern.

We investigated #GDGTs from 7 archives!!

(5/10)

But #archaea live throughout the water columns! So, what happens if #GDGT from deep Archaea mixed in the #sedimentary GDGTs...

Taylor et al. 2013 have shown that increased inputs from deep archaeal clades can be detected by the ratio of GDGTs with 2 and 3 rings (GDGT-2/-3).

(4/10)

Let's start with #GDGTs & #TEX86.

#Archaea adjust the internal structures of their membrane lipids (aka #GDGT) to thrive in a wide range of temp. Marine archaea make #GDGT w/ 0-4 cyclopentyl rings. Hotter?! Let's add more rings! This is the basis of #TEX86 #SST proxy.

(3/10)

But first, what are #archaea?

Thanks to Carl Woese! In 1977, he introduced the 3rd branch of #treeoflife and concluded that #Archaea are more closely related to us #humans (#Eukarya) than #Bacteria.

We can learn about these bugs in past oceans using #lipids in #sediments.

(2/10)

My 1st first-authored paper with incredible coauthors (Yige Zhang, Ann Pearson, Brian P. Hedlund, Shuang Zhang) was published in @pnas.org back in 2022 (doi.org/10.1073/pnas...).

We show that #GDGTs are much more than a #TEX86 temperature proxy! Curious? Here we go!

(1/10)

We also show that TEX₈₆ temperatures appear unusually warm during glacial periods — likely a fingerprint of nutrient stress — which suggests that some previously published TEX₈₆-based temperature records may need a second look.

This "nutrient effect" could bias TEX₈₆-based temperature reconstructions.

In our new paper, we show that this nutrient effect isn’t limited to lab cultures — we can detect it in lipid distributions from globally distributed surface sediments.

But there’s a catch:
Marine archaea don’t just respond to temperature — they also change their membrane lipids when nutrients are scarce. In lab experiments, nutrient-stressed archaea produce lipids that mimic the signature of warmer temperatures, even if the water is cool.

If you’re wondering what TEX₈₆ is — it’s a proxy that lets scientists reconstruct past ocean T, going back over 190 million years! It’s based on membrane lipids produced by marine archaea — micro-organisms that tweak their lipid chemistry depending on seawater temperature.