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Jiawei Da

@paleoisocw.bsky.social

17 followers 29 following 20 posts

I study past climate and biogeochemical cycles. I like to dig around, both literally and figuratively. Geochemists never die, they only reach equilibrium. https://da-jiawei.github.io/

da-jiawei.github.io

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Jiawei Da @paleoisocw.bsky.social · Jul 19

This work was a collaboration across Nanjing University, UT Austin, Purdue, UC Santa Barbara, and others.
Big thanks to our coauthors and field teams! 🙌

Jiawei Da @paleoisocw.bsky.social · Jul 19

This has implications for understanding future warming:
📌 Fast feedbacks (like water vapor and clouds) likely dominate ECS, and these feedbacks operated similarly in cold and warm states over the past 2.6 million years.

Jiawei Da @paleoisocw.bsky.social · Jul 19

And here's the key result:
👉 No apparent state-dependency in ECS between glacial and interglacial periods.
In other words, climate sensitivity to CO₂ forcing was remarkably consistent despite major background climate changes.

Jiawei Da @paleoisocw.bsky.social · Jul 19

Using compiled glacial and interglacial CO₂ and temperature records, we estimate:
🌍 Earth System Sensitivity (ESS): ~6.2–7.4 K per CO₂ doubling
🌡️ Equilibrium Climate Sensitivity (ECS): ~3.3–3.7 K

Jiawei Da @paleoisocw.bsky.social · Jul 19

Our data show a stepwise decline in glacial CO₂, from ~300 ppm to below 200 ppm.
This mirrors global cooling and the intensification of glacial cycles, suggesting a tight CO₂–climate coupling.

Jiawei Da @paleoisocw.bsky.social · Jul 19

We reconstructed atmospheric CO₂ during glacial periods from 2580 to 800 ka using pedogenic carbonates in paleosols from the Chinese Loess Plateau.
This is the first continuous early Pleistocene glacial CO₂ record from a terrestrial archive.

Jiawei Da @paleoisocw.bsky.social · Jul 19

Quantifying Earth’s climate sensitivity is critical for projecting future warming. But is sensitivity state-dependent — does it vary between glacial and interglacial periods?
Paleoclimate data offer a deep-time perspective on this question.

Jiawei Da @paleoisocw.bsky.social · Jul 19

Our new study is out in @natcomms.nature.com!
We present a glacial CO₂ reconstruction from the Chinese Loess Plateau over the past 2.6 million years and explore what it reveals about climate sensitivity during the Pleistocene.
🔗 rdcu.be/ewIfh

Jiawei Da @paleoisocw.bsky.social · Jul 9

50 days' free access:
🔗 authors.elsevier.com/a/1lOtb26gar...

authors.elsevier.com

Jiawei Da @paleoisocw.bsky.social · Jul 9

The findings call for a re-evaluation of previous δ¹⁸O-based reconstructions using land snail shells—especially in semi-arid or dew-prone regions.

Want to try it yourself?
The R + JAGS code is open source:
📂 github.com/da-jiawei/la...

Jiawei Da @paleoisocw.bsky.social · Jul 9

This study highlights the importance of thinking beyond rainfall. Dew is isotopically distinct and forms under different conditions.
Snails are active at night—just when dew forms—making them prime dew harvesters. 🌙🐌

Jiawei Da @paleoisocw.bsky.social · Jul 9

To fix this, I modified the classic flux balance model to account for dew formation via the Craig-Gordon model.
The revised model better reproduces observed isotopic values—and yields rainfall-δ¹⁸O predictions consistent with observations.

Jiawei Da @paleoisocw.bsky.social · Jul 9

This is a big deal:
Neglecting dew could lead to systematic underestimation of rainfall δ¹⁸O when back-calculating from snail shell δ¹⁸O.
That’s a potentially serious bias in many paleoclimate reconstructions based on snail shells.

Jiawei Da @paleoisocw.bsky.social · Jul 9

Snail body water δ¹⁸O and δD consistently plot above the local meteoric water line—right where you’d expect dew to plot.
In fact, modeling shows dew can account for up to 50% of the snail’s water intake! 💧🌫️

Jiawei Da @paleoisocw.bsky.social · Jul 9

Using a modern high-resolution dataset from Xi’an, China (Zong et al. 2023), I modeled δ¹⁸O and δD in snail body water with a Bayesian inversion approach.
The key result? The isotopic signature doesn’t match rainfall alone. Something’s missing.

Jiawei Da @paleoisocw.bsky.social · Jul 9

Traditionally, it's assumed that rainfall is the main water source for snails, and therefore the main oxygen source in their aragonite shells.
This assumption underpins shell-δ¹⁸O-based reconstructions of past precipitation. But is it valid? 🤔

Jiawei Da @paleoisocw.bsky.social · Jul 9

Land snail shells are widely used to reconstruct past rainfall δ¹⁸O. But what if snails aren't just drinking rain? 🌧️🐌
I tested this using isotope modeling—and dew plays a much bigger role than we thought.
📄https://doi.org/10.1016/j.chemgeo.2025.122953
#Paleoclimate #StableIsotopes

nam12.safelinks.protection.outlook.com

Jiawei Da @paleoisocw.bsky.social · Jun 30

This just made my day☺️

Jiawei Da @paleoisocw.bsky.social · May 22

The highlights are evidence from the numerical modeling of sensible heat transport and isotope mass balance. 50-day free access: authors.elsevier.com/c/1l8HX52cui...

authors.elsevier.com

Jiawei Da @paleoisocw.bsky.social · May 22

I am pleased to share this work showing that atmospheric vapor can be directly utilized by clay-rich vertisols with potential implications towards drought mitigation.

Reposted by Jiawei Da

Ian Hall @ianhall.bsky.social · Feb 28

Today, as the Trump administration issued mass layoffs to NOAA scientists, its worth remembering Syukuro Manabe, whose groundbreaking climate models, presented to the Senate in 1985, predicted the very changes we now face.

Attacks on science threaten our future.

youtu.be/jGXjkkJ8yZg?...

Syukuro Manabe PhD: Climate Forecast in 1985 Senate Hearing

YouTube video by greenmanbucket

Reposted by Jiawei Da

Jiang Zhu @climate-z.bsky.social · Jan 23

🚨 CESM Paleoclimate Working Group Meeting - Jan 29

Join us for 13 exciting talks (mostly from early-career researchers) and in-depth discussions!
📅: Wednesday, Jan 29
📍: Zoom (free registration) or in-person at Mesa Lab

Register now and connect with the community! www.cesm.ucar.edu/events/worki...