David Harning

Earth scientists Maggie Osburn and Mia Tuccillo bag up plant samples in a rocky Greenland landscape, with an iceberg-spotted fjord and glacier-covered mountains in the background.

New paper! PhD student Mia Tuccillo has uncovered another big impact of past warming in Greenland: lakes lost oxygen for thousands of years and cyanobacteria took over 🦠 🧪 🦠. It's kinda yikes...
With collaborator @geobiomaggie.bsky.social (1/3)

🚨 New paleoclimate proxy paper from a team of INSTAARs, working with colleagues from UC Santa Cruz & U of Iceland. 1st author David Harning now works with CIRES & NOAA, but remains an INSTAAR Affiliate. Congrats all! 👏🏽

Both redox potential and climate control molecular proxies in Icelandic Holocene lake sediments Communications Earth & Environment - Recovery of complementary materials from well-ventilated and seasonally stratified lakes can allow reliable reconstruction of local temperature and...

New paper on ancient DNA and lipids from Icelandic lakes. This one threw some unexpected results and now has me thinking a lot about lake oxygen’s role in organic matter preservation, the climate proxies derived from them, and past methane cycling. #Paleosky www.nature.com/articles/s43...

Registration for experts interested in serving as Expert Reviewers and providing scientific comments on the First Order Draft of the Special Report on Climate Change and Cities is now open!

Register here: apps.ipcc.ch/comments/src...
⚠️ Registration closes 30 Nov2025

🔗 www.ipcc.ch/2025/09/17/p...

Development of new global lake brGDGT-temperature calibrations: advances, applications, challenges, and recommendations Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a group of temperature-sensitive membrane lipids found in bacteria that have been widely …

🚨New paper!🚨🥳

Delighted to share our new paper out now on global lake brGDGT temperature calibrations: advances, applications and challenges:

www.sciencedirect.com/science/arti...

@hassfacultyncl.bsky.social @bas.ac.uk @ogu-bristol.bsky.social

Reminder: Applications are open until October 31st! 📣

Call for SSC nominations - due Oct 24.
AND join us Sept 23 at 3p for a info webinar on submitting your activity proposal to us + highlights of recent successful proposals. mailchi.mp/whoi/2025-oc...

Alpine wildflowers bloom on the tundra of Niwot Ridge. Photo by William Bowman.

Know a CU Boulder undergrad who might want to be an Ecology Lab Technician for 8-10 hrs/wk?
• Process alpine plant seeds collected in Colorado.
• Ideal start date: Oct 1 (or as soon as possible).
• Application deadline: Sep 19.
Look for student jobs at www.colorado.edu/instaar/jobs

🦣🍖🧬 Fully funded 3-yr PhD in palaeogenomics & bioinformatics! Help me push non-model palaeogenomes beyond their limits @DTU in Denmark.

Start: Feb 2026 (flexible)
Application deadline: 24 Oct 2025

For details click here: tinyurl.com/BioExtPhD

Reposts appreciated 😁

A grassland on a sunny day near Boulder, CO

We're recruiting!! Myself along with Nathan Gill, Dylan Schwilk @schwilk.org, and Katharine Suding are recruiting people for Master's, PhD, and postdoc positions in GrassFire, an NSF funded project examining fuels and fire risk in grassland ecosystems across the Southern Great Plains! 🔥🌿🐮

"mentorship is a two-way exchange that energizes and inspires all participants to become active agents of change"
tos.org/oceanography...

I'm looking for a driven PhD student to join us at @au.dk and to both generate new paleoclimate data in the lab and work on computational problems to understand climate relationships across timescales.

Get in touch if you'd like to hear more, and apply by Nov 1!

phd.nat.au.dk/for-applican...

Journal of Quaternary Science Call for Papers Beyond the Eruption: Advances and applications in distal tephra analysis across the Geosciences <em>Journal of Quaternary Science</em> publishes papers on any field of Quaternary research, advancing understanding of earth's history over the last 2.58 million years.

🌋📢 Calling all #tephra researchers!
Join us in shaping this new JQS Special Issue.

"Beyond the #Eruption – Advances and Applications in Distal Tephra Analysis Across the Geosciences"

Deadline: 2 Jan 2026.

Further details below: onlinelibrary.wiley.com/page/journal...

Cosmogenic Isotope Laboratory Manager in Doerr School of Sustainability, Stanford, California, United States The Stanford Cosmogenic Isotope shared laboratory within Stanford University’s Doerr School of Sustainability (SDSS) is seeking an experienced.....

The Stanford Cosmogenic Isotope Lab is hiring a new (permanent) Lab Manager. Please share and apply if you are qualified. phxc1b.rfer.us/STANFORDSD1UPF

Converging evidence constrains late pleistocene bering land bridge history The Bering Land Bridge was an important biotic corridor and climatic modifier during the Pleistocene (2.58 million to 11,700 thousand years ago [ka]).…

Out today in Quaternary Science Advances! @cwanket.bsky.social's paper linking terrestrial, marine, and GIA model results to constrain the last (most recent) formation of the Bering Land Bridge to between 40 and 35 thousand years ago:
www.sciencedirect.com/science/arti...

Abrupt weakening of deep Atlantic circulation at the last glacial inception - Nature Communications Zhou et al. report an abrupt weakening of the Atlantic Meridional Overturning Circulation at the last glacial inception. The observed circulation slowdown could explain the delayed timing of the atmos...

Earth scientists know a lot more about getting out of an ice age than going into one. We report an episode of AMOC slowdown at 115 thousand years ago that's likely astronomically forced (via sea-ice) and coincides with a delayed drawdown of atmospheric CO2 @natcomms.nature.com rdcu.be/eALD1

#PaleoSky

Let me know if you can’t access - I’m happy to share a copy!

@cires.colorado.edu @instaar.bsky.social

Spatiotemporal Variability in the Holocene Extent of Pikialasorsuaq (North Water Polynya), Baffin Bay We reconstruct the Holocene variability of Pikialasorsuaq using foraminifera and geochemistry from 4 marine sediment records Upper water column stratification, low sea ice, and low primary produc...

New paper on the Holocene evolution of Pikialasorsuaq (aka North Water Polynya), with implications for the future biodiversity it supports agupubs.onlinelibrary.wiley.com/doi/10.1029/... 🌊 🧪

Air pollution and warming are changing Colorado’s remote alpine lakes The Oleksy lab has taken over a 42-year-old monitoring project in Rocky Mountain National Park. Their investigations reveal how remote alpine watersheds are

Isabella Oleksy's Mountain Limnology Lab has taken over a 42-year-old monitoring project in Rocky Mountain National Park. Their investigations reveal how remote alpine watersheds are changing in the Anthropocene www.colorado.edu/instaar/2025...

@isabellaoleksy.bsky.social & @jbaron4.bsky.social

A 15,800 year record of productivity, carbon accumulation and environmental change at Eight Mile Lake and its catchment, central Alaska Despite their efficient burial of organic carbon (OC), the role of high-latitude lakes in storing and processing OC under changing climates is poorly understood. We investigate a 15,800 year sedime...

Check out our new paper about carbon, productivity and climate over 15,800 years in central Alaska. Out in @aaarjournal.bsky.social this paper pairs new sediment records from Eight Mile Lake with soil cores from the adjacent hillslope.

www.tandfonline.com/doi/full/10....

Shifting seas: understanding deep-time human impacts on marine ecosystems | Philosophical Transactions of the Royal Society B: Biological Sciences Humans have interacted with, and impacted, marine ecosystems for millennia. During this time, the oceans have experienced ecosystem degradation through harvesting, habitat change, pollution, the introduction of invasive species and climate change. Despite ...

🐚 Out today “Shifting Seas – Understanding Deep-Time Human Impacts on Marine Ecosystems.” 🌊

A theme issue asking how, when, and where humans have impacted oceans over millennia.

🔗 doi.org/10.1098/rstb.2024.0026

🧶 below on how it came to life!...

🚨The Trump Administration is proposing devastating cuts to key national agencies in Colorado that play a vital role in protecting our country, including through cutting-edge research on wildfires, droughts, and more.

Senator Bennet and I are fighting back against the attacks on NOAA, CIRES & CIRA 👇🏾

A Nutrient Effect on the TEX86 Paleotemperature Proxy Nutrient stress alters GDGT distributions in marine sediments, resulting in elevated TEX86 ${\text{TEX}}_{86}$ values beyond those related to thermal effects Paleoclimate case studies from the Ar...

Now published in @agu.org Geophysical Research Letters!

What happens to marine archaea when they’re hungry? And what does that mean for the TEX₈₆ paleothermometer?

Full paper here: doi.org/10.1029/2025...

Thanks to my coauthors and mentors for their support — and stay tuned, more is coming!

Postdoctoral Fellow: Self-Developed Project (280531) | University of Oslo Job title: Postdoctoral Fellow: Self-Developed Project (280531), Employer: University of Oslo, Deadline: Monday, June 23, 2025

Come postdoc in Oslo! 3 years. You design the project! Get in touch with me or others at our museum! Deadline 23 june www.jobbnorge.no/en/available... share and repost !

Sediment records provide a glimpse into Iceland’s past, and hope for its future Just a couple of kilometers inland from the coast of Northern Iceland, lie Torfdalsvatn, a small, deep freshwater lake. Winters here are frigid, snowy and dark,

A new paleoclimatology investigation, led by INSTAAR affiliate @davidharning.bsky.social (@cires.colorado.edu+NOAA NCEI), uncovers a story of ecosystem resilience at a lake in coastal Iceland. The analysis could aid future conservation and climate modeling efforts www.colorado.edu/instaar/2025...

Very excited to have this manuscript out!! During an #NSF Workshop, we brainstormed 100 future questions facing lake ice study today, and how we integrate #remotesensing #modeling #insitu work to get at those questions!
@agu.org #OpenAccess

Extreme Heat and Rain Turned These Arctic Lakes Brown - Eos Scientists are stunned by the changes in multiple Arctic lakes, all transforming in the same way.

Here’s what turned these Arctic lakes brown.

eos.org/articles/ext...

Read more in our May issue: bit.ly/Eos-May2025

Welcome to Save The U.S. National Science Foundation A Girl Looking at a Physics Model TAKE ACTION Save NSF is a coalition of concerned scientists and allies who are working to save funding for scientific grants through the U.S. National Science Foundation. Our mission is to support and advocate for the continuation of vital research and innovation in various scientific fields. NSF funding is critical to this work. Join us in our endeavor to ensure a sustainable future for scientific exploration and discovery.

I am so heartened to this seriously AWESOME #SaveNSF website go up today!!!!

Has a take action toolkit with:

1. Press outreach templates
2. Social media toolkit
3. Elected official outreach
4. Talking points

Check it out and share widely!!!! Likely more to come.

www.savensf.com