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Flavio Lehner

@climateflavors.bsky.social
2.2K followers 486 following 226 posts

Climate Scientist Assistant Professor @ Cornell University Chief Climate Scientist @ Polar Bears International flaviolehner.eas.cornell.edu

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Reposted by Flavio Lehner
Daniel Swain @weatherwest.bsky.social · 30/09/2026
Wading into the "relative versus absolute" El Niño intensity debate: I genuinely think both are important--and I think we lose important information if we focus solely on one vs another. And both, as of late Sep, have now reached or exceeded record levels! [Thread]
Plot by Daniel Swain showing temporal evolution of ONI vs RONI index during 2026, representing two different ways to visualize El Nino intensity. The ONI has been at record levels since May, and the RONI has been at near-record levels since June. Data directly from NOAA.
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Kelly Hereid @kellyhereid.bsky.social · 22/09/2026
Also, if you want to follow climate people, quite a few of these folks are on bsky I'm sure I won't catch them all, but in addition to @bobkopp.net @costasamaras.com I see @sidersadapts.bsky.social @bistline.bsky.social @johncallahan.bsky.social @jmijin.bsky.social @jessemkeenan.com ... 1/2
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Bob Kopp @bobkopp.net · 22/09/2026
NEW PAPER: In a new paper, jointly published in @agu.org Earth's Future & @ametsoc.org BAMS, and co-led by Melissa Kenney, @costasamaras.com and me, 175 authors outline priorities to guide the future of scientific assessments of climate change in the United States. 🧵
doi.org
Research Priorities for Robust Climate Assessments in the United States
A network of climate assessments plays a critical role in synthesizing the state of science to support evidence-based decision-making To support future U.S. and sub-national climate assessments, ...
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Climate.us @climate.us · 09/09/2026
Sea Ice Today is back! For nearly two decades, scientists at the National Snow and Ice Data Center, or NSIDC, have helped people understand what is happening to sea ice in the Arctic and around Antarctica. Its monthly science analyses were paused last fall. buff.ly/e20zCU6
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Zack Labe @zacklabe.com · 05/09/2026
The second edition of Canada’s Changing Climate Report (CCCR2026) is now published, which discusses past and future climate change for the region, as well as Indigenous science and perspectives. Canada is warming at twice the global rate. Learn more at www.canada.ca/en/environme...
Graphic showing future climate-related changes in Canada would be much larger under current or weaker policies than in a net-zero future, which is from chapter 3 at https://www.canada.ca/en/environment-climate-change/services/science-technology/changing-climate-report-2026/cccr-chapter-3-en.html.
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Flavio Lehner @climateflavors.bsky.social · 02/09/2026
New paper on Pacific SST trends, reverting back to ~'this is mostly internal variability, the models are probably fine'. However, I struggled a bit to understand what is new about the line of argument. Thoughts? @robbjnglinwills.bsky.social @cristiproist.bsky.social www.pnas.org/doi/abs/10.1...
pnas.org
Major role for internal variability in tropical Pacific warming pattern over satellite era | PNAS
Home to El Niño, the tropical Pacific is a key player in the global climate system. While most of the planet has warmed during the satellite era of...
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Flavio Lehner @climateflavors.bsky.social · 01/09/2026
Definition of grunt work. Tedious and seemingly unglamorous but very important and useful. Upshot: some of the observed recent drying in arid regions was overestimated, but not enough to fully explain the discrepancy between models and reality. agupubs.onlinelibrary.wiley.com/doi/full/10....
agupubs.onlinelibrary.wiley.com
Identifying and Correcting Inhomogeneities in the Near‐Surface Specific Humidity Record
Changepoint detection is applied to ERA5 and HadISDH humidity data with a circulation-constrained climate model simulation as the reference Changepoints are identified across 31% of global land a...
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Minas Karamanis @minaskar.bsky.social · 30/03/2026
Hey, I wrote a thing about AI in astrophysics ergosphere.blog/posts/the-ma...
ergosphere.blog
The machines are fine. I'm worried about us.
On AI agents, grunt work, and the part of science that isn't replaceable.
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Flavio Lehner @climateflavors.bsky.social · 21/08/2026
Indeed, this summer didn't come as a surprise to most climate scientists, but it nonetheless leaves an eerie feeling to see once outlandish events become "normal".
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Robert Rohde @rarohde.bsky.social · 14/08/2026
With record-breaking heatwaves, France just had both its warmest June and July on record. Systematic collection of weather data basically began in Western Europe, giving Europe the longest thermometer-based histories in the world. After more than 250 years, we have changed the climate. 🧪
Time series graph of June-July average temperature in France relative to the 1850-1900 baseline.  Data from Berkeley Earth.
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Daniel Swain @weatherwest.bsky.social · 14/08/2026
I've been talking a lot about the disastrous recent loss of American institutional capacity regarding climate science. But today, I'd like to announce something we've been working on, quietly, in the meantime to offer a lifeline to some of those affected. [Thread]
First page of a 2-page flyer describing the Climate Science and Communications Fund. It shows a map of gift recipient locations, and also summarize statistics regarding the program thus far (including over $3 million disbursed to date), with testimonials from individual recipients.Second page of a 2-page flyer describing the Climate Science and Communications Fund. It further describes the need for and goals of the program. It also includes a point of contact email: roshan@climate-talent.org
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Gernot Wagner @gwagner.com · 05/08/2026
"Heat kills — both lives and livelihoods." "And it is often rather small changes in the average that lead to large threshold effects" @chinadailyusa.bsky.social gwagner.com/china-daily-heat "only one additional day above 32 C in any given year lowers annual payroll by 0.04 percent" gwagner.com/hle
China Daily: "Is El Nino's economic risk too hot to handle?"
by Yang Gao
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Project Drawdown @projectdrawdown.bsky.social · 31/07/2026
🚨 Scientists have been warning for more than a century that catastrophic weather events were inevitable if humanity kept emitting GHG's. But is it worse than even they expected? Climate scientist @drkatemarvel.bsky.social shares her expert perspective in our latest Insights: bit.ly/4wsYPMw
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John Fasullo @jfasullo.bsky.social · 12/07/2026
Objective measures of @NCAR_CGD climate science show it to be at the forefront of scientific discovery www.dailycamera.com/2026/07/11/n...
dailycamera.com
Amid the administration’s attacks on climate change, NCAR and CU Boulder rank top 10 in the world for climate research
NCAR earned second place globally out of more than 40,000 institutions, with Carbon Brief noting it had some of the most highly cited authors.
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Robert Koch-Institut @rki.de · 09/07/2026
🌡️ Wie hat sich die Hitzewelle in der Kalenderwoche 26 auf die Sterblichkeit in Deutschland ausgewirkt? Zur Schätzung der hitzebedingten Sterbefälle erstellt das RKI eine Modellierung, die Daten vom Statistischen Bundesamt und @dwdderwetterdienst.bsky.social kombiniert. ➡️ www.rki.de/hitzemortali...
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IPCC @ipcc.bsky.social · 06/07/2026
📣 IPCC opens registration for experts to review the First Order Draft of Working Group I contribution to Seventh Assessment Report. The review runs from 10 August until 2 October. Interested experts can register until 25 Sept 2026: bit.ly/4vi25cq Read more 🔗 bit.ly/WGI7Fod
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Gernot Wagner @gwagner.com · 01/07/2026
Pay peer reviewers $290 per submission, see review times go down from 38 days (with a long upper tail) to 5.5 days (with v. few 'late' reviews), and watch quality go up to boot. Who knew? #IncentivesIncentivize www.nature.com/articles/d41...
Paying peer reviewers speeds up editorial decision time
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Maddie Stone @themadstone.bsky.social · 25/06/2026
I’ve spent more than a year reporting on how the fossil fuel industry has infiltrated academia over the last 30 years, shaping fundamental paradigms on how to address climate change. My first story in the new @propublica.org and @drilledmedia.bsky.social series, “Carbon Captured”, is out today.
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Ed Hawkins @edhawkins.org · 22/06/2026
The UK summer of 1976 was an extraordinary heatwave for its time. On the 50th anniversary, we look back to learn about what that event can tell us today. For those who experienced the heatwave it is engrained in the memory, but it gives us a stark warning about future extreme heat for the UK.
Heatwave 1976-2026. Our memory. Their future.
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aederocher.bsky.social @aederocher.bsky.social · 21/06/2026
As Hudson Bay sea ice melts, the bears are moving onshore. This is a bit early than optimal but depends on the condition of the bears & how long until freeze-up in autumn. Bears were lean in April-May when I was out sampling in the spring but a lot can change later in spring (most critical time).
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Flavio Lehner @climateflavors.bsky.social · 18/06/2026
What is the probability (and physical mechanisms) of having your local record temperature occur earlier or later than the climatologically hottest time of year? E.g., the 2021 PNW heatwave occurred >1 month before the hottest time of year. Anyone know a study? Figure based on ERA5 1940-2025.
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Zack Labe @zacklabe.com · 13/06/2026
El Niño is here, which means it's time for me to dust off and refine my old collection of ENSO-related climate visualizations. Check out how much sea surface temperatures have already warmed this year across the equatorial tropical Pacific. Wow! Data from psl.noaa.gov/data/gridded...
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Amy McGovern @profamymcgovern.bsky.social · 12/06/2026
NY times covered our cut today (gift article) www.nytimes.com/2026/06/12/s...
nytimes.com
She Used A.I. to Improve Forecasts for Extreme Weather
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Katharine Hayhoe @katharinehayhoe.com · 09/06/2026
Context: in 2018, FB labeled clean energy & climate as “political” topics. I was told I had to “register as a political entity.” I’m a scientist, I said. Over my dead body. So my previously thriving page was shadowbanned-til Dec when the algo was altered to deliberately promote divisive content 😳
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Dr. Jeff Masters @drjeffmasters.bsky.social · 08/06/2026
May 2026 had the second-worst May drought conditions in contiguous U.S. history, with a Palmer Drought Severity Index (PDSI) of -6.93. The only worse May: the Dust Bowl year of 1934 (a PDSI of -7.03). Three of the top-10 months for worst U.S. drought since 1895 have been in 2026:
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Kevin Schwarzwald @kschwarzwald.bsky.social · 06/06/2026
Ein problem für ganz Europa, und wo die USA ausnahmsweise auch voraus liegt (durch ua die flächendeckende Klimaanlagenaustattung ist die Anzahl der Hitzetote generell viel niedriger, auch bei ähnlichen und teils viel schlimmeren Hitzeperioden!) (zB hannahritchie.substack.com/p/heat-guns-... )
hannahritchie.substack.com
Do more Europeans die of summer heat than Americans die of guns?
An attempt to improve a viral chart.
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Andrew Williams @andrewilwilliams.bsky.social · 05/06/2026
Thank you for joining us and speaking out in support of weather & climate science, @repericsorensen.bsky.social ! @wclivestream.bsky.social
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The Weather & Climate Livestream @wclivestream.bsky.social · 04/06/2026
That's a wrap! - 50 hours of science + calling Congress - 300 letters given to Congress after a 250-mile walk We provided the templates and our viewers and supporters injected their voices. And like last year, we feel so uplifted by our community. Thank you for spending your time with us
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Flavio Lehner @climateflavors.bsky.social · 03/06/2026
Thanks Jeff! Emphasis on "may". Lots of competing (and complementary) theories out there on which forcing will win out. I did make a bet with another professor re snow drought occurrence this decade. The looser will have to give a guest lecture explaining why they lost. :)
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Katharine Hayhoe @katharinehayhoe.com · 30/05/2026
I’m a climate scientist. Let me fix this headline. “Nearly a century ago, scientists showed that burning fossil fuels warms the planet. Today, we know human emissions account for over 100% of the warming. Yet dark money and disinformation still work to keep Americans addicted to fossil fuels.”
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Andrew Williams @andrewilwilliams.bsky.social · 25/05/2026
@wclivestream.bsky.social 's very own Syl Foisy is walking 250 miles from NYC -> DC ! Follow along on our Bluesky, YouTube & Instagram (all at @wclivestream)! The walk culminates in a 50 hour-long Livestream starting June 1st! GET HYPED! 😁
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Virginia Schutte @vgwschutte.bsky.social · 23/05/2026
The 250-mile @wclivestream.bsky.social walk to deliver letters in support of science directly to Congress doesn't begin until 10am, but I am officially claiming the first miles traveled on behalf of the walking team 🏆 (the others live in NYC but I have to get there!)
Me, smiling to camera, in my car. I'm buckled up and ready to go : )
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Flavio Lehner @climateflavors.bsky.social · 21/05/2026
If you're a reviewer or an editor for a scientific journal, I urge you to not hop on the "RCP8.5 is dead" train. There are now editors that reject RCP8.5 but are ok with 1pctCO2. 🤯 Both are what-if scenarios, useful to science. Don't let politics influence what we can research and publish! 1/3
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The Weather & Climate Livestream @wclivestream.bsky.social · 08/05/2026
🚨 The Weather and Climate Livestream is back, June 1st - 3rd 2026!! We're streaming 50 hours for our future in the face of a new round of proposed budget cuts and attacks on science. Want to speak at the event? wclivestream.com/volunteer/
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Vivek Srikrishnan @vsrikrish.bsky.social · 19/05/2026
We have a new preprint on this, led by my former postdoc David Lafferty (now at Verisk) and with a great set of co-authors including @climateflavors.bsky.social. We use a "meta-ensemble" of downscaled climate products to partition temperature and precipitation projection uncertainty across CONUS.
essopenarchive.org
Varying sources of uncertainty in risk-relevant hazard projections across the United States | ESS Open Archive
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.For more information or tips please see 'Downloading to a citation manager' in the Help menu.
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Chris Parker @chrisjparker.bsky.social · 19/05/2026
🧵 There's been a lot of noise about the 'dropping' of RCP8.5 and what that means for worst-case climate outcomes. But this debate is largely missing the point. 1/6 #ClimateScience #ClimateRisk #Adaptation #ClimateModels
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ClimateFran @climatefran.bsky.social · 18/05/2026
Very interesting paper teasing out the nuances of flood risk distribution in the US using an incredible individual-level dataset. Documents a huge concentration of flood risk among the very highest income group - lots of wealthy people enjoying the coast and river views from their second homes.
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Flavio Lehner @climateflavors.bsky.social · 17/05/2026
A propos: progressivereform.org/publications...
progressivereform.org
RCP 8.5 Is Fine, Actually - Center for Progressive Reform
While the high levels of fossil fuel emissions mapped in the RCP 8.5 scenario are unlikely, it remains an important scenario for modeling future climate impacts, particularly at local scales.
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Lukas Brunner @lukasbrunner.bsky.social · 08/05/2026
If you are like me and prefer to read the typeset version of papers, here you go: the final version is out fresh from the print 😊 www.nature.com/articles/s43...
Screenshot of the title page of the article entitled: Three decades of simulating global temperature patterns with coupled global climate models
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Ben Sanderson @benmsanderson.bsky.social · 05/05/2026
Hi everyone, gridded data for the flat10MIP project is now open and public on the Norwegian Research Data Archive. Research using these data for understanding carbon-climate feedbacks, including climate commitment and reversibility is super relevant for AR7-WG1. archive.sigma2.no/dataset/flat...
archive.sigma2.no
Sigma2 Data Catalogue
Sigma2 Data Catalogue
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Ed Hawkins @edhawkins.org · 04/05/2026
In the SPM of IPCC AR6 WGI there was a hexagon gap in assessed trends of heatwaves & extreme rainfall in Central Africa Can the hexagon gap be filled for AR7? @derrickmuheki.bsky.social et al. have rescued millions of historical observations from the Congo: egusphere.copernicus.org/preprints/20...
A hexagon map of Africa showing heatwave trends with a gap over Central Africa
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Flavio Lehner @climateflavors.bsky.social · 04/05/2026
Wondering how to motivate students in intro programming classes? "... writing skill and CS achievement are significant predictors of vibe-coding performance, and CS achievement remains a significant predictor after controlling for domain-general cognitive skills." dl.acm.org/doi/10.1145/...
dl.acm.org
Computer Science Achievement and Writing Skills Predict Vibe Coding Proficiency | Proceedings of the 2026 CHI Conference on Human Factors in Computing Systems
You will be notified whenever a record that you have chosen has been cited.
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Benjamin Cook @dustybowl.bsky.social · 04/05/2026
I regret to inform you that they are once again allowing me to share my opinion in public tasteofscience.org/new-york-eve...
title slide for upcoming presentation:

Geoengineering as a Climate Solution
(No, Really, This Time is Different, We Swear Bro))
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Flavio Lehner @climateflavors.bsky.social · 23/04/2026
After a year of repairs, one of the world's most beautiful commutes - the Cascadilla Gorge trail to Cornell - is open again!
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Project Drawdown @projectdrawdown.bsky.social · 09/04/2026
"Climate science is not innately politically charged, whatever the administration says. ... It was our job to study the laws of physics, which remain true no matter who’s in power." - Kate Marvel, Sr. Scientist, Project Drawdown 📰 Full article in the @newyorktimes: nyti.ms/4tBNtEf
nyti.ms
Opinion | NASA Flew by the Moon, but Behind the Scenes, Its Science Is a Chaotic Mess (Gift Article)
Without science, the stunning images of Earth from space are only pretty pictures.
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Ben Sanderson @benmsanderson.bsky.social · 08/04/2026
So... now we can breathe again. Let's talk about ScenarioMIP. The final version is now up on GMD - and there's some changes since the first draft. /THREAD/ gmd.copernicus.org/articles/19/...
gmd.copernicus.org
The Scenario Model Intercomparison Project for CMIP7 (ScenarioMIP-CMIP7)
Abstract. Scenarios serve as a critical tool in climate change analysis, enabling the exploration of future evolution of the climate system, climate impacts, and the human system (including mitigation...
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Dr. Genevieve Guenther (she/they) @doctorvive.bsky.social · 02/04/2026
This excellent piece from @madisoncondon.bsky.social shows why (nerd alert!)—even if the scenario underlying RCP 8.5 is implausible, RCP 8.5 serves an important role in our understanding of and planning for climate change, and is therefore not misleading. progressivereform.org/publications...
progressivereform.org
RCP 8.5 Is Fine, Actually - Center for Progressive Reform
While the high levels of fossil fuel emissions mapped in the RCP 8.5 scenario are unlikely, it remains an important scenario for modeling future climate impacts, particularly at local scales.
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Flavio Lehner @climateflavors.bsky.social · 27/03/2026
Indeed, wild to be in CO at this moment in time talking about our new 3km snowpack simulations. Great visit to a great department! Lots of fresh ideas on what drives Southwest drying. Thanks Maria Rugenstein and CSU!
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Kate Marvel @drkatemarvel.bsky.social · 25/03/2026
My resignation letter
screenshot of a resignation letter expressing sadness at leaving NASA
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