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Flavio Lehner

@climateflavors.bsky.social

2K followers 470 following 180 posts

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

Videos

Environmental science 55%

Geography 18%

Posts Media Videos Starter Packs

Reposted by Pierre Friedlingstein, Peter Thorne, Michael Wehner , and 1 more Pierre Friedlingstein, Peter Thorne, Michael Wehner, Flavio Lehner

Dr. Genevieve Guenther (she/they) @doctorvive.bsky.social · 4h

The attack on @frediotto.bsky.social was seeded years ago by Roger Pielke Jr, who started arguing that this table from a recent @ipcc.bsky.social report proved that climate science cannot attribute extreme weather to climate change.

But Roger is of course lying. And we know this for 2 reasons.

🧵

CLIMATEWIRE
Climate critics try to discredit IPCC author for linking
disasters to global warming
By LESLEY CLARK, SARA SCHONHARDT, CHELSEA HARVEY | 10/09/2025
06:22 AM EDT Roger Pielke Jr. and oil industry supporters are attacking climate scientist Friederike Otto, whose
work has been used in lawsuits against polluters.

Table 12.12 | Emergence of CIDs in different time periods, as assessed in this section. The colour contesponds to the confidence of the region with the highest confidence: white cells indicate where evidence is lacking or the signal is not present, leading to overal bu confidence of an emerging signal.

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Reposted by Flavio Lehner

David Ho @davidho.bsky.social · 23h

It seems there are two main reasons things haven’t gone completely to shit in the US: 1. Lawyers and the courts; 2. Journalists and the media. Most of us can’t do anything about the first, but we can support journalism. Stop complaining about paywalls and subscribe to news & donate to public media.

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Reposted by Anthony Ricciardi, Flavio Lehner, Justin H. Kirkland , and 5 more Anthony Ricciardi, Flavio Lehner, Justin H. Kirkland, Jussi T. Eronen, Mirya R. Holman, Emily Grubert, Paul Nightingale, S. Laurel Weldon

Kevin J. CREATURE @kevinjkircher.com · 5d

Sometimes I think about how from 1935-1975ish, Bell Labs produced an insane amount of revolutionary science and technology, including 11 Nobel Prizes, the transistor, UNIX, C, the laser, the solar cell, information theory, etc. The secret? Provide scientists with ample, steady, no-strings funding.

sites.stat.columbia.edu

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Flavio Lehner @climateflavors.bsky.social · 10d

Fyi, you can have global entry with only a greencard.

Fingers crossed you don’t have to have any such discussion.

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Reposted by Flavio Lehner

Nate Howes TWN @natetwnclimate.bsky.social · 10d

If there is one piece of good news regarding our planet's future, it's our ozone layer and ongoing shrinking of its hole. New @wmo-global.bsky.social report said Earth's protective ozone layer is healing and the hole in 2024 was smaller than in recent years. www.theweathernetwork.com/en/news/clim...

Smaller ozone hole in 2024 pushes Earth closer to seeing it vanish - The Weather Network

A new World Meteorological Organization (WMO) report offers good news about Earth's ozone layer, which is on the road to a recovery to 1980 values in the coming decades--a positive sign for the health...

www.theweathernetwork.com

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Reposted by Flavio Lehner

Jeff Berardelli @weatherprof.bsky.social · 10d

This is why two hurricanes can not merge into a monster.
Watch as #Imelda’s growing outflow and sinking air impinges on #Humberto’s core, likely soon leading to weakening. Systems are now under 600 miles apart.

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Reposted by Peter Thorne, Flavio Lehner, Colin Murray , and 6 more Peter Thorne, Flavio Lehner, Colin Murray, Andrew Curry, Adrian Vickers, David Bartram, Henrik Skaug Sætra, Klaus Oschema, Renaud Morieux

Ben Sanderson @benmsanderson.bsky.social · 10d

Paris-Berlin sleeper: low carbon, 2 years old, constantly full, but currently losing SNCF a few million EUR/yr

Intl Jet fuel tax exemptions are 80 years old and cost the EU 22 million EUR/yr for the Paris-Berlin route alone.

And you're cutting... the sleeper?

www.theguardian.com/travel/2025/...

It’s goodnight Vienna as Paris sleeper train to Austria and Berlin hit by cuts

Some Nightjet services suspended from mid-December after French withdrawal amid public budget crisis

www.theguardian.com

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Dave Vanness @djvanness.bsky.social · 10d

A lot of people think that every international student admitted means one fewer spot for domestic students, when the opposite is more likely true - the tuition revenue international students bring allows public universities to provide substantial discounts to domestic students, improving access.

Nick Fleisher @nickfleisher.bsky.social · 10d

30% drop year over year!

Amid visa restrictions, international freshmen enrollment plummets at UW-Madison

This year’s number of international freshmen is the lowest recorded since at least 2015.

www.jsonline.com

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Reposted by Flavio Lehner, Joshua S. Weitz, Silvia Secchi , and 1 more Flavio Lehner, Joshua S. Weitz, Silvia Secchi, Jason Williams

Lauren Kuehne @omfishient.bsky.social · 10d

🧪 Were you one of the many thousands of STEM students (and mentors) impacted by the sudden change in #NSF #GRFP eligibility last week?

We created a petition to NSF leadership and Congress to reverse the changes - please sign and share your stories here!!

laurenkuehne.github.io/grfpChanges/

Petition to NSF to Restore Eligibility for the 2026 Graduate Research Fellowship Program Competition

laurenkuehne.github.io

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Reposted by Flavio Lehner

Cristi Proistosescu @cristiproist.bsky.social · 14d

New paper out. In which we helped the folks at the Allen Institute for AI (AI2) show that their climate emulator does a good (though not perfect) job at reproducing E3SMs' response to different SST boundary conditions.

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agupubs.onlinelibrary.wiley.com/doi/full/10....

Applying the ACE2 Emulator to SST Green's Functions for the E3SMv3 Global Atmosphere Model

The Ai2 Climate Emulator broadly captures the top-of-atmosphere (TOA) radiative response to local sea surface temperature (SST) anomalies ACE and EAMv3's global TOA radiation sensitivity to all S...

agupubs.onlinelibrary.wiley.com

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Reposted by A. E. Dessler, Gavin A. Schmidt, Flavio Lehner

AGU (American Geophysical Union) @agu.org · 14d

📢 Submissions are now open for the U.S. Climate Collection, a joint @theAGU + @ametsoc initiative.

This special collection will publish U.S.-focused climate assessment science that’s free to read, ensuring rigorous, accessible science informs decisions for years to come.

🔗 buff.ly/1tHUSLC

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Reposted by Gavin A. Schmidt, Flavio Lehner

James Goodwin @jamesgoodwin.bsky.social · 15d

"... Zeldin intends to sign off next week on the final policy and legal justifications for repealing the so-called endangerment finding and Biden-era climate rules for cars and trucks... before agency staff have time to sift through all public comments...." subscriber.politicopro.com/article/eene...

E&E News: Internal docs: Zeldin races ahead without analysis in endangerment rollback

The EPA administrator plans to sign off on the repeal's policy and legal justifications before his staff finishes the regulatory impact analysis.

subscriber.politicopro.com

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Reposted by A. E. Dessler, Ben Bond‐Lamberty, Gavin A. Schmidt , and 10 more A. E. Dessler, Ben Bond‐Lamberty, Gavin A. Schmidt, Jesse H. Kroll, Julie L. Lockwood, Flavio Lehner, Lauren B. Buckley, Michael J. Allen, Dustin Mulvaney, Dawn J. Wright, Juan Rocha, Halley E. Froehlich, Beth Tellman

Climate.us @climate.us · 16d

🚨 NCA5 is now LIVE! 🚨

They took it down, but we've brought it back at: nca5.climate.us

Bookmark. 👏 this. 👏 page. 👏

This is just our first step in restoring trusted science information that Americans need to understand what's happening with the climate.

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Reposted by Michael Wagner, Johannes Quaas, Jamie Hannaford , and 8 more Michael Wagner, Johannes Quaas, Jamie Hannaford, Ben Bond‐Lamberty, Gavin A. Schmidt, John Fasullo, Flavio Lehner, Jürgen Maier, James Connelly, Richard M. Carpiano, Alan McNally

Zeke Hausfather @hausfath.bsky.social · 16d

In a UN speech today, President Trump said that "all of these [climate] predictions were wrong".

Back in 2019 I led a research effort to digitize old climate model projections and assess how well they did. Turns out they got future warming pretty spot on!

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Flavio Lehner @climateflavors.bsky.social · 17d

Sorry, I meant 5.0.2...

Flavio Lehner @climateflavors.bsky.social · 17d

Thanks and nice to see this, Tim! What's happening over North America in CRUTEM 5.1 minus 5.2? Just random variations in stations reporting or something more systematic?

Reposted by John Kennedy, Peter Thorne, John K. Pinnegar , and 3 more John Kennedy, Peter Thorne, John K. Pinnegar, Du Toit, Ed Hawkins, Flavio Lehner

Tim Osborn @timosbornclim.bsky.social · 17d

After a brief (ahem) hiatus, the HadCRUT5 global temperature dataset has now been updated to June 2025 by @metoffice.gov.uk @climateuea.bsky.social and @ncas-uk.bsky.social

1850-2025 time series of global mean temperature anomaly from the HadCRUT5 dataset.

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Reposted by Flavio Lehner

Cristi Proistosescu @cristiproist.bsky.social · 19d

#realktalk though, when is the deadline for papres to be accepted to be considered for AR7?

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Reposted by A. E. Dessler, Kevin J. Anchukaitis, Flavio Lehner

Cristi Proistosescu @cristiproist.bsky.social · 19d

ECS <2 is absurd in the year of our lord 2025.

The data used in Sherwood et al is now almost a decade old (not to mention Lewis and Curry 2014).

Even ignoring pattern effects, we’re now already at ~1.5C with less than 2xCO2 and an even larger energy imbalance.

No way Effective ECS is <2.

Ken Rice @kenrice.bsky.social · 19d

But it's not just uniform vs Jeffreys. There are other priors and there are other ways to estimate ECS. As Andrew points out, if your method suggest a good chance of the ECS being < 2K, then there's probably an issue with the method, or it's at least worth considering this.

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Reposted by Flavio Lehner

Scott St. George @scottstgeorge.paleohydrology.com · 24d

Yet another Nat Cat job? Actually, we're searching for TWO experts, specialized in tropical cyclones or earthquakes. US or UK, remote work definitely an option. Great job for an ECR physical scientist looking to join the insurance/reinsurance industry! eedu.fa.em3.oraclecloud.com/hcmUI/Candid...

Natural Catastrophe Analyst - Earthquake/Hurricane Specialist

An exciting opportunity to join an established research network team at Willis (a WTW business), helping clients understand and manage risk while shaping the Willis “view of risk.” Using your scientif...

eedu.fa.em3.oraclecloud.com

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Flavio Lehner @climateflavors.bsky.social · 24d

Idk of an online source for that specific data but I should have the global means lying around somewhere. Can you send me an email?

The full data is available via MMLEA or ESGF but that's a pain if you just need global mean.
www.cesm.ucar.edu/community-pr...
aims2.llnl.gov/search/cmip6/

Multi-Model Large Ensemble Archives | Community Earth System Model

www.cesm.ucar.edu

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Reposted by Felix Creutzig, Jakob Zscheischler, Flavio Lehner

Prof. Sonia I Seneviratne @soniaseneviratne.bsky.social · 28d

Es ist eine grosse Ehre, den 2025 Deutschen Umweltpreis zu erhalten! Danke an alle meine jetzigen und ehemaligen Gruppenmitglieder und viele Kolleg:innen!
@lukasgudmundsson.bsky.social @yasserhaddad.bsky.social @yannquilcaille.bsky.social @michaelgwindisch.bsky.social @usyseth.bsky.social

DBU Deutsche Bundesstiftung Umwelt @umweltstiftung.bsky.social · 28d

Ausgezeichnet!🏆Mit dem Deutschen Umweltpreis 2025 von der DBU #uwp25 werden die Klimaforscherin @soniaseneviratne.bsky.social @ethz.ch & das Geschäftsführungsduo Lars Baumgürtel und Dr. Ing. Birgitt Bendiek des Stahlverzinkungsunternehmens ZINQ geehrt. buff.ly/QEDIjX0

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Reposted by Brigitte Nerlich, Richard Betts, Flavio Lehner

Ed Maibach @maibached.bsky.social · 29d

Every avoidable death is a tragedy. Smoke from Canada’s wildfires killed nine-year-old Carter Vigh – and 82,000 others around the world. #EndFossilFuels.

@gchalliance.bsky.social
@docsforclimate.bsky.social
@fossilfueltreaty.bsky.social

Smoke from Canada’s wildfires killed nine-year-old Carter Vigh – and 82,000 others around the world

Toxic particles spewed by 2023’s wildfires were even responsible for 22,000 early deaths in Europe, researchers say

www.theguardian.com

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Reposted by Katharine Hayhoe, John Quiggin, Flavio Lehner , and 2 more Katharine Hayhoe, John Quiggin, Flavio Lehner, Jonathan A. Foley, Federica Genovese

Zeke Hausfather @hausfath.bsky.social · Sep 9

The current administration has claimed renewables are making the grid less reliable. If that were the case, I'd expect states adding the most renewables over the past decade to have the largest increase in outages.

However, the opposite seems to be true!

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Flavio Lehner @climateflavors.bsky.social · Sep 8

It's Reviewer classics week:
- This work is not novel but I can't provide literature to back up my verdict.
- While you have now included all the datasets that I asked you to, you are still not considering enough datasets.
- Do this analysis that you already did (in the supplement).

Reposted by Flavio Lehner

Nate Howes TWN @natetwnclimate.bsky.social · Sep 2

Thanks to @climateflavors.bsky.social of @polarbearsinternational.org for the chat, help with this. With the Arctic's sea ice loss a worrisome trend, projections continue to indicate when the region could see its first instance of individual, ice-free day. www.theweathernetwork.com/en/news/clim...

Arctic may see single occurrences of ice-free days sooner than predicted - The Weather Network

A recent study presents an alternate take on when the Arctic could see individual instances of ice-free days, with models pinpointing a quicker timeline for than previously thought--as early as this d...

www.theweathernetwork.com

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Andrew Dessler @andrewdessler.com · Sep 2

Our 400+ page comment on the DOE climate working group report is now out.

Our conclusion: The merchants of doubt are back, and they're coming for climate science.

DOEresponseSite

On July 29, 2025, the Department of Energy (DOE) published a report from its Climate Working Group (CWG). This report features prominently in the EPA's reconsideration of its 2009 Endangerment Finding. In response, over 85 scientists have come together to write a comprehensive review, which is

sites.google.com

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Reposted by Dorothy Bishop, Gavin A. Schmidt, Flavio Lehner , and 9 more Dorothy Bishop, Gavin A. Schmidt, Flavio Lehner, Jonathan A. Foley, Charles West, Adrian Vickers, Christine Kooi, Brian Keegan, Jessica Vitak, S. J. Holmes, Laurent Jégou, Eugene McCann

Mike Dickison @adzebill.bsky.social · Aug 31

Wikipedia editors trying to fend off the onslaught of AI crap have crowdsourced some telltale signs of LLM-generated writing; it might be handy for editors and proofreaders generally. Thanks to @ellenrykers.com for pointing me to it. en.wikipedia.org/wiki/Wikiped...

Wikipedia:Signs of AI writing - Wikipedia

en.wikipedia.org

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Reposted by Rohini Kumar, Flavio Lehner

Jakob Zscheischler @zscheischlerjak.bsky.social · Aug 29

Our new study on how large floods will change in Europe under climate change, led by @bfang.bsky.social, with @bevacquae.bsky.social

Communications Earth & Environment @commsearth.nature.com · Aug 29

❄️🌧️Reduced snowmelt dominates changes in Northern Europe's largest floods, while heavy precipitation dominates Western Europe flood events.

@bfang.bsky.social @zscheischlerjak.bsky.social

👉Read more here:
www.nature.com/articles/s43...

Diverging trends in large floods across Europe in a warming climate - Communications Earth & Environment

Reduced snowmelt dominates northern Europe’s largest floods variation while heavy precipitation dominates western Europe flood events, according to a joint assessment of changes in the timing, spatial...

www.nature.com

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Andrew Dessler @andrewdessler.com · Aug 28

Our comment on the DOE CWG report is done. It tips the scales at 439 pages, approx. 3x longer than the DOE report.
This is related to Brandolini's law: The amount of energy needed to refute bullshit is an order of magnitude bigger than that needed to produce it.

Example: refuting one sentence.

DOE CWG STATEMENT (second paragraph of section 2.1.1, page 3): “Piao et al. (2020) noted
that greening was even observable in the Arctic.”
COMMENT: This statement implies that the Arctic greening signal was caused by elevated CO2
,
however that is not the scientific consensus. Piao et al. (2020) attribute the greening trend in the
Arctic predominantly to growing season length driven by warmer temperatures (see also Y.
Zhang et al., 2022). Piao et al. (2020) also note that this positive impact of increasing
temperatures appears to have weakened over the past four decades, “suggesting a possible
saturation of future greening in response to warmer temperature” (see also comment on
greenness trends related to Section 2.1.1, first sentence of Page 4). It is also important to put
Arctic greening more broadly into the context of the carbon cycle and other impacts. While
above-ground plants may have displayed more leaf area over the past decades, rising
temperatures also thaw permafrost and drive accelerated decomposition in highly carbon rich
soils (Turetsky et al., 2020), a process which is expected to accelerate as climate continues to
warm (Miner et al., 2022). Thus even with Arctic greening, high latitude terrestrial systems may
become net carbon sources to the atmosphere, causing an amplifying feedback (Braghiere et
al., 2023). Other risks to the Arctic linked to higher CO2

levels and rising temperatures are not
mentioned in this report (Virkkala et al., 2025). The Arctic is warming at a rate of 2 to 3 times the
global average, leading to thawing of permanently frozen soils (permafrost), with downstream
impacts including loss of structural support for buildings and subsidence, threatening
communities, roads, runways, and other assets across Alaska (Manos et al., 2025; University of
Alaska Fairbanks Institute of Northern Engineering US Army Corps of Engineers Alaska District
& Laboratory, 2019).

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