Flavio Lehner

Trump Is Attacking Climate Science. Scientists Are Fighting Back. It’s easy, looking at the past year, to see the damage the administration has done. But researchers are also stepping up, trying to fill the gaps.

One year in the federal assault on climate science — a review and prospective

Hudson Bay polar bears took a big jump to the northwest this week. Why? I'm guessing favourable winds that made hunting that direction more effective (but we don't know for sure & it's something we're investigating).

Trump's Climate Supercomputer Plans Threaten US Insurance Market: Actuaries A new letter from the American Academy of Actuaries draws a direct line between the planned dismantling of NCAR and higher homeowners insurance costs for US consumers.

Need more industries to speak up against the attacks on NCAR.

www.riskmarketnews.com/trumps-clima...

Hudson Bay are well spread out & doing different things. One female (K) has moved close to shore. Bear C has emerged from a den - it's a bit early if she's got new cubs but we'll see if she stays there or moves onto the ice.

docs.google.com/document/d/1...

Hey folks, tried putting together a letter in direct response to the NSF unprompted decision. Feel free to offer suggestion or to add your name as a signatory, and thanks to those that did it alredy! Current text follows (errors all mine!)...

YouTube video by The Weather & Climate Livestream We ❤️ NCAR - Let's Save It!

Last December, weather and climate scientists sat down with us to tell us why they loved the National Center for Atmospheric Research, and why it benefits us all. Last night, the NSF began dismantling it. Listen to what they have to say, and why it's urgent that we #SaveNCAR wclivestream.com/act

*DEADLINE EXTENDED* February 8

Submit your suggestions and nominate (yourself or others) as a co-author for the 2026 edition of the 10 New Insights in Climate Science

Glad to hear. I’ve been missing your awesome loops.

🧵How might snowfall change in a warming world? I set up a very simple “toy” statistical model to explore this question.

Isn't it obvious that snowfall decreases as temperatures get warmer? Yes, but …

Plot showing steadily increasing December temperatures in the Northeast US

I honestly thought December was way colder in the Northeast than what the numbers indicate. Seven mild Decembers in a row really messes up your perception...

Lego day (this past Wednesday)

Stop Guessing, Start Planning.
Ever look at a single snow forecast and think, "But what are the actual odds?"

The Probabilistic Precipitation Portal is a resource to help you get ahead of the storm by moving beyond a single number to give you the full picture. www.wpc.ncep.noaa.gov/Prob_Precip/
👇

Join UCAR President Antonio Busalacchi at a town hall meeting this afternoon at #AMS2026 to discuss the threats facing NSF NCAR.

https://bit.ly/3NNXHS5

What Americans Lose If Their National Center for Atmospheric Research Is Dismantled - Eos Five ways dismantling NCAR will cost the American people, and two ways to save it.

eos.org/opinions/wha...

Map centered on North America showing 2-meter temperature, jet stream, and stratospheric polar vortex for 12 UTC, 26 Jan 2026.

2-meter temperatures, jet stream (light blue), and stretched stratospheric polar vortex (dark blue), for 12 UTC, 26 Jan 2026.

Cascadilla Creek

We knew the NSF letter about NCAR would come. I think this is an occasion that will require great coordination and strategical thinking. UCAR should respond as a block, coordinating a response across universities (especially in the South, and large public universities that use NCAR data a lot)

A time series of the January–February frequency (in days) of the AKR regime from 1979 to 2025 using ERA5 data, based on the year-round classification of Lee et al. 2023 (J. Climate) updated through 2025.

The extreme cold across eastern N America is due to the Alaskan Ridge regime, which on average brings the coldest winter weather to this region.

Is this happening more often?

No. During the modern warming era, there has been no observed trend in the occurrence of this regime at this time of year.

Paleoclimate pattern effects help constrain climate sensitivity and 21st-century warming | PNAS Paleoclimates provide examples of past climate change that inform estimates of modern warming from greenhouse-gas emissions, known as Earth’s clima...

Really excited to see this paper out!! Led by @vtcoop.bsky.social we show that if you use cold and warm paleoclimates together, you can reduce uncertainty in Earth's climate sensitivity by quantifying the pattern effect and more precisely constrain future climate change www.pnas.org/doi/10.1073/...

Introduction to Climate Science Introduction to climate science is for college students of both science and non-science majors and for everybody interested in the topic.

Check out the new version of my climate science textbook. Free, accessible and online. Let me know what you think. open.oregonstate.education/climatescien...

Indeed, the world will turn gray at 2°C. 🤪

Late-night plotting in R for me is like speaking French after a few too many glasses. I can do it but it's not going to be great. 😅

Thanks! Here it is relative to "preindustrial" (1850-1900).

(since ERA5 does not go back that far, I used the difference between 1850-1900 and 1940-1969 from DCENT as an offset, i.e., ~0.25°C)

I created this one but it's inspired by @erwanrivault.com's version from previous years.

Daily global temperature anomalies from 1940 to present, grouped by year, showing gradual global warming

2025 goes down as the ~3rd-warmest year on record (based on ERA5).

Like in 2024, every single day this past year was warmer than the average of even the most recent reference period (1991-2020).

This past month showed us once again how extraordinary our weather and climate community is (scroll for 🧵).

Whether you’re joining us as student, scientist, hobbyist, or concerned citizen, let’s #SaveNCAR and put an end to the war on science together 💯

Looking for: postdoc on quantitative history of China; postdoc on measuring wildfire fuels with LiDAR; PhDs on modeling fire in the boreal forest and the Pacific Northwest; MSc’s on earth system science; interns in many topics. Check it out!

Our guide to approaching (and starting!) conversations about NCAR and the importance of weather and climate science. #SaveNCAR

There aren't a lot of resources for what people can do to prevent the destruction of NCAR, so I made this:

#NCAR #climate #climatescience #weather #meteorology #activism #myresources

From wildfire warnings to flood forecasts, NCAR's research impacts everyone in America.

President Trump's attempt to dismantle it for political vengeance is beyond reckless.

We will fight against this dangerous scheme every step of the way.

From @AGU.org: Senators are working on legislation to save NCAR, but we need extra support for these 8 states. Your Senators in Alabama, Alaska, Florida, Louisiana, Mississippi, North Carolina, Texas, and Wyoming need to hear from you.