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Reposted by Casey Ivanovich

AGU Advances @aguadvances.bsky.social · 30/09/2026

🌟 Editor's Pick! 🌟 “NASA’s MERRA-2 reanalysis of past weather and climate reveals substantial shifts in extreme heat seasonality over the past 45 years.” 🔗 eos.org/editor-highl... #AGUPubs @eos.org

eos.org

Seasonality is Changing for Extreme Dry and Humid Heat Events  - Eos

NASA’s MERRA-2 reanalysis of past weather and climate reveals substantial shifts in extreme heat seasonality over the past 45 years.

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Reposted by Casey Ivanovich

Columbia Climate School @climate.columbia.edu · 13/09/2026

Extreme heat has become more common, but also more frequent in the months before and after typical warm seasons, finds a new study led by climate scientist Catherine Ivanovich of NASA GISS. Via State of the Planet: bit.ly/4yB6iKc

Bright sun in an orange sky. Credit: Drought.gov

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

I had the exciting opportunity to write a guest post for @carbonbrief.org about our new paper on the expansion of extreme heat seasons around the world. Take a read for a digestible summary of our approach and key results!

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Reposted by Casey Ivanovich

Benjamin Cook @dustybowl.bsky.social · 10/09/2026

Get in losers-we're talking about how extreme heat seasons are changing around the world! New work led by former (sniffle) excellent postdoc @ccivanovich.bsky.social (advised by me and Sonali McDermid)

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

Excited for this work done in collaboration with my wonderful postdoc advisors, @dustybowl.bsky.social and Sonali McDermid, to be out now! (6/6)

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

These results motivate expanded early warning systems and cooling infrastructure which have historically been scheduled around the summer. The asymmetric changes in extreme heat seasonality may also increase the overlap of extreme heat with other seasonal hazards, like wildfire and hurricanes. (5/6)

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

We check if these asymmetries are explained by intensifying baseline seasonality, given that some regions' spring or fall seasons are already hotter on average. However, this is not enough to explain the observed changes in the fraction of annual heat events occurring in the shoulder seasons. (4/6)

Six panel figure showing an evaluation of whether seasonal extreme heat frequency changes can be explained by an intensification of baseline seasonality. Map of locations across the globe where existing seasonality in the 1980s shifted up by annual mean warming does not explain observed changes in (top row) overall extreme heat seasonality as measured by a Kolmogorov–Smirnov Test with a p-value below 0.05 and (middle row) shoulder season asymmetry as measured by a bootstrapping test. Green (purple) shades indicate that observed asymmetry is larger in the pre-season (post-season) than predicted by intensification of baseline seasonality. Darker shades of each color indicate that the observed asymmetry is in the opposite direction than in the synthetic distribution. Bottom row: Box plots showing the share of asymmetry explained by intensifying existing extreme heat seasonality, categorized by whether that asymmetry favors pre- or post-season extremes. Only grid cells which exhibit at least a 5% shoulder season asymmetry as measured by the bottom row of the previous figure are included. Left and right columns show dry and humid heat patterns, respectively.

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

But this is starting to change! Extreme heat seasons have lengthened in about half of global land areas, and this lengthening is asymmetric. Most regions have experienced a larger expansion in either the months before or after their local heat season (analogous to spring and fall). (3/6)

$Six panel figure showing maps of the change in the fraction of extreme heat events happening in the shoulder seasons. Top row (blue to red colorbar): Change in the fraction of annual events occurring in the pre-season from the early to late period. Middle row (blue to red colorbar): Change in the fraction of annual events occurring in the post-season from the early to late period. Bottom row (green to purple colorbar): Difference in the fractional change in shoulder season extreme heat events (post-season minus pre-season). Black shading indicates grid cells without a consecutive 3-month heat season.$

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

We find that historically, extreme heat was well-constrained to a singular local heat season throughout most of the world – even the tropics where there’s much less of a swing in seasonal temperatures. (2/6)

$Six panel figure (two columns, three rows) showing maps of the global climatological extreme heat seasonality during the baseline period, 1980-1989. Top row: month with peak frequency of extreme heat events. Middle and bottom rows show the fraction of 1980-1989 extreme heat events happening during peak heat season and the locally defined shoulder seasons, respectively. Left and right columns show patterns for dry and humid heat, respectively. The second and third rows have different colorbar ranges in order to better visualize spatial heterogeneity in each measurement. Black shading indicates grid cells without a consecutive 3-month heat season.$

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Casey Ivanovich @ccivanovich.bsky.social · 10/09/2026

Feel like heatwaves started early this year? Or like they're dragging on later than ever? Our new @aguadvances.bsky.social paper shows that extreme heat is no longer limited to summer and is now creeping into the shoulder seasons -- but unevenly so. (1/6) doi.org/10.1029/2026...

doi.org

Extreme Dry and Humid Heat Seasons Are Changing Asymmetrically

Extreme dry and humid heat events show distinct seasonality often not aligned with meteorological summer, even in the tropics Extreme heat seasons have expanded since the 1980s over about half of...

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Reposted by Casey Ivanovich

miriam nielsen @zentouro.info · 08/07/2026

a bunch of losers in the office of management and budget are trying to tear apart federal science and research funding in the US. in my professional opinion, this is a very very bad idea.

youtu.be

this ends science as we know it

YouTube video by zentouro

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Casey Ivanovich @ccivanovich.bsky.social · 19/06/2026

Yes! I’ve been looking at something similar about the increasing rate of extreme heat events creeping into the shoulder seasons. Paper should (hopefully) be out in the coming months, but I talked about part of this project in the W&C Livestream. Would love to chat more about this in the meantime!

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Casey Ivanovich @ccivanovich.bsky.social · 05/06/2026

Many thanks to @dustybowl.bsky.social and Sonali McDermid for their essential contributions to this work!

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Casey Ivanovich @ccivanovich.bsky.social · 05/06/2026

Our paper on extreme dry and humid heat in the North American Monsoon region is out today! Learn more about how the seasonality and dynamics of these two flavors of extreme heat differ and are shaped by the progression of the monsoon: agupubs.onlinelibrary.wiley.com/doi/10.1029/...

agupubs.onlinelibrary.wiley.com

Dry Versus Humid Heat Seasonality and Drivers in the North American Monsoon Region

In the North American Monsoon region, dry and humid heat are distinct in overall seasonality and the timing of individual extreme events Drivers of dry heat extremes are spatially and temporally ...

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Casey Ivanovich @ccivanovich.bsky.social · 03/06/2026

Time change: now presenting 1 hour earlier at 11:20pm ET!

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Casey Ivanovich @ccivanovich.bsky.social · 01/06/2026

The Weather & Climate Livestream is back to remind us all of the *huge* range of services provided by federally funded science! I'll be up far past my bedtime at 12:20am ET on Wed to talk about how extreme heat seasons are changing around the world -- tune in this week and write/call your reps!

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Reposted by Casey Ivanovich

The Weather & Climate Livestream @wclivestream.bsky.social · 23/05/2026

With friends! It *is* a lovely day Thanks to everyone who came to support us in-person this morning as we started our walk from NYC to DC!

A group of science supporters smiling to camera in Central Park

Two people close to camera and the group strung out behind on them on the main footpath through Central Park

The group as pictured from the back, with the NYC skyline around Central Park on the horizon

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Casey Ivanovich @ccivanovich.bsky.social · 29/04/2026

Very excited to kick off #EGU26 with a solicited talk Monday morning! I'll be presenting my work on the emerging risk for heat extremes during unexpected times of year around the world. Stop by bright and early to learn more from this and other exciting presentations in this session!

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Casey Ivanovich @ccivanovich.bsky.social · 17/04/2026

But will the moistening hole get stickier (🥴)

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Casey Ivanovich @ccivanovich.bsky.social · 22/12/2025

This work would not have been possible without the collaboration of my wonderful co-authors @adamsobel.bsky.social, Radley Horton, Ana Nunes, Rosmeri Porfírio da Rocha, and @scamargo.bsky.social!

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Casey Ivanovich @ccivanovich.bsky.social · 22/12/2025

Our paper exploring the drivers of the November 2023 “Taylor Swift” heatwave in Rio de Janeiro is officially out in WCD! Take a read to learn more about the causes of this record-breaking heatwave and Rio’s emerging risk for extreme heat: wcd.copernicus.org/articles/6/1...

wcd.copernicus.org

Physical drivers of the November 2023 heatwave in Rio de Janeiro

Abstract. Because extreme heat has not historically been a major hazard for the city of Rio de Janeiro, the November 2023 Heatwave magnitude and timing were staggering. Here we conduct a case study of...

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Casey Ivanovich @ccivanovich.bsky.social · 10/12/2025

Excited to be giving two invited presentations on the influence of monsoon systems on extreme (humid) heat at this year's #AGU25! Stop by NH44B-02 Thursday afternoon and A51H-01 Friday morning to learn more and chat!

Flyer for Casey Ivanovich's two AGU 2025 presentations.

The information for the first presentation reads: Dry versus Humid Heat Seasonality and Drivers in the North American Monsoon Region. Session: NH44B Compound, Consecutive, and Cascading Events: Challenges for Risk Assessment and Management I Oral. Thursday, December 18, 2025, 4:30PM-4:40PM CST, Room 297. QR code links to the following webpage: https://agu.confex.com/agu/agu25/meetingapp.cgi/Paper/1849473

The information for the second presentation reads: Subseasonal Variability of Humid Heat during the South Asian Summer Monsoon. Session: A51H: Weather and Climate Extremes over South Asian Monsoon Regions II Oral. Friday, December 19, 2025, 8:30am-8:40am CST, Room 271. QR code links to the following webpage: https://agu.confex.com/agu/agu25/meetingapp.cgi/Paper/1897447

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Reposted by Casey Ivanovich

Da'Vel Johnson @davelrj.bsky.social · 19/06/2025

With the Heat Wave expected across the Central and Eastern US this weekend into early next week, this was an excellent video primer on the Limit of Compensability for adults and associated Heat Risk. Great Job by @ccivanovich.bsky.social and the PBS Terra team youtu.be/7hBMbQ9de1g?...

youtu.be

When Will Extreme Heat Become Unlivable?

YouTube video by PBS Terra

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Reposted by Casey Ivanovich

The Wall Street Journal @wsj.com · 16/08/2025

Summer heat across the Eastern U.S. is off the charts in a new "stickiness" measurement that combines heat and humidity—and it isn’t over yet. 🔗: on.wsj.com/3Uwf7D1

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Reposted by Casey Ivanovich

Brenda Ekwurzel @brendaekwurzel.bsky.social · 28/05/2025

Casey Ivanovich @ccivanovich.bsky.social shared during @wclivestream.bsky.social the factors influencing dangerous extreme heat events plus ‬a public communication tip for conveying the difference between humid and dry heat extremes – “sticky” vs “crispy”

Schematic presented by Casey Ivanovich @ccivanovich.bsky.social during @wclivestream.bsky on May 28, 2025. "Explore how the land surface influences the tradeoffs between temperature and moisture to affect both dry and humid heat extremes." Schematics has the following labels next to images representing each: "solar insolation, large-scale circulation, precipitation, cloudiness, advection, urbanization, evapotranspiration, deforestation/land use change, proximity to water bodies, and irrigation."Text for questions also displayed, " How is this linked to heat seasonality?" and "How are humans altering these balances?"

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Reposted by Casey Ivanovich

miriam nielsen @zentouro.info · 28/05/2025

feeling toasty? @ccivanovich.bsky.social is about to talk heat waves and stickiness on the 100-hour @wclivestream.bsky.social wclivestream.com/watch

Casey Ivanovich sits in front of a live streaming setup in a nearly empty NASA GISS office, preparing to give a live talk.
She's wearing a NASA GISS t-shirt

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Casey Ivanovich @ccivanovich.bsky.social · 27/05/2025

Tune in for the kick off of the livestream tomorrow (1pm ET) from NASA GISS during the final hours before we're removed from our office. I'll be speaking about the federally-funded work I've done over the past six years to help understand the drivers of extreme humid heat events.

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Reposted by Casey Ivanovich

Kate Marvel @drkatemarvel.bsky.social · 16/05/2025

The people telling you climate change isn’t real would also like you to believe that paying rent on an empty building saves money www.nytimes.com/2025/05/16/n...

nytimes.com

NASA Office Above ‘Seinfeld’ Diner Is a Target of Trump Budget Shrinkage

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Reposted by Casey Ivanovich

Lamont-Doherty Earth Observatory @lamont.columbia.edu · 18/02/2025

Meet @ccivanovich.bsky.social, NASAGISS postdoc & Lamont-Doherty Earth Observatory PhD, who studies climate extremes & humid heat, including their physical & social drivers, and is also passionate about relaying complex scientific concepts to the public. #IDWGS ➡️ lamont.columbia.edu/news/women-s...

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Reposted by Casey Ivanovich

Nature Reviews Earth & Environment @natrevearthenviron.nature.com · 05/02/2025

📣New Review! Mortality impacts of the most extreme heat events By Tom Matthews et al., including @regclimo.bsky.social & @ccivanovich.bsky.social. www.nature.com/articles/s43...

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Reposted by Casey Ivanovich

Colin Raymond @regclimo.bsky.social · 04/02/2025

For extreme heat, each year seems to bring fresh examples of precedents being surpassed — in heat severity, but also in understanding of its physics and risks. A group of us led by Tom Matthews and Radley Horton have assembled a review of this knowledge whirlwind: www.nature.com/articles/s43...

nature.com

Mortality impacts of the most extreme heat events - Nature Reviews Earth & Environment

Extreme heat is increasing in magnitude and frequency, threatening human health. This Review assesses mortality risk associated with extreme heat, revealing that human thermal tolerances (that is, unc...

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Reposted by Casey Ivanovich

Kevin Schwarzwald @kschwarzwald.bsky.social · 08/12/2024

Great paper from my brilliant climate scientist colleague @ccivanovich.bsky.social and economists @rdbressler.bsky.social @ajsw.info ! Great example also how we can improve climate impacts studies when incentives align to allow for this kind of interdisciplinary collaboration and design.

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Casey Ivanovich @ccivanovich.bsky.social · 10/12/2024

Amazing to see this work dreamed up by Danny and I in the early years of our PhDs in its final form! By combining high resolution climate and mortality data, we paint a more complete picture of the evolving risk for temperature-related deaths in Mexico. Take a read!

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Casey Ivanovich @ccivanovich.bsky.social · 03/12/2024

Afterwards, make sure to swing by poster A53H-2194 presented by Ana Nunes that afternoon on our set of collaborations about extreme weather in Brazilian megacities! agu.confex.com/agu/agu24/me...

agu.confex.com

Extreme Weather Events in Brazilian Megacities

The IPCC Sixth Assessment Report projects with high confidence an increase in w...

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Casey Ivanovich @ccivanovich.bsky.social · 03/12/2024

Excited to present my recent work deriving the new variable "stickiness" at #AGU24 next Friday -- stop by to learn more about our new tool to quantify the temperature versus humidity contributions to humid heat! For more context, find the paper here in JAS: journals.ametsoc.org/view/journal...

Graphic showing the session information about Casey's presentation at the American Geophysical Union Fall Meeting.

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Casey Ivanovich @ccivanovich.bsky.social · 25/11/2024

Excited to share our recent paper led by Sophie Johnson on the relationship between sequential humid heat and precipitation events 🌡️☔ We identify where humid heat is associated with suppressed or enhanced rainfall, with implications for compound extremes! iopscience.iop.org/article/10.1...

iopscience.iop.org

Temporal connections between extreme precipitation and humid heat - IOPscienceSearch

Temporal connections between extreme precipitation and humid heat, Sophie Johnson, Catherine Ivanovich, Radley M Horton, Mingfang Ting, Kai Kornhuber, Corey Lesk

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Reposted by Casey Ivanovich

CompoundNET @compoundnet.bsky.social · 14/11/2024

Welcome to all the Bluesky newbies! We've created a starter pack of compound events and multi hazard researchers and groups. Please send through suggestions for who else to add to the list go.bsky.app/Cy8PZju

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Casey Ivanovich @ccivanovich.bsky.social · 20/11/2024

Hi Bluesky! I’m a climate scientist researching the dynamics and impacts of extreme events, currently studying the physical drivers of extreme humid heat. I’m passionate about collaborating with interdisciplinary research teams and look forward to connecting with folks in climate and other fields!

Casey stands in front of the Oceanography Building at the Lamont-Doherty Earth Observatory where she completed her PhD.

Casey points to the results of her dissertation chapter on a presentation slide during her defense.

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