Dr Theodosios Chatzistergos
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damagedonegr.bsky.social
Dr Theodosios Chatzistergos
@damagedonegr.bsky.social
800 followers 760 following 990 posts
Researcher at Max Planck institute for solar system research.
Studying solar activity and variability.
I am not on x (twitter), my account there is deleted.

https://scholar.google.com/citations?user=8gnK6BsAAAAJ&hl=en
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damagedonegr.bsky.social
Dr Theodosios Chatzistergos @damagedonegr.bsky.social · Nov 16
If you've heard the claim that the Sun is responsible for global warming in recent decades, you've likely encountered the Hoyt & Schatten 1993 (HS93) total solar irradiance (TSI) series cited to support this assertion. But, is this correct? [tldr: no]🧵
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
Does the solar magnetic field migrate towards the poles faster than expected? Results using the data from #ESA ’s #SolarOrbiter are published today in #ApJL. More infos here: www.mps.mpg.de/sun-first-gl...
@science.esa.int @ioppublishing.bsky.social
Sun: First Glimpse of Polar Magnetic Field in Motion
In March, ESA's spacecraft Solar Orbiter had its first clear view of the Sun’s south pole. A first analysis has now been published. Huge cells of hot plasma cover the Sun and create the large-scale, ...
www.mps.mpg.de
November 5, 2025 at 3:16 PM
damagedonegr.bsky.social
www.lifo.gr/videos/on-ai...
«Απέκτησα αναπηρία, αλλά όχι λιγότερη ζωή» | LiFO
Ο Παναγιώτης Πιτσίνιαγκας μιλά για τη δύναμη της επανεκκίνησης, για την ψυχή που «θεραπεύτηκε» και για μια Ελλάδα που ακόμα μαθαίνει τι σημαίνει πραγματικά ισότητα.
www.lifo.gr
October 16, 2025 at 6:20 PM
damagedonegr.bsky.social
The deadline for submission to the topical issue has been extended until 31 January 2026.
☀️🔭🧪
damagedonegr.bsky.social Dr Theodosios Chatzistergos @damagedonegr.bsky.social · Feb 26
We are pleased to announce that the Topical Issue (TI) on “Space Climate: Solar Extremes, Long-Term Variability, and Impacts on Earth’s System” is now open for submissions at the Journal of Space Weather and Space Climate (JSWSC) site:
www.swsc-journal.org/topical-issu....
🧪🔭☀️
logo for the space climate symposium 9 that took place in Nagoya, Japan on October 1-4, 2024
October 8, 2025 at 8:32 AM
Reposted by Dr Theodosios Chatzistergos
andrewdessler.com
Our comment to the DOE and EPA about the DOE Climate Working Group report is now posted on ESSOAR preprint server. It has a DOI and can now be cited!

essopenarchive.org/users/260056...
Screenshot of an ESS Open Archive preprint page. A green “Download PDF” button sits at top left. The title reads “Climate Experts’ Review of the DOE Climate Working Group Report.” Below are subject tags “Atmospheric Sciences” and “Climate Science,” followed by two listed authors. A “Preprint timeline” box shows “Submitted to ESS Open Archive” on 24 Sep 2025 and “Published in ESS Open Archive” on 29 Sep 2025. A citation block includes the DOI 10.22541/essoar.175745244.41950365/v2 and notes version v2 (processing). A right-side box says “Non-exclusive” and “No reuse.” A yellow banner at the bottom states: “This is a preprint and has not been peer reviewed. Data may be preliminary.”
September 30, 2025 at 2:54 PM
Reposted by Dr Theodosios Chatzistergos
emilywilliams.bsky.social
Grateful to @andrewdessler.com for coordinating this (and keeping us on schedule)! I feel proud for having contributed to this monumental effort alongside some of my role models in this field. It felt necessary to respond to the report that was misleading at best and dangerous at worst.
September 2, 2025 at 4:10 PM
Reposted by Dr Theodosios Chatzistergos
hausfath.bsky.social
Proud to be part of an effort by 85 scientists from around the world to respond to a misleading DOE climate science report last month.

The fact that our rebuttal is more than 3x the length of the DOE report is a good example of Brandolini's Law in action...
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
September 2, 2025 at 5:28 PM
Reposted by Dr Theodosios Chatzistergos
ccolose.bsky.social
There's a lot of very interesting material in the response from experts across many domains if you want to learn something solar reconstructions, coral reefs, U.S. temperature data, atmospheric temperature trends, climate models, etc. Andrew did a great job organizing with a very small (30d) window.
September 2, 2025 at 4:29 PM
Reposted by Dr Theodosios Chatzistergos
andrewdessler.com
Great article in the NYTimes about our comment to the DOE about their climate report.

Gift link:
www.nytimes.com/2025/09/02/c...
Scientists Denounce Trump Administration’s Climate Report
www.nytimes.com
September 2, 2025 at 1:43 PM
Reposted by Dr Theodosios Chatzistergos
andrewdessler.com
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
September 2, 2025 at 1:24 PM
Reposted by Dr Theodosios Chatzistergos
bobkopp.net
The Department of Energy hired five academics to raise doubts about climate change. 85+ climate experts (organized by @andrewdessler.com) reviewed their report. Our conclusion, detailed in 450 pages of analysis: it is biased, full of errors, and not fit to inform policy making.
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...
sites.google.com
September 2, 2025 at 1:07 PM
Reposted by Dr Theodosios Chatzistergos
andrewdessler.com
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).
August 28, 2025 at 1:13 AM
Reposted by Dr Theodosios Chatzistergos
damagedonegr.bsky.social
We are pleased to announce that the Topical Issue (TI) on “Space Climate: Solar Extremes, Long-Term Variability, and Impacts on Earth’s System” is now open for submissions at the Journal of Space Weather and Space Climate (JSWSC) site:
www.swsc-journal.org/topical-issu....
🧪🔭☀️
logo for the space climate symposium 9 that took place in Nagoya, Japan on October 1-4, 2024
February 26, 2025 at 9:45 AM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
Could the #Sun be responsible for #ClimateChange? In his #TEDx talk on the subject, #mpsgoettingen director Sami Solanki looks into our star’s capricious past, at its more recent behavior – and gives a clear and definite answer. View here: www.youtube.com/watch?v=bQ21...
Could the sun be responsible for climate change? | Dr. Sami K. Solanki | TEDxHHN
YouTube video by TEDx Talks
www.youtube.com
August 22, 2025 at 10:34 AM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
#ParkerSolarProbe was in the right place at the right time in Sept 2022: It passed through a magnetic reconnection region in the Sun's corona. #SolarOrbiter observed the event from a distance. Study led by #SwRI in
@natastron.nature.com
. #NASA
@science.esa.int

www.mps.mpg.de/flying-throu...
solar flare as seen by Solar Orbiter on September 5th and 6th, 2022
August 28, 2025 at 6:34 AM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
And here's a video of the flare!
August 15, 2025 at 10:27 AM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
Here are some great shots from our #GREGORSolarTelescope observation campaign in July. Peering into the #photosphere and #chromosphere, we caught several emerging active regions – and a #flare! This will help us study the plasma dynamics in active regions and how energy builds up to create a flare.
emerging active region as seen by GREGOR emerging active region as seen by GREGOR
August 15, 2025 at 10:27 AM
damagedonegr.bsky.social
A quick reminder that the claim that "TSI
variability can explain more than 70% of the temperature variability since preindustrial times" is based on outdated and implausible TSI models. Thus, it is a misleading statement.
link.springer.com/article/10.1...
www.sciencedirect.com/science/arti...
Screenshot from the conclusions of the Chatzistergos 2024 paper https://link.springer.com/article/10.1007/s11207-024-02262-6 . The included text is: "Overall, our work highlighted issues with the original HS93 TSI series by identifying artefacts in the processing HS93 applied, while also discussing the issues with the arbitrary choice of activity indices used by this model. In addition, by updating the activity indices the model uses, we demonstrated that the original HS93 TSI series suggests an implausible magnitude of variations, which is incompatible with recent TSI data. We also showed that replicating and updating the HS93 model with recent data results in TSI variations since 1700 that are consistent with those by SATIRE-T and NRLTSI, that is those used by IPCC. In particular, the updated HS93 model suggests a TSI difference between the 1700s and 1986 of 0.5 W m−2, which is significantly lower than the 4 W m−2 suggested by the original HS93 series. Finally, we found the updated TSI series with the HS93 model exhibits a rather poor agreement with Earth’s temperature (linear correlation coefficients between 0.13 and 0.23 when considering the entire period of TSI reconstruction, 1700 – 2010). This demonstrates that the high agreement that was previously reported is due to artefacts in the processing applied by HS93 and the exaggerated magnitude of variations they imposed. As a consequence, this also renders void arguments about the solar influence on Earth’s climate that were drawn based on the original HS93 series (e.g. Connolly et al., 2020, 2021; Scafetta, 2023; Soon et al., 2023; Georgieva and Veretenenko, 2023)."
July 30, 2025 at 7:38 AM
Reposted by Dr Theodosios Chatzistergos
livingrev-solphys.bsky.social
"It's Alive!" — Yes, after a break, Living Reviews in Solar Physics has resumed publication:

Greg Kopp. Solar irradiance measurements. #LivingRevSolPhys 22, 1 (2025). doi.org/10.1007/s411... #OpenAccess #Review @laspatcu.bsky.social
Space-borne TSI Record. The TSI has been measured from space via an uninterrupted series of overlapping instruments since 1978. Scale differences between instruments are due to calibration differences.
July 11, 2025 at 6:26 PM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
The German radio station "Bayern 2" has devoted the latest episode of its show “IQ” to the #Sun - and to Solar Orbiter’s first views of the solar poles. Interview partner is Sami Solanki of #mpsgoettingen : www.ardaudiothek.de/episode/urn:... In German. Enjoy!
#SolarOrbiter @science.esa.int
Podcast: Magnetfeld der Sonne - Ist das ihr letztes Rätsel?
Die Sonne ist ein lebendiger Stern: Die Oberfläche brodelt, Sonnenflecken tauchen auf und vergehen, Eruptionen schleudern Ströme geladener Teilchen ins All. Sogar ihr Magnetfeld dreht sich regelmäßig ...
www.ardaudiothek.de
July 11, 2025 at 10:54 AM
Reposted by Dr Theodosios Chatzistergos
drnereide.bsky.social
🧵
Did you know that sunspots, those dark "marks" on the Sun surface have been observed for over 400 years?

They are the key to studying solar activity, but combining them into a single story is a challenge!

A new study has tested methods for "calibrating" this historical data, collected by

🔭 🧪
damagedonegr.bsky.social Dr Theodosios Chatzistergos @damagedonegr.bsky.social · Jul 7
New paper alert 🧪☀️☄️
In this study, we assessed different methods of combining sunspot number records from various observers, which will strengthen our ability to construct a consistent solar activity history.
doi.org/10.1051/0004...
Screenshot of title and abstract of the paper. title: Assessment of sunspot number cross-calibration approaches
July 8, 2025 at 7:32 AM
damagedonegr.bsky.social
New paper alert 🧪☀️☄️
In this study, we assessed different methods of combining sunspot number records from various observers, which will strengthen our ability to construct a consistent solar activity history.
doi.org/10.1051/0004...
Screenshot of title and abstract of the paper. title: Assessment of sunspot number cross-calibration approaches
July 7, 2025 at 6:14 AM
damagedonegr.bsky.social
Willie Soon's latest video is a textbook case of climate-change propaganda.
This short clip shows him making outrageously misleading claims about the Sun.
🧵🧪 #climatechange
June 26, 2025 at 12:57 PM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
We are looking forward to welcoming you! All of the #MPSGoettingen 's around 300 employees are helping, and most of us gathered for this group picture yesterday to mark the kick-off of the final preparation phases for this year's Night of Science. See you soon @ndw-goe.bsky.social
Crowded into the corner of a two-story foyer inside a lofty building, a large group of people are posing for a group picture. People are arranged in several rows, and are all wearing the same black t-shirts with a small logo on the left chest. The walls are white, the floor is dark. On the left wall high up over everyone's heads hangs a large illustration of the Sun showcasing our star's inner structure. To the top right, a part of a model of the Solar Orbiter spacecraft hanging from the ceiling is visible. On the bottom right, the instrument suite sitting on the back of the Sunrise III telescope dominates the foreground.
June 20, 2025 at 7:31 PM
Reposted by Dr Theodosios Chatzistergos
timosbornclim.bsky.social
Explore past and future climate on your PlayStation.

Including CRU-TS observational data from Climatic Research Unit @uniofeastanglia.bsky.social @climateuea.bsky.social
playstation.com PlayStation @playstation.com · Jun 18
🌎 Climate Station launches today on PS5 and #PSVR2, transforming decades of complex climate science into an immersive, interactive story: play.st/4edqM2G
June 18, 2025 at 4:08 PM
Reposted by Dr Theodosios Chatzistergos
mpsgoettingen.bsky.social
Experience space exploration up close! 🚀
At the Night of Science, you can admire our satellite models from up close – including PLATO by #ESA! 🛰️

It all kicks off on Saturday at 5 PM – don’t miss it!
#ndwgoe #ndwgoecountdown #mpsgoettingen #ndwgoemps
Model of plato and image of the sun
June 18, 2025 at 8:52 AM