Prof Michael E. Mann Profile picture
Scientist/Author; Pres. Distinguished Prof/Director Center for Science, Sustainability & the Media, U Penn; Nat Academy of Sciences; Royal Society; Tyler Prize
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May 13 4 tweets 2 min read
The resilient "scientists should never engage in advocacy" admonishment has once again reared its head in mainstream science discourse.

I've written on why such thinking is misguided and in fact dangerous on several occasions: 🧵 From "If You See Something, Say Something" (my 2014 @NYTimes op-ed):

"If scientists choose not to engage in the public debate, we leave a vacuum that will be filled by those whose agenda is one of short-term self-interest. There is a great cost to society if scientists fail to participate in the larger conversation — if we do not do all we can to ensure that the policy debate is informed by an honest assessment of the risks. In fact, it would be an abrogation of our responsibility to society if we remained quiet in the face of such a grave threat.
nytimes.com/2014/01/19/opi…
Nov 13, 2023 4 tweets 3 min read
The collapse of the great "ocean conveyor" is one of the more likely climate tipping points in the absence of concerted climate action: 🧵 We (@Rahmstorf et al) inferred this scenario eight years ago in this @NatureClimate study:
(see also Stefan's #RealCimate commentary: )
Key figure below. Even then, there was evidence that conveyor collapse might be underway: nature.com/articles/nclim…
realclimate.org/index.php/arch…
Image
Oct 25, 2023 4 tweets 2 min read
Remember when climate deniers were claiming back in 2012 that global warming had paused and models were overestimating greenhouse warming?🧵 Image That was based on cherry-picking starting & stopping dates, exploiting a decadal excursion of natural climate variability that led to a temporary slowdown of warming through 2012 or so (the observations are red, the average over models is black: ) realclimate.org/index.php/arch…
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Oct 16, 2023 10 tweets 4 min read
Interesting analysis and op-ed in the @NYTimes the other day from my friend & colleague Zeke @Hausfath which argues for an acceleration of recent surface warming:


I decided to try to reproduce it!
🧵 nytimes.com/2023/10/13/opi…
Image I decided to use my favorite global surface temperature data set, @NASAGISS #GISTEMP: (provisional value for 2023 here ) data.giss.nasa.gov/gistemp/
columbia.edu/~mhs119/Temper…
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Oct 15, 2023 5 tweets 2 min read
Remarkable to me that some seemingly cannot hold these two entirely compatible facts in their minds at the same time: 1. The Hamas attack was a barbarous act of terrorism. 2. Disputes over resources (esp. water) have been a contributing factor behind all middle east conflict. 🧵 Instead, I get angry responses from some that reduce this nuanced point, made in my recent @TheHill op-ed (), to the childish caricature that I somehow claimed that water access was behind the Hamas attack.thehill.com/opinion/energy…
Jun 23, 2023 6 tweets 3 min read
It's instructive to look at the actual North Atlantic Sea Surface Temperatures right now (): 🧵 https://t.co/DwAGkkGfM9climatereanalyzer.org/clim/sst_daily/
If we look at the SST ANOMALY pattern (departure from normal) instead, the eastern North Atlantic looks extremely warm. As we see above, it's actually cool there (as it always is). Just no nearly as cool as normal.
Jun 12, 2023 5 tweets 2 min read
El Niño and human-caused warming often combine to yield record new levels of global warmth. This is a major factor in what we're currently seeing:
🧵 Image Here are a couple articles we've published on the underlying statistics of this:
nature.com/articles/srep1…
agupubs.onlinelibrary.wiley.com/doi/full/10.10…
Apr 26, 2023 5 tweets 5 min read
From "It's the Anomalies, Stupid" (apologies to @GStephanopoulos) in "The Hockey Stick & the Climate Wars" (#HSCW amazon.com/Hockey-Stick-C…).

Time we start taking seriously the possibility that climate models are missing a La Nina (rather than El Nino)-like response to warming. ImageImage Here's an article we published in @Nature back in 2003 that was suggestive of a La Nina-like response to warming (via paleoclimate evidence for an El Nino-like response to volcanic cooling): nature.com/articles/natur… Image
Apr 22, 2023 14 tweets 13 min read
Twenty five years ago, on this #EarthDay, Apr 22 1998, the #HockeyStick reconstruction of temperatures was born (nature.com/articles/33859). Here's an interview I did on @CBSEveningNews with @johnrobertsFox (anchor @DanRather):
🧵 The Hockey Stick was extended to the past 1000 years in 1999 (agupubs.onlinelibrary.wiley.com/doi/10.1029/19…) and appeared in it's most recognizable form in the @IPCC_CH 3rd Assessment Report "Summary for Policymakers" (ipcc.ch/site/assets/up…) Image
Nov 14, 2022 6 tweets 1 min read
So we sought to answer a few very specific questions in this survey.
🧵 1. Many proponents said it's unclear whether the public would respond negatively or positively to the protests. It's clear that it is the former, regardless of partisan affiliation, gender, etc.
Nov 14, 2022 10 tweets 3 min read
"Public Disapproval of Disruptive Climate Change Protests" | Results of our new @APPCPenn/@PennCSSM survey, summary by Shawn Patterson Jr. (@stp_polisci ) & yours truly
🧵
web.sas.upenn.edu/pcssm/commenta… A few highlights of the study:
⚡️A plurality of respondents (46%) say disruptive non-violent actions decrease their support for efforts to address climate change, while only 13% say that these actions increase their support.
Oct 24, 2022 4 tweets 3 min read
I want to talk about art and climate...

My visit to the @MainLineArtCtr today to see their "Risky Beauty: Aesthetics & Climate Change" exhibit | Thanks to curator Dr. Cynthia Haveson Veloric for the one-on-one tour! 🧵 Art plays a critical role in communicating affectively, complementing the more cerebral approaches based on facts & figures. I loved the way this exhibit paired hope & urgency: ImageImage
Apr 10, 2022 5 tweets 2 min read
I am pleased to report that the manager of the hotel has gotten back to me and has informed me that this is NOT the policy of this @Marriott (i.e. to have a single, namely Fox, news channel on the TVs in the fitness facility as was the case yesterday). 🧵 He informed me that, contrary to what the presiding employee indicated yesterday, the channels CAN be changed in response to the requests of their guests (yesterday Fox was the only news channel; the rest were sports channels).
Aug 9, 2021 4 tweets 3 min read
A short thread on the just-published #IPCC #AR6 scientific working group (#WG1) report (ipcc.ch/working-group/…).

Three key takeaways IMHO: 🧵 1. The Hockey Stick grows longer, blade grows sharper. Recent warmth may be unprecedented in at least 100,000 years (see my @Time op-ed for further details: time.com/6088531/ipcc-c…)
#IPCC #AR6
May 5, 2021 6 tweets 3 min read
"What Matters More, Personal Responsibility or Collective Action? Students provide interesting answers to the question of carbon" | Interesting piece by @LloydAlter for @TreeHugger premised on The #NewClimateWar (publicaffairsbooks.com/titles/michael…) (thread) 🧵
treehugger.com/what-matters-m… It's fascinating to read the thoughtful commentary by the students quoted in the piece. Both individual and collective action are of course important, and it's easy to lose sight of that in these discussions. Nuance here matters.
Apr 26, 2021 5 tweets 4 min read
This is DANGEROUSLY misguided and unhelpful take from @BillGates (gatesnotes.com/Energy/Leaders…). It promotes classic #NewClimateWar (publicaffairsbooks.com/titles/michael…) climate inactivism tropes. Among these are: 🧵 1. The climate problem is “too complex” to solve w/ existing technology. That’s false. Research Gates inexplicably neglects shows we can get there w/ existing renewable energy. See my @Newsweek commentary, “The Right Path Forward on Climate Change” newsweek.com/right-path-for…
Mar 11, 2021 7 tweets 2 min read
In his posthumously published (1997) book "Billions & Billion", the late great Carl Sagan provides an interesting discussion of "rules of the game", e.g. different codes of behavior/policy, such as the "Golden Rule", the "Silver Rule", the "Iron Rule", etc. 🧵 Sagan discusses the "science" (game theory) & human experiments that have been done to assess the effectiveness of competing strategies. The conclusion is that the so-called "tit-for-tat" rule out-performs the others, i.e. leads to greatest likelihood of a positive outcome.
Feb 25, 2021 7 tweets 5 min read
"Scientists see stronger evidence of slowing Atlantic Ocean circulation - Atlantic meridional overturning circulation [weakest in] 1,000 years" by @afreedma & @ChrisCMooney in @WashingtonPost, on new @NatureGeosci article by @rahmstorf & co (thread)
washingtonpost.com/climate-enviro… We (@Rahmstorf et al) reached that conclusion in a 2015 @NatureClimate study (nature.com/articles/nclim…). It featured a reconstruction over the past 1000 years of the sub-polar "cold blob" (below) that is indicative of an AMOC slowdown.
Feb 19, 2021 7 tweets 5 min read
There's a lot of "friendly fire" in the #NewClimateWar (publicaffairsbooks.com/titles/michael…). Despite having some of the best climate journalists on staff, @NYTimes editorial decisions have often played into the tactics of climate inactivists (presumably unwittingly). Some examples (thread): The @NYTimes engaging in "deflection" (i.e. it's all about individual lifestyle change rather than systemic change)
Nov 7, 2020 12 tweets 4 min read
Congratulations #PresidentBiden!
Now let's get to work.
We must reassert the climate leadership that was lost under Trump.
A lot of us stand ready to help!
Here's my full statement below.
Let's hit the ground running in January! 🙂
#NewClimateWar
facebook.com/MichaelMannSci… Congratulations to President Elect @JoeBiden!
And congratulations to US for having used the power of our vote to create an opportunity for meaningful progress on climate going forward (thread)