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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Explaining climate change science & rebutting global warming misinformation

Scientific skepticism is healthy. Scientists should always challenge themselves to improve their understanding. Yet this isn't what happens with climate change denial. Skeptics vigorously criticise any evidence that supports man-made global warming and yet embrace any argument, op-ed, blog or study that purports to refute global warming. This website gets skeptical about global warming skepticism. Do their arguments have any scientific basis? What does the peer reviewed scientific literature say?


Spanish and Ukranian translations of The Debunking Handbook 2020

Posted on 11 June 2021 by BaerbelW

Since its publication last October, The Debunking Handbook 2020 has already been translated into 11 languages. Some of the translations have been created by volunteers who also help with Skeptical Science translations while others have been provided by outside or mixed teams.

DBH-2020-ES-Cover The Spanish translation was created by Claudia Edith Álvarez Domínguez, Irene Méndez Sánchez, Laura Ramos Aranda, Manuel Alcántara Plá and Sandra Mora López. It was published on May 27, 2021.
The Ukranian translation was created by Anna Schamko. It was published on June 2, 2021. DBH-2020-UA-Cover

Thanks to all the translation teams who created these and earlier translations!

If you'd like to translate The Debunking Handbook 2020 into another language or help with a translation currently in progress, please contact us by selecting "Enquiry about translations" from the contact form's dropdown menu. We'll then get in touch with additional information.



California, ‘America’s garden,’ is drying out

Posted on 10 June 2021 by dana1981

This is a re-post from Yale Climate Connections

California, along with much of the rest of the western United States, is once again mired in drought. In fact, California has experienced significant drought conditions in 13 of the 22 years (60%) since the turn of the century.

A 2020 study in the journal Science concluded that 2000 through 2018 was the second-driest 19-year period in the U.S. Southwest in at least the past 1,200 years, and a 2014 paper in Geophysical Research Letters found that 2012 through 2014 was the driest three-year period in California over that same timeframe.

Nearly the entire state is currently in the ‘severe’ drought category or worse, and three-quarters is experiencing ‘extreme’ to ‘exceptional’ drought, according to the U.S. Drought Monitor.



Skeptical Science New Research for Week #23, 2021

Posted on 9 June 2021 by doug_bostrom

LIfe cycle analysis of "Dirk" 

Life cycle analysis (LCA) is a method used to evaluate the environmental impact of a product through its life cycle encompassing extraction and processing of the raw materials, manufacturing, distribution, use, recycling, and final disposal. From: Journal of Environmental Management, 2010. -- Science Direct

Continuing with getting our terms straight, by "product" in this case we're speaking of "Dirk," a person living in Germany and enjoying a decent lifestyle accoridng to accepted current standards. Using established methods repurposed to a prevously untried application, David Bossek et al evaluate Dirk's major environmental impact features. It's a  new means of looking at ourselves, a form of quantification that could certainly be helpful in establishing goals as well as  comparing relative levels of responsibility for remedying our climate mess. In Life-LCA: the first case study of the life cycle impacts of a human being (open access) the authors find room for improvement in a typical human environmental footprint, and identify how to complete their analysis in future research:

Dirk emitted 1,140 t CO2-eq., 4.48 t SO2-eq., 1.69 t PO4-eq., and 0.537 t C2H4-eq. emissions over his current life. Transportation dominated all considered impact categories (40 up to 55%). Energy and water consumption is the second dominant product category for GWP (39%). Food products are with 10% the third biggest contributor to GWP, but rather contribute significantly to the impact categories AP (34%), EP (42%), and POCP (20%). The optimized scenario analysis revealed significant reductions for all studied impacts in the range of 60–65%. CO2-eq. emissions were reduced from 28 to 10 t/a. The remaining challenges include data collection from childhood, gaps and inconsistencies of existing data for consumer goods, the allocation between product users, and depreciation of long-living products.

This paper is remarkable not least for its "radical transparency," given that the Dirk in question is a named, individual person. Dirk's personal footprint size and shape is not the least bit speculative. 

Don't look left, don't look right, look in the mirror

Continuing with new applications of reliable means of assessment, Lépissier and Mildenberger employ the  "synthetic control method" (SCM) to look at unilateral policy efforts to mitigate national carbon footprints, thereby helping us to answer seductively excusing objections to mitigation along the lines of "if they won't, why should we?" From Unilateral climate policies can substantially reduce national carbon pollution (open access):

Existing efforts to evaluate the overall impact of climate policies on national carbon emissions rely on Business-As-Usual (BAU) scenarios to project what carbon emissions would have been without a climate policy. We instead use synthetic control methods to undertake an ex post national-level assessment of the UK’s CCP without relying on parametric BAU assumptions and demonstrate the potential of synthetic control methods for climate policy impact evaluation. Despite setting lax carbon targets and making substantial concessions to producers, we show that, in 2005, the UK’s CO2 emissions per capita were 9.8% lower relative to what they would have been if the CCP had not been passed. Our findings offer empirical confirmation that unilateral climate policies can still reduce carbon emissions, even in the absence of a binding global climate agreement and in the presence of regulatory capture by industry.

A prosaic analogy to "why should I try to clean up alone?" might be that if there's a pile of smelly rotting garbage in the house, we could be very stubborn and refuse to move it unless everybody else lends an equal hand. We'd "win" even as we continued to reside in stench worse than if we moved what we alone could cope with. Lépissier and Mildenberger help to remind us what winning looks like, in numbers.



The day Oil Giants lost the Climate Fight

Posted on 8 June 2021 by Guest Author

Oil companies have long been one of the biggest blocks to action on climate change. But yesterday (26 May 2021) saw huge news, that could see Exxon, Shell & Chevron forced to ramp up their efforts against global warming.

Support ClimateAdam on patreon:



Cooling effect of clouds ‘underestimated’ by climate models, says new study

Posted on 7 June 2021 by Guest Author

This is a re-post from Carbon Brief by Ayesha Tandon

Clouds could have a greater cooling effect on the planet than climate models currently suggest, according to new research.

The paper, published in Nature Climate Change, aims to correct a “long-standing” and “unaddressed” problem in climate modelling – namely, that existing models simulate too much rainfall from clouds and, therefore, underestimate their lifespan and cooling effect.

The authors have updated an existing climate model with a more realistic simulation of rainfall from “warm” clouds – those that contain water only, rather than a combination of water and ice. They find that this update makes the “cloud lifetime feedback” – a process in which warmer temperatures increase the lifespan of clouds – almost three times bigger.

The authors note that the newest generation of global climate models – the 6th Coupled Model Intercomparison Project (CMIP6) – predicts faster future warming than its predecessors. This is largely because the new models simulate a smaller cooling effect from clouds.

However, the lead author of the study tells Carbon Brief that fixing the “problem” in rainfall simulations “reduces the amount of warming predicted by the model, by about the same amount as the warming increase between CMIP5 and CMIP6”.

Due to this, he says that the key takeaway from the study is to “take the extra warming in CMIP6 with a grain of salt until some of the other known cloud problems are also fixed in the models”.



2021 SkS Weekly Climate Change & Global Warming News Update #23

Posted on 6 June 2021 by BaerbelW

Listing of articles linked to on the Skeptical Science Facebook Page during the past week: Sun, May 30, 2021 through Sat, June 6, 2021

This week we included links to some older videos which we think are still valuable because they provide some good basic information about climate science, like Kerry Emanuel‘s What we know about climate change from 2014, Kevin Anderson‘s Delivering on 2°C: evolution or revolution? from 2015 or Eric Rignot, Glaciologist studying ice-sheet dynamics from 2019. 

Articles Linked to on Facebook



The New Climate War by Michael E. Mann - our reviews

Posted on 4 June 2021 by BaerbelW , timo, jg

Since its publication in January 2021, several members from our team have read Michael E. Mann's latest book "The New Climate War". This blog post contains our reviews as well as the recording of a book reading from a side event at the Leipzig Book Fair.


Forewarned is forearmed - Bärbel Winkler

Michael Mann‘s book is essential reading for anybody who doesn‘t accidentally want to fall for the latest tricks utilized by the fossil fuel industry and other groups heavily invested in the status quo. He shines the spotlight on the various underhanded tactics with which these vested interests and inactivists try to drive a wedge into the climate movement or try to shift the blame for the climate crisis from them to us as consumers. Once you know what to be on the lookout for, you‘ll no longer fall prey to these methods and can also call them out when you see others falling for them, who haven‘t been made aware of the tactics yet. Forewarned is forearmed as the saying goes!

Michael Mann also offers hope as he sees outright climate science denial on the way out, basically fighting rearguard skirmishes as the evidence for human-caused global warming is more and more in front of everybodys eyes, making it ever harder to deny. Even though there‘s obviously urgency needed to tackle the climate crisis he‘s nonetheless hopeful that we can do it because we also have the agency to act, meaning that we already have most of the needed options in our toolbox with which we can set ourselves on a path to wean ourselves from fossil fuels.

What we have to make sure to not lose sight of that task however, is to all be aware of the tactics applied by the various breeds of inactivists like the downplayers, deflectors, delayers, dividers, and doomers. Michael Mann‘s book is a great help with that!



Ambitious action on climate change could be Biden’s ‘moon shot’

Posted on 3 June 2021 by greenman3610

This is a re-post from Yale Climate Connections

Some cable TV personalities, talking heads, and plain old historians and historian wannabes have taken to finding connections between President Joe Biden and former Presidents Franklin D. Roosevelt and Lyndon Baines Johnson. A common rationale: The historic eras in which both FDR and LBJ, and now Biden, first took office. And the scope of public policy initiatives all three initiated virtually from the day they were sworn in.

Like most sweeping generalizations, there are strains of truth and fact and lots to quibble about in these comparisons. One analogy not having gotten much attention, however, is that involving Biden’s ambitious climate change action items and how they compare with President John F. Kennedy’s May 25, 1961, commitment to land Americans on the moon and bring them safely back to terra firma.

In this month’s original “This Is Not Cool” video by Yale Climate Connections independent videographer Peter Sinclair, the link between the historic “moon shot” goal and the Biden hoped-for climate objectives is front and center (and posted here, coincidentally, on the 60th anniversary of Kennedy’s pronouncement to Congress). Moon shot? Wishful thinking? How can such sweeping changes occur in the tight time frames often assigned to them? The video explores those questions and more. Take a look.



Skeptical Science New Research for Week #22, 2021

Posted on 2 June 2021 by doug_bostrom

CO2 and staple crop nutritional quality

Dr. Kristi Ebi leads a diversely skilled author team to lend us a thought-provoking tap on the shoulder concerning our lack of full understanding of how increased concentration of CO2 in the atmosphere will affect primary sources of food, particularly grains, and how we intend to maintain key nutritional qualities in the face of adverse effects as a result of more CO2 suddenly being available for plant metabolism. As indicated by supporting work in the article, early signs are that with increasing carbon dioxide in the air staple crops comprising  substantial dietary components for billions of people (we're all included, more or less) will show significant declines in nutrients mandatory for good health. Nutritional quality of crops in a high CO2 world: an agenda for research and technology development (open access) provides a very useful synopsis of concerns and then a welcomely unsubtle appeal to put more noses to the grindstone of research, so that we can anticipate these effects and understand how to cope with them.  This seems reasonable; it's not as though we're all over-nourished even at this juncture and with so many people living on the edge of their metabolic requirements we don't have any slack as it stands now. From the abstract, a prescription as concise as it is challenging: 

Transdisciplinary research involving at least ecologists, plant physiologists, economists, and experts in human nutrition is essential for developing a systems-based understanding of the potential impacts of rising CO2 concentrations for human nutrition and the attendant consequences for achieving the sustainable development goal on food security.

Let alone the main point of the work, Ebi 2021 reiminds us that when we hear somebody cheerfully chirping "but CO2 is plant food!" they're navigating onto a reef of complications. Follow references in the paper to learn about the complexities. 

Drive EVs faster?

In common with all human artifacts, mass production and employment of electric vehicles undeniably creates an environmental footprint, including CO2 emissions. Leaving aside spurious "solutions denier" arguments against electrification of road transport, the more we account for our impacts the better our future will be. Unlike 110 years ago when fossil-fuel powered vehicles exploded into use with barely a second thought we're now a bit sadder and a lot wiser about willy-nilly behavior involving millions of copies of bulky objects made from raw materials and needing copious energy to function.  In modern times, we do do the math on the messes we make— in advance. Hence we're assiduously trying to account for cradle-to-grave external effects of EV deployment at scale. In Global perspective on CO2 emissions of electric vehicles (open access) Märtz et al take a detailed look at how electrified road transport will fit into our overall remaining carbon budget (actually an enormous red figure on our balance sheet, it might be argued). Previous studies on this topic miss important details concerning expected transitions of our energy supplies to more modern sources. Factoring in ongoing updating and modernization away from primitive combustion-centered energy manipulation techniques, the authors find mashing the throttle pedal on electrification will more rapidly take us closer to where we need to be on our carbon budget. Here is a case where inclinations to overweening perfection are the enemy of "good enough to start." From the abstract:

The rapid uptake of renewable electricity generation worldwide implies an unprecedented change that affects the carbon content of electricity for battery production as well as charging and thus the GHG mitigation potential of PEV. However, most studies assume fixed carbon content of the electricity in the environmental assessment of PEV and the fast change of the generation mix has not been studied on a global scale yet. Furthermore, the inclusion of up-stream emissions remains an open policy problem. Here, we apply a reduced life cycle assessment approach including the well-to-wheel emissions of PEV and taking into account future changes in the electricity mix. We compare future global energy scenarios and combine them with PEV diffusion scenarios. Our results show that the remaining carbon budget is best used with a very early PEV market diffusion; waiting for cleaner PEV battery production cannot compensate for the lost carbon budget in combustion vehicle usage.

"Deploy, deploy, deploy." 

89 Articles

Physical science of climate change, effects

Natural Variability and Warming Signals in Global Ocean Wave Climates
Odériz et al Geophysical Research Letters
DOI: 10.1029/2021gl093622

Observations of climate change, effects

More than a nuisance: measuring how sea level rise delays commuters in Miami, FL
Hauer et al Environmental Research Letters
Open Access pdf DOI: 10.1088/1748-9326/abfd5c



A critical review of Steven Koonin’s ‘Unsettled’

Posted on 1 June 2021 by Guest Author

This is a re-post from Yale Climate Connections by Mark Boslough

I would normally ignore a book by a non-climate scientist promising “the truth about climate science that you aren’t getting elsewhere.” Such language is a red flag. But I’ve known the author of “Unsettled” since I took his quantum mechanics course as a Ph.D. student at Caltech in the 1970s. He’s smart and I like him, so I’m inclined to give his book a chance.

But smart scientists aren’t always right, and nice guys are still prone to biases – especially if they listen to the wrong people. In an apparent quest for fairness when he led a committee of the American Physical Society (one of my professional organizations) to assess its statement on climate change, he recruited three scientists to represent the 97% consensus, and three contrarians, presumably to speak for the other 3%. The lack of proportionate representation amplified the contrary opinions that he heard, and only in one direction. He completely ignored another, equally unfounded, contrary view. The position sometimes referred to as “doomism” (the belief that the worst-case is inevitable and it is too late to prevent it) was not represented.

The three contrarians had a long and well-documented history of engaging in ad hominem attacks on mainstream climate scientists and misrepresenting their work. Most of the technical mistakes and misrepresentations in “Unsettled” may simply be attributable to Koonin’s trust of those advisors and lack of rigorous independent verification.

Some books CAN be told by their cover. This is one of them.

Unfortunately, “Unsettled” is a book you can accurately judge by its cover. Koonin’s title hints at a logical fallacy called the “strawman” argument. The blurb on the flap confirms this with its opening sentence: “When it comes to climate change, the media, politicians, and other prominent voices have declared that ‘the science is settled.’”

A bit of fact checking by the author or publisher would have shown that this claim is not true.  In fact, Koonin makes use of an old strawman concocted by opponents of climate science in the 1990s to create an illusion of arrogant scientists, biased media, and lying politicians – making them easier to attack.

The phrase “science is settled” is repeated as Koonin’s target throughout the book, even though it has never been in common use by climate scientists and their supporters. If it were, then Google and LexisNexis searches would surely turn up instances, but the opposite is true. All the examples I found were from critics claiming that advocates of the consensus had said it.



Skeptical Science needs your help!

Posted on 31 May 2021 by BaerbelW , doug_bostrom, John Cook

The primary goal of Skeptical Science is to make peer-reviewed climate science more accessible to people, particularly research relevant to climate misinformation. But as happens with most long-standing websites, we’ve fallen prey to “link-rot” where links once working now give “404 not found” errors. This is especially unfortunate when it happens in our rebuttals - which are Skeptical Science’s backbone - where many links have gone stale since the rebuttal was first created or last updated.

Now, we’d like to enlist your help in a concerted effort to fight link rot! Skeptical Science is an immensely useful resource to hundreds of thousands of people, but our content can always be improved. Achieving this is a relatively easy task (you don’t need to be a climate scientist) that will make a big difference in helping SkS be a more useful resource for anyone wanting to make sense of climate misinformation.

we want you

Volunteer opportunity #1 - Slayer of rotten links (or for the resume-conscious: External resource curator)

First and foremost, we’d like to update all broken links found in our rebuttals with working links to correct, contextually appropriate sources. We have a list of those broken links and in some cases, it will require some sleuthing to find replacement links. While updating these links, two other items should also be fixed:

  1. Updating graphics which currently aren’t hosted on the Skeptical Science server - the danger of hot-linking to external graphics is that the images can break if the external source changes. So we’ll be uploading any currently hot-linked images to the SkS website (as well as resizing any large graphics).
  2. Many of our rebuttals contain embedded YouTube videos, most of which need to be updated to follow best practices.

All told, the list of updates currently contains about 500 items, so it’s not an insurmountable task, albeit one requiring some “legwork”, and we figure that a small team can mow through it in a month or less.

For now, this is a one-off activity but other links will break in the future, so this is also a task requiring permanent effort once this first big push is out of the way.

Volunteer opportunity #2 - Glossary Editor/Curator

A couple of years ago, we started adding scientific papers to the Skeptical Science glossary. This was a powerful addition - it provides the scientific references to the studies we mention in our rebuttals. But, there obviously are many more to add - this task is time-consuming and as an all-volunteer operation, we can’t simply pay to have this work done.

We’d like to enlist your help for this. Unfortunately, given the “loose” citations particularly in many of our early articles, we can’t produce a list of references to add via automation, so part of this task will be to read through the rebuttals and as a first step collect mentions of and links to published papers. To help with prioritizing, we’ll provide a list of most viewed rebuttals for this task. We’ll also have a list of references already available in the glossary to avoid duplication of efforts. In some cases, the reference might already be in the glossary and a small tweak to how it’s mentioned in the rebuttal is all that’s needed to trigger the functionality. We’ll also use this opportunity to standardize references in our older articles.

A step-by-step guide of how to add glossary entries will also be provided for this task. We are hoping to establish a somewhat permanent team of 3 volunteers to keep adding references to our glossary.


Requirements and application

“What are the requirements for these tasks?” you might ask, so here are a few answers:

  • Willingness to volunteer an hour or two per week
  • Some experience with an HTML-editor (we use TinyMCE)
  • Experience working with Google Drive
  • Some stamina to hunt down replacement links or put together glossary entries
  • Willingness to collaboratively work in a team

The skills involved in using TinyMCE or Google Drive are not hard to learn so please don’t be deterred solely by lack of familiarity with those. Veteran Skeptical Science volunteers will be available to help with all of the work entailed in these positions, and as mentioned we’ll be providing instructional materials and other resources to help with getting started and maintaining momentum. We’ll vet applications and meet with you to get to know you before setting you loose on our database.

So if you’d like to join us in our goal of fighting climate misinformation and making climate science more accessible to the public, we’d love to have your help! To get started, please fill out this Google-form by Sunday, June 6 and we’ll reach out to you. We look forward to working with you!



2021 SkS Weekly Climate Change & Global Warming News Roundup #22

Posted on 30 May 2021 by BaerbelW

Listing of articles linked to on the Skeptical Science Facebook Page during the past week: Sun, May 23, 2021 through Sat, May 29, 2021

This week we (again) shared several articles related to Steve Koonin and his book "Unsettled", some of which were related to Ben Santer's understandable reaction to Koonin being given a chance to peddle his book at Lawrence Livermore National Laboratory: Top Climate Scientist Blasts Government Lab After Denier Invited to Speak, Settled enough: Climate science, skepticism and prudence, and A critical review of Steven Koonin’s ‘Unsettled. Another article apparently of interest was The Fallacy of Our Carbon Footprint, judging from the stats provided by FB.

Articles Linked to on Facebook



Talking about climate change: Necessary, yet so uncomfortable

Posted on 28 May 2021 by timo

This is a re-post from Timo's blog Tmag

Talking about climate change in order to prevent climate change is a necessity. And just like many other necessities, it's painfully uncomfortable to do. How come?

Climate change is a problem that affects every last one of us. It is a real looming threat and requires urgent action by as many people as possible. Although climate change is a known problem, too many people are still ignoring it, refuse to act, or simply shrug it off. It seems like a majority of people do acknowledge the reality of it and agree that "something needs to be done". But this does not mean that they are willing to actually do something. Which brings us to today's (literal) talking point: We need to talk about climate change. This is necessary to get more people to understand its urgency and thus getting them to act like the urgency demands. Yet, - I don't know about you, but - I often find it painfully uncomfortable to talk about it with others. Here, I want to analyse why that is.

Well, first of all - even though climate change is a very complex topic with loads of very diverse scientific sub categories, nearly everyone seems to have a rather black or white opinion on the matter. Most often, these opinions are anchored so deeply in a person that they defend their stance on the topic so passionately as if they themselves were experts on the underlying science. Very often, people have one or two go-to-arguments that exemplify why they are 100% sure that their opinion is correct (e.g. "climate changed before humans were around", "Studies say it's solar activities", "I heard the science is not settled" etc). And since their conviction is rooted so deeply, people tend to get emotional over the topic. For me personally, it is no fun to argue about a scientific topic with a person that is overly emotional. And pretty often I find myself surprised, who among my friends, family, and casual acquaintances are so convinced of their opinion regarding climate change that they are willing to truly pick a verbal fight over it - although their stance very often solely relies on one of their errant go-to-arguments or on anecdotal "evidence" ("I go swimming in the Netherlands every year - I saw no sea level rise whatsoever").




SkS Analogy 22 - Energy SeaSaw: Part II

Posted on 27 May 2021 by Evan, jg

Tag Line

Illustrating periodic, apparent GW pauses.

Climate Science

We previously described events that cause energy to cycle between the oceans and the atmosphere at time scales on the order of years, to decades, and longer. To illustrate how the energy SeaSaw creates periodic, apparent pauses in global warming (GW), we combine two simple functions to show how they predict short-term, atmospheric cooling trends that are not indicative of long-term, GW trends.

A sine wave describes the motion of many waves, such as those moving across a body of water. Imagine you are sitting stationary in a rubber boat on the ocean. The waves pass under you causing you to rise and fall in a pattern called “sinusoidal”. This is the approximate motion that represents the up-down pattern when two people use a teeter-totter.

The elevator motion is represented by an upward angled line, which shows the vertical position at a given time. If the elevator is rising with a constant speed of 1 m/s, then after 1 sec it will be 1 m above the ground, after 2 sec it will be 2 m above the ground, etc. Plotting the vertical position of the elevator (which can also be interpreted as the temperature anomaly) on one axis and time (i.e., current year) on the other axis produces an upward, slanted line. Figure 1 shows what the individual sinusoidal (SeaSaw) and constant-vertical motion (Elevator) traces look like, plotted as vertical position (temperature anomaly) vs. time (year).

Shows line going up at 45 degrees, representing rising energy of Earth, and a sinusoidal wave, indicating the energy cycling between the ocean and the atmosphere.

Figure 1. Sinusoidal function (dotted line) plotted together with a constantly increasing function (solid line).



Skeptical Science New Research for Week #21, 2021

Posted on 26 May 2021 by doug_bostrom

Moving targets

In Permafrost carbon feedbacks threaten global climate goals, Susan Natali & crew point out a potential serious omission in Paris Accords climate targets: the changing "nature" of permafrost and the carbon and hence readily available CO2 therein. The abstract: 

Rapid Arctic warming has intensified northern wildfires and is thawing carbon-rich permafrost. Carbon emissions from permafrost thaw and Arctic wildfires, which are not fully accounted for in global emissions budgets, will greatly reduce the amount of greenhouse gases that humans can emit to remain below 1.5 °C or 2 °C. The Paris Agreement provides ongoing opportunities to increase ambition to reduce society’s greenhouse gas emissions, which will also reduce emissions from thawing permafrost. In December 2020, more than 70 countries announced more ambitious nationally determined contributions as part of their Paris Agreement commitments; however, the carbon budgets that informed these commitments were incomplete, as they do not fully account for Arctic feedbacks. There is an urgent need to incorporate the latest science on carbon emissions from permafrost thaw and northern wildfires into international consideration of how much more aggressively societal emissions must be reduced to address the global climate crisis.

We've a lot to keep track of, much of it shifting beneath our feet. Natali et al is open access and free to read. 

Moving targets #2

What can change the mind of a person stubbornly resistant to facts? Certain kinds of facts, maybe. Grant McDermott sets up an experiment to assess how self-professed climate "skeptics" adjust their beliefs when confronted with evidence of climate change from instrumental records. For McDermott the interest of the experiment lies in unifying seemingly disparate theories of accessibility of "skeptic" cognition but his paper is also suggestive of yet another set of mental buttons to push in the pursuit of progress. The abstract:

How much evidence would it take to convince climate skeptics that they are wrong? I explore this question within an empirical Bayesian framework. I consider a group of stylized skeptics and examine how these individuals rationally update their beliefs in the face of ongoing climate change. I find that available evidence in the form of instrumental climate data tends to overwhelm all but the most extreme priors. Most skeptics form updated beliefs about climate sensitivity that correspond closely to estimates from the scientific literature. However, belief convergence is a nonlinear function of prior strength and it becomes increasingly difficult to convince the remaining pool of dissenters. I discuss the necessary conditions for consensus formation under Bayesian learning and show that apparent deviations from the Bayesian ideal can still be accommodated within the same conceptual framework. I argue that a generalized Bayesian model provides a bridge between competing theories of climate skepticism as a social phenomenon.

Skeptic priors and climate consensus is open access and free to read. 

95 articles



Dr. Ben Santer: Climate Denialism Has No Place at Lawrence Livermore National Laboratory

Posted on 25 May 2021 by Guest Author

This is a repost of Dr. Santer's statement via the Union of Concerned Scientists blog and we thank UCS for this permission. 

Lawrence Livermore National Laboratory (LLNL) has invited Professor Steven Koonin to give a seminar on May 27, 2021. Professor Koonin’s seminar will cover material contained in a book he published on May 4. His book is entitled “Unsettled”. Its basic thesis is that climate science is not trustworthy.

Professor Koonin is not a climate scientist. I am. I have worked at LLNL since 1992. My primary job is to evaluate computer models of the climate system. I also seek to improve understanding of human and natural influences on climate.

In collaboration with scientific colleagues around the world, our research group at LLNL has identified human “fingerprints” in temperature changes at Earth’s surface, in the atmosphere, and in the oceans. We have also found human fingerprints in rainfall and moisture. LLNL’s fingerprint research is one small part of a large body of evidence that contributed to scientific findings of a “discernible human influence on global climate”.

I have interacted with Professor Koonin since late 2013. Back then, he argued that uncertainties in climate science were large and were not fully acknowledged by climate scientists. In his view, climate science was not sufficiently “mature” to be useful to policymakers. Similar claims are advanced in his new book.

It is simply untrue that Prof. Koonin is confronting climate scientists with unpleasant facts they ignored or failed to understand. The climate science community treats uncertainties in an open and transparent way. It has done so for decades. At LLNL, we routinely consider whether uncertainties in models, observations, and natural climatic variability call into question findings of a large human influence on global climate. They do not.

It is of concern to me that Professor Koonin will be speaking at LLNL. He is not an authoritative voice on climate science. LLNL climate scientists have devoted their careers to measuring, modeling, and understanding changes in the climate system. Professor Koonin has not.

The decision to invite Professor Koonin will not help LLNL to attract and retain the best and brightest climate scientists. More importantly, LLNL is participating in the dissemination of Professor Koonin’s incorrect views on climate science. This makes it more difficult for US citizens to reach informed, science-based decisions on appropriate responses to climate change.

We live in a democracy. Free speech is important. It is important to hear diverse perspectives on issues of societal concern. It is equally important for US citizens to receive the best-available scientific information on the reality and seriousness of climate change. The National Laboratories should be providing this information. When they provide inaccurate and misleading information, there should be ample opportunity for actual climate scientists to set the record straight.

I conveyed to LLNL management my concerns about the decision to invite Professor Koonin to speak at Livermore. I do not believe my concerns were adequately addressed. I therefore decided that I will no longer have any affiliation with LLNL after I retire on September 30, 2021. There is no personal satisfaction in this decision.

Writing and releasing this statement may be viewed by some as an act of disloyalty. I do not see it that way. I chose to remain loyal to the climate science we have performed at LLNL for over three decades. I do not intend to remain silent while the credibility and integrity of this research is challenged.

Ben Santer is an atmospheric scientist at Lawrence Livermore National Laboratory. He studies natural and human “fingerprints” in observed climate records. His early research contributed to the historic 1995 conclusion of the Intergovernmental Panel on Climate Change: “the balance of evidence suggests a discernible human influence on global climate.” Ben holds a doctorate in Climatology from the University of East Anglia, England. After completing his Ph.D. in 1987, he spent five years at the Max-Planck Institute for Meteorology in Germany, where he worked on developing and applying climate fingerprint methods. Ben joined Lawrence Livermore in 1992. Ben has received a number of awards for his research. These include a MacArthur Fellowship (1998), membership in the US National Academy of Sciences (2011), and the Procter Prize (2019). The most significant awards are the friendships he has made during his career. He currently serves on the board of the Union of Concerned Scientists. 



Ten Thousand Years of Climate Change History

Posted on 24 May 2021 by Guest Author

We talk so much about how global warming is reshaping the present, and what the future might bring. But what did Earth's past look like. To celebrate hitting 10k subscribers, I'm looking ten thousand years into our history, to put today's changes in context...

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2021 SkS Weekly Climate Change & Global Warming News Roundup #21

Posted on 23 May 2021 by BaerbelW

Listing of articles linked to on the Skeptical Science Facebook Page during the past week: Sun, May 16, 2021 through Sat, May 22, 2021

We started the week with two "left-overs" from the previous week's concurrently running series and Revisiting some Analogies - A sinking ship reaches new heights became the post garnering the most attention. A running thread this week were articles related to misinformation and how to tackle it: Escaping the Rabbit Hole: How to Help Your Conspiracy Theorist Friend, From Denial to Ambiguity: A New Study Charts the Trajectory of ExxonMobil’s Climate Messaging, A New Book Manages to Get Climate Science Badly Wrong, Fake News Spreads Like A Virus. These New Online Games Could ‘Vaccinate’ People Against Misinformation, How natural gas propaganda made it into elementary classrooms in deep blue America, Science Had a Misinformation Problem Before COVID. Scientists Want to Fix It, and Climate Guilt, Brought To You By Big Oil.

Articles Linked to on Facebook



Greens: Divided on ‘clean’ energy? Or closer than they appear?

Posted on 20 May 2021 by dana1981

This is a re-post from Yale Climate Connections

Several media outlets over the past week or so have run stories about environmental groups setting up a “circular firing squad” because more than 600 such organizations sent a letter to Congress opposing the clean electricity standard that may become a centerpiece of Democrats’ climate and infrastructure package. The standard would likely require that 80% of U.S. electricity be generated by “clean” sources (meaning those that do not release significant greenhouse gas emissions into the atmosphere) by 2030, and 100% by 2035.

The issue in contention: whether certain technologies like fossil fuels that capture their carbon emissions, nuclear, and biomass power should be considered sufficiently “clean,” or whether they should be eliminated from the American power generation mix for the sake of environmental justice. This potential infighting has triggered flashbacks among many advocates to their last shot at passing serious climate legislation over a decade ago, when in 2009 a proposed carbon cap and trade system died a quiet death in the Senate after having been narrowly passed in the House.

But several key players believe the two sides are not so far apart and remain optimistic that the proposed climate policy this time around could garner sufficient support to become law.



Skeptical Science New Research for Week #20, 2021

Posted on 19 May 2021 by doug_bostrom

Deep dive into shady finances of climate misinformers

Skeptical Science is dedicated to combating malformed and especially fake "skepticism" about climate science, so it's hardly necessary for us to explain the relevance to  our mission of a paper exploring the headwaters of misinformation and cultivated confusion.  Instead we'll let the introduction of Obstructing action: foundation funding and US climate change counter-movement organizations by Brulle et al speak for itself. The paper is open access and free to read.

In a 2016 congressional hearing on the climate crisis, Senator Sheldon Whitehouse (D-RI) held up a book entitled Why Scientists Disagree About Climate Change and asked: “Who funded this phony climate science denial textbook that the Heartland Institute published and mailed to thousands of schoolteachers around the country? ... We know it costs a lot of money to print [but] we don’t know who paid for it!” (SDC 2019). The publisher of the “textbook” was the Heartland Institute, a central organization in the Climate Change Counter-Movement (CCCM). The CCCM is a complex network of organizations that functions to obstruct climate action (Brulle 2020). Senator Whitehouse’s question points to the extensive network of anonymous funders that supports the CCCM. This anonymous funding allows unaccountable, unknown entities to promote climate misinformation and obstruct climate action. Several analyses have shown that this deliberate and organized effort to misdirect and distort public discussion of climate change drives widespread misunderstanding of climate science and legislative gridlock on the issue (NRC 2011, p. 35).

For these ongoing efforts to continue, it is imperative that CCCM organizations mobilize sufficient financial resources (Jenkins 1983). Thus, an examination of the funding sources of the CCCM can provide a deeper understanding of the institutional dimensions of this effort. The effort to understand the financial support of the CCCM has been the topic of scholarly concern (Brulle 2014; Farrell 2015, 2016, 2019). The most extensive analysis was that of Brulle (2014). In his analysis, he found that over the time period 2003 to 2010, the majority of identifiable CCCM funding came from several conservative philanthropies and, increasingly, through Donors Trust, a donor-directed philanthropy designed to preserve funders’ anonymity. In this research, we revisit and update Brulle’s initial analysis. We double the timespan of the prior study, analyzing data from 2003 to 2018, add an analysis of the amount of unidentifiable funds supporting the CCCM, and considerably sharpen prior estimates by approximating the proportion of this funding that directly supports work on climate change.

For those of us curious to understand how our public policy for dealing with anthropogenic climate change is arrested by misunderstandings over matters of basic physics, the foundations of the answer to this puzzle are to be found in this paper and its antecedents.  Brulle et al 2021 is a significant extension and refined quantification of what might be termed industrialized vandalism and degradation of public cognition, competence and ultimately impetus to remedy our unfortunate error in becoming stuck in "caveman mode" by fixating on combustion of fossil hydrocarbon fuel.

 117 Articles 

Physical science of climate change, effects

The impact of increasing stratospheric radiative damping on the quasi-biennial oscillation period
Zhou et al 2021 Atmospheric Chemistry and Physics
Open Access pdf DOI: 10.5194/acp-21-7395-2021

The mechanism of increasing summer water vapor over the Tibetan Plateau
He et al 2021 Journal of Geophysical Research
DOI: 10.1029/2020jd034166




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