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I wrote this cartoon months ago… and then realized that it shouldn’t be released until after the first snowfall of the year, so put it in a (virtual) drawer for a while.
The cartoon reflects my growing skepticism about the utility of logic and evidence as methods of persuasion, especially regarding an issue like climate change. I used to be a great believer in the value of logical argumentation; I would spend hours trying to argue with people, I was on the debate team in college, etc..
But my faith in debate has, I’m sorry to say, faded. Climate change denialism is not an evidence-based position in the first place, and evidence will not cause most people who hold that position to shift it.
I still try to be civil, and with the right person I can enjoy a good debate. But emphasizing that sort of exchange as the only legitimate way to make change, as some people do, is an unrealistic position at best (and a self-indulgent, privileged position at worst).
It’s not that people never change their minds; sometimes huge portions of the public change their minds on an issue with surprising speed (as happened with same-sex marriage). But why people change their minds is a lot more complicated than the “public debate” model assumes.
* * *
This was a hard one to draw! Drawing a snowstorm is a challenge, for me, and I had to experiment a bunch. I added a lot more solid blacks in the backgrounds just to have some areas that the white snowflakes would clearly show against. I struggled to figure out how to draw waves on a beach with snow looking at the beach from the water (it’s rare that I can’t find a reference photo for something, but in this case my googling skills were not up to the task).
Still, adding the snowflakes was like a big layer of static on top of the images. I ended up adding a greater variety of colors than I’ve been using on my strips lately, to make it easier for readers to see what’s going on. (I prefer the way limited color looks – I think it’s prettier and also more distinctive-looking – but clear storytelling is a higher priority).
(While drawing this comic, I’d sometimes glance out the window and feel surprised that the ground outside wasn’t covered in snow.)
(This isn’t deep, but I really like the snowman playing with a smartphone in panel five.)
Thanks to the folks who are supporting my Patreon! I couldn’t make an oddball cartoon like this one without the support I get from y’all, and it means so much to me. Extra thanks to $10 patron N.K. Jemisin, who is also thanked on the sidebar. N.K. (who needs no introduction from me) is an amazing novelist; if you haven’t read her books, do yourself a favor.
Here’s the graph that’s partly visible in panel 2. The graphic was created by Mike Shibao for the University Corporation for Atmospheric Research.
Related link: Does cold weather disprove global warming?
TRANSCRIPT OF CARTOON
This cartoon has six panels.
PANEL 1
Two women stand outside a building. It is snowing heavily; the ground is covered with snow, and there’s a snowman in the foreground. One woman has red hair and is wearing a down vest, while the other has a red jacket and glasses. The Readhead is talking cheerily with one hand raised in a dismissive “get outta here” sort of gesture; Red Jacket is doing the “explaining hand” thing (upturned palm at a bit above waist height).
REDHEAD: Global warming can’t be real! Look at all this snow!
RED JACKET: I can see why you’d think that, but can I try to change your mind?
PANEL 2
The two characters have apparently gone somewhere sheltered from the snow. Red Jacket is holding up a graph, which shows red lines (increasing) and blue lines (decreasing) superimposed over a map of the USA. Redhead is leaning forward to examine the graph.
RED JACKET: …there are still record-setting cold days, but look at this graph – we’re having them much less often nowadays, and we’re having record hot days much more often.
PANEL 3
The two characters are standing on a beach, looking out at the water. It’s snowing, and the beach is covered in snow except near the shoreline. There’s foam from a little wave coming in. Red Jacket is gesturing towards the wave, while Redhead scratches her head thoughtfully.
RED JACKET: Looking at the ocean, we can see that there are still some waves coming in even when the tide is heading out.
REDHEAD: So the waves are like cold days?
PANEL 4
The two characters are now standing by a building, which has a satellite dish on the roof and the NASA logo on the side. It’s still snowing. Red Jacket is introducing Redhead to a third woman, who is wearing a white coat, glasses, and a knit hat. Redhead is listening attentively.
RED JACKET: …now let’s go visit NASA!
NASA PERSON: Hi, ladies! Let’s talk about the difference between climate and weather.
PANEL 5
The two characters are back on their won, standing outside a building and talking. It’s still snowing; in the foreground, a snowman appears to be checking their cell phone. Redhead is talking energetically and cheerfully, with her hands spread wide, as Red Jacket listens.
REDHEAD: Wow, that was incredible! You’ve proved your point – cold weather really doesn’t mean global warming isn’t real!
PANEL 6
This panel shows Redhead, in the same vest as the previous five panels but with different clothes on under it, talking to a balding man wearing a red scarf. Redhead is in exactly the same pose as in panel 1. Around the corner, unseen by Redhead, we can see Red Jacket looking surprised and annoyed. It’s still snowing.
CAPTION: Literally the next day.
REDHEAD: Global warming can’t be real! Look at all this snow!
I imagine the frowning snowman checking the weather and seeing a warming trend…
I accept your headcanon!
Those last two panels happen regardless of what public issue people debate.
Ron:
I think this was covered in the commentary after the cartoon.
The issue, of course, is not whether there is warming but whether there is anthropogenic / people-caused global warming. There have, of course, always been heating and cooling cycles.
I have a question about AGW (it looks like Charles is the expert here? – maybe he could help):
There have been much hotter periods in history and there have been periods with much higher CO2 levels (1950 ppm in the Jurassic period vs. pre-industrial levels of around 250 ppm, for instance), and not necessarily at the same time. I know that the CO2 levels and heat levels can be disputed somewhat, but please just go with me here about the general concept – even in recent times there have been minor heat-ups (e.g. the Roman and medievel periods). But getting to the point, and my question for Charles:
What was the mechanism that naturally reduced these prior hotter times and prior times with high levels of CO2? As I understand it, the water-vapor hypothesis doesn’t really cut it. To what extent does this cooling mechanism – whatever it is – flow into today’s climate – change models?
Murph:
I’m not Charles, obviously, and Charles knows a lot more than I do about this.
But according to this video by Peter Jacobs, the answer is that CO2 is not the only driver of global temperature.
Two very large factors that helped cool the earth in the Jurassic period were:
1) The sun was less active then, so less solar radiation was hitting the Earth in the first place.
2) The Earth’s land mass was much more in equatorial regions than today. This is important because land reflects more solar energy out of the earth’s system than ocean – put another way, the ocean absorbs more of the sun’s energy. And more solar energy hits the equatorial region than other regions. So when there’s more land mass in the equatorial region, less of the sun’s energy is absorbed by the earth, and that has a cooling effect.
This two factors together were two mechanisms that reduced the heating of the climate system back then.
Regarding the medieval warm period, scientists believe that although some regions had high temperatures, globally the Earth is hotter now. And, importantly, the things that caused the regional high temperatures back then – a spurt of high solar radiation, low volcanic activity, and a change in currents bringing warm water to the Northern Atlantic – can’t be the cause of the current, higher global level of warming. (Here’s a skeptical science page on the subject, with lots of references – click on “intermediate” for more detail.)
Then why wouldn’t those two factors prevent the heat-up in the first place?
I also can’t see, for the life of me, how those two factors could lower the CO2 concentration (I’m not saying the CO2 concentration CAUSED a warm-up, I’m just saying the concentration was high in certain periods — how was it lowered?).
By the way, your first factor is called the “dim sun” hypothesis. On another website, a person asked for evidence of this (similar to “LINK PLEASE”), and there were crickets chirping after that. I know there was the “Maunder Minimum” and the “Spörer Minimum” in recorded times, but I have no clue as to how you would know what the sun activity was in the Jurassic period.
As far as the recent warming periods go (Roman and medieval), I don’t care to argue those because there were much, much hotter periods – I only mentioned them in case someone wanted to completely dispute that there were ever any hotter periods than now. I thought recorded history would help. I just wanted to move along with my question and not get stuck in the mud.
Anyway … how did the alleged dim sun and the different configuration of land masses lower CO2 levels? What was the mechanism, and does this mechanism figure into the present-day models?
1) I seem to have misunderstood your question. I thought you were asking why the higher CO2 levels in the Jurassic period didn’t cause much, much higher temperatures. The answer to that question (which maybe you weren’t asking) is, a dimmer sun and more land mass in equatorial regions. (In fact, one theory is that without the greenhouse effect caused by high CO2 levels counteracting the dimmer sun, all water on Earth would have been frozen. See this National Geographic article, or this one in Science.)
2) I didn’t claim, or intend to claim, that either a dimmer sun or the different land masses caused CO2 levels to eventually go down.
3) So why has the sun grown brighter over millions of years? “The gradual increase in luminosity during the core hydrogen burning phase of evolution of a star is an inevitable consequence of Newtonian physics and the functional dependence of the thermonuclear reaction rates on density, temperature and composition.” (Source.) It’s a model, but one that (if I’m understanding this correctly) is grounded in both well-known physics, and in observations of other stars of various ages.
Scientists who study the sun have concluded that stars have a standard life cycle, which includes being dimmer when young, for decades (the earliest references I found when I looked just now are from the 1950s (for example: Structure and Evolution of the Stars by M. “Schwarzschild, Princeton Univ. Press, 1958)).
As far I can tell, physicists who study the sun mostly agree that this is something that happens. David Taylor, a professor of Physics at Northwestern, explains the causes of the brightening:
Is there any reason to think that physicists who study the sun are wrong about all this? I’d be interested in reading any link to a legitimate source you could provide.
4) How does CO2 get taken out of the atmosphere? It’s called the carbon cycle; wikipedia has a page explaining the concept. Basically, as various things – for instance, new plant growth – trap CO2 on or below the surface of the Earth, there’s less CO2 in the atmosphere. As I understand it.
5)
But in this case, the “mud” (as you put it) is facts. Your claim about it being hotter during the medieval period was false; surely you can’t expect me not to correct a false claim.
As far as I know – and as far as climate.gov knows – there has never been a warmer period than right now, in recorded human history. (There were hotter periods in pre-human history, of course). If you want to claim that there have been warmer periods in “recorded history,” could you please link to a source for that claim, as I’ve been linking to sources for my claims? Thanks.
Sure, if you want to state that there have not been any warmer periods in recorded history, I will be glad to plead nolo contendere because – as I mentioned – I don’t care to argue it (I retract it if that is allowed). That wasn’t my original question, and I didn’t want to get bogged down in detours.
It seems like your answer to my question is that hotter times were cooled down by the dimmer sun, is that right? I still want to ask why the dimmer sun didn’t prevent the heat-up in the first place, but first and foremost I want to make sure I understand what you are saying.
It seems like your answer to my question about what reduced the very high levels of CO2 in the atmosphere in prior times (I am using the Jurassic period as an example here) was the carbon cycle – because there was new plant growth that traps CO2 on or below the surface of the Earth so that there’s less CO2 in the atmosphere.
Let me know if I am putting words in your mouth or distorting what you are saying.
Well, this makes it sounds sequential (first there were hotter times, and then the dimmer sun cooled things down). If that’s what you meant (and I’m not sure it is), then no, it’s not right.
What I’m saying is that a variety of things had (and have) an effect on global temperature. 450 million years ago, the mix included a lot more CO2 in the atmosphere, which on its own would push temperatures up, and also a dimmer sun and much more equatorial landmass, which are factors that push temperature down. All of those factors (and probably others as well) combined to create temperatures about 3 degrees hotter than in our current period. (As I understand it; I could be mistaken).
Organic carbon trapping is part of the carbon cycle, but it’s not all of it. Chemical weathering – inorganic carbon trapping – is also a major part of the carbon cycle system.
* * *
I should say, in case I haven’t made this clear, that we’re now discussing far beyond my understanding, and I’m not 100% confident in my answers. This discussion has moved far afield from what the cartoon discussed! If you have additional information, I’d be interested in hearing it. However, the kinds of questions you’re currently asking might be better asked at the askscience reddit, because the people who answer there are more likely to know what they’re talking about.
This article on skeptical science: “Do high levels of CO2 in the past contradict the warming effect of CO2?” may be useful to you.
The shorter term variations in temperature in the paleo-climate are a large part of how we are able to determine the climate sensitivity to changes in CO2. I think Hansen and Sato (2012) is a good demonstration of this (first link is a pdf on arxiv, second link is a summary article on skeptical science).
It’s useful to remember timescales. The earth can change a lot “on its own” because of various phenomena, but we can’t rely on this warming cycle being naturally reversed – even if it may – because it will happen on a timescale completely irrelevant to humans.
The earth is actually fairly robust. Mostly, we’re going to fuck things up for ourselves, not the earth. The earth is in it for the long haul.
1. Yes, because “we” humans will never be able to exploit a mechanism to reverse any man-made climate change that may exist to our benefit and on our time scale. [/sarcasm]
2. It’s damn good that we have humanities-type people to do the “big thinking”. The scientists just kind of do detail stuff, but they are not able to think about consequences and stuff. The humanities-type people *could*, of course, do all of the detail stuff, but they do the big thinking that scientists aren’t capable of. Right?
Ampersand sez:
What you are saying, implicitly, is that although you’re 100% sure that man-made global warming is occuring, you cannot see the reason why you believe it 100%.
If someone says that 2 + 2 = 4, and I understand what + and = mean, I can put up two fingers on one hand and then two fingers on the other and count up a total of four fingers. I can see for myself that this is true.
If you don’t understand climate change, what you are doing is relying on what others say. I know that the Kool Kidz are saying that if you have questions about man-made climate change, you are like square. But maybe lighten up, man.
Here’s how you should approach very complicated topics like climate change: Think and read and gather evidence and don’t make an unwarranted, rash or precipitous decision until you have to. Lawmakers have to make decisions, so they should act on their best information and do the best they can. I want to add, though, that there may already be patent applications (they are kept secret for 18 months) that exploit mechanisms to reverse global warming. Then I guess you can move on to your next self-righteous outrage.
JTV, could you please try to dial down the sneering tone a couple of notches? Thanks!
If we’re exploiting a mechanism – somehow vastly speeding up the process of chemical weathering, for example, to trap more carbon in the oceans – then it’s not the earth doing it “on its own.”
And although it’s conceivable that some completely game-changing tech will come along (and I’d love it if that happened! That would be great!), policy shouldn’t make the assumption that it will happen. It’s also conceivable that no such game-changing tech will come along to rescue us, and policy should account for that.
Literally no one is saying this, so implying Mandolin has said this is dishonest. Please just reply to what Mandolin (or me, or Charles, etc) actually write, rather than making up strawmen. If your views are strong and well-supported, then making up strawmen shouldn’t be necessary.
Also, my view – and Mandolin’s, I’m pretty sure – reflects what most scientists in this area are saying when we make our polity preferences. And Charles is in the sciences.
I think it’s more that, although I’m 99% certain that man-made global warming is real – because I’ve read a lot by actual climatologists on the subject, and their arguments and the evidence they cite makes a lot of sense – I haven’t read much at all about the physics of why young suns are dimmer, so that’s a subject I’m less certain about.
And I’m 100% sure (going back to the comic strip) that cold weather doesn’t prove there’s no global warming.
Yes, I am relying on what others say – specifically, on what climatologists and other experts in this field, many of whom have spent their entire careers studying these questions, have said.
Don’t we always have to do that? A Senator has to deal with hundreds or thousands of issues over the course of their career. They can’t independently study everything they have to vote on; relying on what other people say is pragmatically necessary at some points. But we can also exercise judgement in who we listen to, for example by taking the views of the vast majority of climate scientists especially seriously when deciding what climate policy should be.
But the consensus of expert opinion is that we do have to. By putting off mitigating the problem, we are (barring the sudden appearance of completely gamechanging technology) making it much harder for humans to live on this planet going forward.
In general, I think it’s important to remember that the decision to do nothing is, itself, a decision. So “not deciding” isn’t one of our options. We either decide to take action, or we decide to continue on our current course, but either way we’re making a decision. I think making a decision based on the best understanding of the large majority of expert scientists, is better than making a decision based on ignoring what those scientists are telling us.
JTV,
Surely you understand that there is a vast distance between “that there may already be patent applications … that exploit mechanisms to reverse global warming,” and having a solution that can actually be scaled up to absorb 37 billion tons CO2 (and rising) per year. It’s not as though we don’t have a bunch of known technologies in various states of testing (including industrial scale pilot projects) for absorbing CO2 out of the atmosphere at vastly increased rates relative to the baseline carbon cycle, so one secret trick that is still in the patent application process is not likely to utterly transform the field. Who knows, maybe it will! However, I’m not sure why we’d need your secret technology if, in fact, there were not anthropogenic global warming happening, and if that warming were not, in fact, a serious threat to humanity. So your promise that you’ve solved the problem of global warming (just need to get that patent, and then spend decades figuring out how to scale it up and spend billions implementing that! totally solved!) only makes sense if we silly humanities types (never mind my actual degree) are actually right to believe the actual experts in climate science, and anthropogenic global warming is actually happening and is actually a threat.
The sequence of denialist claims (often made in random and rotating order):
1) It’s not happening,
2) It’s natural cycles,
3) It’s happening, but anything we might do about it is luddite communism
4) It’s happening, but there’s a magic techno-fix just around the corner that means we don’t have to do anything! (…except spend trillions on developing and implementing a magic techno-fix, spending financed by carbon taxes or cap and trade schemes that were luddite communism back at point 3…)
That we will eventually develop and implement scalable, cost-effective negative emissions technologies is an assumed part of the plans to dramatically reduce emissions immediately under the Paris Agreement. Vast scale negative emissions are basically the only way we avoid going over 2C global warming by 2100, and definitely the only way we avoid 1.5 C. So, yay for some supposed new techno-fix, and good luck with scaling it up to sequestering billions of tons of CO2 per year, but don’t try to pretend that that means any of those 4 denialist claims. That someone is going to come up with viable negative emissions technologies, and then we’re going to restructure our economies to eventually spend trillions implementing them, is already baked into the need to start moving towards zero emissions immediately.
Charles,
As requested above by Murph, please
a) Explain exactly how hotter times have been cooled down – what is the exact mechanism? Not: … and then there was a dimmer sun in those times, I mean the model has to come out that way, and then (*rapidly waves hands to get through the next steps*) and … then some other stuff … and the dim sum didn’t prevent the warmup in the first place because … just trust me, it didn’t.
b) Explain how much higher levels of CO2 were reduced. What is the exact mechanism? Please break it down so that a person reasonably versed in science can follow it.
Please don’t provide links that are not on target. Please do not — after that condescending and arrogant post above — claim that you are not an expert. Please do not find an excuse if you can’t really cash the check that your mouth is writing. It is going to take a while (won’t be today or tomorrow), but your work is going to be checked!
JTV, Murph, Zunf2… There’s a common theme here but I can’t… quite… put my finger on it.
Honestly, it’s tiresome to see people who keep asking questions that have been answered and to which the answers are easy to find on one’s own.
This whole line of inquiry reminds me of the “gotcha’s” that creationists think they have on scientists.
JTV,
Are you arguing that global warming isn’t happening or that global warming isn’t being driven by anthropogenic CO2 (and methane) emissions? Or are you just hurling insults and demands? If you are arguing that global warming isn’t happening, why are you claiming that it’s going to be fixed by some new patent? Do you understand why you can’t coherently argue both that it isn’t happening and that someone has a fix for it?
If you are arguing that it isn’t happening, what are your arguments that it isn’t happening? Merely insulting me and Mandolin and Amp and demanding more and more explanations of various things is not an argument, it’s just being a tedious asshole. Make a coherent argument about global warming or go away.
Because detailed explanations make more sense when describing a specific thing, here’s an explanation for the late Ordovician climate change, when CO2 levels decreased and temperatures decreased and then eventually CO2 levels rose and temperatures increased: a peer reviewed journal article from 1999, with 200+ citations, a Skeptical Science summary, also another Skeptical Science summary about the end-Ordovician extinction which has more details on the carbon cycle.
It is basically what Amp said already: increased silicate rock weathering and increased plant biomass (this is the era of the evolution of land plants) decreased atmospheric CO2 and, combined with continent location and a dimmer sun, the decreased CO2 (still very high relative to the modern day) lead to ice sheet expansion across Gondwanaland (located at the south pole), which increased albedo (ice is white and shiny) and decreased temperature further, leading to a positive feedback loop of more ice sheet and lower temperature (and an ice age cycle controlled by the same “orbital wobbles” as controlled the modern ice age cycle). Eventually, ice sheets covered so much that they reduced rock weathering (because there was less exposed rock), which lead to a decrease of CO2 uptake in rock weathering, which lead to an accumulation of atmospheric CO2, which eventually overbalanced the high albedo and led to global warming again. It looks like there was also a massive volcanic eruption (a large igneous province) at the very end of the glaciation period, which released massive amounts of CO2 and may have been the actual final driver of the end of the glaciation period.
Solar brightness changes very slowly (and slowly increases). As Ampersand said, the dimmer sun explains why a higher CO2 level in the very distant past would produce a lower temperature than the same CO2 level in the current day (continent location and other factors held the same). Continent location changes very slowly (although much faster than solar brightness), but it can change the climate of the world substantially over tens to hundreds of millions of years. Orogeny (the formation of mountain ranges) can also change climate by changing atmospheric circulation patterns (this is argued to have happened with the Tibetan Plateau formation). CO2 levels change much faster, although it is easier to increase them very quickly (e.g. the start of the PETM or the Siberian Traps at the end-Permian or the end-Ordovician Suordakh LIP or the modern day) than it is to draw them down very quickly (weathering of massive volcanic eruptions (e.g. large igneous provinces) and orogeny seems to be about the fastest way to draw down CO2 in the paleo-climate, although massively increasing plant biomass is also a good technique, as is trapping massive quantities of biomass in sediment). Orogeny can actually change the climate in at least three ways: changes in atmospheric circulation, draw down of CO2 in weathering of newly exposed rock, and release of CO2 in metamorphosis of carbonate rocks.
To be clear, I am not an expert in any of what I’ve just described. The actual development of all of that knowledge took the careful, painstaking effort of experts many decades of work in each tiny component of that description, collecting and managing samples, developing laboratory analysis methods, developing numerical models, synthesizing data. Hundreds of people worked tirelessly for decades to develop that understanding, and that work is still ongoing. There’s lots that isn’t known and probably plenty of things we think we know will turn out to be mistaken, but this particular episode is just one of many that supports our broader understanding of how the climate works. I don’t work in paleo-climate or geology and I’m not one of the people doing this work. I have a negligible amount of formal training in paleoclimate (1 graduate course nearly 2 decades ago). I am, however, capable of reading their work and understanding what they are saying. So are you. So is Ampersand. You can insult our qualifications all you please, and you can cavil at my understanding of any part of that, but that doesn’t change the actual scientific knowledge.
If you have arguments against the scientific knowledge, make them, but you, unlike Murph or lurker23, don’t really have the right to be asking basic questions about any of this anymore. You’ve claimed to have enough knowledge to be able to judge my answers, so you can’t claim to be puzzled about the basic science. You can go look it up for yourself.
Thank you for your response, Charles.
Regarding the Ordovician period, the very first paragraph in your first link to Skeptical Science is deceptive (unfairly slanted towards what they are trying to prove), so I have a rough time slogging through the rest of it. I can’t catch every deceptive statement, and I don’t like reading information that is intentionally biased towards a certain viewpoint.
They write: “Older scientific papers inferred very high CO2 levels in the Ordovician, generating a paradox of a cold climate during a time of high greenhouse gas levels. But recent work …”.
https://skepticalscience.com/CO2-was-higher-in-late-Ordovician.htm
The problem here is that it is not just “older scientific papers”, but instead a lot of new papers as well. They are making it look like an issue that is still being debated has already been settled in their favor. Here is one of many papers, as an example, that is from November of 2014:
https://www.sciencedirect.com/science/article/pii/S0031018214001710
One of the major points: Glaciation began either prior to the Katian or during the Hirnantian.
Beginning of the abstract: The major glaciation at the end of the Ordovician is associated with the 2nd largest mass extinction event of the Phanerozoic. Growth of Late Ordovician ice sheets requires a dramatic cooling from the ‘greenhouse’ conditions that prevailed for most of the Ordovician, but when and how fast this cooling occurred is controversial. […]
The next issue is that you provided these links in answer to my questions about (1) what reduced the temperature of hotter periods and (2) what reduced the CO2 in periods of high CO2 content. The links you provided are, however, aimed at the question of linking the level of CO2 with the level of global temperature. They are trying to prove that CO2 is the “principle control knob” on climates (as they put it).
Just as a side note, I am not arguing and have never tried to argue any link or lack thereof between temperature and CO2 here. It is also interesting that the website Skeptical Science argues in other places that CO2 is NOT the principle control knob, that there were other major factors driving climage change, in other places in answer to Denialists, for instance here:
https://www.skepticalscience.com/co2-higher-in-past-intermediate.htm
Both arguments seem to be necessary to their world view, and they seem to reconcile it by saying that other major factors also drove global warming episodes in the past (to answer questions about times when CO2 clearly was not linked to temperature), but this time (today) it’s pretty much just CO2 driving it.
Anyway, just to be clear, here is what I understand your answers to be with regard to my two questions. I first want to be clear about what you are saying, and please let me know if I am putting words in your mouth or framing your statements in a misleading way:
Regarding the mechanism that reduces temperature:
Ice sheet expansion, which decreases albedo (ice is white and shiny), leading to a feedback loop which decreases temperature further, orbital wobbles. The dimmer sun furthers the decrease.
Regarding the mechanism that reduces CO2:
Silicate rock weathering and increased plant biomass; at other times, weathering of massive volcanic eruptions (e.g. large igneous provinces) and orogeny; trapping massive quantities of biomass in sediment.
For clarity – and to anticipate a negative response – the paper I linked to at Sciencedirect (Journal: Paleogeography, Paleoclimatology, Paleoecology) studies the onset of the late Ordovician ice age and discusses a CO2 level of around 11 times higher than the present-day level (4500 ppm compared to around 400 ppm today).
I didn’t really make that clear.
CO2 was linked to temperature back then. The high levels of CO2 in the atmosphere made the planet much warmer than it would have been otherwise.
Also, it’s not that those “other major factors” like the sun’s luminescence or continental drift, aren’t part of the system today. Of course they are. No one denies that, that I know of.
It’s that, in the time scale we’re mostly interested in (i.e., the coming decades), we have no reason to expect that either of those inputs to the system will significantly change. They change over the course of hundreds of millions of years, but changes that occur over the course of just one century are going to be too small to drive any major changes. But that’s not the case for CO2.
Do you doubt this is so? If so, why?
Think of it like multiple control knobs, such as you’d see on an old-fashioned stereo. The knobs for “sun” and “continental drift” are there, and they have big effects – but they are very stiff and can only be turned very very very very slowly. In contrast, the CO2 knob, which also has big effects, can be turned relatively rapidly.
But what is your opinion on this question?
With all due respect, I wonder if you’re protecting your own views from critical questioning, and yourself from having to actually make arguments, by setting yourself up as a “skeptical questioner,” rather than admitting what your views are. It feels like you’re not participating in this conversation in an equitable manner.
I think the co2 levels being high in the Jurassic is part of the point. If I remember the explanations of my husband (and his silly humanities masters of science in geology) part of the issue is that a lot of that co2 was sequestered. We are, in burning fossil fuels, un-sequestering it, which drives the climate back toward those earlier conditions.
Which, to be clear, were good for a lot of critters. But when we talk about that, we’re talking about prevailing conditions over millions of years, not local level crises. We don’t really worry about transitional periods killing thousands or millions of a population that recovers on the species or genus or sometimes even higher level category 70 million years ago. The question of whether any apes or even primates will survive in a million years, with the assumption that if they do, our evolutionary branch has won this round – that’s not the question we’re dealing with, The deaths of millions of humans are of immediate concern.
I think I’m setting myself up as the “skeptical questioner” because that’s exactly what I am, and I think I’m approaching you as the “100% believer” because that’s exactly what you’ve said that you are.
No you’re not. Your questioning is completely one-sided; you haven’t asked any skeptical questions of Erin, or of JTV. You’re acting like a partisan who is interested in trying to debunk the ones you disagree with, not like a neutral party who is approaching both positions evenly.
I don’t think I have said that. Here’s what I said to Erin a bit over a week ago:
In the face of a great deal of very strong evidence, and a near-consensus among scientists who are expert in this area, I think that’s a reasonable position to hold.
Murph,
I’ve read through multiple extremely biased denialist articles in the last week or so for these discussion. If you aren’t willing to read well sourced summary articles because you think that the opening line (which is always going to be an extreme summary) is biased, then we really aren’t going to be able to have a discussion. That’s okay, because it looks like your recent argument is just a case of googling “Ordovician CO2 levels” and regurgitating the lies from the first denialist blog that pops up, so I think we are done anyway.
Googling “Ordovician CO2 levels” turns up a link to the article that you presented as proof of something- on a denialist blog. “4500 ppm compared to around 400 ppm today” is a summary of what the denialist blog says, not a summary of what the research paper says. The research paper you linked is about temperatures inferred from conodont fossil δ18O, not about CO2 levels. The number 4500 does not appear in the paper you linked to, and the word “CO2” appears only once in the introduction (talking about evidence of dropping CO2 levels in the Katian) and twice in the titles in the references for that sentence in the introduction. This paper says exactly nothing about CO2 levels in the late Ordovician during the period of glaciation, and can in no way be read as a rebuttal of the claim “Older scientific papers inferred very high CO2 levels in the Ordovician, generating a paradox of a cold climate during a time of high greenhouse gas levels.”
It looks to me like you googled “Ordovician CO2 levels” and blindly accepted a denialist blog post that misrepresented the contents of this paper, without bothering to even understand the abstract of the actual paper.
Actually reading the paper, the conclusion that the Katian had a relatively stable temperature and did not support extensive glaciation is consistent with the results highlighted in the Skeptical Science article that I linked and that you were trying to argue against. Young et al (2009) “A major drop in seawater 87Sr/86Sr during the Middle Ordovician (Darriwilian): Links to volcanism and climate?”, which the Skeptical Science article I linked to cites and relies on, describes a sudden draw-down of atmospheric CO2 at the very end of the Katian: “A close balance between volcanic outgassing and CO2 consumption from weathering produced steady pCO2 levels and climate through the middle Katian, consistent with recent Ordovician paleotemperature estimates. In the late Katian, outgassing was reduced while volcanic weathering continued, and resulted in a cooling episode leading into the well-known end-Ordovician glaciation.” The research article that you linked to as though it were a disproof of the Skeptical Science article shows steady temperatures during the Katian, (a 2018 paper by the same author shows no cooling prior to the Katian). That leaves the end of the Katian as the period when sudden cooling happened, coinciding with the rapid draw-down of CO2, consistent with Young.
We are now deep into the weeds of a still-evolving area of paleo-climate study, well outside either of our areas of knowledge (although well within Mandolin’s humanities-type geologist husband’s area of knowledge), so I think the important take-away from this is that your attempt to make an excuse for not being able to argue with that skeptical science article was a bitter failure of dishonest linking and summarizing.
Amp already answered your other points, in which you claim that the articles I linked to didn’t answer your questions “about (1) what reduced the temperature of hotter periods and (2) what reduced the CO2 in periods of high CO2 content.”