I know nothing about this topic, but I can caution to point out that Scientific Reports is the lowest rung of the Nature journal heirarchy. When I published there, I was very unimpressed with the quality of the refereeing and editing. Certainly doesn't mean the work is wrong, but laymen shouldn't interpret this as having the same sort of seal of approval as a normal Nature article. In my field (physics), Scientific Reports is held in similar esteem to a run-of-the-mill specialized journal, with the added worry that the editors are not sufficiently specialized to give the paper a hard look.
Having reviewed several papers for Scientific Reports in the past year, it was very similar to my experience reviewing for PLoS One. You are mandated not to factor in the significance of the work and only to critique the methodology and conclusions [1]. My experience reading articles there ranges from complete junk to papers that probably just missed the mark of getting into Nature proper.
Articles should make it more clear the distinction between Nature Publishing Group, Nature (journal), and Scientific Reports (open access journal). Confusion then propagates to the headlines of the articles when posted to content aggregators, take /r/science and it's related subreddits for example.
Here, it is hard to see how the potential significance of the work would be in question if the methodology and conclusions are reasonably sound as publication implies based on your comment.
I've published in Nature, Nature Communications, Nature Materials, Scientific Reports, etc. also in physics. Perhaps my impression is wrong, but Scientific Reports does have editors in different subfields and I didn't find the refereeing level to be that different from a more specialized journal such as Physical Review Letters or Physical Review B. The main criteria is that the result simply has to be technically correct as compared to "impactful". I think that there's definitely a reason to have a peer reviewed place to publish articles about findings that are correct, but not as exciting as we might have hoped. I think of it as community service...
One other thought comes to mind--the submission pattern of different subfields of science vary tremendously. There are also questions of expediency--for example, perhaps a student was graduating and they decided that the work would be published quickly in scientific reports, or perhaps another group was rumored to be publishing soon. It's impossible to say. If it were my field, I would just read the paper myself to see if it were technically sound instead of stressing too much about the fact that it's a scientific report. If it wasn't my field, I would check to see how cited it was in the future...
TLDR: Global warming causes a weakened jet stream, which results in less movement of weather patterns. Less movement makes a normal event 'extreme' by turn rains into floods and droughts. Still highly contested.
Personally, I think it might just be confirmation bias, as the definition of 'flood' changes a lot due to urban landscape and population density.
Interestingly, flooding is made worse by low density housing, like suburbs.
Forests, meadows, wetlands, they all act like sponges. They soak up recent rainfall and release it slowly, or just keep it. Cut that down, replace it with suburbia- concrete roads, short-grass lawns, nothing that holds much water for long but instead does it's best to get it into a drain and then a river system immediately.
Instead of a continuous flow that varies mildly, it's all or nothing. Bone dry, or biblical.
Most cities have realized these problems now, but have decades of poorly-thought-out development already in place.
Grass, as in lawns are a little bit different than wild fields. Most people design good drainage into their lawns so water doesn't pool and flows off quickly. Drainage is key to permeability, the longer water stays on soil, the more time it has to absorb into the soil. If it flows of quickly it will never reach full saturation.
After it permeates, then what? The water still has to go somewhere, and usually it's into nearby ditches (and then streams, and then rivers). As well, with any larger rainfall the local water table below the grass will fill up quickly- now the water is running on the surface.
Permeation is definitely good, but having more stops before it gets there is important to prevent floods.
(To be clear, I'm not expert on this at all. But I did marry one, and you sort of absorb a lot just from conversations over dinner).
they have no idea how the mechanism work, no model actually predicted it until it was discovered and added as a factor to the models themselves etc. etc.
It makes me think of the red spot on Jupiter. I remember a few years back a hurricane parked itself off of the Eastern US coast and stayed there for a couple of days. It was really weird, but it made me wonder then if there was some sort of stable solution to the equations of meteorology.
I have a question for the anthropogenic climate change doubters and deniers out there.
You say either that it is certain that human activity is not having a significant influence on the climate, or it is not certain whether or not it is.
My question is, it there any sort of scientific evidence that might be discovered in the future that would lead you to change your mind, and if so what would it be? Or is you view simply fixed for now and the future?
For most lukewarmists it is certain that humans (GHG emissions) are causing the global temperature to increase. But how much? About +0.5C since pre-industrial times.
Everybody also understands there's some natural variation, year-to-year noise which is 20x greater than the human caused warming signal. The trend over the past century is +1.0C / century. Or +0.2C / decade in the second half.
So lukewarmists believe humans are responsible for about half of the observed warming this century (0.5 out of 1.0), the other half is noise which will cancel out in the long run. That implies the projection for future warming is small.
The alarmist position is the opposite: believing that the noise was probably saving us from more warming, and that other mechanisms have acted to keep the observed warming down. In this view, humans are maybe responsible for over a 100% of the warming. This implies that the noise which has kept things manageable will eventually cancel out and we'll see a sharp increase in the rate of warming in the next two decades.
So yes, I think skeptics, lukewarmists, and alarmists are all interested in GMT through 2030 to get a better idea for how much warming we'll get this century.
>I think skeptics, lukewarmists, and alarmists are all interested in GMT through 2030 to get a better idea for how much warming we'll get this century.
So in term of the question I asked, you are saying that skeptics and lukewarmists would change their minds if GMT went up significantly more than their present views predict? And is this something they explicitly state, and all of them?
Also, I was directing my question to deniers and skeptics, so let me ask what is your position.
> you are saying that skeptics and lukewarmists would change their minds if GMT went up significantly more than their present views predict?
Yes, absolutely.
One thing which makes this seemingly completely empirical topic difficult though is the ~20x noise-to-signal ratio and the "red noise" inherent in the process. This means end points for the analysis make a huge difference. Both skeptics and alarmists will cherry-pick when they can, and will reflexively dismiss each others trend lines as cherry picked.
My view is the "two sides" act as the prosecution and defense in an adversarial courtroom. Neither should be expected to raise evidence or lines of reasoning which detract from their own agenda. And both will constantly try to get the other side's evidence thrown out, even if they know it would get the general public closer to the truth.
Thank you for your answer. However, I think that a large proportion of skeptics and deniers would still not be persuaded if GMT went up significantly. I say that because it seems the question is all tied in with political philosophy and often religion for most of them. You seem to be more epistemologically neutral.
I am not a "denier", but I do struggle with the evidence I have read as most of it has too much subjectivity or is based on meta studies where all underlying papers are highly subjective.
What is missing from the debate is 2-3 papers that are agreed on to be the clearest evidence that temperatures are changing due to human inputs.
Calling people 'deniers' is an ad hominen attack that doesn't prove anything, and most importantly doesn't help change people's minds.
>I am not a "denier", but I do struggle with the evidence I have read as most of it has too much subjectivity or is based on meta studies where all underlying papers are highly subjective.
So you would be persuaded if you thought the evidence was objective, not subjective. What are some criteria you use for determining if evidence is subjective or objective?
I am open to evidence that clearly shows that climate change is in part or completely caused by humans. Subjectivity would be one measure that I would apply.
I think we are using the term "subjective" differently. In your original comment, I thought you were using the term to indicate biased thinking. Now you seem to be meaning people's direct experience of the temperature. Or am I misunderstanding you?
Basically, you are commenting in circles. I am looking for, no, pleading with you to present... is a clear and compelling case that global warming is at least partially caused by humans. When you or anyone else presents that evidence, I and others will apply various techniques to determine how credible that evidence is. One of those techniques I will apply is to examine subjectivity vs objectivity.
What I am asking you to do is clarify what you mean by the terms "subjectivity" and "objectivity". I am asking that because it is common for people to differ as to whether a given claim is objective or subjective, and so I would like to know how you yourself decide.
Yes, what is obviously subjective to me, may be objevtive to you. We wont know unless we look at the evidence and debate it. Why dont you start by presenting some. I have looked and looked, but I am failing to draw causality
> I am looking for, no, pleading with you to present... is a clear and compelling case that global warming is at least partially caused by humans
If you think that in 2017 there is no clear and compelling case that global warming is at least partially caused by humans I think you won't accept any fact about it
That is what everyone says, but no one actually presents the paper or research that convinced them. I would think that if I held a deep conviction about something I would know why I held that belief. Unless I just decided that all my friends and TV people said something is true so it must be. That would be very alarming though...
How is calling someone who denies something a 'denier' an attack? I am a denier of prayer healing, chemtrails and the illuminati, to name a few. You can call me that all day, because it's true.
> Calling people 'deniers' is an ad hominen attack that doesn't prove anything, and most importantly doesn't help change people's minds.
This is true, but the people who are, in fact, deniers likely won't change their minds anyway and likely will not be alive long enough to see any undeniable evidence that could.
It's the same thing with discussing religion, I learned long ago to keep my mouth shut about it when talking to anyone who didn't express even a touch of an open mind about it.
I agree that the magnitude of the effect has not been demonstrably measured by anyone yet, but I don't see that as any reason to not take action to at least try to reduce whatever damage we might have done, are currently doing, and might do in the future.
There are major costs associated with cutting carbon emmissions before we have better technology. That is why people are questioning the 'science' of global warming. If we as a species are wrong about global warming in either direction, that is a big problem.
>There are major costs associated with cutting carbon emmissions before we have better technology.
But the technology has been rapidly getting more economical, and in some ways is now actually cheaper than fossil fuels (which also has many negative externalities of its own). And this has been happening only because there has been an enormous investment in renewable energy. The idea that the scientists all on their own will work for decades and come up with fully-ready technologies that then will be put into full production is just not how these things actually work.
No it does not. For a supposed MIT grad with a PhD I would expect excellent reading comprehension and the ability to understand scientific fields even when outside of your main one. Given your comments and misunderstandings here and elsewhere I am inclined to think you are not. Read the IPCC reports, if you don't have time, look at the summary for policy makers, particularly the physical science basis.
Do you understand the difference between average and 15-40%? How about the difference between average and median, non-normal distributions, etc.?
There's no changing of definitions from anyone except yourself in your misleading "quote".
>Calling people 'deniers' is an ad hominen attack that doesn't prove anything, and most importantly doesn't help change people's minds.
There are many people who openly state that the climate is not changing. It is objectively correct to use the term "denial" to describe their position.
However, you say we should not use this term, and don't propose any alternative labels, so in effect you are saying we should not talk about them at all. I think that is a very bad idea.
As far as changing people's minds, I was asking what would do that.
The problem with "climate science" is that so many things about it set off my internal BS detector.
But on specifics, it would be good to get a clear answer to the question - how come CO2 concentration was much higher in several past periods and it didn't turn the Earth into a desert?
>But on specifics, it would be good to get a clear answer to the question - how come CO2 concentration was much higher in several past periods and it didn't turn the Earth into a desert?
So are you saying that if you got a persuasive answer to that question, you would then be persuaded that human activity is causing global warming, at least to a considerable degree?
If there is not a good answer to that question, then I would reject the hypothesis outright. If there is a good answer, then I would accept it as a working hypothesis, unless any other screaming contradictions come up.
I would also find it persuasive to see people with skin-in-the-game make informed decisions. For instance, selling off desirable waterfront properties because they believe rising sea levels will make them worthless within a century.
But let's say 10 or 20 or 30 years from now, we have not observed any additional warming or maybe we've even had cooling. I would not be surprised. Whereas I imagine there would be a lot of people walking around thinking "How could 97% of scientists have been so wrong? How could so much well funded research produce the wrong conclusion?" They would struggle to integrate it into their worldview. (although I guess they would probably just say it's a temporary pause or something)
> If there is not a good answer to that question, then I would reject the hypothesis outright. If there is a good answer, then I would accept it as a working hypothesis, unless any other screaming contradictions come up.
Why should I accept any hypothesis that hasn't be proven either by controlled experiment or logical/mathematical deduction? The only appropriate stance in such situations is "I currently think this hypothesis is likely/unlikely to be true" and act accordingly (in a risk-adjusted way) but keep an open mind.
I think it would be interesting to turn the question back on you: what evidence, if any, would convince you that the broad scientific community has been seriously wrong about AGW and that we are not facing any real crisis?
> Why should I accept any hypothesis that hasn't be proven either by controlled experiment or logical/mathematical deduction?
The problem is that it has been proven but you don't accept the data
> I think it would be interesting to turn the question back on you: what evidence, if any, would convince you that the broad scientific community has been seriously wrong about AGW and that we are not facing any real crisis?
A compelling theory that can de3al with the actual data.
Well I guess we just have different standards of what makes something proven. To me there is hierarchy
1. Mathematical or logical proof
2. Proof by controlled, reproducible experiment
3. Proof by predictions bourne out reliably by observations
We certainly don't have the first two here, and for the third, given the time frames, we find that predictions (from computer models) from the past have been wrong compared to realised events. But I suppose if backfitting a model is proof enough for you then you already have all you need.
Two hours after posting my original question, I am realizing that some skeptics and deniers might be persuaded by additional evidence, but others wouldn't. A next question then would be how many in the US are persuadable and how many not. I am pretty sure most are not, but it would be good to have some survey data.
I am also struck that most of the skeptics and deniers either didn't answer the question as to whether they they could be persuaded, or at least implied they could, but didn't say what specific sort of evidence it would take.
First things first - I would not call me a denier, but I would call me understander.
An outcome from what I have read somewhere was that, if Sun increased its output by 1% (and kept it so for some years) it would cause equivalent warming to the one observed now. As far as I can say, Sun's activity was never constant. There may be other factors as well.
On few occassions I showed this page to believers: https://en.wikipedia.org/wiki/Milankovitch_cycles - I do not remember getting any answer. The question was simple: what caused previous global warmings? What made the last glaciation melt down? I have searched for Milankovitch on HN and this was posted few times, but always zero comments from what I can see.
So in terms of my question, are you saying that if you were presented with persuasive evidence that it is not the case that the global warming we observe is being caused by increasing solar radiation, would you then be persuaded it is instead being caused at least to a considerable degree by human activity?
Solar radiation, changes in Earth's orbit (it has been proved to be chaotic, longterm, AFAIK), microvawe from space hitting steam in atmosphere, volcanic production. There are few things that come to my head and might be connected to the problem. Some of this may sound as fringe. Nevertheless I would like to see credible debunking, using data and logic. May include calculus. If I see worth, I will relearn calculus. Heck, it may include whatever that will make me want to think about it - models, tables, photos.
Given the gravity of the problem and weight on future if there is miscalculation, I claim this should be taken out of politicians' hands. Wikipedia style.
The hockeystick scandal did not help, either.
And last but not least: what made the last glaciation melt and what caused it in first place? Model, please. Something I can compile on my computer. Twenty five years ago, maybe twenty, it would have easily placed itself among first ten fastest supercomputers (if I am correct). I am sure this machine can handle some computation. Even if not, give me a source code and let me worry how to run it.
EDIT: Ok, I would prefer a bunch of equation, differential too, rather than source code.
EDIT2: As of "being caused at least to a considerable degree by human activity", I am already rather certain that humans did their best to be part of the problem. The question I am trying to answer is "to what degree", not "if".
I would say I 100 percent know people change the climate. How much I do not know.
I have yet to see any scientific proof as to what percentage of change will be man made, or what degree the earth will change without human intervention. I dont think of myself as a denier but I do think of myself as someone who likes facts. In the research I have done when I have dug deeper it turns up a lot of assumptions\models. I think the science has to develope more to answer those type of questions accurately. I am not jumping to a conclusion of severity, I just want more facts so the correct action can be taken.
> I just want more facts so the correct action can be taken.
So you do think your mind could be persuaded by more scientific evidence, but you don't state specifically what sort of evidence it would take to do it.
>I would say I 100 percent know people change the climate.
No, there are lots of people who deny the climate is changing and that it is due at least in part to humans. They argue for instance, that the temperature data is inaccurate, or that any temperature rise we have seen recently is just random, or that it is systematic but due to increased solar radiation. I am rather surprised you aren't aware of these views.
Thinking some more, I am realizing that, as someone who believes in anthropogenic climate change, I ought to be open to the possibility that in the future further evidence will disprove it. That said, at present that seems to me pretty unlikely.
It is simple physics as to how CO2 works as a greenhouse gas. Seeing the clear trend of increasing CO2 in the atmosphere makes warming sort of obvious (at least to me). All of the complex second order effects (how much warming, how climate and weather patterns will react, and so on) are much more complicated and therefore less clear. Nevertheless, we are having a strong clear effect on the atmosphere which is going to warm the planet. The rest is details (though those details are getting a lot scarier, recently).
Much as I like Randall Munroe and xkcd, I don't see any sources cited in that comic.
I don't know that we know, precisely, how fucked we are yet, but I do think it's clear that humans are having an effect, and we know very convincing reasons for why we're having an effect, so we should work to reduce that effect regardless of whether we're fucked in 100 years if we continue this way, or if it will take 1000.
I see several things about the climate science that can be substantially improved.
* general discourse. Whenever someone raises some objection, the response is not a thoughtful argument, but many times a quick dismissal. you are certainly not one to do that, it is much appreciated
* unfalsifiability. scientific theories should be falsifiable. anything else is religion or politics. For example, what happens if there is a large volcano, or something like Saddam burning thousands of oil wells in Kuwait. I read somewhere that some climate models did check their predictions against the actual outcomes, and this is good. More evidence of this type would be great.
* model and data validation, audit and oversight. I am a quant working with both data and models in finance. I know about model uncertainty, and how messy is real world data. The regulators demand a lot of model testing, documentation, validation, ongoing monitoring, and audit. Our bible is the supervisory letter SR 11-7. Banks are investing billions in this and regulators hired hundreds of people to beef up their oversight. I don't see a similar scrutiny over the climate models that arguably are more important for the humanity
* all results in climate science can be spun to align to the climate change thesis. If there is a large uncertainty about the results, one picks the worse outcome and the result is presented as "new research show that the [melting of Antarctica, let's say] may be happening much faster than previously thought". Well, the same research show that the X thing may be also happening much slower, but who cares about that? If something completely new comes up (e.g. number of trees in the Amazon basin being off by a factor of 10), then more funding is needed.
* the 97% or so consensus of the climate scientists. My perception is that most of them know their own piece, and they are scrupulous, but can't conclude from their area of research one way or another about the whole global warming. They don't contradict it either, so if asked they say that global warming is most likely real. But that's not really a strong consensus, it's a polite agreement to not disagree. Here's a recent example on Hacker News: and antarctic ice researcher did an AMA on HN when his research regarding some Larsen C breakage made waves in the media [1]. The media spin was obviously that the world is getting warmer, and this is new evidence to support that. When someone on HN asked what we can do to stop further ice breaks, his answer was this: "Nothing! This is a completely natural process - ice builds up over time in the shelf and it has to be lost somehow. The calving of the iceberg is, in itself, not a result of human activity. If you mean more broadly how can we help prevent the loss of ice from Antarctica, then I'm not a climate policy expert". This gentleman is clearly a climate scientist, but he does not consider himself a "climate policy expert"
* Freeman Dyson [2] judges the climate models as having too much uncertainty: "The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields and farms and forests. They do not begin to describe the real world we live in ..."
By the way, I'm not a shill of the oil/coal/car industry. I do have a STEM PhD from MIT, and I can continue with more scientific arguments, but this message is getting already too long. I'm using a throwaway account.
I think you need to understand magnitudes: "For example, what happens if there is a large volcano, or something like Saddam burning thousands of oil wells in Kuwait. I read somewhere that some climate models did check their predictions against the actual outcomes, and this is good. More evidence of this type would be great."
and to my point from your other comment, this is from the link above: . Within a thousand years, the remaining atmospheric fraction of the CO2 emissions (see Section 6.3.2.4) is between 15 and 40%, depending on the amount of carbon released (Archer et al., 2009b).
I'm not sure why you rush to dimiss me like that. The question was "what would make you believe that AGW is real", and I mentioned that the climate models should be falsifiable. We know climate models cannot predict the weather beyond 2 weeks or so, but climate scientists claim that this is not their point. Fine, it's not their point. Then how do I know that this black box is correct, besides peer review? A model should state: X should happen (where X was not used in the calibration). Until yesterday I knew of only 2 such predictions: a periodic climatic phenomena similar to El Nino [1] (where the result is mixed) and the global temperature changes following the Pinatubo eruption [2] (where the result looks promising).
I didn't read your link where you say the models are performing very well, but I'll do it. Thanks.
Elsewhere in this thread, you resort to a bit of lower argumentation tactics ("supposed MIT PhD"). May I suggest you read Paul Graham's essey on desagreements [3] ? In return, here's a bit of mea culpa for my facile attack that the quoted very long life of the CO2 is only the result of a change of definition: while technically I was right, the definition change is one in good faith, and my critique was not.
"I'm not sure why you rush to dimiss me like that." Perhaps you should re-read how you dismissed what I put forward and you will understand the favor I returned with supporting evidence and perhaps too much snark.
I'd be interested to know what you're reading that brought you these arguments as they seem to be targeting them. So it is evident that they are being passed around circles of skeptics (not saying deniers).
There's a big difference between a climate model and a weather model and I believe you're familiar with the differences between long term changes (climate) and short term ones (weather). Just like we can't predict the interaction of every atom in a balloon yet we can predict how they will act as a whole when inflating one.
"In return, here's a bit of mea culpa for my facile attack that the quoted very long life of the CO2 is only the result of a change of definition: while technically I was right, the definition change is one in good faith, and my critique was not."
Thanks, I guess....but you are not technically right. You completely altered the state of my argument. I wasn't talking about the average. 15-40% (depending on the IPCC emissions projection) of CO2 remains in the atmosphere for upwards of 1,000 years. If our projections of climate change are correct we're in very big trouble as we've already locked in a significant amount of warming.
Additionally, you should be looking at AR5's physical science basis files, not AR4's if you want to be following the state of the science 4+ years ago instead of 10+.
In this link, after a short introduction, we learn that there are about 750 GT of CO2 in the atmosphere, and about 200GT enter and leave the atmosphere each year, which is about 27%. CO2 molecules are indistinguishable from one another (leaving aside the trace amounts of molecules that contains isotopes different from C12 and O16). A molecule produced by human emissions does not look in any way different from another CO2 molecule. Moreover, in no time all the anthropogenic CO2 is equally mixed in the rest of the CO2 (by diffusion). Because of that the proportion of CO2 that stays in the atmosphere for a given time follows an exponential law with a decay coefficient of -log(1-0.27)=0.19 ( * ). So out of all the CO2 in the atmosphere at a given time, only 83% stays there for 1 year, only 15% for 10 (uninterrupted) years, and only 5.610^(-9) after 100 years. And this is true both for all the original CO2 as for the anthropogenic CO2.
Now, if you change the definition of what it means for CO2 to remain in the atmosphere, then you get the long life you mentioned, but you do need to change that definition.
And this has nothing to do with averages vs medians or percentiles or other statistical concepts (which by the way, I am very familiar with).
( ) I'm skipping another step there, how to go from indistinguishability of CO2 to the exponential law, but if you want me, I can fill that in too.
Anthropogenic CO2. I thought that was apparent. Naturally emitted CO2 emissions are relatively constant and balanced over the last several hundred years, anthropogenic CO2 is not. Therefore as we continue to produce excess CO2 which cannot be absorbed by the system it results in excess CO2 which is not removed for upwards of 1000 years. We're removing sequestered CO2 and putting it in the atmosphere. It's not that complex.
From the same article I posted and you referenced:
"Dissolution of CO2 into the oceans is fast but the problem is that the top of the ocean is “getting full” and the bottleneck is thus the transfer of carbon from surface waters to the deep ocean. This transfer largely occurs by the slow ocean basin circulation and turn over (*3). This turnover takes 500-1000ish years. Therefore a time scale for CO2 warming potential out as far as 500 years is entirely reasonable."
You stated:
"Because of that the proportion of CO2 that stays in the atmosphere for a given time follows an exponential law with a decay coefficient of -log(1-0.27)=0.19" this was not in the article. You're applying equations which are not appropriate to the system.
Within a thousand years, the remaining atmospheric fraction of the CO2 emissions (see Section 6.3.2.4) is between 15 and 40%, depending on the amount of carbon released (Archer et al., 2009b).
Again....I'd be interested to know what you're reading that brought you these arguments as they seem to be passed around circles of skeptics (not saying deniers).
> "You're applying equations which are not appropriate to the system."
Why are you saying this? Because it's not in the paper you linked? Are you sure that equation is not appropriate, and if so, because you know of an argument, or because you believe some expert?
On my side, I'm not reading things that circulate in some "circles". I'm just a guy who's curious about climate change, but who is not an expert. But I have a strong math and science background, and I can follow pretty much any scientific argument.
That being said, I'm faced with this conundrum: supposedly 97% of experts agree on a topic. The result of their agreement happens to be the result that brings in more funding for their research. There is an obvious conflict of interests. But this conflict in itself doesn't mean the consensus is wrong.
So, I'm trying to inform myself and reach a conclusion. I use both scientific reasoning and non-scientific heuristics.
Non-scientific heuristics are like this: Nate Silver (the guy behind the 538 blog) explains how he used statistics to get to the conclusion that climate change is real and is caused by the anthropogenic CO2. This sways me a bit towards believing the consensus. Freeman Dyson says the models fail to capture clouds. This sways me a bit in the opposite direction.
As for the scientific reasoning, it goes something like this. I get the general idea about CO2 absorbing the infrared radiation coming from the ground and therefore trapping some extra heat in the atmosphere. But CO2 is only 400 ppm, it's a very tiny part of the mass of the atmosphere. The youtube videos that you see with a bottle full of air and a bottle full of CO2 and how they heat up under a lamp are not very relevant. In the real world we are talking about an increase from 250 ppm to 400 ppm, not from 250 ppm to 100%. So the argument needs to be a bit more complex, and the IPCC report goes in more details. Following the details shows me they are thoughtful, and it's not junk science, so it swings me a bit towards the consensus.
But something is missing. Maybe you can fill it in, considering that you read a lot about these things. And it would honestly be appreciated (and by the way, you seem to be quite prejudiced against me, please give me a bit of benefit of the doubt).
Here's what's missing (imho). Bear with me, the story is a bit long. We are fortunate to live in a world with a lot of water. Water is special for a lot of reasons, but one absolutely remarkable property of water is that its specific heat exceeds by leaps and bounds the specific heat of any other substance that shows up in any abundance in our environment (e.g. at room temperature you need 4.2 Joules to warm up 1g of water by 1 deg Celsius, only 2.4 J for 1g of ethanol, and 1.0, 0.9 and 0.8 for air, O2 and CO2 respectively). But the truly astonishing number is the specific latent heat of vaporization for water, which is 2265 J/g. This exceeds any other specific latent heat for any other substance for any phase change by a very large amount (on a tangent note, this is what allows warm-bodied animals to keep their temperature constant, or put it another way, without this little curious property of water, humans would not exist).
There are about 750 GT of CO2 in the atmosphere (all gaseous) and about 13000 GT of water (both liquid and gas). Now the typical energy balance equation described in the IPCC report tells you how this water absorbs and re-emits radiation and in what spectrum and in what amount. But the missing piece is this: by far most of the radiation is absorbed and released by water upon the change of phase, i.e. when it evaporates from the oceans and then when it condenses in the clouds (before it falls downs as rains). When the water condenses in the clouds it must release that tremendous amount of energy I mentioned above (2.2 kJ per gram). It can do that in 2 ways: it heats the surrounding atmosphere (but that can't absorb much because of the other constants I mentioned, the 1.0 J/g/K for air, which is a puny number applied to a very rarefied substance) or it radiates. From the radiation, half points down, but half points up, towards space. To me this way of releasing energy in space should be by far and away the main way of the planet to get rid of extra heat.
Can you point me in the IPCC report where this heat enters in the heat balance of the atmosphere? I looked for it, and I didn't find it.
(PS I didn't read this thing anywhere, it's my own thinking)
I love how interested you are in this and your desire to work this out from first principles. I say the equation is not appropriate for the same reason we're having this discussion on the residence time of CO2, particularly anthropogenic. It doesn't account for multiple processes and time scales. The IPCC uses the Bern Model discussed here:
Frankly I don't care about the 97% agreement. I'm sure it is just as high if not higher in terms of biologists agreeing that evolution is occurring. It's a talking point to get people with no scientific training on board. Unfortunately it has the opposite result in many cases since it's a weak argument from authority.
Excellent point about water vapor particularly when it precipitates and release energy during the phase change. I'm on mobile so not as good at finding things, here's some information from AR4 with sources, AR5 may go into more detail:
9.5.4.2.1 Detection of external influence on precipitation
Mitchell et al. (1987) argue that global mean precipitation changes should be controlled primarily by the energy budget of the troposphere where the latent heat of condensation is balanced by radiative cooling. Warming the troposphere enhances the cooling rate, thereby increasing precipitation, but this may be partly offset by a decrease in the efficiency of radiative cooling due to an increase in atmospheric CO2 (Allen and Ingram, 2002; Yang et al., 2003; Lambert et al., 2004; Sugi and Yoshimura, 2004). This suggests that global mean precipitation should respond more to changes in shortwave forcing than CO2 forcing, since shortwave forcings, such as volcanic aerosol, alter the temperature of the troposphere without affecting the efficiency of radiative cooling. This is consistent with a simulated decrease in precipitation following large volcanic eruptions (Robock and Liu, 1994; Broccoli et al., 2003), and may explain why anthropogenic influence has not been detected in measurements of global land mean precipitation (Ziegler et al., 2003; Gillett et al., 2004b), although Lambert et al. (2004) urge caution in applying the energy budget argument to land-only data. Greenhouse-gas induced increases in global precipitation may have also been offset by decreases due to anthropogenic aerosols (Ramanathan et al., 2001).
Several studies have demonstrated that simulated land mean precipitation in climate model integrations including both natural and anthropogenic forcings is significantly correlated with that observed (Allen and Ingram, 2002; Gillett et al., 2004b; Lambert et al., 2004), thereby detecting external influence in observations of precipitation (see Section 8.3.1.2 for an evaluation of model-simulated precipitation). Lambert et al. (2005) examine precipitation changes in simulations of nine MMD 20C3M models including anthropogenic and natural forcing (Figure 9.18a), and find that the responses to combined anthropogenic and natural forcing simulated by five of the nine models are detectable in observed land mean precipitation (Figure 9.18a). Lambert et al. (2004) detect the response to shortwave forcing, but not longwave forcing, in land mean precipitation using HadCM3, and Gillett et al. (2004b) similarly detect the response to volcanic forcing using the PCM. Climate models appear to underestimate the variance of land mean precipitation compared to that observed (Gillett et al., 2004b; Lambert et al., 2004, 2005), but it is unclear whether this discrepancy results from an underestimated response to shortwave forcing (Gillett et al., 2004b), underestimated internal variability, errors in the observations, or a combination of these.
Thanks for the link, it's fascinating. I'll see if I can download some data and play with it to get a feel for it. As for the water vapor condensation, thanks for pointing me into the relevant part of the report, I'll take a closer look. At first sight, I like it that they paid attention to this issue, and I don't like that they didn't pay enough attention (a statement of the type "this may be offset by that" sounds a bit too cavalier to me). But it's a start. Back to the data and the transparency. This is really, really positive, it should go a long way towards assuaging the discomfort of climate skeptics (like me).
the short answer is "science," specifically "observation."
the long answer is that my skepticism comes from climate being a classic complexity issue where trying to isolate a single factor (carbon) as being the main forcing for climate change requires a lot of real evidence.
i'd turn the question back around on you by asking "why do you believe in CAGW?" when i asked myself that question (because i was like most people and believed the standard news reports before i tried to really understand it), i discovered two main pieces of observational data that were overwhelming for why the increased carbon is going to lead to run-away warming:
1. the correlation of atmospheric carbon and temperature in the geologic record (ice core samples and tree ring data). it's very clear looking at those records that atmospheric carbon and temperature are correlated. but, when i dug into it i found out that in the geologic record the temperature increase PRECEEDS atmospheric CO2 by hundreds of years. if we were going to infer causation by correlation, then it would have to be the other way around. so that strong piece of evidence turned out not to be actual evidence.
when i sought answers for this from the global warming alarmist scientists, what they had to say was "yes, it's true. what we know is that the temperature increases for some unknown reason, then carbon is released because of the temperature, which then causes the temperature to increase more and a positive feedback loop is created."
but, if this were really how it happened and co2 is the overwhelmingly main forcing for temperature increase, then why wasn't the planet already destroyed back when we had 10x+ the amount of carbon in the atmosphere than what we are doing today?
2. after #1 melted away, i realized that the strongest evidence for CAGW was rooted in the predictions of climate models. it wasn't being proven by geologic or current observations, so what do the models tell us?
well, the models are very interesting because they are mechanisms we use to try to understand a classic complexity problem. these are notoriously difficult problems to fully understand down to it's constituent components.
add on top of it the timeframes we are talking about with the models, and it becomes very difficult to understand it right now. the models predict noticeable temperature increase in the 100s of years timeframe, not in the decadal timeframe.
so to be able to actually observe the predictions of the models, we'd have to wait 100s of years.
so, i wondered if there were other things that the models predicted that were more in the annual/decadal timeframe that we could observe to be happening.
as it happens, the answer is yes. all models that predicted runaway warming due to the co2 greenhouse effect ALSO predicted a warming of the atmosphere at a greater rate than a warming of the surface. (which makes sense based on the theory)
so all we'd have to do, is show that the atmosphere is heating up at an accelerated rate than the surface, and that would be a significant data point.
but what we actually observe is the opposite. the surface temperature is increasing at a faster rate than the atmospheric temperature. so the observed data appears to be going against the theory.
now, to be clear, i don't disagree that the planet is warming. i'm just skeptical that an increase in co2 is the main culprit.
with that in mind, i'd love to hear other people's observational evidence that backs the theory up. that's what will convince me.
and to make it clear, what will not convince me are fear mongering about "what if the theory is right?!" or the quasi-religious appeals to authority by saying "all these smart people believe different than you."
i want predictions made by the theory that show observational corroboration (with, preferably, an elimination of other explanations for the outcome).
This is a thoughtfully written post, thank you for taking the time to put it together. As a software engineer, I'm not really qualified to have a complex, technical discussion on climate change. However, one point that you made, I can address...
> but, if this were really how it happened and co2 is the overwhelmingly main forcing for temperature increase, then why wasn't the planet already destroyed back when we had 10x+ the amount of carbon in the atmosphere than what we are doing today?
A sharp increase in CO2 is thought to be one of the precipitating factors in the Permian extinction, which wiped out >70% of land-dwelling vertebrates and >90% of all marine species. No credible person is saying the planet is threatened by climate change, they're saying humans are. This planet, and even life itself, will go on no matter what happens - cold comfort taken against the damage it could cause to our species.
thanks for your insight. i also am a software engineer, so maybe i'm not qualified to have a complex, technical discussion either. but, i do think that most issues can be summarized/presented in a way that makes the technical discussion available to anyone of reasonable intelligence. it just takes either a feynman-type or a collaborator with an einstein-type to be interested in doing it. (i, myself, learned quantum mechanics well enough to present on it because i had a professional interest in quantum computing).
as per the theory of co2 precipitating the Permian extinction, i am aware of some very recent research that makes the claim that the extinction entirely happened during an 80,000 year ice age on the border of the Permian and Triassic periods. (https://www.sciencedaily.com/releases/2017/03/170306091927.h...)
if the data are correct, it seems pretty convincing to me that it wasn't the warming that caused that extinction.
btw, your point about the planet not being destroyed is well taken. i guess what i'm trying to understand is how the positive feedback loop of temp->co2->temp is broken if trace amounts of co2 is such a massive forcing. when the earth had 4000+ ppm of co2 in the atmosphere, there had to be some other, much stronger, forcing to bring the temperature back down.
i don't propose a "main culprit" as i understand climate to be a classic complex system. i simply don't know what the main culprit is or even if there IS a main culprit.
i'm not yet convinced that the temperature increase that we've seen in the past 150 - 200 years is abnormal from a geologic timeframe. esp. considering the warming pause of the past ~20 years.
as far as the article you posted, i've read it before. it's fairly standard in that it adds another theory (southern warming -> release co2 -> increase northern warming) that, for me, would require more observable predictions to prove. that's not an easy task, but my scientific skepticism requires it.
maybe if we could see that effect happening in our modern temperature data? i'm just riffing here, but it seems like if that's the mechanism to explain the ~800 year lag where temperature increase preceeds co2 increase, then it should also be observable today.
That's not really a theory (southern warming -> release co2 -> increase northern warming), that is well-established physical and biological processes.
Why should there be a similar 800-year lag today? The past CO2 increases were due to natural processes whereby as the temperature increased more biological activity was occurring and thus emitting more CO2. The historical lag makes complete sense from that perspective.
Currently, were artificially adding sequestered CO2 (which is known to trap heat) to the atmosphere and the temperature is increasing, with a fairly strong correlation, as a result.
>now, to be clear, i don't disagree that the planet is warming. i'm just skeptical that an increase in co2 is the main culprit.
Do you have any alternative possible explanations for what is causing the temperature rise? And what do you think of the ones that have been proposed, like increased solar radiation?
i do not. as i pointed out, it's a classic complex mechanism that might not be able to be attributable to one single factor.
i guess i'm also not convinced that the warming of the past 150 - 200 years is out of the range of normal variation (esp. with the latest warming pause) when looking at geologic times. i know it's a difficult thing to prove since constructing geologic GLOBAL temperature is very difficult, but i just don't know.
it does seem like the increase of carbon in the atmosphere is abnormal, if not entirely unprecedented.
Let's just admit it: we have no clue about what's going to happen weather-wise.
A warmer planet will have a massive impact on seas, winds, and life, at all levels. Each effect may cause more effects or cancel other effects out. I don't think it's we'll ever be able to make an all-encompassing model that can assess that there will be more dramatic weather locally.
At this stage, all we can say is that the planet is globally getting warmer, and that it's likely to continue.
I'll admit you have no clue? It seems like there are some competing groups in climate science, but so far the trend of the warming, regional precipitation, jet stream changes, ocean ph changes, methane in warming tundra, the pattern of polar ice melt all seem to have been pretty well predicted years or decades ago by the most mainstream groups (that financially motivated groups have worked hard to undercut and delegitimize).
Yeah, I think there is a pronounce deficiency on accurate and appropriate communication on this topic on the part of media. The general pattern of "funded a group producing scientific-enough sounding disputing theories + some astroturf groups to loudly complain about media bias for not covering it" has devastatingly effective in my lifetime. A sad artifact of hiring for looks/presentation over intellect in many news outlets.
It's apparently an active area of research, so there are _some_ clues. More research will be done and then, hopefully, we will know a bit more. Just like in the 80s climate change itself was on shaky ground and now it is well researched and we know the facts.
Weather is very short term. Hard to predict more than 5 days in advance. There are a lot of factors that effect it, but within 3 or so days, the weather is pretty good.
Climate models are the long term. What climate scientists seem to do, is create the model, then test it against the last period of time where they have good data. (Given what we know about past climate, what would we predict for the last 5? years. since the last 5 years already happened, they can compare the model to reality). Obviously since we only have only one planet and a short time to test on this verification isn't perfect, but they have a lot of computing power and its the best we can do.
I agree with this. However, we can also say with regard to weather that change is bad. After all what little macro level predictability we have is key to agriculture, infrastructure etc..
Progress isn't liniar though, I mean, if you asked the people, who were responsible for cleaning out hundreds of thousand tonnes of horse shit out of London each year, if they would ever be obsolete a year before the car assembly line. They would probably have laughed at you.
"We don't know yet" is the whole point of science, and of research. Over the past 30-40 years progress in our understanding of this field has been rapid, and there's no reason to think that won't continue.
1. look at data
2. form hypothesis with associated way of testing it (demonstrating it false)
3. perform tests, see if hypothesis stands up
The argument I guess is whether in this example, the "finding evidence" stage would ever have ever shown the hypothesis wrong. I guess it would have, but if there's a criticism maybe a negative result wouldn't have gotten press?
Using the scientific method, you come up with a hypothesis, then you test that hypothesis. If the testing shows your hypothesis to be incorrect, you throw it out.
Ideas give you hints where to look for evidence. Ideas don't come from nothing of course, they come from first principles or from circumstantial evidence that you happened to observe, but in a large and chaotic system you need to know where to look (or in most systems, this is true for most of natural science).
I was more thinking, who writes a headline where an idea is suddenly sentient and goes out and finds evidence for itself? Oh, the same person who assures me how bewildering the synoptic-scale wave thing is, twice, and uses enough words doing it, that they could've just defined it.
There are hundreds of big changes like this, and likely many, many more. They must be considered together rather than independently before we can understand the true severity of this crisis.
Maybe this piece of evidence will be the one that finally convinces the governments of the world to take climate change seriously. And maybe I will wake up tomorrow with a third arm.
I hate when people call it Climate Change. Thats a phrase right wing think tanks cooked up to soften the blow of the sound of Global Warming.
No amount of evidence is going to convince Global Warming deniers. But those who deny but also suffer from the effects will be the first ones with their hands out asking the government for money to save to bail them out.
I'm glad the WashPo is writing these kinds of articles, but nothing is going to convince climate 'skeptics'. Stop wasting your time trying to reason with people who cannot be reasoned with.
> I hate when people call it Climate Change. Thats a phrase right wing think tanks cooked up to soften the blow of the sound of Global Warming.
I find this statement ironic, considering that most of my friends believe that "global warming" became "climate change" because the predictions of the former failed to materialize.
It's obvious you never even considered reading the article:
Barrett and Gast published a letter in Science in 1971 entitled simply 'Climate Change'. The journal 'Climatic Change' was created in 1977 (and is still published today). The IPCC was formed in 1988, and of course the 'CC' is 'climate change', not 'global warming'.
Lutz proposed this as a PR method during the Bush administration.
