waxliberty

Actually I typed faster than I reasoned on that last one (between flights) and made a muddied comment about ECS of 1 implying 1.1 warming which is nonsensical, the ECS figure is absolute degrees, my apologies. Overenthusiastic about injecting the physics logic behind the unmodified CO2 contribution to ground the conversation. Correcting the representative napkin math (taking out the 1.1) you get 1.74 and 5.22 warming by 2100, which doesn't change the commentary, but does provide the requisite opening to argue I don't know what I'm talking about.

*5*. Here you're misunderstanding what the numbers mean and comparing apples to oranges, although the confusion is understandable. ECS refers to "degrees warming per doubling of CO2". At ECS = 1 (no net feedback effects), warming would be about 1.1 deg C for a doubling of CO2. (For those interested in physics and math, this is a great site/web series that walks through the basic calculations of enhanced CO2 effect and derives the common 1.1 figure.) IPCC's RCP 8.5 (the highest emission scenario, where we just OK the pipelines and unleash the market to go after all remaining fossil fuel sources with enhanced technology throughout the century, essentially our current path) projects CO2 concentration reaching 936 ppm. Very rough math at ECS 1.5 temperatures would be 1.9 degrees warming above where we are today (one doubling and 16% of another) by 2100. This is absolutely considered very high impact / catastrophic warming. Roughly 3 degrees total warming in the modern industrial era since 1880, while not the ice age order of 5 degrees by 2100 we would be getting close and still warming. The Eemian (previous interglacial 120K years ago) was thought to be just a degree or two warmer, and sea level was about 4 to 6 meters higher. Do you have an idea what the order of economic cost is for that kind of sea level rise, the magnitude of human populations and cities impacted? We see significant acceleration of ice melt from the land already today, with the IPCC reporting a *5x* increase in measured melt: "The average rate of ice loss from the Antarctic ice sheet has likely increased from 30 [–37 to 97] Gt yr–1 over the period 1992–2001 to 147 [72 to 221] Gt yr–1 over the period 2002 to 2011" (though this is not high confidence/precision because the satellite gravimetric analysis is relatively immature – relevant papers for anyone interested here, here, here.) At the other end, ECS = 4.5, it's 5.7 degrees warming by 2100. This isn't "high impact", it's "sweet mother of God". It is literally, very probably, game over for human civilization as we know it, well underway by 2100. You are so comfortable with the 1.5 possibility these are the stakes you blithely let ride on your dice roll. And what are you gambling for? The IPCC impact report gives the best estimate of economic cost of mitigation is reducing the median annual growth of consumption over this century by 0.06%. It is a complete false economy to imagine this makes remote economic sense even in the 1.5 scenario. In fact it is so far from any form of rational cost/benefit analysis it defies description. In business, your colleagues would consider you not laughable but dangerously insane. Only because we are talking about the world (merely human suffering and economies) are you able to step back and apply an ideological filter, that says there are exceptional philosophical obstacles to taking any action like this, enabling you to back additional demands of "certainty" into the physical science on an a priori basis to satisfy your ideological preferences. Well it is academically interesting to watch you try to square this. You are simply in (textbook psychological) denial of what the mainstream consensus is saying. The NAS can state "climate change is one of the defining issues of our time" and you think that squares with your "cool it, it's no big deal let's see if we learn anything" approach. Let's select a more explicit statement, this time from the European Federation of Geologists: "The EFG subscribes to the major findings that climate change is happening, is predominantly caused by anthropogenic emissions of CO2, and poses a significant threat to human civilization." I wonder if I am reading concern into this, when none really exists? You really should spend some time with the actual impacts report, with articles like this and this. Oh, for crying out loud, you don't sound familiar with the topic. For sea ice (which is different from land ice), just compare the arctic/antarctic changes visually in animations like these. It's actually chilling to hear this sort of intense irrationality so calmly conveyed. I realize speaking bluntly about this sort of logic probably comes across (to you) as strident, alarmist, and “impolite”, but really the stakes are unbelievably high (both on the specific question of global warming, and the general question of the rejection of rational scientific epistemology in a world where it is increasingly not just a luxury but a survival requirement.) Your standards of epistemology massively overweight selective uncertainty (and paranoia) relative to the approach of rational, conservative scientific epistemology, one of the many reasons I think it is defensible to characterize the position as anti-science. It’s great you reject creationism, but I think you fail to see the similarity of the trap. One can easily reject much of modern scientific understanding of the planet – evolution, the age of the earth, understanding of cosmology etc. – by demanding “certainty” and “proof” in the way commonly done here, resisting mainstream understanding of the planet and history. Quote from another forum today: “Climate denial isn't really about intelligence, anyway. Being intelligent often just means that you can concoct more elaborate rationalizations as to why your preconceived notions are correct.”

Do you mean "why, just because the science points to us triggering a new 'hot age', different than what we've seen before, is anybody talking further about it?'

I'm sure you did, given how it was going for you.

I understand this all sounds good to you on a superficial level, but it's not defensible or actually well-formed. Despite the fact that you can't reproduce a globe in your lab, physical science lends itself quite well to reproducible validation. I'm well aware. It's something of an internet cliche – engineers animated by their ideological presumptions decide their engineering skill renders them an instant expert in any field of science they like, able to dismiss whole fields via ill-formed and strikingly shallow argument. I'm aware that you think those things are related or analogous.

"Past results do not guarantee future returns" – possibly more confusing than helpful. If you mean the "past is not the future", that's clear enough to not need to be stated. If you mean "the way the climate responded to a physical variable in the past is no guarantee how it will respond in the future" is more problematic; clearly it is believed that you can apply learning from how the system responded in physical situations in the past. But it is not a simple question of expecting the same end results or assuming situations are exactly analogous. The statement from "climate science is largely concerned with discerning trends" through "from this, future projections are made" may put too much emphasis on "discerning trends" in context. Something like: climate science is concerned with understanding the physical mechanisms of the climate – informed by studying the paleoclimate record, directly applying principles from physics, chemistry and thermodynamics, and from empirical observations – from this, future responses are projected.

I think my comparison here reads like it is stating more than intended – there can be shorter term ups and downs within the Holocene and the proxy data just doesn't have the resolution to capture, it wasn't necessarily so smooth. (Certainly see Younger Dryas etc. near the volatile beginning.) Sustained and global warming at such a rate would be unusual relative to the Holocene, and a ten year slowdown doesn't very detectably mess up the 'spike' or hockey blade effect underway.

This gets into philosophical questions of determinism not really central to the topic at hand. In terms of the potential for infinite precision – quantum mechanics says this is extremely non-trivial, to say the least. Weather is exceptionally difficult because it involves chaotic factors per chaos theory, which basically concerns the fact that underlying deterministic mechanisms do not guarantee that a system is predictable. Climate is hard to model because the earth is complicated. For predicting just its balance of heat energy specifically, you can make some set of assumptions on the major variables (solar, human, and so forth) and make some projections with some stated error bounds, in the same way you can conceptually make calculations about how long a pot of water is going to boil if you know key variables like the volume, the temperature of the heat, and so forth. The thermodynamic problem is not inherently chaotic, in the same way weather modeling is. The further out in the future the uncertainty increases because more and more dynamics may come into play that you didn't have the opportunity to study from where started. (However, paleoclimate data is a huge rich store of information that is continually being mined to try to answer questions about "what does the real climate do in response to conditions X, Y and Z".)

"fabrication of data where none exists" – no. It's calculating the best "average global surface temperature" possible, in this case applying data from satellites to improve the interpolation that is implicit in the entire enterprise. At the extreme this is just saying "if you can't actually measure every molecule's heat, you don't actually know what the 'average temperature is'." Who cares. Can you validate the statistical assumptions? Why, you can. You can apply the technique to areas where you have data coverage, temporarily withholding that data. Then you can compare the method to what you get from the direct thermometer coverage. That's what the paper is about – the validation of the technique and what it says when applied to the data gaps. For tracking global warming, the actual precise-to-n-digits temperature of the surface at a particular instant is not particularly critical to anything. We're tracking warming which means deltas and trends, so if you use a consistent measurement technique you expect to see trends you can meaningfully analyze over time. The heat swirls around the planet, and it's not reasonable to assume that a grid won't work because the cold air will always snake around the measurement points or some such. It's only a problem if you have a big gap in a geographically interesting region, like say the entire arctic. Tamino's post is just an exercise in separating "noise" you understand relative to a "signal" you are interested in, for whatever reason. It is completely straightforward. Let's take an example from software. Let's say you are tracking the availability of your servers and targeting a very high degree of uptime. You have active monitors (other servers) which ping your servers regularly to record their availability. This gives you some figure for their uptime – say 99.85%. (Which is deceptive – when the monitor wasn't pinging, we don't know whether the server was up, so we are essentially making up data where none exists!) Let's say you also have data that tells you when your monitors were down – i.e. the monitor service itself wasn't running, so it gives you some spurious false negatives during those periods. So to improve your measurement you remove the data from those time periods, which improves your uptime measurement to 99.97%... hold it right there! Cover the children's eyes, reprehensible data molestation. Highly irregular. Just delete any data you like, and think this is acceptable engineering? Yes, poisoned well, ad hominem etc. Realclimate was formed by 10 or so active publishing climate scientists, explicitly for the purpose of explaining the science to the public, and the material presented is meticulously sourced to published research. Contributors include Mann but also NASA's Gavin Schmidt, German oceanographer Stefan Rahmstorf, U.S. geophysicist Ray Pierrehumbert (as referenced above), and others. But yes, if we've got people believing one guy is a fraud, even if we don't have evidence of that, definitely best to try to tar as many scientists as possible...

:-) I am not aware of any research saying this is a compelling mitigation scenario, but happy to hear about it. Quick search got me some chemical used to spray for them is a GHG? and they're moving north, run!

For the record (just to clarify definitions), I would suggest something more along the lines of that offered in this useful here. The working groups and all IPCC stuff is categorized by the different RCP scenarios, which are based on different emission outcomes and "a model set-up that probabilistically takes into account the overall consensus understanding of climate sensitivity uncertainty". The scenarios with little mitigation (4.5 and above) all project significant impact. That's the mainstream view. 1.5 would be the ideal obviously, but it is unlikely (it is the extreme low end, many lines of evidence indicate it is implausible at best) and it still drives negative impact with unmitigated emissions. It is not rational to assume the extreme low end, it is a very common cognitive bias to think uncertainty can only break in your favor. You can justify it on the presumption that the IPCC is irresponsibly alarmist ("because everyone knows that"), but so far it has really been more the other way, as arguably the biggest IPCC model failure to date is ice melt, which proceeded much faster than predicted. Criticisms of the IPCC as overly conservative (responding to pressure) run pretty hot among climate scientists. Hansen and others lobbied for including higher ranges based on a variety of research, including the evidence of so-called slow feedbacks being not as slow as assumed. I just mention to underscore the dubiousness of assuming the low end is more probable. Your WUWT article doesn't quote from the Cato Institute, it's written by the Cato Institute (so, funded by Koch brothers and fossil fuels, sigh), and Knappenberger is somewhat infamous. I obviously would be happier with some scientific / reviewed source, as WUWT type hit pieces are legion, but let's not ad hominem *too* much, the general conclusion that "if" temperatures flatten or fail to warm models will be rejected is obviously not deeply objectionable. I would just watch the "if", especially with an El Nino brewing (which could fail to pan out, but if it doesn't we're highly likely to get our latest new record hottest year, maybe 2015.) I don't see an analysis of this newer post, but if you like the back and forth you can get the idea what some climate scientists think of Chip Knappenberger's analysis from Tamino's series of responses e.g. here, including his assessment that Knappenberger's attempt to reason from Tamino's own published paper is "some of the most ludicrous nonsense ever written" and general discussion of model performance, more here and here, somebody's snarky parody article here...

LOL. Well that's quite a sweeping rebuttal. You wrote "However, the implication that this means industrial emmissions have caused the Earth's temperature to rise by 1 degree Celsius, isn't even close to true. Clearly. Such an conclusion would rest on the obviously false assumption that normally, the lowest and highest temperature over 11,700 years is the same." I was simply stating that I couldn't make sense of what you are trying to communicate with that bit with the 11,700 years. (I suppose it is something along the lines of 'what baseline are you comparing to'. Yes, it is a reference to the Holocene timeframe.) Points for desperation though. (I'd say I'm a believer in science and scientific literacy more than an expert, but I appreciate the insults...)

"How come the scientists warning of much higher temperatures did not see all this coming?" Their models provide big error bounds for these things, so they "saw them coming". I think most scientists would agree they haven't done a great job communicating all this, but of course a highly motivated (and well funded) oppostion saturating media with counter-narratives to exploit confusion doesn't help matters. You do have to ask when you hear this line of argument – see all what coming, specifically? La Nina? I explained that it is not easily predicted, tied up in chaotic large scale weather. They can also easily go wrong because predictions have to model in some economics as well: human CO2 emission rates, Chinese industrial output of smog aerosols, etc., things not known to be trivial to predict but that don't reflect on core physical theory. Many of the common talking points about Hansen's or IPCC predictions "failing" goes after that class of error. The "hockey stick" is on the scale of the Holocene (Nicky's 11,700 years :-), so the "pause" is not really a detectable shift of a pixel on that chart, it would have to flatten out more and stay that way. In historical terms, even the "slow" pause period (say it is only 0.1deg C per decade; e.g. eyeballing UAH 1999 to 2013 looks like about 0.25 degree difference) would be extremely fast by Holocene standards, which doesn't look like it cooled a full degree in about 7,000 years of cooling. So what might look like uninteresting surface warming isn't obviously so; still spiking. (In truth, sampling a short period of time does not yield a statistically significant estimate of a trend easily – either to support "the trend flattened" or "the trend continued". Critics use this fact to argue that lack of statistical significance can only mean "not warming", one of the many other PR tricks.) Surface warming should be looked at (all climate scientists will tell you, as many times as you would like to ask) on decadal timeframe. So the key question is whether each decade is significantly warmer than the preceding one, and so far that continues to be quite dramatically true.

Measurement challenges, data processing and signal/noise analysis are common to a pretty big number of problem domains. You mention medical research. In a previous reply I mentioned the kriging improvements to hadcrut to address the data gaps proposed in a paper by Kevin Cowtan. Cowtan is not a climate scientist – he is a data analyst and medical researcher who built up statistical expertise in contoured data sets working on "electron density functions in X-ray Crystallography", and was able to cross over and apply that expertise in a published contribution on climate data sets! There are some unique challenges with the complexity of climate, but in terms of the type of data and the physical properties being studied it really is not very different from other physical sciences. Think about geology, plate tectonics etc.; the link I referenced in #46 refers to how the noisy data and large error bounds for dating the age of the world were used to attempt to debunk the entire process of radiometric dating and/or the entire discipline of geology. Think about oceanography. (Really both of these are components of climate science.) Think about cosmology, trying to infer physical truths about structures tens of thousands of light years away from an incredibly noisy panorama of data up and down the EM spectrum. With uncertainty comes error bounds, part of why you see so many in the IPCC summaries. As with the dating of the earth, I claim critics react (defending a perceived attack on their world view) by seeking to aggressively (and erroneously) conflate "imprecise" with "completely meaningless", "unknowable", "incompetent" or "hoax". It is an interesting thought regarding economics, though I certainly don't see a unique relationship with climate. I think the core thing that makes economics extra devilish is that you are trying to model the behaviors of economic actors who are fully sentient with a set of possible synaptic combinations that breaks math, such that the complexity of predicting their behavior in all circumstances can explode a bit (especially if they are self-aware you are studying them and seeking to game it, etc.)

I pasted the wrong link (that's a longer signal/noise exercise by Tamino that uses the data available for solar, volcanic and El Nino to show the leftover warming trend.) Sorry for noise; meant to post this summary by Rahmstorf of his view on causes/interpretation of "pause" all up – the Global Temperature Jigsaw.

I was emphasizing that meteorology in general is not core to the chain of logic behind global warming. I did make some references to the stochastic role of El Nino, which relates to "pause". The term "pause" is itself a bit of another PR victory, there certainly hasn't been a "cooling period", just some slowing of surface warming (if you ignore the discussion about the arctic measurement gap for the moment). As ocean heating has continued and we've seen La Nina dominance (where you expect less surface warming – again >90% of heat storage is in the oceans), we're not very close to any fundamental challenge to the energy budget story described above. Surface warming is tied up in many things so it's hard to use it to establish one specific conclusion in a short time frame, it requires a more complicated discussion. Of course on some timeframe low observations there get meaningful to different parts of the current methods of projecting temperature. But keep in mind temperatures ran much hotter than projected for awhile in the 90s due to El Nino, and that didn't turn out to argue for revising much of significance. For now, if you just feed the observed sequence of El Nino to models, they reproduce the observed temperatures pretty well. You can see the warming signal by taking simple steps like plotting El Nino, La Nina and ENSO Neutral years separately – smooth warming trend for each type of year. Longer discussion from Rahmstorf here.

Feel free to highlight the passage you find "rude" toward you personally, as opposed to toward your arguments, in #44. I will assume you are unaware of the tone you set yourself (review your first contribution to the thread – how helpful was it?) And how 'polite' is it to level broad accusations of fraud and incompetence against scientists without apparently seeing much need to defend that, really?

Funny I wrote that just before catching up on the new Cosmos #7, which tackles the lead poisoning question and frames the story as one of the first big conflicts of this kind, very much along the lines of the discussion in this thread. Some discussion in articles like this. It is striking the way the pattern replays itself. Robert Kehoe as the Richard Lindzen of the day, the exploitation of uncertainty to reject whole areas of understanding, the rigging of "burden of proof" to prevent action, the associated human cost. It underscores the philosophical dilemma – you may not have an explicit problem with science as a philosophy and as a force in society in the abstract, but what good is it going to do for you, really? As with these cases, it's going to work against you – it's going to discover that leaded gasoline is poisoning people, or that second-hand cigarette smoke is causing cancer, or that CO2 is causing global warming, in short it's going to pit science against industry, which is to say science against John Galt. Requiring you to side with Kehoe and the fossil fuel industry against the fussy scientists griping about a little lead, be wrong and lose (here's the chart of how lead blood levels dropped after lead was removed from gasoline, and here's a chart exploring the subsequent correlation to drop in crime rate). Or, against the fussy little bureaucrats nattering about cigarettes (as Lindzen literally did), be wrong and lose. Of course this time is different, no doubt. A role for science in policy and society is a recipe for more of this, not less, hency any collateral damage to "science" as an institution and concept in these debates is always a positive rather than an unfortunate side effect, in terms of ideological utility.

Walk through my post #39 and pinpoint the spot where it is required that "scientists must predict the weather with precision" as part of the chain of logic. Your characterization of the topic as long-range weather forecasting is a complete and utter misunderstanding of the relevant scientific theory and logic. Weather is the swirling around of heat and moisture within the climate system. It is chaotic and governed by Navier-Stokes. It is also not required that this problem be solved to make thermodynamic observations about the climate system over time. Of course the climate can be modeled. ("Cannot be modeled" is a somewhat inherently anti-science statement to make.) Above in #39 I stated we start by "modeling the planet as a big rock in space covered with a fluid "envelope" that can hold various amounts of heat." Inside that envelope, heat swirls around chaotically, mixing between the ocean and the air in giant oceanic oscillations that dominate year to year surface temperature readings, alternately pushing heat deeper in the ocean via wind-driven coastal downwelling or releasing it in calmer phases, etc. Nevertheless, we can look at the overall questions of radiative balance (incoming and outgoing energy) to understand what is happening with the heat content of the envelope as a whole, over time. The common analogy is putting a pot of water on an open flame. Scientists see the "energy imbalance" and predict that the water will warm, bubble and eventually vanish. "Boiling" skeptics are outraged, and they want answers – if scientists are so omniscient as to predict the future(!), why can't they predict precisely when and where each of these bubbles will appear, exactly, and how many there will be. If they can't predict even these basic bubbles well enough in the short term, why do they think they can project this bubbling further into the future to a point where the bubbles have catastrophically taken all the water away?! Scientists reply hey, we're interested in those details, and we're working on modeling them specifically but it's extremely chaotic in there and I think you're missing the forest for the trees. The skeptics launch FOIA lawsuits, demand access to the scientist's personal email in order to document conspiracy to defraud, and proclaim the whole thing a proven hoax. (Just kidding, that part is only in the real global warming debate.) The chaotic nature of weather does imply that scientists will not generally be making high precision forecasts of surface temperature. They will project ranges of what we will see on the surface based on the increasing total heat content of the climate system over time. This means contrarians can point to that imprecision as proof "the theory has been falsified!" for as long as they perceive the science to be a threat to their core view of the world.

It is a conceptual description of the strength of a warming response to a doubling of CO2. It says if you double the CO2 content in the atmosphere and allow the incoming/outgoing radiation to reach equilibrium again (which will take time as the climate has to absorb heat before it can radiate enough out through the enhanced greenhouse chemistry to match incoming radiation) you will see a temperature change between 1.5 and 4.5 degree C increase in global surface temperature relative to where you started. (Which of course is a staggering amount of heat energy, but then doubling CO2 is a big deal – we have only increased it 40% so far). I'm not sure what you are complaining about. I said "The sum of all this looking at many different lines of evidence has produced a range of estimates from 1.5 to 4.5 "warming per doubling" for awhile now, which is the offiical IPCC sensitivity assessment." My comment was that the sum of research has pointed to this range centered around 3 degrees for a couple of decades now, and that 1.5 to 4.5 is the current official IPCC assessment. You then say this is "not the case at all" and quote the latest IPCC saying it is ... 1.5 to 4.5. El Nino and internal variation was not a new concept for oceanographers in 1998. Just more circulation of internet lore.

Well, I think this is good anecdotal support for my thesis above – "until climategate I believed AGW was real". Once you were convinced (erroneously) that scientists had been caught red-handed falsifying data, you became more open (susceptible) to a variety of claims like these, correct? (Though the sweeping tone of your screed, broad blanket rejection of entire fields, without even attempting lip service to any grounding in specific or verifiable example, makes this look more like the typical ideological reactivity in general.) What you list is mostly the earlier generation anti-science PR, back when it was all about denying the temperature record, trying to claim that the difficulty measuring "average surface temperature" precisely prevents and invalidates the concept of scientific discussion of global temperature. This line of attack has receded a bit for a variety of reasons, e.g. once the early errors in Spencer and Christy's satellite data set were worked out and it started looking like the rest of the temperature sets, the fact that the warming trend was consistently similar in rural and urban areas regardless of urban heat effect, and also big projects like the Berkeley Earth Surface Temeprature re-analysis. That's the one that was funded by the Koch Foundation among others and was aimed at fully documenting exactly these allegations, "addressed scientific concerns raised by skeptics including urban heat island effect, poor station quality, and the risk of data selection bias." It of course re-confirmed all the earlier analyses including those by NASA, NOAA etc. Naturally a rational person would also use other heuristics here, like wondering if this area of science was truly riddled through with such a calamitous degree of incompetence, so far below the professional standards of "other fields of science", would the National Academy of Science and the U.K.'s Royal Society really be issuing forceful joint statements in its defense? Would all of the professional organizations of different disciplines, including the likes of the American Statistical Association or the American Physical Society, really release similar supporting statements? Across every country in the world? But of course this sort of rational reference to expert opinion has been successfully demonized as the very core of the evils of our time. End of day, your (unsupportable) broad brush statements are part and parcel of the political backlash against science – the side effect, that your attack necessarily erodes confidence in science as a whole (after all, how was this sort of colossal hoax not caught by the institutions of science??) is pure benefit from your point of view (consciously or unconsciously), not a cost.

I don't know how you can not see all this as just demonstrating the claim, you perceive a world view threat, react with attacks and misrepresentations (implicitly, attacks on the trustworthiness of scientists involved, "it's a cult!"), already it's straw men and "give me a short summary in a blog comment that proves CO2 causes doom and gloom or admit it is propaganda!" etc. A rather direct analog is "point me to a bone I can dig up right now to prove evolution or admit it's propaganda!" Alright. We'll put that aside and just assume you asked for more elaboration from where I left off, per: So, you agree on the first basic steps of CO2 increase and absorption, that's great, plenty jump off the wagon there. The conceptual model that connects the GHG increase to predictions of heat gain in the system over time (global warming) is straightforward, at a high level. It's based on conservation of energy, and modeling the planet as big rock in space covered with a fluid "envelope" that can hold various amounts of heat. A critical insight is to note (and validate) that you can only meaningfully create or destroy heat in this system via radiation to/from space. There are two main parts: (1) Assessing all of the variables having to do with incoming and outgoing radiation ("forcings"). Physics of radiation here. The variables include incoming raw solar energy (flux) and all things which modify it, i.e. the planet's reflectiveness (albedo)/absorptivity, and then the outgoing longwave radiation (earth's "blackbody" radiation yielded by the Stefan-Boltzmann law) and all things which modify that, namely the greenhouse chemistry of the atmosphere. Calculations of the solar energy hitting the planet and of the outgoing longwave radiation are straightforward (Fourier roughed out these calculations in order to deduce the existence of the greenhouse effect in 1824.) With modern instruments we now observe the greenhouse effect directly (bites coming out of radiation as seen from satellites, extra spikes coming back down as seen from the ground.) The major variable measured least effectively is the albedo effect of aerosols, so modeled error ranges are larger. From this, you can look at the balance of incoming/outgoing energy and deduce a magnitude of heat accumulation (warming) in watts per square meter (a forcing). (2) Assessing "feedbacks" – more complexity enters here (which of course exists in spades in general). You need to model what happens when the climate starts to absorb heat and whether this in turn starts changing any of those key variables in (1). Turns out it does. A response to warming which causes yet more warming is referred to as a positive feedback, notably including water vapor (warmer air holds more water vapor, the chief greenhouse gas) and ice cover (more warming drives drop in albedo and more absorbed solar). Critically, we start with a useful framing and reference point here – using the variables understood in (1), we can investigate paleoclimate in as much detail as possible, reconstruct what atmospheric chemistry looked like (directly sampling air bubbles trapped in ice), what temperature and ice cover looked like, and model how these key variables changed over time, thereby observing how the climate responded to forcings and deducing the total magnitude of built-in feedbacks. This yields a measurement of "climate sensitivity" of roughly 3 degrees warming total as a result of an initial doubling of the quantity of CO2. The strong thing here is that this sort of calculation rolls in all of the possible climate feedbacks, from water vapor to clouds to ice cover and any we haven't identified. In parallel there is lots of research looking to tally and quantify the specific feedbacks directly and empirically observe responses in modern times. The sum of all this looking at many different lines of evidence has produced a range of estimates from 1.5 to 4.5 "warming per doubling" for awhile now, which is the offiical IPCC sensitivity assessment. Meaning, still centered around that ~3 figure; that general range hasn't really moved for several decades now despite continual refinement of understanding (uncertainty disproportionately still tied up in clouds.) So you put all that together with some assessment of thermal capacity and how the ocean and air will roughly balance heat storage between them (about 90+% in the ocean, with El Nino oscillations over time causing stochastic shifts one way or the other on decade time scales.) You rough calculate it out (as Hansen presciently and accurately did in 1981) or develop computer models that play it out, and end up with similar projections either way for the amount of warming, depending chiefly on human emissions and the sensitivity factors. The current mainstream overall estimate from the IPCC is 1.4 to 4.8 deg C by 2100 – that's using the less mitigated emission scenarios i.e. RCP6.0/8.5 since we are talking about the justification for mitigation, the "likely" (>66% likelihood) ranges. Yes I handwaved the middle-of-the-road "2-3" degrees in the prior post when outlining the overall picture, just giving a sense of the scale of the warming question... going down the middle here gives ~3 degrees as a placeholder for mean warming.) I don't understand the 11,700 years reference, but yes the ~1 degree to date is not all anthropogenic. The context of the comment was roughing out the scale of total warming and what that means about impact, the context was not attribution, so not a relevant detail in context. Solar has been flat or declining since the 50s, the modern bulk (and the warming happening from here) is all human-caused. The IPCC statement is "It is extremely likely [i.e. >95% likely] that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together."

I linked to the AR5 impact paper above, you can read the outline of what the concerns are, and on what timeframe, and with what basis in research. To understand the overall context, it's important to emphasize just how major a change in climate we are talking about, a shift to a different mode (equilibrium state) for the planet as a whole, and a transformation of the climate away from the state that human civilization grew up in. The difference between ice age (glacial) and not ice age conditions is about 5 degrees C global average surface temp. We've warmed 1 so far (from the lowest temperatures of the Holocene to the warmest in a geologic eyeblink) and project 2-3 more by 2100, so comparable to that kind of "ice age" scale shift, only this time in unprecedented (for us) warming direction. During the ice age, the physical differences driven by this degree of change included the likes of mile-thick slabs of ice over New York. So we get to project what that kind of change in the opposite direction looks like, fueled by awareness that ice melt is a "wetter" processes that can happen faster than the time it takes to grow glaciers to that size (the record shows periods where 1m sea level rise every two decades is normal, and the anthropogenic forcing is sharper than the far slower/softer orbital-type forcings that drive past climate shifts per prevailing theory). Temperature zones are already estimated to be shifting about 4 feet a day which is what ecosystems have to keep up with. The paleoclimate record is clear that rapid changes of this scale are a big deal for all kinds of systems. You can read the impact report for more discussion of the risks scoped to coming decades. You are welcome to believe such risks don't exist, I just don't believe you have a rational basis for that bias and assumption.

Jeez, well I've been a gigantic KJ fan forever, so will humbly accept your correction without comment.

Counter the science, then. Simplly asserting it is all just religion and there is no rational basis is incredibly uncompelling logically. Why won't CO2 absorb infrared? You can observe in any lab you like. Why won't increasing CO2 in atmosphere trap energy on a global level? We directly observe that changes in outgoing longwave matching predicted changes via dedicated satellites. Why won't trapped heat warm the climate? First law of thermodynamics says it will. Why won't warmer air hold more water? Humidity monitoring confirms it is. And so on, a highly validated chain of science and logic that has been developed for over a century, across disciplines and countries. Scientific epistemology is actually a significantly different method for building understanding of the world than religious dogma, although its critics frequently assert that it is equivalent. Drawing conclusions from understanding of radiative physics may seem the very height of religious fanatacism to you, but be careful that you don't accidentally use such physics while operating your computer and connecting to the internet to say so, as that could be unintentionally ironic.