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

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Comments 251 to 300:

  1. Why trying to prove yourself wrong is the key to being right

    99% of people who "got sick" lived.

    99.99% of the population did not get sick or got mild symptoms.

    The vast majority of people who got sik and died were very old and sick and the next major group were all this and also obese.

    Of the people under the age of 35, 99.999% did not get sick and die

    Those who have died fit the demographic of those who are going to die every year, just more so.

    All deaths are tragic....wait a minute....there not....WE ALL DIE!

    This issue does not fit any of the parameters of a pandemic. Also they lie when they say that natural immunity is not as good as vax.

    The genetic based injections are not vaccines by the historic definitions.

    The injections neither prevent infection nor transmission whis were the two reasons sold to the public for why every man, woman, and child in the world must be injected.

    All of this is age old, well established SCIENCE and needs to be understood.

    Moderator Response:

    [RH] Off-topic.

  2. Can Hydrogen Fuel Power the Planet?

    This is not simply about energy efficiency. Its all about user friendliness and hydrogen fuel cell cars have a big problem: Nobody is likely to buy these hydrogen fuel cell cars without an extensive and easily accessible refueling network, because you cannot refuel these cars at home ( to my knowledge). And no company is likely to provide a decent refueling network in case the cars still dont attract buyers.

    And so what we see are quite small and experimental refueling networks. Japan has 134 refueling stations. Germany has 90, The USA 46, China 39,  about 20 other countries have typically around 6 refuleing stations. It doesn't seem like not a lot of refueling stations to inspire public confidence, given it's for entire countries, and uptake of hydrogen fuel cell cars has been slower than EV's, unsurprisingly. Obviously other factors contribute, but I know I would be nervous buying one if there weren't many refuling stations reasonably close by and between cities.

    However hydrogen fuel cell trucks have a future, because they have good range, and  the truck companies provide their own refueling facilities. Information on hydrogen fuel cell trucks already being trialled is described here.

  3. IPCC reveals how we are changing the climate

    High Ed: If you watched Taylor because you lean conservative and agree with many other things Heartland, I suggest you try his brother Jerry Taylor at the Niskanencenter with respect to climate science etc. instead.

  4. Can Hydrogen Fuel Power the Planet?

    Jan: H2 is not a big problem in the atmosphere, so leaks only matter as a factor of fuel/energy loss. Atmospheric H2 is mostly consumed in soils, and little to none makes its way into the stratosphere.

  5. Can Hydrogen Fuel Power the Planet?

    Jan, fuel cells are actually not that efficient. I suggets you digest this:

    The battery EV is actually about three times as efficient compared to a hydrgen fuel car with fuel cell ...

  6. Skeptical Science New Research for Week #34, 2021


    If you follow the links to the full report: will see that it says:

    The Technical Summary (TS), the full Report Chapters, the Annexes and the Supplementary Materials are the Final Government Distribution versions, and remain subject to revisions following the SPM approval, corrigenda, copy-editing, and layout. Although these documents still carry the note from the Final Government Distribution “Do Not Cite, Quote or Distribute” they may be freely published subject to the disclaimer above, as the report has now been approved and accepted.

  7. Skeptical Science New Research for Week #34, 2021

    I just tried to download the IPCC report from the top of this homepage. It would appear that the link leads to an incomplete version which is missing figures and with text on certain pages requesting the user not to distribute this version. I think it needs to be replaced with the version that was meant to be released to the public.

  8. IPCC reveals how we are changing the climate

    I'm sure Adam is well-qualified to produce his video's.  But the world is the way it is, and anyone wearing blue nail-polish while he makes his appeals on video is just not going to be taken seriously, by half of the American public.  The other side of this debate is tatted and bulked up, full of colorful language, and appeals to testosterone-laced dominance: probably because the fossil-fuel corporations know it sells. 

    Half of America will take 2 seconds to decide if this is someone they want to spend 10 minutes of their lives with.  Its wrong, but in those 2 seconds, they are judging based on visual cues.  I didn't make this world: I'm just reporting on how it is.

  9. Jan van Dalfsen 1 at 01:54 AM on 27 August 2021
    Can Hydrogen Fuel Power the Planet?

    The engineer Rosie Barnes said they could burn H2 which could be useful for aircraft, but what about its use in fuel cells where electricity is produced without burning Hydrogen. Fuel cells simply reverse the electrolysis that produced the green hydrogen. Fuel cells produce electicity without wasting energy producing heat as well as electricity.                                                                                                                        I agree with the video that the best thing is to produce electricity as close as possible to where it is to be used. However, for industries with a high electricity appetite green hydrogen can be efficiently and safely transported as NH3 which doesn't take up anyway near as much space as H2. That would be useful for providing energy to factories requiring a higher concentration of energy than they can produce in the limited space they have at the factory.                                                                                                                                                                                     My first worry is that H2 is so small a molecule it could easily leak little by little. Eventually what effect is all that extra H2 going to have in the upper atmosphere?                                                                                                                                                                                                      My second worry is that the distinction between blue hydrogen and green hydrogen might get blurred in practice.                                                                                                                                                                    Thirdly, some natural gas miners like Twiggy Forrest promise to implement a plan to eventually transition to using green hydrogen in their natural gas facilities. They say that the facilities they are building for the natural gas they have rights to now so that these facilities can later be transitioned to using green hydrogen. Even with his marine ecology doctorate, if Twiggy Forrest is mining lots of natural gas, when does he switch to using his facilities for green hydrogen instead of using the natural gas, especially if he still has an abundant supply of natural gas? Is the promise of transitioning to green hydrogen a type of green washing of natural gas mining?

  10. One Planet Only Forever at 04:51 AM on 25 August 2021
    IPCC reveals how we are changing the climate

    Ed Evans,

    I agree with Eclectic.

    And I would extend the comment to all the "Popular in the Moment" crowd who are "uninterested in fuller presentations of information" or won't bother to independently verify if a claim they had an instant instinctive liking for was a valid understanding of what is going on, what is harmful, and how to limit harm done based on increased awareness.

  11. IPCC reveals how we are changing the climate

    Ed Evans @1 :

    Don't waste your time dealing with James Taylor and his Heartland crew.

    Taylor's climate science is distinctly of the Flat-Earth sort.

    And Taylor's only economics interest is : being economical with the truth. 

  12. IPCC reveals how we are changing the climate

    I need to get into the report. And I'd like for someone to come up with web pages linking to what the report actually says. Here's why:

    I watched James Taylor from the Heartland Institute comment on "Biden Administration's Climate Change Agenda," Span.  He plays a yin and yang call-in game with democrats and republicans, giving each an equal chance to determine our future prospects, at least regarding climate change. He makes alludes to the IPCC report. He needs to be fact-checked in real time.  I did not know enough to do so.

    Moderator Response:

    [BL] Link activated.

    The web software here does not automatically create links. You can do this when posting a comment by selecting the "insert" tab, selecting the text you want to use for the link, and clicking on the icon that looks like a chain link. Add the URL in the dialog box.

  13. Volunteer opportunity turned into a big win for SkS and students!

    I see that I need to spend more time here because I missed the blog post for help. I would have volunteered. So, here's my email should you need help in the future. If the task is within my reach, I will happy to help. Eddie Evans

    Moderator Response:

    [BL] Email address redacted. As much as we appreciate your desire to help, we don't want your email address harvested by spammers. Your best bet is to use the Contact link buried at the bottom of the web page.


  14. The new IPCC Report includes – get this, good news

    To make the point maybe a bit more succinct:

    What the terresrial bisophere and the ocean take up each year is driven by atmospheric concentrations of CO2, not annual man-made CO2 emissions. While the latter change dramatically in the SSP1 scenarios, the former do not. Atmospheric CO2 levels drop only slowly as the new equilibria get established over different timescales.

  15. Key takeaways from the new IPCC report

    ilfark2, some of the answers you seek are in sections B4 and B5 of the SPM.

    First of all, note that this is a complete hypothetical because we won't stop emitting tomorrow; even a reduction to "net zero" by 2050 (aka within 30 years) is a stretch.

    That said, note that the assumption of a linear drop you made @10 is unrealistic. Due to feedbacks in the earth-atmosphere carbon cycle system the drop is exponential as illustrated by the graph under @9, quite slow, and not returning to pre-spike conditions in equilibrium (after some 10s of thousands of years). OTOH, the graph @9 illustrates a spike of 5000 Pg; the actual spike at this point is closer to 1000 Pg. The graph is meant to illustrate a general system behavior, not a real-world scenario.

    As atmospheric CO2 concentrations fall slowly after the emissions cease, the climate effect would linger, and as the SPM highlights in section B5, that means several climate parameters (e.g. sea level, ice cover) would remain altered for "centruries to millenia".

  16. Why the IPCC climate reports are so important

    re around 1:40 min: "extremely likely" is actually defined by the IPCC as a 95-100% likelihood, not "95%" as CliamteAdam states.

  17. Science and its Pretenders: Pseudoscience and Science Denial

    Wonderfully well written, dense in content yet concise and easy to follow. I will make undoubtedly use of this in the future.

  18. It's not bad

    DPiepgrass @400,

    The accounting of deaths due to hot/cold weather is not at all easy. While I have no idea as to the source of the OP statement "deaths attributable to heatwaves are expected to be approximately five times as great as winter deaths prevented," there is a source that puts the 'prevented' total across 49 large US cities at 100/y while projecting "that changes in extreme hot and extreme cold temperatures would result in 9,300 additional premature deaths per year by 2090."  So that is approaching a whopping 100-to-1.

    But, to repeat, the assessment of the level of death due to hot/cold weather is not a straightforward exercise. If you're curious as to why that would be, see this Jeff Masters web-page (which does mention the numbers yielding that 100-to-1 finding), an account that sets out some of the difficulties.

  19. It's not bad

    dpiepgrass & Eclectic

    If you don't mind, could you please use the Google form linked above in the "Argument feedback" box to provide this feedback on the rebuttal? It's then easier for us to track instead of trying via the comment threads. Thanks!

  20. It's not bad

    DPiepgrass :  (to continue)

    Allow me to add a little anecdote : On another forum (not nearly so calm, logical and scientific as this one) there is a certain frequent poster who very often states that hospital / coroner / & other studies show that currently cold is a far greater threat to humanity, because cold deaths greatly exceed heat deaths.  And as he never fails to mention, his own name is in authorship on one of these studies.

    Eventually I found this too tiresome, so I followed his citation(s)  . . . and there was some truth to his claims (though limited to data from three small regions).   And as I followed, his cited studies referenced other studies, and they in turn led to other studies ~ many of which came to the opposite conclusion i.e. that heat deaths are greater than cold deaths.

    I threw my hands in the air, for there were many confounding factors of tropical/non-tropical ; urban/rural ; First World / Third World regions.  Not to mention the validity of reportage and sampling.

    So, DPiepgrass , we will have to fall back on some armchair speculation on these matters, rather than use scientific precision.  Whatever the present-day circumstances, my "bet" would be that a hotter world will increasingly progress to kill more frail elderly living in poverty ( in the Global South, versus the Global North ).

    Good luck finding a comfortable armchair plus a Socrates/Aristotle.

  21. It's not bad

    DPiepgrass, (and with my apology for multi-paragraph reply) :

    @400 , you ask: What is the source of this claim  [which I paraphrase as: that in the future we can expect heatwaves to cause five times as many deaths than the warmer clime would reduce cold-caused deaths].

    As you point out, the Basic / Intermediate / Advanced versions of the OP are considerably different.  Not different in a contradictory way . . . but different.  (Like very condensed versions of non-identical essays.)

    In the Basic version, the quantified "five times" is carried along in a single sentence.  It gives the impression - at first glance - that "heat deaths" would be five times the "cold deaths".  But on closer reading , that is not the actual meaning written ~ as I hope my expansion [in square brackets, above] can convey with more precision.

    Worse, the very following sentence tends to imply that a significant portion of these heatwave deaths include an insect-vector disease linkage.  Though it does not actually convey that.

    It is all too condensed, for it to be capable of a knowledge-full conveying of information.  Quite possibly it would be correct ~ yet it is unsupported within the Article.

    DPiepgrass , I do not think I can concisely answer the question behind your question.  Are/will heat deaths be exceeding cold-caused deaths?  Obviously the answer must stretch across a wide spectrum  ~ of degrees of climate warming ; of frequencies / extents / and intensities of heat waves ; of regional localities.  It would be a very difficult task to scientifically assess the outcomes even in hindsight , let alone in future projection.  Speaking for myself, I would not like to touch the task even with a 12.2 meter barge pole.

  22. It's not bad

    The Basic Edition of this rebuttal says "deaths attributable to heatwaves are expected to be approximately five times as great as winter deaths prevented" (and oddly, only the Basic version says this).

    What is the source of this claim?

  23. Is Western U.S. experiencing a ‘megadrought’?

    I was curious what caused these megadrougts in the past, and found this:  "Civilization-Collapsing Megadroughts of Medieval Times Could Be in Store for a Warming Earth".

  24. The new IPCC Report includes – get this, good news

    thanks very much

  25. Is Western U.S. experiencing a ‘megadrought’?

    William DeBuys...that pesky speller, sorry

  26. Is Western U.S. experiencing a ‘megadrought’?

    A shorcut to understanding Western drought cycles can be found in William DeButs book "A Great Aridness", Oxford U., 2011. I think he reminds us that those cycles have been repeating about every 1,000 years since the end of the last ice age. The last "bad one" was around 1050 CE

  27. The new IPCC Report includes – get this, good news

    ilfatk2 @4,

    I assume you are asking how additional warming will be constrained to keep us under +1.5ºC if we are already at +1.1ºC. Thus what you describe being "as we go back down the CO2 curve over the next 80 years" concerns our reduction in CO2 emissions in coming decades.

    The processes that will determine whether we will keep warming under +1.5ºC are detailed and complex but I am assuming you are happy with the idea that when we do at last reduce CO2 enissions to zero, the global temperature rise will effectively stop.

    (If you are not entirely clear on the reason for this 'stopping', it is because the "earth system" is not actually absorbing half our emissions. It is absorbing annually a level of CO2 that happens to be equal to roughly half our annual emissions. In rough numbers, we emit into the atmosphere 10Gt(C) per year while the planet sucks 5Gt(C) out of the atmosphere in the year. Very little of this 5Gt(C) 'in the year' is due to our emissions 'in the year'. If we didn't emit any CO2 next year our rough absorption number would only drop by something like 0.3Gt(C) because what is being absorbed is the accumulation of our CO2 emissions thrugh the years.)

    So if AGW effectively stops when we achieve zero emissions and 2050, in three decades time, is often given as a lacklustre target date consider the rate of AGW is today running at something like +0.25ºC per decade. So at that rate we would see +0.75ºC additional warming by 2050.

    But we hopefully will not be mad enough to run up to 2050 without large cuts running through those three decades 2021-50. So that +0.25ºC/ per decade will drop with successive decades, perhaps halving that post-2021 warming, say +0.20ºC+0.15ºC+0.5ºC=+0.40ºC, and allowing AGW to be restricted to +1.5ºC.

    I hope that makes sense of the basics of  the situation.

    It will require deep cuts and even then note the negative emissions factored-in post-2050 to achieve +1.5ºC. 

    Sadly I am not entirely convinced that politicians (& I speak here for UK which is where I am) are truly understanding of the deep deep do-do we are facing and why deep deep cuts in emissions are essential and essential quickly. Instead the process seems to be drowning in greenwash.

    I note your comment on tipping points and the link to the Lenton biog. My understanding is that the likes of Lenton are calling for the +1.5ºC limit to be taken seriously (as per Lenton et al (2020) 'Climate tipping points — too risky to bet against'). I am not aware of stronger scientific messaging although I would say that +1.5ºC is not without risks and is a level of warming that should be avoided rather than be seen as some target.

  28. citizenschallenge at 02:08 AM on 19 August 2021
    Science and its Pretenders: Pseudoscience and Science Denial

    Another excellent summary by Melanie Trecek-King.

    All I might add is,


    Unidirectional Skepticism, Equals Denial.

  29. Philippe Chantreau at 03:32 AM on 18 August 2021
    Thinking is Power: The problem with “doing your own research”

    I'm not sure the comparison is valid Graydrake. What you are describing is like delving in the cloud feedback litterature and finding a detail that will allow to refine regional forecasts. What is seen in the so-called "doing my own research" crowd when it comes to climate science is more like: "all these scientists have had it wrong but I know where the truth is, look at this YouTube video." Or someone trumpets that there is no GH effect when they clearly have no understanding of the radiative properties of the gases involved.

    Medicine is indeed art and science, and there is a big difference between medical practice and medical research. However, you wouldn't give credence to anyone questioning the fact that we are made of cells or that sterile technique must be used to prevent surgical infections.

    It is an already well known problem for practitioners that the quantity of new research findings coming out in a constant stream is impossible to keep up with. It would be convenient if there was an IPCC-like body for every specialty, that would synthesize the findings and come up with a "summary for practitioners." There is no such thing, unfortunately, and practitioners who have many patients to manage must rely on practice guidelines established by their specialty's associations and other bodies. These try to keep up but it always takes time to form guidelines, so they appear often years after research has been confirmed.

    Doing no harm is the ultimate guiding principle; that often translates into simply doing less, or waiting until there is more scientific evidence. Every medical action or intervention, including diagnostic, carries risks; every medication can have adverse effects. Information obtained from tests and diagnostic procedures is only worth obtaining if it is truly useful and actionable, and the benefits from said action outweighs the risks of both the action and the diagnostic.

    It sounds like you're alluding to recent guidelines recommending the use of Metformin outside of the range for which it is approved by the FDA. That may be advisable in some cases but any practitioner faced with that choice must weigh the risks and benefits and make an educated guess of how they will play out for a specific individual. Using a medication off label (i.e. Metformin for someone whose A1C falls below the range of FDA approved use) also carries liability risks for the practitioner. Metformin is not a benign drug. It sounds like you already had a good A1C and low enough blood glucose, what benefit did you obtain from using the medication?

    Humans are the ultimate complex system, with a brain that can create therapeutic effects, side effects and even severe adverse effects when given placebos, whether they are placebo drugs or placebo procedures. Devising effective therapies for humans is a constant struggle because of that, and because of the level of refinement that has been attained by medical science. Practitioners also have to contend with people showing all sorts of dysfunctional relations to health and health care: high anxiety, hypocondriacs, Munchausen, and everything in between on the spectrum. You did not expand on your back pain MRI but, from the practitioner's point of view, if there is a well identified cause for it visible on the scan, trying to treat another possible cause is difficult to justify. In fact, practitioners can be questioned by insurance companies and ethics boards if they do that. 

    The positive outcomes you claim still fall under the "anecdotal" category. Practitioners are obligated to rely on well established evidence before recommending anything to their patients. Of course, we know that's not always the case, and that shooting in the dark can give results, nothing is perfect. 

  30. Is Western U.S. experiencing a ‘megadrought’?

    You should investigate your usual origin of humidity. Isn't it the Amazon? The tremendous destruction of the Amazon hinders water vapor escape to the north and the south, causing drought and fire. A hot evapotranspirating Amazon brings rain and lower temperatures from the higher layers of the troposphere. This year, the Amazon is cool itself and has no energy for maintaining the convectional water-export in the right height.

    Moderator Response:

    [DB] This post is about megadroughts in the western US, not the Amazon.  For background on the effects of water vapor in the atmosphere (a feedback to temperature changes, not a driver of them), read both versions of this post and the comments section.  Please stay on-topic.

  31. The new IPCC Report includes – get this, good news

    Ok, so there's still something I don't get (maybe it's a dumb question and feel free to ignore it).

    So at 280 ppm CO2 (and whatever other GHGs at the time), the earth was at a given avg temp. Climbing up to 410 ppm CO2 (plus other GHGs), Anthro forcing brought the temp up at least 1.1 degrees C.

    Over 150 years (using 1850 as baseline).

    So, as we go back down the CO2 curve over the next 80 years, it seems hard to believe we won't increase the temperature by more than .5 C.

    And this assumes the earth system continues to absorb over half of human emissions.

    Odd they suggest there is "no tipping points temperature" since there is evidence we might have crossed it already:

  32. Thinking is Power: The problem with “doing your own research”

    I am not a doctor, I have never taken a medical course and I am not a health nut. The following three issues, however, define the reason the concept of this thread is crucially important in creating a better tomorrow.
    I read a brief article on an interesting non-invasive cardiac test, but my cardiologist recommended against it because conclusions were not always scientifically viable. I told him, as an engineer, more information never resulted in a worse decision, and we went forward with the test. Following the results, the cardiologist said, “I am not sure why you pressed for this test, but the results have identified a previously unknown condition, and I am going to change your treatment regimen.”
    I abandoned one sporting activity after another over 50 years with chronic back problems. I ran across a piriformis muscle treatment in a university journal, and during a particularly painful episode suggested it to my orthopedic physician. He replied, the piriformis is not your problem based on my MRI and test data, but again I persuaded the doctor to perform the treatment. In two days my pain subsided and I have used this treatment successfully multiple times since.
    Finally, I have type 2 diabetes. With my stable A1 C and glucose levels, my internist indicated for a couple of years I was not at a level that required medication. A non-scientific article suggested the newest opinion on diabetes management offered medication was now being recommended beneath my AI C and blood glucose levels. I am now taking medication to control blood sugar, a medication that has been around for over two decades.
    These events certainly do not intend to detract from the contribution being made by medical science, however, they speak to decisions made by scientists on the continuum from art to science on complex issues. On every complex subject, quality conclusions combine proven science and artful judgment. The quality of the scientist's conclusion on the human body and climate management, it seems, is heavily based on his rational acknowledgment of where his database stands on the continuously moving science/art continuum – 60/40, 80/20, 95/5………

  33. The new IPCC Report includes – get this, good news

    anticorncob6 @1,

    The CO2 budgets quickly become very complicated and comparing them takes a little spade-work. Here is my simplistic take on it.

    That 2013 Carbon Budget you link to is quite a generous one, even though it is for +2ºC AGW. Its 1,000Gt(C) emissions budget or 3,664Gt(CO2) with an Airborne Fraction of 45% would yield [1,000 x 0.45 / 2.13 + 275ppm=] 486ppm atmospheric CO2 by 2090 (followed by negative emissions). Other Carbon Budgets, for instance the IPCC SR1.5 budget from 2018 set a budget at 432ppm for a 66% chance of avoiding +1.5ºC AGW, this with large negative emissions to follow the reaching of zero. (My assessment here using the simplistic Af=45%.) The AR6 SSP1-2.6  with its 2% annual reductions for a +2ºC AGW, again followed by negative emissions post 2075, I'd assess at something like 285Gt(C) post-2020 so 474ppm, not greatly less than that 2013 Budget you linked to @1. Mind the real wake-up numbers come from AR5 which put the 66%  +1.5ºC AGW at 417ppm.

    You mention the "positive feedbacks" and perhaps nigelj @2 should have added that land ice will continue melting away unless global temperatures are reduced, the worry being that Greenland will melt down (taking millennia) with warming somewhere between +1.0ºC & +2.0ºC AGW and with nothing to stop it once its summit drops down to warmer altitudes. And the stability of the West Antarctic ice is potentially even more sensitive to warming.

    Specific to being "positive feedbacks" (which melted ice fields are not unless they entirely disappear & so reduce albedo), the melting tundra is also a process which will continue for centuries without a return to a chillier climate. The size of such the feedback from melting tundra will depend on how hot we make it.

    Keeping the ice sheets intact and the tundra frozen is one of the more obvious reasons why limiting AGW to +1.5ºC is a sensible policy.

  34. The new IPCC Report includes – get this, good news

    anticorncob6. My understanding from what I've read is if we stop emissions by for example 2050 temperatures will stop increasing quite soon after that,  and the the arctic will stop melting fairly quickly, and acting as a positive feedback to warming, provided it hasn't crossed a tipping point where melting has become self reinforcing. This scenario makes sense to me.

    It's not certain just when the arctic would cross a tipping point and it may have already. From memory the range is 1-3 degrees c. I could be wrong on all this and maybe someone has better information.

  35. Philippe Chantreau at 08:58 AM on 15 August 2021
    Skeptical Science New Research for Week #32, 2021

    This may not fall into the "New Research" category but is nevertheless worthy of mentioning: faced with unprecedented natural disasters having him deal at the same time with massive floods and gigantic fires, even Vladimir Poutin is acknowledgeing the threat of climate change and the urgency of action. It is quite remarkable coming from him, considering that he had consistently dismissed both ideas for decades and that Russian troll factories have worked very hard at influencing public opinion against action, including suspected attacks against SkS.


    If the English translation did not cross, I had a translate option just by right clicking on the page.

  36. The new IPCC Report includes – get this, good news

    To stay below the main Paris target of 2°C (3.6°F) warming, global carbon emissions in SSP1-2.6 plateau essentially immediately and begin to decline after 2025 at a modest rate of about 2% per year for the first decade, then accelerating to around 3% per year the next decade, and continuing along a path of consistent year-to-year carbon pollution cuts before reaching zero around 2075. The IPCC concluded that once global carbon emissions reach zero, temperatures will stop rising.

    This makes no sense to me. We can still avoid the 2C limit by reducing CO2 emissions by just 2-3% per year? And aren't there positive feedback mechanisms that will cause the world to keep warming after emissions hit zero (e.g., artcic methane release)?

    Current emissions are 38 billion metric tons per year. If we integrate (38 * 10^9)*(0.97^x) from x = 0 to x = 55 we get 1 trillion tons of CO2 that will be emitted by 2075, and I haven't seen a carbon budget for two degrees that's anywhere near that big. So a 3% reduction per year wouldn't be nearly enough.

    This source here says we have 469 billion metric tons left, and that was written in 2013, meaning that now we only have about 200 billion metric tons left, which at current rates means we will blow the two-degree target in only five years.

    Perhaps better data since then might give us a better budget, but could it change by that much?

  37. It's Urban Heat Island effect


    I have also replied to your post # 66 over on the Albedo Effect where Michael Sweet has responded.

  38. It's albedo

    Also in response to blaisct's comment #66 posted over on the Urban Heat Island discussion.


    You continue to make poor choices in the numbers and calculations that you are doing. Going over your latest effort by number:

    1. You continue to select an albedo for urban areas that is too low for anthropogenic surfaces, and you have failed to cite a reference for your value. In my comment # 64 on the Urban Heat Island discussion, I gave a reference to several artificial surface materials, all with albedo values that exceed the the value you have chosen. "Urban" areas are a mix of things like grass, roads, houses, etc. You would need to calculate how much of the surface is covered by each type, and work out an albedo for an "urban" area that way. If that is what you have done, you need to show your detailed calcuations on how you arrive at the 0.08 value.

    2. There are no assumptions in the 0.31 albedo value for the earth as a whole. That is based on satellite measurements, and includes reflection from the surface, clouds, clear atmosphere, etc. Note that the only part of the surface reflection that reaches space is the part that makes it back out through the atmosphere and cloud cover. To calculate this in a model (which is what you are trying to do), you need to account for spatial variations (and daily/seasonal cycles) of solar input, surface albedo, cloud cover, and atmospheric conditions.

    3 to 14. You continue to make unreasonable assumptions about the area that is undergoing a surface change, and how it relates to population. There is no reason to think that they are related through a simple proportion.

    15 to 20. You continue to make errors in converting solar output (1367 W/m^2 measured perpendicular to the sun's rays) to an areal average over the surface of the earth. As MIchael Sweet points out, there is a factor of 4 involved, not a factor of 2. I also mentioned this in my earlier comment. If you do not understand why this is the case, then it is difficult to see how you can expect to do any useful calculations. You also need to consider seasonal variations in solar radiation distribution and seasonal albedo.

    21. Converting radiative forcing to global temperature change involves looking at the top-of-atmosphere changes (what is seen from space), not surface changes alone. To properly incorporate surface changes into a calcuation, you need to use a much more complicated model of climate response to surface albedo changes.

    22. You still get a wildy incorrect answer, due to bad data input and bad assumptions.

    I have not bothered to follow the link to the Mark Healey document you mention. If that is the source you are getting your incorrect ideas from, then it is not worth bothering. The result you quote (that albedo changes can account for all the obsvered temperature rise) is completely inconsistent with the science.

    Over at RealClimate, they have recent posted several articles on the just-released IPCC reports. One of those summarizes 6 key results. In that post, they provide the following graph from the IPCC report, which shows the estimated temperature response due to a variety of factors over the last 100 to 150 years. "Land use reflection and irrigation" is the second-last bar on the right. Note that the calculated effect is minor cooling, not warming.

    RealClimate IPCC radiative forcings

    Michael Sweet's suggestion to read the IPCC reports is a good one. I often suggest that people start with the first 1990 report, as this covers a lot of the basic climate science principles in a manner that is easier to understand for the non-expert. In the 1990 report, they mention the Sagan et al paper I linked to in my first comment. Google Scholar can probably help you fnd a free copy.

  39. It's Urban Heat Island effect


    I have replied to you here, which is a more suitable thread to continue discussion.

  40. It's albedo


    From here: It is generally a waste of time to do your own calculations.  The albedo of urban areas cannot have changed more that 50%.  The area of urban areas is less than 1% of the Earth's surface.  A 50% change in albedo in such a small area cannot have such a large effect.

    For starters you need to devide incoming solar radiation by 4 and not 2 to account for day/night and the curvature of the Earth. 

    Vacant land converted into farmland has significant (possibly greater) changes in abedo than urban areas and is a much greater part of the Earth's surface.  The melting of Arctic ice causes a greater change in albedo than the rural/urban change does.  We see that reflected in the Arctic increasing in temperature faster than the rest of the Earth.  If urban areas caused 30% of the warming they would all be extremely hot during the day.  This is not observed.  If your calculations were correct than albedo changes would account for all of global warming and that is not what is observed.

    If you look in the just released IPCC report you will undoubtedly find a chapter on albedo change.  See what the scientists say.  An old saying among grad students is "An hour in the library will save you a week in the lab".  See what you can find in the IPCC report and come back here to inform us.

  41. Philippe Chantreau at 10:16 AM on 14 August 2021
    Skeptical Science New Research for Week #32, 2021

    Don't know if this has been mentioned but it would deserve a mention in the Climate Change Economics section: a survey of academics, professionals, regulators and policy economists reveals that there is a widely shared opinion that risks are grossly underestimated:

  42. Key takeaways from the new IPCC report

    This assumes we don't get widespread ocean stratification and a die off of the marine photosythesizers... which I assume Archer et. al. could not factor into their models.

    This, e.g.,

    from the abstract (pay blocked), seems to indicate models are sea surface temperature dependent.

    Thanks for your explanations, they are very helpful.

  43. It's Urban Heat Island effect

    Thanks All for the input. You are increasing my understanding of the albedo effect. I appreciate the articles you mentioned and see that the subject is very complex and calculations like mine are only useful for understanding the simple significance of the many variables and not useful for reaching conclusions or predictions. One general conclusion that seem to come from all the articles and papers is that albedo is most likely significant but there is not agreement on how significant, or the range of each of the variables, or the total interaction of all the albedo variables. I sure hope that the GW experts are improving their models with new NASA satellite data. Does anyone out there know how much of the current GW data (1.1’C) in the IPCC model is accounted for by albedo change?
    For entertainment only, I redid the significance of the 0.7% urban of total earth surface what if calculation to include some of the comments.
    1. The reported albedo of urban areas is about 0.08 (double the 0.04). (Albedo on a 0.0 to 1.0 scale)
    2. The reported total albedo of the earth is about 0.31. (Assume that includes clouds and urban albedo)
    3. % of earth that is urban: =0.7%
    4. The non-urban area of the earth is: 100%-0.7%= 99.3%
    5. The contribution of urban areas to the total albedo is: 0.08 * 0.7% = 0.00056
    6. The total non-urban area albedo contribution to the total is: (0.31-0.00056)/ 0.993 = 0.31162
    7. Assume the non-urban area albedo in the 1880 era was the same as today: =0.31162
    8. Current earth population is about = 7.8 B
    9. 1880 era population is about =1.3 B (Using 1880 as the approximate start of IPCC temp data)
    10. Assume the 1880 era urban area was proportional to population: = 1.3/7.6*0.7% = 0.12%
    11. The 1880 era urban area contribution to total albedo was: 0.07*0.12% = 0.0000933
    12. The 1880 era non-urban area contribution to the total albedo was: (1- 0.12%)*0.31162 = 0.311257
    13. The 1880 era total albedo estimate is: 0.311257+ 0.0000933 = 0.311351
    14. The difference in 1880 vs 2021 albedo is : 0.311351 – 0.31 = 0.00135 (or about 0.14% albedo change)
    15. The reported output of the sun reaching the earth is about: 1367 W/m^2
    16. Assume that the urban albedo is only seeing one half (balk of urban areas are in the middle half of the earth’s surface) of the above due to the curvature of the earth: 50%
    17. Average surface of the earth cloud cover: =67%
    18. Average albedo of clouds: = 50%
    19. Total sun’s output reaching cloud covered urban areas + non cloud covered urban (corrected for curvature) is : 455 W/m^2.
    20. Therefore, this energy of the albedo difference is: 0.00135* 455= 0.61W/m^2
    21. I have seen conversion factors for converting this to ‘C in earth temperature rise of 0.5 to 0.7 ‘C/W/m^2. I’ll use the 0.5.
    22. The equivalent earth temperature rise of the above albedo change from 1880 to now is: 0.61*.5 = 0.31’C

    The IPCC reported temperature rise over the 1880 to now is about 1.1’C. This what if calculation implies that a 0.7% urban area could account about 30% of this temperature rise – not insignificant.
    One of the papers (in your previous references) on land use albedo change seems to agree that man-made albedo changes (mainly in agriculture by Mark Healey are significant and could account for all the IPCC temperature rise. Mark Healey’s paper suggest that land use changes since 1910 are stronger than the UHI albedo effect.
    I am switching over to the “It’s albedo” thread. What are all the possible albedo changes since 1880?

    Moderator Response:

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    The web software here does not automatically create links. You can do this when posting a comment by selecting the "insert" tab, selecting the text you want to use for the link, and clicking on the icon that looks like a chain link. Add the URL in the dialog box.

  44. Key takeaways from the new IPCC report

    ilfark2 @10,

    I would not be so definite about the speed of CO2 draw-down as to put a value on it but the 3ppm you give is not unreasonable, but only as the initial value.

    If we stopped emitting CO2 tomorrow, with 45% of our emissions now in the atmosphere, perhaps half of that will be drawn down into the oceans. (Note this also involves an additional transfer into the oceans, out from the biosphere which is more advanced along the path to equilibrium.) So +45% of our emissions, or that atmospheric increase of +140ppm, would roughly halve suggesting a drop of 70ppm, back to ~350ppm, this taking some 1,000 years although most would occur through the firat 100 years.

  45. Volcanoes emit more CO2 than humans

    Thanks guys, very helpful.  Yes the difference is huge I knew it was for land volcanoes and suspected the ocean activity wasn't significant, great to have the useful sources to confirm, also found the Wong 2019 from above useful.

  46. Volcanoes emit more CO2 than humans

    Here's what the peer-reviewed published literature shows, that humans produce 100x more CO2 than all Earth's volcanoes combined:

    - Just two-one thousandths* of 1% of Earth's total carbon—about 43,500 gigatonnes (Gt)—is above surface in the oceans, on land, and in the atmosphere. The rest is subsurface, including the crust, mantle and core—an estimated 1.85 billion Gt in all.

    - CO2 out-gassed to the atmosphere and oceans today from volcanoes and other magmatically active regions is estimated at 280 to 360 million tonnes (0.28 to 0.36 Gt) per year, including that released into the oceans from mid-ocean ridges.

    - Humanity’s annual carbon emissions through the burning of fossil fuels and forests, etc., are 40 to 100 times greater than all volcanic emissions.

    - Earth’s deep carbon cycle through deep time reveals balanced, long-term stability of atmospheric CO2, punctuated by large disturbances, including immense, catastrophic releases of magma that occurred at least five times in the past 500 million years. During these events, huge volumes of carbon were outgassed, leading to a warmer atmosphere, acidified oceans, and mass extinctions.

    - Similarly, a giant meteor impact 66 million years ago, the Chicxulub bolide strike on Mexico’s Yucatan peninsula, released between 425 and 1,400 Gt of CO2, rapidly warmed the planet and coincided with the mass (>75%) extinction of plants and animals—including the dinosaurs. Over the past 100 years, emissions from anthropogenic activities such as burning fossil fuels have been 40 to 100 times greater than our planet’s geologic carbon emissions.

    - A shift in the composition of volcanic gases from smelly (akin to burnt matches) sulphur dioxide (SO2) to a gas richer in odorless, colorless CO2 can be sniffed out by monitoring stations or drones to forewarn of an eruption—sometimes hours, sometimes months in advance. Eruption early warning systems with real-time monitoring are moving ahead to exploit the CO2 to SO2 ratio discovery, first recognized with certainty in 2014.

    Regarding the release of CO2 from volcanoes:

    "Earth’s total annual out-gassing of CO2 via volcanoes and through other geological processes such as the heating of limestone in mountain belts is newly estimated at roughly 300 to 400 million metric tonnes (0.3 to 0.4 Gt).

    Volcanoes and volcanic regions alone outgas an estimated 280–360 million tonnes (0.28 to 0.36 Gt) of CO2 per year. This includes the CO2 contribution from active volcanic vents, from the diffuse, widespread release of CO2 through soils, faults, and fractures in volcanic regions, volcanic lakes, and from the mid-ocean ridge system."

    Kelemen and Manning 2015 - Reevaluating carbon fluxes in subduction zones, what goes down, mostly comes up

    de Moor et al 2016 - Short-period volcanic gas precursors to phreatic eruptions: Insights from Poás Volcano, Costa Rica

    McCormick et al 2016 - Observing eruptions of gas-rich, compressible magmas from space

    Johansson et al 2018 - The Interplay Between the Eruption and Weathering of Large Igneous Provinces and the Deep‐Time Carbon Cycle

    Tamburello et al 2018 - Global-scale control of extensional tectonics on CO2 earth degassing

    Lee et al 2019 - A Framework for Understanding Whole-Earth Carbon Cycling

    Black and Gibson 2019 - Deep Carbon and the Life Cycle of Large Igneous Provinces

    Kamber and Petrus 2019 - The Influence of Large Bolide Impacts on Earth’s Carbon Cycle

    "pCO2 is a result of the balance between the rate of CO2 inputs through magmatic/metamorphic degassing and the rates of carbon removal via silicate weathering and organic carbon burial."

    McKenzie and Hehe Jiang 2019 - Earth’s Outgassing and Climatic Transitions_The Slow Burn Towards Environmental Catastrophes

    Mikhail and Furi 2019 - On the Origins and Evolution of Earth’s Carbon

    Schobben et al 2019 - Interpreting the Carbon Isotope Record of Mass Extinctions

    Suarez et al 2019 - Earth Catastrophes and Their Impact on the Carbon Cycle

    Werner et al 2019 - Carbon Dioxide Emissions from Subaerial Volcanic Regions_Two Decades in Review

    "All studies to date of global volcanic carbon dioxide emissions indicate that present-day subaerial and submarine volcanoes release less than a percent of the carbon dioxide released currently by human activities. "

  47. Volcanoes emit more CO2 than humans

    jon_zz09 - the killer for that argument is the volcanic CO2 has very different C isotopic signature to that fossil fuels. The changes in atmospheric C isotopic composition are consistant with FF source. Furthermore, the studies referenced in this article (and see more here) account for submarine volcanoes. While estimation is difficult even the high end of the estimates is small compared to FF emissions. Finally, there is no evidence of an increase in volcanism as Rob says ( see here from Global Volcanism Program).

  48. Key takeaways from the new IPCC report

    So we would expect to see something like a 3 ppm decrease per year to start and dimish over time upon 0 emissions. So if we wanted to get back to 300 ppm, it would take about 40 years at 0 emissions. So that would be another 40 years over the pre-Human climate equilibrium... though Archer et. al.'s models show we wouldn't get back down to 300 anyway.

    This is assuming the Earth sinks continue to behave the way they have.

    Is that what they are saying?


  49. Volcanoes emit more CO2 than humans

    jon_zz09... My understanding is that, any CO2 emitted from underwater volcanoes would be dissolved before reaching the surface. That could be a complicating factor for ocean acidification, but it does nothing to explain the rapid rise in atmospheric concentrations starting with the industrial revolution.

  50. Key takeaways from the new IPCC report

    ilfark2 @8,

    The usual work that sets the scene for the fate of our CO2 emissions is that of David Archer (eg Archer et al (2009) 'Atmospheric Lifetime of Fossil Fuel Carbon Dioxide'  Fig 1b from the paper is pasted below.) Such work tends to involve the modelling of a big impulse of CO2 rather than the 'slow' release over decades we are managing at the present. 

    This graphic shows that 30% of a very big release of CO2 is still in the atmosphere millennia after its release. Fig1a (which I can't see on-line to post here) models a 1,000Pg release which is closer to what we humans will likely manage (So far we have managed 700Pg.) and suggests the final CO2 level would consist of 20% our total emissions.

    Archer et al (2009) fig 1b

    The situation with our present emissions is that annually the rise in CO2 levels equates to about 45% of our annual emissions, this referred to as the Airborne Fraction. Thus annually we are emitting roughly 36Gt(CO2) = 10Gt(C), and seeing an atmospheric increase of some 2.4ppm or [2.4 x 2.13 =] 5.1Gt(C) or [x 3.664 =] 18.7Gt(CO2).

    However the 55% that is thus being swepted from the atmosphere into oceans and the biosphere should not be seen as 55% of our annual emissions but as a smaller fraction of the accumulative emissions over past decades.

    And because that is 55% of past emissions (which all our emissions will become when we stop emitting), that draw-down will continue although slowly diminishing with time. This reduction in atmospheric CO2 will thus reduce the climate forcing from AGW and counteract the 'in-the-pipeline' warming from the planetary energy imbalance. So warming will quickly stop. I don't think there is much reversal of warming, your "stabilize at a lower temperature."

    I am a little surprised to read the comment in recent web articles suggesting this reasonably quick end to warming following a termination of CO2 emissions is somehow new learning. It has been well understood for many years now. What perhaps has prevented the communication of this knowledge is the absence the political will to enact such a cut in emissions. Thus the gradual reduction over several decades was what the science modelled, not a sudden zeroing of our emissions.

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