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Comments 1201 to 1250:

  1. 2023 SkS Weekly Climate Change & Global Warming News Roundup #29

    OPOF - blog-post in an advanced state of preparation to dispel the latest emergent climate-myths. Expect to see it fairly soon.

  2. One Planet Only Forever at 04:10 AM on 29 July 2023
    2023 SkS Weekly Climate Change & Global Warming News Roundup #29

    The following BBC News: Science item is a recent example, only one of many, regarding the communication challenge I refer to in my comment:

    "False claims that heatwave is bogus spread online"

    In spite of meticulously correct reporting 'one of many characters' is used as a clear example of false claims made about the reporting.

    The BBC did an excellent job of quickly rebutting the false and harmfully misleading claim. However, it is likely that not everyone who sees and prefers the non-sense false claims will see the refutation and corrections of understanding. And it is also likely that many of the fans of the falsehoods will believe that they are the ones with 'the common sense understanding' and everyone who disagrees with them has been duped ... by The Globalist Elitist Programming.

  3. At a glance - How do we know more CO2 is causing warming?

    Walsculer - see my comment below the following piece, in response to the very similar comment you posted there a few days ago:

    At a glance - Empirical evidence that humans are causing global warming

  4. Flying is worse for the climate than you think

    It's true that the original problem was introducing additional CO2 from the lithosphere beyond what was already in the biosphere. In other words, growing a tree then burning it was, if averaged out over the long run, fine. Just as long as we leave the fossils in the ground.

    Two problems with that. One: there is some sensitivity to timing. Maybe we can't burn everything at once. Different gasses have different forcing effects over different time spans.

    The second relates directly to flying. Burning things up there is not the same as burning them down here. The contrails are mostly just water but they still heat up the planet. Greenhouse effect. Emitting CO2 is just a third of the problem with flying. Adam explains this in the video.

  5. One Planet Only Forever at 11:57 AM on 28 July 2023
    2023 SkS Weekly Climate Change & Global Warming News Roundup #29

    Bob Loblaw,

    I understand the focus on presenting defensible statements. But the science is pretty clear that the use of fossil fuels has produced the majority of human influence on observed Climate Change.

    We are clearly in a system/state where the 'popularity of an idea' can trump the 'merit of an idea'. I am not sure that any significant portion of humanity has ever developed out of this condition. Even current day science, what is investigated and how it is reported, can be seen to be influenced by powerful interests that conflict with how a ‘pure pursuit of science’ would improve the understanding of what is going on.

    It seems that the degree of power held by ‘popularity of impressions favouring those with higher status’ has varied. But ‘popularity of impressions’ has rarely been fully governed by the ‘pursuit of improved understanding’. In such a system/state it seems that people who are willing to mislead others in the hopes of benefiting from popular misunderstanding will have a competitive advantage ... no matter how carefully worded a statement of understanding that they dislike is ... no matter how much evidence supports the understanding they dislike ... no matter how much evidence contradicts the belief/misunderstanding they prefer and want to promote.

    Competition for status has developed in a diversity of nations and cultures. The result is a diversity of ways that 'many people with higher status' potentially have to lose status relative to others if 'increased awareness and improved understanding governed'. That applies 'Big Time' to the matter of the harms of climate change.

    It seems there is little chance of increased risk of harm from indicating that fossil fuel use is causing unacceptable climate change (unacceptable because the persons benefiting from harmful fossil fuel activity are not the persons being harmed by that activity).

  6. At a glance - How do we know more CO2 is causing warming?

    Perhaps you do nto think it worth mentioning in this brief the following early work in the area of CO2 and climate change. This includes de Saussure's demonstration of the focusability and transmission of "obscure chaleur" (dark heat) and the measurement of atmospheric heat trapping as a function of altitude with an insulated, dark interior, double glazed cubic foot box he transported from seal level to Alpine peaks: Fourier's mention of human industrial pollution's heat trapping potential in 1827 (which refers to de Saussure), and Arrhenius' 1896 paper with the first computed (single equation, single flat layer) atmospheric model, that sought to explain recently discovered evidence of ice ages by calulating the effect of halving, and also up to tripling the then current concentration of CO2 (about 295pmm) month by month at 10 degree latitude intervals to display the effects on changes of seasonal solar inputs. I think at lleast the last of these is worthmentioning in the brief.

  7. Increasing CO2 has little to no effect

    The only [snipped] wavelength of Earth's radiation the Co2 can effectively absorb is the 14-16 micron Band.  The other two bands are in an area where Earth radiation is minimal.

    NASA data now available shows that the 14-16 band energy is already totally absorbed at present levels of CO2.  (NASA Technical Memorandum 103957, Appendix E)

    Therefore more CO2 can not result in more energy absorption, thus can have no effect on Warming.

    This information is only recently available.  

    It is time to quit trying to find complicated verbal arguements trying to get around the facts.

    Moderator Response:

    [BL] Strike five. As this user seems to have nothing else to say except to repeat this snippet, he will no longer be participating in this forum.


  8. Wildfires are not caused by global warming

    Scott @12 , thank you for the link to the Royal Society research article (by Doerr & Santin) published in 2016.  This was somewhat earlier than the disastrous wildfires recently in Australia and in California ~ disastrous not so much in their extent as in their effect on human lives & livelihoods.

    Also earlier than the more recent ( non-Mediterranean ! ) wildfires in Canada that were "smoking out" regions of New England, into the bargain.

    Also earlier than the [current] disastrous wildfires in southern Greece and Rhodes.  (Difficult to picture a more Mediterranean scenario than southern Greece and Rhodes.)   Human impact is a large factor in assessing the significance of fires ~ but I am sure the inhabitants & tourists in Rhodes are at present comforted by by the knowledge that the island of Rhodes is small in area, in global terms.


    [IPCC] was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 ... to provide policymakers with regular assessments on the current state of knowledge about climate change.  [And was endorsed by the UN General Assembly in 1988.]      So I suppose we can say that the IPCC is a political body in a sense . . . perhaps rivalling the well-known political nature of the WMO.    Scott , you need to explain what you mean by the "political agenda"  being "pushed"  by all these international bodies.  Are they in any way partisan or nefarious?

  9. 2023 SkS Weekly Climate Change & Global Warming News Roundup #29

    Wild and One:

    I'm going to have to express some disagreement. Although in public discourse and discussion there may be reasons to keep emphasizing the links between human activities, fossil fuels, and changing climates, in the scientific discussion (which Skeptical Science tries to focus on), the terms such as "climate change" have specific scientific meaning.

    Not all climate change is induced by burning fossil fuels or other recent human activities. Using vocabulary that fails to recognize that will lead to a risk of losing credibility. Number 1 on the SkS "Most used climate myths" is "Climate's changed before". Number 89 is "They changed the name from 'global warming' to 'climate change'." Number 209 is "IPCC edited out natural causes of climate change".

    It's unfortunate, but you need to be careful on how contrarians will twist your words.

  10. Wildfires are not caused by global warming

    Scott @ 12:

    Frankly, you appear to be having some difficulty in reading comprehension. You make the serous accusation that "the IPCC is a political body with a political agenda to push", but you have very little in the way of logic or data to support that claim. Such an accusation flirts with the Comments Policy here, but let's entertain your case for a bit.

    So,, you reference in your very first paragraph "the diagram from the IPCC". Can you be specific as to which diagram you are referring to? The original post references the IPCC just once, near the end, where is says:

    ...the latest IPCC report found in 2014 that “fire weather is projected to increase in most of southern Australia,” with days experiencing very high and extreme fire danger increasing 5–100% by 2050.

    The first diagram in the post, in the tweet from Robert Rhode, has no citation, but states that the data are from the Australian Bureau of Meteorology. The graph is for Australia.

    The second diagram is for California data. Again, the diagram is not attributed to a reference, but states "Data from Cal Fire", and is titled "California Wildfire Acres Burned".

    The third diagram looks at the forest area burned in the western US. It is sourced from page 1105 in the referenced  Fourth National Climate Assessment. The "national" part of that report title relates to its origin: the US Global Chance Research Program.

    ..and that is the last diagram in the post. So where is this "diagram from the IPCC"???

    The original post also makes specific reference to Australia and California in its opening paragraph (the green box at the top). Under "heat worsens wildfires", the post specifically says (emphasis added):

    In simple terms, vegetation and soil dry out, creating more fuel for fires to expand further and faster. This is particularly a problem in Mediterranean climates that are prone to drought, like in California and Australia.

    So, the post is specifically looking at certain regions. What about the paper you link to? You make the claim:

    Yet research published by the Royal Society shows the opposite...

    Now, you do add "(globally)" after that. But why are you presenting this as if it evidence that goes again the evidence provided for Australia, California, and the western US? If we dig into that reference (which is now 7 years old), what we find is statements like the following, in their Synthesis and Conclusion:

    We do not question that fire season length and area burned has increased in some regions over past decades, as documented for parts of North America, or that climate and land use change could lead to major shifts in future fire consequences, with potential increases in area burned, severity and impacts over large regions

    That reference discusses many of the factors affected fire statistics, and make frequent reference to regional variations. (It also provides no new research - it is a review of existing research and expresses an opinion.)

    And the figure you provide - which you introduce with "In particular in Europe..." is, as it says in the caption (which you included), for the European Mediterranean region.

    So, your case seems to boil down to "but if we average out the areas where burning is less with the areas where burning is more, then the areas where burning is more won't be affected"??? Add in a bit of "but if there is not a trend in current data, there won't be a problem in the future", and you have someone that simply does not like the science. The OP and the references all indicate that increased risk of fire is something that is worth worrying about.

  11. Wildfires are not caused by global warming

    Something is not adding up here. The diagram from the IPCC shows the area of wild fires increasing (for the Western US). Yet research published by the Royal Society shows the opposite (globally) and I give a link to the article:

    "Analysis of charcoal records in sediments [31] and isotope-ratio records in ice cores [32] suggest that global biomass burning during the past century has been lower than at any time in the past 2000 years."

    "The availability of satellite data now allows a more consistent evaluation of temporal patterns in area burned. Thus, from an analysis based on MODIS burned area maps between 1996 and 2012, Giglio et al. [35] present some rather notable outcomes. In contrast to what is widely perceived, the detected global area burned has actually decreased slightly over this period (by 1% yr−1). A more recent global analysis by van Lierop et al. [36], based primarily on nationally reported fire data supplemented by burned area estimates from satellite observations, shows an overall decline in global area burned of 2% yr−1 for the period 2003–2012."


    In particular in Europe there has been a gradual declining trend in area burnt since 1980: Wildfire occurrence (a) and corresponding area burnt (b) in the European Mediterranean region for the period 1980–2010. Source: San-Miguel-Ayanz et al. [37].

    Wildfire occurrence (a) and corresponding area burnt (b) in the European Mediterranean region for the period 1980–2010. Source: San-Miguel-Ayanz et al. [37].


    Given that the concern should be for GLOBAL CO2 why is the emphasis on wild fires in the Western US? I'm beginning to suspect that the IPCC is a political body with a political agenda to push.

  12. One Planet Only Forever at 05:43 AM on 25 July 2023
    2023 SkS Weekly Climate Change & Global Warming News Roundup #29


    I agree. And my initial impulse was to simply add the importance of reducing unnecessary consumption, especially energy consumption. More is not always an improvement.

    Then I wondered about the merit of the change. It seems that the problem is that when there is competition for the ‘popularity of ideas’ rather than ‘evaluation of the merit of ideas’ less ethical and more misleading marketers have a competitive advantage. Successful misleading marketing has already developed many people who are interested in dismissing or denying that fossil fuel use is a significant problem – mainly because they consider that ‘their perceived benefits from fossil fuel use’ off-set or justify ‘any perceived harm done’ (higher discount rates used by the likes of Nordhaus are examples of that). And adding the mention of fossil fuels may not change that.

    However, it is important to avoid distracting debates about what is ‘more or most helpful’ among the diversity of helpful harm reduction understandings and actions. Many things are helpful and need to, and can, happen concurrently to improve conditions for others, especially for future generations.

    My interest is increased awareness and improved understanding regarding Sustainable Development. I have developed the understanding that a root of the problem is that a lot of harmful unsustainable actions have become popular and profitable ... and ... a lot of misunderstanding exists that resists correction because becoming more aware of, ‘awakening to’, the harmfulness of what has developed leads to changes that can reduce developed perceptions of superiority.

    Applying the Imrov Comedy approach of “Yes ... And” may be helpful. So...

    Yes to calling it many versions of ‘fossil fuel use caused climate change’

    And ... Consider saying climate change ‘primarily’ caused by fossil fuels.

    And ... Consider mentioning that there are many other harmful impacts of fossil fuel extraction, processing and use.

    And ... An additional related problem is misleading marketing fuelling misunderstandings.

    Yes to the list of actions

    And ... Reduce unnecessary consumption, especially energy consumption. Limiting unnecessary actions is not harmful no matter what is claimed by people who like benefiting from being unnecessarily harmful.

    And ... Minimize the harms done by the remaining necessary actions. Note that actions that limit climate change should not cause other harms.

    And ... Repair the damage that has been done ... and ... require those who benefited most from the damage done to do the most to repair the damage done. Note that not everyone in a ‘most harmful nation’ is a ‘most harmful person’... and ... Very high impact people can hide in a nation that has low per capita impacts.

    And ... Understand that the current developed, and developing, condition includes harmful over-consumption and related developed desires to resist giving up any of the incorrectly and unjustified developed perceptions of superiority or opportunity to obtain more personal benefit.

    And ... Understand that mitigation and adaptation are both versions of ‘repair of damage done’, including the damaging fundamentals of developed socioeconomic political systems, especially the harmful ‘conflict of interests’ and related desires for more freedom to do whatever a person or group develops an interest or desire to do.

    And ... Help people increase their awareness and understanding of what is harmful, which includes helping others become more aware of the importance of more people becoming “more woke”.

    And ... Call-out harmful people who try to promote the misunderstanding that “being woke” is harmful. More people being more woke only harms the interests of people who want to benefit from lack of awareness and harmful misunderstandings. Woke is a Helpful and necessary part of harm reduction


    Understand that it is harmful for leaders to compromise actions that would reduce harm done by ‘being considerate and accepting of harmful interests and related misunderstandings’. Some people will passionately resist learning to be less harmful and more helpful. They are personally interested in having more freedom to believe and do whatever they perceive to be ‘beneficial to them’.

    ... A more comprehensive understanding may be ...

    Harmful climate change and resistance to limiting and repairing the harm done is due to unnecessary and harmful human activity that incorrectly became popular and profitable. And the developed harmful activity and related misunderstandings can powerfully resist being limited and corrected.

  13. wilddouglascounty at 15:01 PM on 24 July 2023
    2023 SkS Weekly Climate Change & Global Warming News Roundup #29

    The term "climate change" has buried the lead for too long, so it's time to correct this. When Sammy Sosa, Barry Bonds and Mark McGuire were not voted into the Baseball Hall of Fame, it was not because of Home Run Change, it was because of Performance Enhancing Drugs. And everyone who watches baseball knows that.

    When the severity and frequency of extreme weather increases, the sea level rises and gets more acidic, wildlife populations move and wildfires abound, it is not because of Climate Change. It's because fossil fuel use that has changed the atmospheric and oceanic chemistry, allowing it to store more heat, changing the climate. Everyone who watches the weather needs to be reminded of that, too.

    It's time to stop using euphemisms that don't explicitly connect the changing climate to fossil fuel use so that folks understand in the same way that folks understand the role of performance enhancing drugs in sports. Everyone needs to be reminded of the role fossil fuels has in climate change, just as they know about the role of performance enhancing drugs in turbocharging the natural talents of the users. Whenever discussing any of the things related to Climate Change we should make that link explicit by using phrases like:

    - Fossil fuel induced Climate Change

    - Increased greenhouse gases from Fossil Fuel use

    - Climate Change caused by Fossil Fuel use

    - Changed atmospheric chemistry through the widespread use of fossil fuels

    and the like. And if someone says that you're politicizing the weather, tell them that this isn't just political; it's based on overwhelming scientific evidence. Refer them to the IPCC or skepticalscience websites if they are still deniers, and change the focus to how to become more energy efficient first, replace fossil fuel use with renewables second, and nurture local ecosystems third. We don't have a choice but to make things super-clear if we are to have a chance to turn the ship away from almost unimaginable disasters for future generations.

  14. Water vapor is the most powerful greenhouse gas

    Please note: the basic version of this rebuttal has been updated on July 23, 2023 and now includes an "at a glance“ section at the top. To learn more about these updates and how you can help with evaluating their effectiveness, please check out the accompanying blog post @

    The intermediate version was updated as well to update some links.

  15. At a glance - Empirical evidence that humans are causing global warming

    Re. #1, yes it does. At a glance is a very brief explanation aimed purely at the lay-person, who it is assumed has never heard of any of the figures involved in the history of climate science. We cover the latter topic in detail elsewhere at Skeptical Science.

    However, your account of the experiments performed by Horace-Benedict de Saussures is very interesting and not widely known - evidently! It would fit well into The History of Climate Science:

    We do update the history page as new information becomes available so if you could use the Contact link to email your translation to us, we can splice it in (with attribution) at some point - thanks in advance!

  16. At a glance - Empirical evidence that humans are causing global warming

    This brief greenhouse gas theory history omits the very important paper, "On the Influence of Carbonic Acid in the Air Upon the Ttemperature of the Ground,"the first true model of the effect, the hand-calculated model by Svante Arrhenius published in 1896. It modeled the atmosphere as a single layer and the effect of setting the concentration of CO2 to 2/3 of the value at his time, and at values up to 3 times higher, for 10 degree latitude steps both north and south, for 4 seasons and for the annual mean. His results for this simple model were within a factor of 10 of current calculations and measurements as the value has grown. His interest was in explaining newly discovered evidence of ancient ice ages.

    You also omit Horace-Benedict de Saussures' important measurements (in "Continuation du Voyage Autour du Mont-Blanc," Chapter XIII, Voyages dans les Alpes VII, 1779, S . Fauche, Neuchatel, pp353-355, and pp365-367). The first demonstrates the existence of "chaleur obscure" (="dark heat" = infrared radiation) and its reflection and concentration, using metal mirrors, just like visible light. The second records measurements of the greenhouse effect temperature rise in a cubic foot wooden box, insulated on all but one side with blackened cork, and that side closed by two layers of glass. He placed thermometers between the glass layers and inside and outside the box, and traveled the assembly from sea level up to high altitude in the Alpes, measuring the temperatures inside and outside the box as he went. He ascribes the decrease of temperature with altitude to the increasing transparency of the air as you  ascend. I made a translation from the French which is available upon request. Fourier refers to this work in the paper of 1827 cited above.

  17. Increasing CO2 has little to no effect

    Most of the major climate indices (ENSO, AMO, PDO, QBO, AO, SAM, MJO, NAO, SOI) show no signs of AGW, as the characteristic secular trend is missing, The only one that does is the IOD, as the West IOD shows a much larger trend than East. In any case, all the indices can be explained by a tidal mechanism, which should be good news to those that worry that natural climate change has no constraints — tides always revert to a mean of zero =>

  18. PollutionMonster at 18:36 PM on 17 July 2023
    “It’s almost like a cult.” Activists shout down rural renewable energy projects

    One part that stuck with me when watching the entire video was that they spent all their time as anti-renewables. This shows that the distrubtive protestors themselves were victims.

    I was a denier in the past and perhaps the greatest harm was it was a huge time sink for me. All that time watching conspiracy thinking videos, books, and going to meetings could have been better spent.

  19. Increasing CO2 has little to no effect

    Please note: the basic version of this rebuttal has been updated on July 16, 2023 and now includes an "at a glance“ section at the top. To learn more about these updates and how you can help with evaluating their effectiveness, please check out the accompanying blog post @

    Thanks - the Skeptical Science Team.

  20. There's no empirical evidence

    The intermediate level version of this rebuttal has been updated with some more current data as well.

  21. The FLICC-Poster - Downloads and Translations

    Nick Palmer @11

    Thanks for your feedback, Nick! I'm however not quite sure what kind of examples you would have liked to also see on the poster. Could you please provide an example? Should it be along the lines of the "Discourses of climate delay", then klimafakten might have something for you in the form of a quiz (and also a poster):

  22. The FLICC-Poster - Downloads and Translations

    What a great poster this is. Those of us 'in the business' know exactly what each item means but, for the general public, the only criticisim I have is that it would have been so much better if it included examples of the rherorical deceit alluded to. Communicating science is hard enough, but trying to point out how people are being misled is so much harder.

  23. One Planet Only Forever at 07:27 AM on 16 July 2023
    2023 SkS Weekly Climate Change & Global Warming News Roundup #28

    In related news, the usual leadership culprits from Alberta and Saskatchewan angrily oppose the federal government's stated objectives including getting COP28 to require the phasing out of unabated fossil fuel projects (without a strict timeline for the stages of the phase-out of unabated projects ... in other words ... just words with no required compliance measurement basis ... in other words ... almost meaningless).

    CBC News: Western premiers push back as Guilbeault calls for 'phase-out of unabated fossil fuels'

    The following quote from the article summarizes what happened among global leaders that the regional leadership in Alberta and Saskatchewan, and perhaps Canada's federal government, object to ... with the only justification appearing to be that it restricts their ability to benefit from continuing to benefit from being more harmful than others (per capita).

    Canada, UAE face pressure to be more ambitious

    When the meeting of international ministers concluded, several countries issued their joint statement that seemingly departed from remarks made by Canada and the U.A.E.

    Countries that support a climate diplomacy bloc, the High Ambition Coalition, called for "an urgent phase out from fossil fuels."

    Ministers from France, Germany, Spain, Ireland and others said this needs to start with a "rapid decline of fossil fuel production and use within this decade."

    It goes on to say that technologies such as carbon capture cannot be used to help prolong the life of the oil and gas industry.

    "Abatement technologies must not be used to green-light continued fossil fuel expansion but must be considered in the context of steps to phase out fossil fuel use and should be recognized as having a minimal role to play in (the) decarbonization of the energy sector," the online statement read.

    The head of a network of climate advocacy organizations said the use of "unabated fossil fuels" waters down the action required to reduce carbon emissions, but admitted the language is still more ambitious than previously proposed by the U.A.E's COP president-designate.

    "Obviously, the word unabated is still a weasel word, but we are progressing in a good direction at the very least," said Caroline Brouillette, the executive director of Climate Action Network Canada.

  24. OA not OK part 20: SUMMARY 2/2

    mm @81,

    The 'plankton and shellfishes' are expending energy pumping ions about, concentrating Ca2+ where it is required** while ejecting H+. I'm afraid the biochemistry of all this pumping is beyond my pay grade (although it could be obtained form them what knows their biochemistry. As an exemplar, consider Calcium ATPase).

    ** Apparently regulating Ca2+ concentration in biology is a common process, but mainly to keep Ca2+ levels down.

  25. PollutionMonster at 17:42 PM on 15 July 2023
    CO2 limits will hurt the poor

    This might sound stupid. I've read from a few websites that the North East United States has gotten more rain from climate change. I don't have much money and have a leaky roof nor the do it yourself skills to fix the roof.

    Now I have a mold problem. Anyways somebody close to me said that mold hates heat. That people use heated cables to kill mold. Therefore even in summer we have been running space heaters to kill the mold. Yet, it doesn't seem to be working.

    Furthermore, I heard about dry rot so I thought the best way to kill mold was heat and moisture. This seems to have backfired. If anything mold seems to like it hot and humid. Afterwards, I read about how dry rot is a misnomer whoops. I consider myself high in critical thinking skills and yet I still make costly mistakes. Best to have some humility.

    I've been running fans in the doors and windows, but the humidity outside is 91% if anything it might be making the situation worse especially when it rains.

    To summarize, can anyone confirm that the overall precipitation trend is increasing in the North East United States from climate change? Second, climate change really does seem to hurt the poor more. I don't think I contribute much co2, yet I cannot afford to fix my leaky roof worsen by climate change. Third, does anyone have any environmentally friendly ways to control mold and humidity?

  26. The FLICC-Poster - Downloads and Translations

    Three more language versions of the FLICC-poster were added on July 14: French (FLIPiC), Luxembourgish (FLOKK) and Polish (PLOWS).

  27. Philippe Chantreau at 09:15 AM on 15 July 2023
    How big is the “carbon fertilization effect”?

    Helpful Michael, thanks.

  28. michael sweet at 06:21 AM on 15 July 2023
    How big is the “carbon fertilization effect”?

    Philippe Chantreau at 29,

    Here is a free copy of the Rodell and Li 2023 paper.  The graphs and tables are at the bottom of the paper.  The captions are separate from the graphs.

  29. Philippe Chantreau at 12:41 PM on 14 July 2023
    How big is the “carbon fertilization effect”?

    Thanks for the additional info Bob. Besides the apparent weaknesses I pointed, that paper was also from 1994 so I wasn't going to put too much stock in it...

  30. How big is the “carbon fertilization effect”?

    Philippe @ 29:

    Yes, SB Idso would be that Sherwood Idso. He has been getting things wrong about CO2 and climate change for something like 40 years, since his early claims that surface temperature was not sensitive to CO2 concentration. He made those claims on the basis of "natural" experiments comparing surface temperature variation to surface changes in incoming IR radiation.

    His mistake there was to not recognize that the important IR changes are the ones for outgoing IR radiation at the top of the troposphere (earth energy balance), not the surface ones (surface energy balance). It's such a shame, as he was a very good microclimatologist in his early years. He moved big time into the CO2 is fertilizer realm many years ago.

    He's listed at Desmog:

    Sherwood B Idso

    and has turned his denial into a family business, including his sons.

    Craig Idso

    Keith Idso

    Desmog also has a page on the family business:

    I am not at all surprised that Dave Burton would find them a useful source of "information".

  31. Rob Honeycutt at 07:30 AM on 14 July 2023
    How big is the “carbon fertilization effect”?

    Dave @22... In order to at least attempt to make this a productive discussion I'm going to focus in on one small point. That is the "greening is turning to browning" which you're rejecting with incessent copy/paste Gish Gallop and little genuine engagement.

    FAQ 5.1 | Is the Natural Removal of Carbon From the Atmosphere Weakening?

    For decades, about half of the carbon dioxide (CO2) that human activities have emitted to the atmosphere has been taken up by natural carbon sinks in vegetation, soils and oceans. These natural sinks of CO2 have thus roughly halved the rate at which atmospheric CO2 concentrations have increased, and therefore slowed down global warming. However, observations show that the processes underlying this uptake are beginning to respond to increasing CO2 in the atmosphere and climate change in a way that will weaken nature’s capacity to take up CO2 in the future. Understanding of the magnitude of this change is essential for projecting how the climate system will respond to future emissions and emissions reduction efforts. [emphasis added]

    Please tell me how you square the idea of "Is natural removal of carbon
    from the atmosphere weakening? No..." with the above text in bold, taken from the exact same AR6 FAQ 5.1.

  32. Philippe Chantreau at 07:24 AM on 14 July 2023
    How big is the “carbon fertilization effect”?

    I am late for this party as many have provided answers and further explored the subject. I will only mention a couple of things from a post further back that was on the wrong thread. 

    A citation in that post was this article:

    Quotes of interest from the abstract:

    "Greatest yield stimulations occurred in the e[CO2 ] late sowing and heat stressed treatments, when supplied with more water." 

    "There were no clear differences in cultivar response due to e[CO2 ]. Multiple regression showed that yield response to e[CO2 ] depended on temperatures and water availability before and after anthesis."

    My main point was that water availability is the major controlling factor.

    Another was not peer-reviewed but a "working paper" from a think tank:

    This paper claims to establish a causal link between agricultural yields and CO2 atmospheric content. They use a six year sample and then attempt to regress backward to the post-war era. I did not bother downloading the pdf so I am not sure about how they controlloed for other factors in the sample and how they integrated the enormous changes in agricultural methods post-war, like increased mechanization  fertilizers, pesticides, herbicides, irrigation, etc. They write this interesting snippet: "In a thought exercise, we apply the CO₂ fertilization effect we estimated in our sample from 2015-2021 backwards to 1940, and, assuming no other limiting factors, find that CO₂ was the dominant driver of yield growth..." So the working paper amonts to a thought exercise involving a rather gigantic assumption.

    The third included S.B. Idso as an author, possibly of infamous CO2 Science website affiliation (I did not verify that). I could only access the abstract and it mentioned nothing about other factors than CO2, such as water availability.

    In post #24, drought is mentioned and Hao et al (2014) is mentioned, with a graph that generated excitement at WUWT come years ago. The data ends in 2012. Looking at more data extending to recent times reveals a different picture, as shown by Rodell and Li (2023) in Nature Water:


    Of course, in greenhouses with very controlled conditions and water distributed carefully, concentrations in excess of 1000 ppm give good results, that remains true.

  33. Rob Honeycutt at 06:27 AM on 14 July 2023
    How big is the “carbon fertilization effect”?

    Daniel @25... So is the Gish Gallop.

  34. How big is the “carbon fertilization effect”?

    Yes, Daniel, Mr Burton certainly is consistent in wandering off topic in his comments. At least in this case he followed it off the Hansen post, but now he is mixing in CO2 fertilization and drought.

    He is also showing his years of experience in picking cherries.

    So many of the "CO2 is plant food" argument depend on studies in greenhouses, etc, where other limiting factors are not limited. The SkS post "Plants cannot live on CO2 alone" provides background. That may be a better place to continue this discussion.

    As for his drought comments, he has picked a global diagram (figure 5 out of the Hao et al paper he references) that  contains absolutely no regional information at all.

    Figure 2 from that paper (available online) shows some examples of the regional droughts as detected by their methodology, but the paper does not provide any information about regional trends. The figure (below) does indicate that "global" really is rather global. I suspect that changes in the desert zones (look at the Sahara) or high latitudes have little effect on agricultural productivity.

    Hao et al figure 2


    Mr. Burton's U.S. drought trend also suffers the same failure: ignoring regional trends. It is also purely a precipitation-based wet/dry analysis - not looking at the important temperature effects on drought. And each classification of "very wet/very dry" is solely an indicator of whether each region is wetter or drier than its own regional value - which tells us very little about drought. Quoting from the original source:

    Climate divisions with a standardized anomaly in the top ten percent (> 90th percentile) of their historical distribution are considered "very warm/wet" and those in the bottom ten percent (< 10th percentile) are classified as "very cold/dry".

    A normally very wet area that is only seeing precipitation in its bottom 10 percent will in all likelihood still be getting more precipitation than a normally dry area that is in its top 10 percent. The student that typically gets 85-95% on exams and score 85% on this one still gets a better grade than the student that typically gets 65-75% on exams and scores 75% on this exam.

    If you start to look at regional patterns, other features begin to emerge. SkS had a re-post of a 2018 Carbon Brief article that looks at specifics. It gives a good explanation of the factors other than precipitation that need to be considered. When it comes to agriculture, even the "correct" amount of precipitation can be bad if it is at the wrong time. Fields that are "too wet to plough", crops ready for harvest that are rotting in the fields and can't be harvested, etc.

    As usual, Tamino does an excellent job of taking data and picking out regional patterns. He did one in 2019, looking at "The West Burns and the East Drowns - so it averages out, right?". Spoiler alert: the two regions show different trends. Borrowing two of his images:

    Tamino US west PDSI

    Tamino US Central PDSI


    Tamino also had a post in 2018 about US drought patterns. Again, there are major regional differences, with the west (especially the southwest) getting drier, and the northeast getting wetter.

    The sort of analysis that Mr. Burton is presenting is the kind of argument that leads one to conclude that the average person has one testicle and one breast.

    Follow-ups on the drought discussion should probably be removed from this thread and posts on the 2018 Carbon Brief article repost.

  35. How big is the “carbon fertilization effect”?

    Daniel Bailey @25 ,

    Yes, agreed, the off-topic is strong . . . and the copying-and-pasting is strong . . . and the Motivated Reasoning is strong.   Twas ever thus, on the Dark Side of the Force  ;-)

    Daveburton @24 ,

    Thank you ~ and you are quite correct about the [magnitude of]  reduced nutritive value of crops in some circumstances.  I mentioned the matter briefly (as a one-liner) as a reminder that one is dealing with vastly  complex biological systems . . . and that one should avoid having a religious fervor for the undoubted benefits of high CO2 for [most] plants.

    Daveburton, you get yourself in a tangle by your third paragraph.   "No possible mechanism"  [unquote] by which a higher CO2 level could cause an increase in natural carbon sink rate?   An examiner would quote that as a Howler, to be circulated for the amusement of his fellow markers.   # Dave, possibly you were expressing yourself extremely poorly . . . but either way, you go on to contradict yourself in one of your later paragraphs.   And you re-contradict yourself in yet another paragraph.  [ Is "re-contradict"  an English word?]

    And then you re-re-contradict yourself soon after.

    [ Oy Veh  to the O.E.D. ]

    Moving on . . . Daveburton, you are looking at the world through a straw.  Please look at the whole world, not just the 49-state USA.   Droughts /floods /heat-waves already are (and will be) increasingly problematic, thanks to AGW.   Unfortunately, the important staple crop maize [yield] is exceptionately sensitive to high and/or prolonged heat-waves.  Luckily, other staple crops are "not quite so much" . . . but the plant geneticists have their work cut out for them, to keep up with future changes.

  36. OA not OK part 20: SUMMARY 2/2

    Hi, I was wondering why CaCO3 precipitate precisely on plankton and shellfishes. Are they catalizing the formation of CaCO3 (i.e. changing some of the reaction cinetic in some ways) locally? If so, what is the contribution on the overall slow C cycle? Would it "turn" much slower if they weren't there?
    PS: Thanks for this amazing website :)

    Moderator Response:

    [BL]  Please avoid posting the same comment on multiple threads. It leads to a fragmented discussion when people respond.

    Readers will find all recent comments on the Comments page. There is a link to that page in the middle of the menu, just below the main header.


  37. OA not OK part 13: Polymorphs - the son of Poseidon

    Hi, I was wondering why CaCO3 precipitate precisely on plankton and shellfishes. Are they catalizing the formation of CaCO3 (i.e. changing some of the reaction cinetic in some ways) locally? If so, what is their contribution to their catalization to the overall  slow C cycle? Would it "turn" much slower if they weren't there?
    PS: Thanks for this amazing website :)

    Moderator Response:

    [BL] For readers wanting to respond to this, please note that the question was asked twice, on two different threads. Please do not respond here - place all responses on the other thread.

  38. Daniel Bailey at 04:09 AM on 14 July 2023
    How big is the “carbon fertilization effect”?

    The off-topic is strong in this one.

  39. How big is the “carbon fertilization effect”?

    Eclectic wrote, "Daveburton @22 ~ Please explain more of your first chart [ IPCC's decadal Carbon Flux Comparison 1980-2019 ]. The natural sink flux figures… show a rather steady proportionality to the total carbon emissions."

    Glad to. Any two things which steadily increase are thereby correlated. There's only a possibility that the relationship might be causal if there's a possible mechanism for such causality.

    There's no possible mechanism by which the rate at which CO2 emerges from chimneys could govern the rate at which CO2 is taken up by trees & absorbed by the oceans, or vice-versa, so the relationship cannot be causal — just as this famous relationship is not causal:

    does cheese consumption cause death by bedsheet entanglement?

    Eclectic wrote, "The land sink shows about 30-35% of total emissions, while the sum of land & ocean remains around 55-60%."

    Yes, I usually say "about half," as in, "If our CO2 emissions were cut by more than about half then the atmospheric CO2 level would be falling, rather than rising."

    It is important to recognize that the relationship is merely coincidental, not causal.

    Eclectic wrote, "as the decades progress, the natural carbon sink flux in absolute terms rises with the rising emissions ~ but does not show a proportional increase."

    The rate at which natural processes, such as ocean uptake, uptake by trees and soil ("greening"), and rock weathering, remove CO2 from the air, is affected in minor ways by many factors, but in a major way by only one: the current amount of CO2 in the air.

    Our CO2 emission rate does not and cannot affect the natural removal rate, except indirectly, in the long term, by being one of the most important factors which affect the amount of CO2 in the air.

    Eclectic wrote, "looking back in time ~ as the atmospheric CO2 level decreases, the size of the natural sink flux decreases also."

    That is correct. It will also be correct looking forward in time, when CO2 levels are falling, someday.

    Eclectic wrote, "this directly contradicts your hypothesis of 'if emissions were halved ... atmospheric CO2 level would plateau.'"

    If you'll allow me to use "halved" as a shorthand for "reduced to the point at which emissions merely equal current natural removals, rather than exceed them," then those two statements are both correct, and perfectly consistent. It's pCO2 (level), not the rate of CO2 emissions, which (mostly) governs the rates of all the natural CO2 removal from the atmosphere.

    Of course there are also minor factors which affect the removal rates. For instance, as we've already discussed, a 1°C rise in water temperature slows ocean uptake of CO2 by roughly 3%. Conversely, a rise in air temperature accelerates CO2 removal by rock weathering. (Sorry, I don't have a quantification of that.) But the main factor which controls the rate of CO2 removals is pCO2.

    Eclectic wrote, "While the nutritive components of some food crops may reduce slightly as CO2 rises…"

    Oh boy, another rabbit hole! That's the Loladze/Myers "nutrition scare."

    It is of little consequence. That should be obvious if you consider that crops grown in commercial greenhouses with CO2 levels as high as 1500 ppmv are as nutritious as crops grown outdoors with only 30% as much CO2.

    CO2 generator

    ≥1500 ppmv CO2 is optimal for most crops. That's why commercial greenhouses typically use CO2 generators to raise daytime CO2 concentration to well above 1000 ppmv. It is expensive, but they go to that expense because elevated CO2 (eCO2) makes crops much healthier and more productive. (They don't typically supplement CO2 at night unless using grow-lamps, because plants can't use the extra CO2 without light.)

    If elevating CO2 by >1000 ppmv doesn't cause crops to be less nutritious, then elevating CO2 by only 140 ppmv obviously doesn't, either.

    Better crops yields, due to eCO2 or any other reason, can cause lower levels (but not lower total amounts) of nutrients which are in short supply in the soil. But that doesn't happen to a significant extent when agricultural best practices are employed.

    I had an impromptu online debate about the nutrition scare with its most prominent promoter, mathematician Irakli Loladze, in the comments on a Quora answer. If you're not a Quora member you can't read it there, so I saved a copy here. He acknowledged to me that food grown in greenhouses at elevated CO2 levels is as nutritious as food grown outdoors.

    Faster-growing, more productive crops require more nutrients per acre, but not more nutrients per unit of production.

    Inadequate nitrogen fertilization reduces protein production relative to carbohydrate production, because proteins contain nitrogen, but carbohydrates don't. Likewise, low levels of iron or zinc in soils cause lower levels of those minerals in some crops. So, it is possible, by flouting well-established best agricultural practices, to contrive circumstances under which eCO2, or anything else which improves crop yields, causes reduced levels of protein or micronutrients in crops.

    But farmers know that the more productive crops are, the more nutrients they need, per acre. Competent farmers fertilize accordingly.

    Or, for nitrogen, they may plant nitrogen-fixing legumes — which benefit greatly from extra CO2.

    If you don’t fertilize according to the needs of your crops, negative consequences may include reductions in protein and/or micronutrient levels in the resulting crops. The cause of such reductions isn't eCO2s, it's poor agricultural practices.

    The nutrient scare is an attempt to put a negative "spin" on the most important benefit of eCO2: that it improves crop yields.

    Eclectic wrote, "it is (as you state) beyond argument that higher CO2 benefits overall crop yield & plant mass."

    That's correct. Moreover, agronomy studies show that for most crops the effect is highly linear as CO2 levels rise, until above about 1000 ppmv (which is far higher than we could ever hope to drive outdoor CO2 levels by burning fossil fuels). That linearity is obvious in the green (C3) trace, here:

    CO2 vs plant growth, C3 & C4

    That improvement is one of several major reasons that catastropic famines are fading from living memory.

    If you're too young to remember huge, catastrophic famines, count yourself blessed. Through all of human history, until very recently, famine was one of the great scourges of mankind, the "Third Horseman of the Apocalypse." But no more. This is a miracle!


    Ending famine is a VERY Big Deal, comparable to ending war and disease. Compare:

    ● Covid-19 killed 0.1% of world population.
    ● 1918 flu pandemic killed about 2%.
    ● WWII killed 2.7%.
    ● The near-global drought and famine of 1876-78 killed about 3.7% of the world population.

    Eclectic wrote, "other CO2/AGW concomitant effects of increased droughts /floods /heat-waves can be harmful to crop yields in open-field agriculture. [And especially so for the staple crop of maize.]"

    Well, let's examine those one at a time.

    Heat-waves. Overall, temperature extremes are not worsened by the warming trend. Heat waves are slightly worsened, but by less than cold snaps are mitigated. That's because, thanks to "Arctic amplification," warming is disproportionately at chilly high latitudes, and it is greatest at night and in winter. The tropics warm less, which is nice, because they're warm enough already.

    1°C is about the temperature change you get from a 500 foot elevation change. (That's calculated from an average lapse rate of 6.5 °C/km.)

    On average, 1°C is similar in effect to a latitude change of about sixty miles, as you can see by looking at an agricultural growing zone map. Here's one, from the Arbor Day Foundation:

    growing zones

    From eyeballing the map, you can see that 1°C (1.8°F) = about 50-70 miles latitude change.

    James Hansen and his colleagues reported a similar figure: "A warming of 0.5°C... implies typically a poleward shift of isotherms by 50 to 75 km..."

    1°C is less than the hysteresis ("dead zone") in your home thermostat, which is the amount that your indoor temperatures go up and down, all day long, without you even noticing.

    In the American Midwest, farmers can fully compensate for 1°C of climate change by adjusting planting dates by about six days.
    Des Moines temperature by month

    Floods. Theoretically, by accelerating the water cycle, climate change could increase the frequency or severity of floods. But the effect is too slight to be noticeable. AR6 says no change in global flood frequency is detectable:

    AR6 on floods

    Droughts. Droughts have not worsened. In fact, the global drought trend is slightly down. Here's a study:

    Hao et al. (2014). Global integrated drought monitoring and prediction system. Sci Data 1(140001). doi:10.1038/sdata.2014.1

    % of globe in drought

    Here's the U.S. drought trend (the bottom/orange side of the graph):

    U.S. very wet and very dry

    Not only does climate change not worsen droughts, it has long been settled science that eCO2 improves plants' water use efficiency (WUE) and drought resilience, by improving CO2 stomatal conductance relative to transpiration. So eCO2 is especially beneficial in arid regions, and for crops which are under drought stress.

    Maize (corn) has been very heavily studied. Even though it is a C4 grass, it benefits greatly from elevated CO2, especially under drought stress. Here's a study (one of many):

    Chun et al. (2011). Effect of elevated carbon dioxide and water stress on gas exchange and water use efficiency in corn. Agric For Meteorol 151(3), pp 378-384, ISSN 0168-1923. doi:10.1016/j.agrformet.2010.11.015.

    "There have been many studies on the interaction of CO2 and water on plant growth. Under elevated CO2, less water is used to produce each unit of dry matter by reducing stomatal conductance."

    Here's a similar study about wheat:

    Fitzgerald GJ, et al. (2016) Elevated atmospheric [CO2] can dramatically increase wheat yields in semi-arid environments and buffer against heat waves. Glob Chang Biol. 22(6):2269-84. doi:10.1111/gcb.13263.

    However, I agree with you that putting a monetary value on the benefits of CO2 for crops is difficult. In part that's because the price of food soars when it's in short supply, and plummets when it's plentiful. So, for example, if we were to attribute, say, 15% of current crop yields to CO2 fertilization & CO2 drought mitigation, and value that 15% using current crop prices, we would be underestimating the true value, because absent that 15% boost the prices would have been much higher.

  40. SkS Analogy 9 - The greenhouse effect is a stack of blankets

    Bobhisey @1 ,

    You have completely misunderstood the physics of the interaction of InfraRed radiation and CO2 (and other molecules).  

    Bob, you are an intelligent guy, and you have been hovering on the edges of the "climate debate" for ages now.  And yet you still keep failing to grasp the basics of science in this regard.  There must be some sort of mental block going on.  Know Thyself !

  41. SkS Analogy 9 - The greenhouse effect is a stack of blankets

    There is a logical fallacy at the root of this misleading analagy.  That is, if some CO2 absorbs some IR, then more CO2 will always absorb more.

    But CO2 can only effectively absorb the Earth's IR in one radiation band.  That of 14-16 microns wavelength.

    1992 NASA data shows that at present CO2  levels, the CO2 absorbs all of the enery in this band.  So more CO2 cannot absorb more energy-it is not there.

    My analogy.  If there is one cup of water in a bowl, and 1 sponge can absorb 1 cup.  1 sponges will not absorb 2 cups-it just isn't there.

    NASA Technical Memorandum 103957.  Appendix E.   This has not been available until very recently.   A full discussion can be found in "Carbon Dioxide-Not Guilty".  Hisey, 2022.  Kindle.

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  42. How big is the “carbon fertilization effect”?

    Daveburton @22  ~ Please explain more of your first chart [ IPCC's decadal Carbon Flux Comparison 1980-2019 ].

    The natural sink flux figures there are indeed broad brush, to be sure ~ but they show a rather steady proportionality to the total carbon emissions.    # The land sink shows about 30-35% of total emissions, while the sum of land & ocean remains around 55-60% .    It may not be statistically significant ~ but the proportion actually reduces as the emissions increase over the last 3 decades.

    In other words, as the decades progress, the natural carbon sink flux in absolute terms rises with the rising emissions ~ but does not show a proportional increase.

    The corollary of that is: looking back in time ~ as the atmospheric CO2 level decreases, the size of the natural sink flux decreases also.  Daveburton, this directly contradicts your hypothesis of "if emissions were halved ... atmospheric CO2 level would plateau."

    [B]  Papers such as Zhu et al. 2016 [Nature Climate Change] and the Charles Taylor & Wolfram Schlenker one (not peer-reviewed) you mention above . . . point out the multifactorial complexities in assessing the relevance of greening & browning (of vegetated land) where measured by Leaf Area Index (seen per satellite).  Very difficult to come to a substantive conclusion of value !    While the nutritive components of some food crops may reduce slightly as CO2 rises . . . nevertheless, it is (as you state) beyond argument that higher CO2 benefits overall crop yield & plant mass.

    However, Daveburton ~ and I presume that this has been pointed out to you many times before ~ the other CO2/AGW concomitant effects of increased droughts /floods /heat-waves can be harmful to crop yields in open-field agriculture.  [And especially so for the staple crop of maize.]

  43. How big is the “carbon fertilization effect”?

    Rob wrote elsewhere, "greening is now turning into 'browning.' ... fertilization [has now been] overwhelmed by other effects... In other words, the greening has now stopped," and here, "You were making the claim that natural sinks were removing more of our emissions, and that is not the case by any stretch of the imagination.""

    Here's AR6 WG1 Table 5.1, which shows how natural CO2 removals are accelerating:

    Here it is with the relevant bits highlighted:
    Or, more concisely:
    Excerpt from AR6 WG1 Table 5.1, showing how natural removals of carbon from the atmosphere are accelerating
    (Note: 1 PgC = 0.46962 ppmv = 3.66419 Gt CO2.)

    As you can see, as atmospheric CO2 levels have risen, the natural CO2 removal rate has sharply accelerated. (That's a strong negative/stabilizing climate feedback.)

    AR6 FAQ 5.1 also shows how both terrestrial and marine carbon sinks have accelerated, here:

    Here's the key graph; I added the orange box, to highlight the (small) portion of the graph which supports your contention that, "greening is now turning into 'browning.' ... fertilization [has now been] overwhelmed by other effects... In other words, the greening has now stopped."
    AR6 FAQ 5.1

    Here's the caption, explicitly saying that natural removal of carbon from the atmosphere is NOT weakening:
    AR6 FAQ 5.1 - Natural removal of carbon from the atmosphere is not weakening

    The authors did PREDICT a "decline" in the FUTURE, "if" emissions "continue to increase." But it hasn't happened yet.

    What's more, the "decline" which they predicted was NOT for the rate of natural CO2 removals by greening and marine sinks, anyhow. Rather, if you read it carefully, you'll see that that hypothetical decline was predicted for the ratio of natural removals to emissions.

    What's more, their prediction is conditional, depending on what happens with future emissions ("if CO2 emissions continue to increase").

    Well, predictions are cheap. My prediction is that natural removals of CO2 from the atmosphere will continue to accelerate, for as long as CO2 levels rise.

    The "fraction" which they predict might decline, someday, doesn't represent anything physical, anyhow. (It is one minus the equally unphysical "airborne fraction.") Our emission rate is currently about twice the natural removal rate, so if emissions were halved, the removal "fraction" would be 100%, and the atmospheric CO2 level would plateau. If emissions were cut by more than half then the removal "fraction" would be more than 100%, and the CO2 level would be falling.

    I wrote elsewhere, "This recent study quantifies the effect for several major crops. Their results are toward the high end, but their qualitative conclusion is consistent with many, many other studies. They reported, "We consistently find a large CO2 fertilization effect: a 1 ppm increase in CO2 equates to a 0.4%, 0.6%, 1% yield increase for corn, soybeans, and wheat, respectively.""

    If you recall that mankind has raised the average atmospheric CO2 level by 140 ppmv, you'll recognize that those crop yield improvements are enormous!

    Rob replied, "If you actually read more than just the abstract of that study you find this on page 3: 'Complicating matters further, a decline in the global carbon fertilization effect over time has been documented, likely attributable to changes in nutrient and water availability (Wang et al. 2020).'"

    Rob, I already addressed Wang et al (2020), but you might not have seen it, because the mods deemed it off-topic and deleted it. Here's what I wrote:

    Rob, it's possible that your confusion on the greening/browning point was due to a widely publicized paper, with an unfortunately misleading title:

    Wang et al (2020), "Recent global decline of CO2 fertilization effects on vegetation photosynthesis." Science, 11 Dec 2020, Vol 370, Issue 6522, pp. 1295-1300, doi:10.1126/science.abb7772

    Many people were misled by it. You can be forgiven for thinking, based on that title, that greening due to CO2 fertilization had peaked, and is now declining.

    But that's not what it meant. What it actually meant was that the rate at which plants remove CO2 from the atmosphere has continued to accelerate, but that its recent acceleration was less than expected. (You can't glean that fact from the abstract; would you like me to email you a copy of the paper?)

    What's more, if you read the "Comment on" papers responding to Wang, you'll learn that even that conclusion was dubious:

    Sang et al (2021), "Comment on 'Recent global decline of CO2 fertilization effects on vegetation photosynthesis'." Science 373, eabg4420. doi:10.1126/science.abg4420

    Frankenberg et al (2021), "Comment on 'Recent global decline of CO2 fertilization effects on vegetation photosynthesis'." Science 373, eabg2947. doi:10.1126/science.abg2947

    Agronomists have studied every important crop, and they all benefit from elevated CO2, and experiments show that the benefits continue to increase as CO2 levels rise to far above what we could ever hope to reach outdoors. Perhaps surprisingly, even the most important C4 crops, corn (maize) and sugarcane, benefit dramatically from additional CO2. C3 plants (including most crops, and all carbon-sequestering trees) benefit even more.

    Rob also quoted the study saying, "While CO2 enrichment experiments have generated important insights into the physiological channels of the fertilization effect and its environmental interactions, they are limited in the extent to which they reflect real-world growing conditions in commercial farms across a large geographic scale."

    That's a reference to the well-known fact that Free Air Carbon Enrichment (FACE) studies are less accurate than greenhouse and OTC (open top container) studies, because in FACE studies wind fluctuations unavoidably cause unnaturally rapid variations in CO2 levels. So FACE studies consistently underestimate the benefits of elevated CO2. Here's a paper about that:

    Bunce, J.A. (2012). Responses of cotton and wheat photosynthesis and growth to cyclic variation in carbon dioxide concentration. Photosynthetica 50, 395–400. doi:10.1007/s11099-012-0041-7

    The issue is also explained by Prof. George Hendrey, here:

    "Plant responses to CO2 enrichment: Much of what is known about global ecosystem responses to future increases in atmospheric CO2 has been gained through Free-Air CO2 Enrichment (FACE) experiments of my design. All FACE experiments exhibit rapid variations in CO2 concentrations on the order of seconds to minutes. I have shown that long-term photosynthesis can be reduced as a consequence of this variability. Because of this, all FACE experiments tend to underestimate ecosystem net primary production (NPP) associated with a presumed increased concentration of CO2."

    Rob wrote, "It does seem that you're claiming CO2 uptake falls with increasing temperature.""

    That is correct for uptake by water. Or, rather, it would be correct, were it not for the fact that the small reduction in CO2 uptake due to the temperature dependence of Henry's Law is dwarfed by the large increase in CO2 uptake due to the increase in pCO2.

    Rob wrote, "But it's unclear to me how you think this plays into the conclusion that CO2 levels would 'quickly normalize' over the course of 35 years" and also, "You also claimed CO2 concentrations would quickly come down (normalize) once we stop emitting it. This is also not correct unless you're using 'normalize' to mean 'stabilize at a new higher level'."

    Perhaps you've confused me with someone else. I said nothing about CO2 levels "normalizing."

    I did point out that the effective half-life for additional CO2 which we add to the atmosphere is only about 35 years. I wrote:

    The commonly heard claim that "the change in CO2 concentration will persist for centuries and millennia to come" is based on the "long tail" of a hypothetical CO2 concentration decay curve, for a scenario in which anthropogenic CO2 emissions go to zero, CO2 level drops toward 300 ppmv, and carbon begins slowly migrating back out of the deep oceans and terrestrial biosphere into the atmosphere. It's true in the sense that if CO2 emissions were to cease, it would be millennia before the CO2 level would drop below 300 ppmv. But the first half-life for the modeled CO2 level decay curve is only about 35 years, corresponding to an e-folding "adjustment time" of about fifty years. That's the "effective atmospheric lifetime" of our current CO2 emissions.

    Rob wrote, "Dave... The fundamental fact that you disputed is that oceans take up about half of our emissions."

    That reflects two points of confusion, Rob.

    In the first place, our emissions are currently around 11 PgC/year (per the GCP). The oceans remove CO2 from the atmosphere at a current rate of a little over 2.5 PgC/year. That's only about 1/4 of the rate of our emissions, not half.

    More fundamentally, the oceans are not removing some fixed fraction of our emissions. None of the natural CO2 removal processes do. All of them remove CO2 from the bulk atmosphere, at rates which largely depend on the atmospheric CO2 concentration, not on our emission rate. If we halved our CO2 emission rate, natural CO2 removals would continue at their current rate.

    Because human CO2 emissions are currently faster than natural CO2 removals, we've increased the atmospheric CO2 level by about 50% (140 ppmv), but we've increased the amount of carbon in the oceans by less than 0.5%, as you can see in AR5 WG1 Fig. 6-1.

    Sorry, this got kind of long. I hope I addressed all your concerns.

  44. Rob Honeycutt at 11:23 AM on 13 July 2023
    How big is the “carbon fertilization effect”?

    Dave... The fundamental fact that you disputed is that oceans take up about half of our emissions. It's a fact that has been clearly stated in the citations both of us have presented.

    You also claimed CO2 concentrations would quickly come down (normalize) once we stop emitting it. This is also not correct unless you're using "normalize" to mean "stabilize at a new higher level". But they're not going to stabilize back to 300ppm.

  45. How big is the “carbon fertilization effect”?

    Rob, in answer to your first question, Bob is correct: they use different units.

    Both the graph and the "plug in suitable values" calculation (above) are for freshwater, but that hardly matters. CO2 is noticeably less soluble in saltwater, but the effect of temperature on CO2 solubility is nearly identical. Here's the same calculation with salinity 35 (typical seawater), for a 1° temperature increase (from 288K to 289K):

    1 - ( (e^( -60.2409 + (93.4517*(100/289)) + (23.3585* ln(289/100)) + 35 * (0.023517 - (0.023656*(289/100)) + (0.0047036 * (289/100)^2)) )) / (e^( -60.2409 + (93.4517*(100/288)) + (23.3585* ln(288/100)) + 35 * (0.023517 - (0.023656*(288/100)) + (0.0047036 * (288/100)^2)) )) ) =

    Bob is also correct that ocean chemistry is more complicated than that, in part because most of the dissolved CO2 immediately dissosiates into various ions. Here's a good resource on ocean chemistry:

    What's more, in the oceans, biology generally trumps chemistry, and that is certainly true for CO2 uptake. Some people think that the capacity of the oceans to take up CO2 is limited to surface water by ocean stratification. But that's incorrect, beause the "biological carbon pump" rapidly moves CO2 from surface waters into the ocean depths, in the form of "marine snow."

    The higher CO2 levels go, the faster that "pump" works. Here's a paper about it:

    Once carbon has migrated from the ocean surface to the depths, most of it remains sequestered for a very long time. Some of it settles on the ocean floor, but even dissolved carbon is sequestered for a long time. For instance, it is estimated that the AMOC takes about 1000 years to move carbon-rich water from high latitudes to the tropics, where it can reemerge. That is obviously far longer than the anthropogenic CO2 emission spike will last.

    Due to the temperature dependence of Henry's Law, a 1°C increase in temperature slows CO2 uptake by the oceans by about 3%. That's a slight positive feedback: more CO2 in the air increases water temperatures, which slows ocean uptake of CO2. But it is very minor, because a 50% (140 ppmv) rise in atmospheric CO2 concentration accelerates CO2 uptake by the oceans by 50%, which obviously dwarfs 3%. That's the main reason that ocean uptake of CO2 continues to accelerate despite the temperature dependence of Hanry's Law.

  46. Rob Honeycutt at 04:47 AM on 13 July 2023
    How big is the “carbon fertilization effect”?

    Dave... Going back to read what you previously wrote. (sigh)

    You stated, "Some people point to that little orange box and say that greening has ceased."

    No, I don't think anyone is pointing to your little orange box, nor are they using the original graph to make such a determination. This was a predicted result long before that graph existed. The determination of whether it's occurring is based on other observations related, I believe, primarily related to ongoing deforestation, changes in land use, etc.

    You also stated, "This recent study quantifies the effect for several major crops. Their results are toward the high end...[etc]" 

    If you actually read more than just the abstract of that study you find this on page 3:

    Complicating matters further, a decline in the global carbon fertilization effect over time has been documented, likely attributable to changes in nutrient and water availability (Wang et al. 2020). While CO2 enrichment experiments have generated important insights into the physiological channels of the fertilization effect and its environmental interactions, they are limited in the extent to which they reflect real-world growing conditions in commercial farms across a large geographic scale.

    That directly confirms for you what I've been saying. (You really do need to read the full papers.)

    It does seem that you're claiming CO2 uptake falls with increasing temperature. But it's unclear to me how you think this plays into the conclusion that CO2 levels would "quickly normalize" over the course of 35 years. Research tells us that's not the case.

    Persistence of climate changes due to a range of greenhouse gases


  47. How big is the “carbon fertilization effect”?

    Rob @ 16:

    daveburton's graph is using different units from the Pro-ocean one - g/100g, rather than mole/kg-atm.

    Before going down this Henry's Law rabbit hole, note that the uptake of CO2 in water is not solely related to the solubility of CO2 in water. The CO2 rapidly dissociates into ions that combine with the calcium carbonate present in sea water.

    Dissociation of CO2

    There is an excellent series here on ocean acidification:

    OA Not OK part zero lists all the individual posts.

    Part 15 mentions how solubility of CO2 depends on the presence of other ions.

    ...but there are many parts to the series. Each individual part is small, so going through them is worthwhile.

  48. Rob Honeycutt at 01:41 AM on 13 July 2023
    How big is the “carbon fertilization effect”?

    Dave... Perhaps also think about what this chart represents. It's saying the solubility of CO2 falls as temperature increases. That means when temperature rises more CO2 remains in the atmosphere leading to more warming.

    I believe this is the same effect that amplifies warming from orbital patterns to produce glacial-interglacial events.

    If I'm correctly interpreting what you're claiming, it seems you're saying that warming oceans will take up more CO2, which would be inverse to the actual effect of CO2 solubility. 

  49. Rob Honeycutt at 01:21 AM on 13 July 2023
    How big is the “carbon fertilization effect”?

    Before we dig into your equation, can I ask why your Y-axis is an order of magnitude greater than the Pro-ocean graph?

  50. How big is the “carbon fertilization effect”?

    I wrote elsewhere, "Due to the temperature dependence of Henry's Law, a 1°C increase in temperature slows CO2 uptake by the oceans by about 3%."

    In reply, Rob asked, "Where do you come up with this 3% figure?"

    From Weiss (1974), an approximate relationship is (as summarized by Pro-Oceanus):

    The equilibrated ratio of partial pressure to dissolved concentration is governed by solubility:

    pCO2 = Kₒ [CO2 (aq)]

    where pCO2 is the partial pressure of CO2 in the gas phase, Kₒ is a solubility coefficient, and CO2 (aq) is the concentration of CO2 dissolved in the water.

    The solubility of CO2 in water is a function of both the temperature and the salinity of the water, one relationship from Weiss (1974):

    ln (Kₒ) = -60.2409 + 93.4517(100/T) + 23.3585(ln(T/100)) + S(0.023517-0.023656(T/100)+0.0047036(T/100)²)

    where the solubility coefficient (Kₒ) has the units of mol kg⁻¹ atm⁻¹, temperature (T) is Kelvin, and salinity (S) is in parts per thousand (approximately equal to PSU).

    Note that for non-saline waters, the second term of the equation becomes zero, leading to

    ln (Kₒ) = -60.2409+93.4517(100/T)+23.3585 ln (T/100)

    To get the "3%" figure, you can plug in suitable values, or you can look at a graph, like this one:

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