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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.

Recent Comments

Comments 7501 to 7550:

Dakota at 06:49 AM on 9 March 2020

2020 SkS Weekly Climate Change & Global Warming News Roundup #10

thanks for the explanation. That really helped me to understand how a photon that strikes a CO2 molecule at 90K altitude and -80C could have enormous effects on the Temperature on the surface of the Earth. Thank you so much. Quantum physics and electron excitation or molecular vibration cannot cause sufficient heat warm the Earth. Swing and a miss.

Name a gas that exists as a single atom. Molecular spin does not cause radiative heat over long distances. Doesn't matter what the infrared flux is when it relates to a single molecule and its vibrations. You cannot expand Quantum physics to explain the temperature of the planet. Heres another idea to explain. The 6 most important factors affecting climate are latitude, ocean currents, wind, elevation, proximity to water. None of those are related to CO2 levels. Causes of Hurricanes: not CO2 levels. Tornadoes, also not caused by CO2 levels. Please name any weather phenomenon that is directly and specifically caused or affected by CO2. Do you know thy the IPCC doesnt talk about the fact that water vapor being the supposed greatest factor in Global warming? Oh, wait. They actually made that statement in 1995. Answer: because they couldnt make a policy or do anything about it because its not a man made factor.

The Inter-Governmental PCC is a Political body with political motives relative to the Goals of the UN. GCC is a political endeavor to try to get developed countries to finance energy development methods for developing nations. Most people in developing nations are not concerned with the future in 100 to 1000 years; they mostly need food,water, shelter, healthcare, etc. Just saying. Please again name Any weather phenomenon that is caused by CO2. Thanks.

Moderator Response:

[TD] Repost your struck out comments/questions either in the post that explains that nobody claims CO2 is the only driver of climate, or in one of the relevant posts about hurricanes or other weather, or water vapor, that you can find by using the Search field at the top left of the page. I snipped your rant about the IPCC's motives. Don't repost that anywhere or you will be banned from this site permanently and without warning. Also abandon your snide attitude.

scaddenp at 06:45 AM on 9 March 2020

2020 SkS Weekly Climate Change & Global Warming News Roundup #10

Dakota, there is a rather useful explanation of photon - molecule interactions here. However, your post makes me suspect that have a very flawed idea as to what the greenhouse effect is. You do understand that radiative heating of the earth surface from backradiation is the important effect not radiative heating of the atmosphere?

"The experiments that attempt to support the "greenhouse gas effect" all require that the CO2 be contained specifically in order for the molecules to have a velocity and then cause a temperature change."

Where do you get this idea? The radiative interactions of CO2 and infrared are particular examples of behaviour described by the radiative transfer equations. You can use these to predict the radiation spectrum at surface, top of atmosphere or anywhere in between. The measurements match predictions with exquisite precesion. (eg Evans 2006, Harries 2001). In general, we depend on the RTEs heavily in numerous applications like remote sensing, laser guided bombs (the MODTRAN program for doing such calculations were initially developed by USAF) and GPS.

Furthermore, the effect of adding CO2 can be directly measured.

MA Rodger at 23:03 PM on 8 March 2020

2020 SkS Weekly Climate Change & Global Warming News Roundup #10

Dakota @1,

It may be worth answering your question directly here as it does not of itself explain the greenhouse effect. Further discussion may be more appropriate on a different thread (eg the suggested Myth No 30).

The Ideal Gas we learn about in school with its PV=nRT involves a constant for specific heat capacity, ĉ_V. For a gas comprising a single-atom gas, this has a value of about 1.5 but for bi-atomic gases or poly-atomic gases this ĉ_V is significntly larger. The increased value is because, as well as the kinetic energy of the gas molecule velocities (which is an average velocity so, as you say, an individual molecule's velocity will not define temperature), there is also energy encompassed by the spin of molecules which will be present in bi-atomic gases and there is also further energy encompassed by the waggling of molecules in poly-atomic molecules. It is these poly-atomic molecules which are the greenhouse gases and which, if waggling, can emit infra-red and, of not absorb infra-red.

The size of the infra-red flux in the lower atmosphere is measured at 340Wm^-2, the same size as the global energy flux from the sun.

So not only does the significant increase in ĉ_V demonstrate that molecular waggling is in no way "miniscule" as you suggest, the 340Wm^-2 also demonstrates that the infra-red fluxes within the atmosphere are also in no way "miniscule."

This, of course, does not explain the mechanism of CO2's influence on the greenhouse effect, but it does demonstrate that there are very significant forces at work powering the greenhouse effect, this being the substance of your comment.

Eclectic at 12:46 PM on 8 March 2020

2020 SkS Weekly Climate Change & Global Warming News Roundup #10

Dakota , read through the Intermediate and/or Advanced version of Climate Myth number 30 [see Climate Myths, listed at top left of this page]. Number 30's title is "Increasing CO2 has little to no effect".

That will be a great help to you in gaining understanding of the science.

(There may well be different threads which you can discover for yourself or which can be recommended by other readers here at SkS.)

AFAIK, there aren't any scientists saying that an individual molecule of CO2 has a particular temperature (since air temperature is a sort of averaging of energies possessed by a mass of [mostly] nitrogen & oxygen molecules constituting our atmosphere). Perhaps you were taking in something of the term "kinetic temperature" ~ which is of technical interest in the atmosphere above the stratosphere, but which lacks relevance in climate of the lower atmosphere at the planet's surface level.

If you wish to discuss the topic, then please do so under the thread Myth No. 30 (or other thread, which the Moderators may suggest).

Jonas at 10:42 AM on 8 March 2020

How I try to break climate silence

I speak a lot about climate change. So hearing these statistics about people not talking about climate change is a little weird for me: climate change is one of the main topics of my live ..

I like best personal situations, where I can adapt to the situation and try to connect. I use whatever situation I can grasp, but I try not to overdo or overload a person: too much does not help. But online posting and mailing to friends (not too often) also is part of the picture. I operate a small garden forum for local gardeners and these people get a good dose of climate information (links to reports, articles, sks, ..), always with a little link to the garden, which is not hard to find: 2016 etc. were so exceptional that nobody doing garden work can ignore it: I try to help connect the dots.

What helps is if there is authentic action: I do not fly, have no car, eat no meat, little milk, mostly regional organic food, grow food myself, heat little (starting at 10C inside, but fortunately my current one room appartement does not get that cold: min 13 (I always live in the roof, so taking away little from other people in the house)), use no refrigerator (but I have computer, smartphone, books, an appartement for myself, an inline kitchen and a small bathroom for myself, a laundry washing machine, .. so far from being an eco angel). Authentic action already helped to impress even (and especially) very conservative people, because it partly fits their mindset, only the reason why I do it does not. Some started to think about it, I guess (I do not ask directly).

What also helps a lot is knowledge about climate change itself and about climate communication and climate fear. It helps to stay calm, even if you happen to encounter a denier argument you did not yet hear of and cannot answer by yourself: you know you can easily look it up (e.g. here at SkS), read about the flaw/fallacy and next time have the answer ready. I also use inoculation, in the form I learned in the SkS MOOC, but also differently: I prepare people that they will be fooled, present a denier argument (preferrably cherry picking, e.g. glaciers are growing or short periods of intermittent cooling after some local maximum), tell them it's true (leaving them stunned and searching for an explanation) and then reveal the whole picture (like in the escalator). I do this, because even ecologically minded people get trapped: they have some taken over opinion (like I do for some topics too) and the denier mechanics is to break trust/confidence. So I try to build resilience to seemingly well founded denier arguments by suggesting to postpone the evaluation until comprehensive valid data (e.g. SkS) is available.

I also regularly promote CO2 and footprint calculators if it fits the course of the conversation, because it helps to get the big picture and the extent of what is necessary. Especially ecologically minded people are often shocked to hear that they too have a long way to go (see https://www.umweltbundesamt.de/publikationen/repraesentative-erhebung-von-pro-kopf-verbraeuchen ). Others have even longer ways to go, but some do not even care (yet, until they meet me ;-) ..).

Recently, I also joined Fridays demonstrations (38 weeks ..): this is also a good opportunity for talking about climate change and networking.

Dakota at 09:53 AM on 8 March 2020

2020 SkS Weekly Climate Change & Global Warming News Roundup #10

How does a molecule of CO2 have a temperature? Exciting the molecule does not count as a temperature increase. For CO2 to actually have any effect on the temperature of anything; it has to be in motion and have velocity, such as when it is in container. Being excited to another state momentarily by a very miniscule amout of energy from an infrared ray does not result in ANY temperature increase to anything. The experiments that attempt to support the "greenhouse gas effect" all require that the CO2 be contained specifically in order for the molecules to have a velocity and then cause a temperature change. A CO2 molecule in the atmosphere cannot have a Temperature simply from its vibration.

DavidR24 at 07:42 AM on 8 March 2020

How I try to break climate silence

My initial attempts to discuss climate change have met with some success but mostly dissappointment. While discussions have sometimes become 'heated', I haven't lost any friends as yet but I feel people are more wary of mentioning the 'c' word in front of me. I'm currently completing the Climate Denial 101x course which I'm finding immensely useful. I also subscribe to a number of websites including greenpeace, greens party and Market Forces and this is useful to get involved by emailing politicians or corporations about certain issues. Finally, I often post political or climate change news on Facebook, unfortunately with very few responses.

nigelj at 05:19 AM on 8 March 2020

How I try to break climate silence

Eclectic & BaerbelW

I'm just trying to say people can so often be "all talk and no action" and I see evidence of this with climate change. Thats why I said the most important thing to do is not to just talk about stuff with friends etc, but to personally do something. By action I mean making some efforts to reduce our personal carbon footprints, but this would also clearly involve voting for climate friendly parties.

I agree the main thrust of climate action does have to come from the top down. Its important to talk about that with people about that, and people vote for the most climate friendly party / politician.

I would think its natural that people will talk with others about what they have personally done. It becomes preachy when people tell other people what they should do in a dictatorial, annoying manner.

BaerbelW at 19:09 PM on 7 March 2020

How I try to break climate silence

Nigelj @2 & Eclectic @3

While talking about climate change was mentioned several times in the article prompting this post, another suggestion mentioned multiple times was "to vote wisely" (my words, not theirs). Here is how Michael Mann put it:

“Putting pressure on our elective representatives to act. We need to put a price on carbon and incentivize renewable energy to accelerate the transition underway from fossil fuels to green energy.

But we cannot do that as individuals. Only our policymakers can do that. That means we must vote in politicians who favor action, vote out those who don’t, and put as much pressure as possible (in the form of activism, letter-writing, organizing, you name it) on our policymakers to act now.”

or Stefan Rahmstorf:

“How would I know what the most effective is? That is guesswork, but if you insist I would say:

Always vote for candidates and parties that work for climate protection.”

This just wasn't the focus of this particular blog post, otherwise I might have mentioned that I'm also actively involved with Citizens' Climate Lobby in Germany and across Europe where we try to engage with our elected parliamentarians in order to get a meaningful price on carbon emissions (but there's a post from 2017 about CCL).

Eclectic at 08:30 AM on 7 March 2020

How I try to break climate silence

Have to disagree with you to some extent, Nigelj.

Of course it's useful to do something at your own personal level ~ the energy economizations, the house solar panels, maybe the electric car. But those activities should not be mentioned pro-actively in ordinary social conversations: or it will come across as "preachy".

You know that those activities only have a very small diminutive effect on the growing CO2 level. There really has to be a top-down approach: which means wholesale conversion to renewables electric power generation; the fiscal encouragement of electric vehicles; the research push into organically-derived hydrocarbon fuels for ships planes and so on. All this can only come from "the top" i.e. from politicians taking action. Politicians tend not to think of the long term ~ they are busy day-to-day and election-to-election. But they do respond to vested interest lobbying by donors . . . and they respond to grass-roots pressure from voters. They don't think about your roof panels . . . but they do think about your vote. En masse voters, expressing an increasing expectation of climate action by governments.

Daniel Bailey at 06:46 AM on 7 March 2020

Skeptical Science New Research for Week #9, 2020

This graphic shows both global temperatures and CO2 levels over the past 10,000 years:

Last 10,000 years

IIRC, Ruddiman's hypothesis helps account for some of that discrepancy that you note.

nigelj at 06:30 AM on 7 March 2020

Skeptical Science New Research for Week #9, 2020

MAR, "More directly addressing your question, the ice cores do show a small increase in CO2 levels over the last 8,000 years..."

The Marcott study here shows global temperatures falling over about the last 3500 years until about 1900. So perhaps the milankovitch cycle cancelled out the slow low level rise of CO2 concentrations over the same period?

nigelj at 06:18 AM on 7 March 2020

How I try to break climate silence

"The single most important thing we can do about climate change is, talk about it!"

Nope. The most important thing is to do something about it, even if its only a couple of things as a start. Then you will have something meaningful to share with other people and you won't come across as seeming too forced or preachy.

Of course talking about it is important. Sadly its become politicised so best to tread carefully like Eclectic says.

Eclectic at 05:51 AM on 7 March 2020

How I try to break climate silence

Thank you, BaerbelW. It's always worth the reminder, that a gentle "background pressure" of normalizing AGW references (into everyday conversations) can help achieve a better general awareness of the problem. (One needs to keep at the Goldilocks Level, where the mention of the subject is casual & ordinary, without seeming forced or fanatically intrusive, of course.) All this, gets to put a grass-roots "upward pressure" on politicians ~ who are the ones who can produce the greatest physical change in the global situation.

Eclectic at 05:26 AM on 7 March 2020

It's CFCs

EGS @33 ,

You have a very strange definition of "anthropogenic" if you are not including FF-related emissions of CH4. Please stick with standard English !

The IPCC summary in AR5 (based on approx 2010 info) on CH4 and other drivers, seems quite straightforward and comprehensive. Easy to make a small extrapolation ~ which does not support your radical contention on halocarbons.

The Hmiel et al. (2020) paper is relevant and interesting. (Thanks for that one, MA Rodger.)

EGS at 05:03 AM on 7 March 2020

It's CFCs

MA Roger,

The atmospheric burden of CH4 has increased. According to NOAA the CH4 mole fraction has increased from 1650 ppb to nearly 1900 ppb between 1980 and 2020. It stabilized around 2000-2005, but has been increasing at a linear rate since then https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/.

Are you disputing that the increased atmospheric concentration of CH4 is not from livestock rearing, farming, and deforestation? And while FF emissions of CH4 are technically not anthropogenic, oil and gas drilling and hard rock mining are releasing it into the atmosphere.

Moderator Response:

[DB] Off-topic snipped.

Please note that posting comments here at SkS is a privilege, not a right. This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

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MA Rodger at 04:08 AM on 7 March 2020

It's CFCs

EGS @29,

You say "The papers I cited above all show that anthropogenic, CH4, N20 O3, and black carbon contribute more than previously thought." I thnk you will find that is incorrect.

Consider you CH4 reference cited @17, Hmiel et al (2020) 'Preindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissions'.This paper argues that FF emissions of CH4 were greater than previously thought. The atmospheric burden of CH4 is not challenged and it is the atmspheric burden that determines the climate forcing, not the source of the emissions that increase that atmospheric burden.

EGS at 02:55 AM on 7 March 2020

It's CFCs

The total anthropogenic radiative focing bars at the bottom of the chart align almost perfectly with what economic historians know about diesel and heating oil emissions, nitrate fertilizer use, methane emissions from farming, deforestation and stock rearing, and industrial halocarbon use.

Moderator Response:

[DB] Please take discussions of animal agriculture to this thread.

MA Rodger at 02:52 AM on 7 March 2020

It's CFCs

Do note that the paper discussed above Polvani et al (2020) 'Substantial twentieth-century Arctic warming caused by ozone-depleting substances' has been the subject of some corrections. And for the record, I would answer the question of EGS @17 "Would that not be evidence that climate sensitivity to CO2 must be much lower than previously modeled?" with a flat "No!"Given the comment thread since, I'm not sure that any explanation would be helpful.

EGS at 02:40 AM on 7 March 2020

It's CFCs

This is clearly outdated. Polvani et al. showed that ozone depleting chemicals alone account for 1/3 of all anthropogenic global warming between 1955-2005. The papers I cited above all show that anthropogenic, CH4, N20 O3, and black carbon contribute more than previously thought. I don't understand why these far more potent anthropogenic greenhouse gasses/particles get relegated to relative insignificance, not least since CFC, HFC, SF6, tropospheric O3, N02, and black carbon have unambiguous anthropogenic sources. Increased ppm of C02 is also anthropogenic, but you can't impute the kind of radiative forcing and amplification feedbacks to it and not apply those to these even more potent greenhouse gasses, otherwise there would have been far more warming than we have been able to measure. Something has to give up some radiative forcing in oder to get anything like the warming we have been able to measure. The underappreciation of CFCs and other GHGs is likely why climate models have been running hot. Michael Mann is himself aware that there are problems with the climate forcing theories. He coauthored a paper in Nature Geophysics in 2017 (https://www.nature.com/articles/ngeo2973) that argued that the failure of climate models to align with the measured level of tropospheric warming since 2000 is unlikely to have been caused by natural variability and model error in climate sensitivity but rather in “systematic deficiencies in some of the post-2000 external forcings used in the model simulations.“

Moderator Response:

[DB] Research shows that climate models are getting future projections right, meaning that the physics of the models are well-validated by subsequent observations.

Sloganeering snipped.

EGS at 01:54 AM on 7 March 2020

It's CFCs

What the science does not say:

"CFCs contribute to global warming at a small level."

Moderator Response:

[DB] Per the AR5, Halocarbon (which includes CFCs) radiative forcing (RF) is small relative to that of CO2 RF.

EGS at 01:49 AM on 7 March 2020

It's CFCs

Poorly understood and misrepresented papers? Which papers have I not understood? The paper by Unger et al. in the proceedings of the US National Academy of Sciences (citing work by the Fourth Assessment working group of the IPCC) that tropospheric O3’s direct cumulative radiative forcing when combined with fine particulates like black carbon may outweigh that of all the CO2 released since the beginning of the industrial era https://www.pnas.org/content/pnas/early/2010/02/02/0906548107.full.pdf.

Moderator Response:

[DB] Off-topic and moderation complaints snipped. You are essentially arguing one of the many subsets of arguments that "It's not us". Pick one of the most-appropriate and repost this line of reasoning there.

Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum. One of the most important of these precepts is to stay on-topic.

Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.

EGS at 01:42 AM on 7 March 2020

It's CFCs

Could ozone depleting chemicals and the other GHGs (with a large revision downward of CO2 radiative forcing and amplification feedbacks?) explain a modestly warming upper troposphere, higher tropopause, and a cooling stratosphere that are among the markers of anthropogenic climate change? Wouldn’t that also align with the strong empirical evidence of very little global warming since the preindustrial era until 1950 that then really accelerated after the 1950s and 1960s as CFCs, HFCs, halons, and SF6 emissions skyrocketed from their industrial use as refrigerants, solvents, propellants, and electrical insulating gasses? The spike in anthropogenic warming from N20 and CH4 could likewise be timed with the massive intensification of agriculture enabled by large-scale application of nitrate fertilizer and changes in land use patterns (deforestation) accompanying the green revolution since the 1970s. This was a time that was also accompanied by dramatically increased diesel tractor and diesel vehicle use, skyrocketing bunker fuel emissions from the expansion of container shipping, and rising heating oil emissions from a switch from coal to oil, which could account for much of the rest of the increase in N20, much of the tropospheric O3, and a large part of the fine particulate emissions increases. The timing of the acceleration of warming would also strongly imply a weaker climate sensitivity to C02 forcing and a greater cumulative forcing of these other greenhouse gasses. It was, after all, in the 1980s and 1990s that global warming really accelerated, not earlier. Would that not also align well with the much stronger warming over the poles (mostly accounted for by CFCs, HFCs, N20, tropospheric O3), strong stratospheric cooling from the depletion of/hole in the polar stratospheric 03 layer, and the much weaker than expected tropical upper tropospheric temperature anomoly and the weaker than expected deep ocean warming?

Moderator Response:

[DB] In the early 20th century human activities caused about one-third of the observed warming and most of the rest was due to low volcanic activity. Since about 1950 it's all humans and their activities.

https://journals.ametsoc.org/doi/10.1175/JCLI-D-18-0555.1
https://onlinelibrary.wiley.com/doi/full/10.1002/wcc.522

Off-topic and sloganeering snipped. Arguments pertaining to Climate Sensitivity is Low must be placed on that thread, not here.

EGS at 23:59 PM on 6 March 2020

It's CFCs

Eclectic,

Are you claiming that the degree of northern hemisphere ice albedo is a trivial amplification feedback in anthropogenic radiative forcing?

Moderator Response:

[DB] Your previous 2 comments were removed as being off-topic and Gish Gallops of rambling assertions lacking foundation. Just throwing out a bunch of poorly-understood and misrepresented papers does not give you any credence in a science-based forum such as this. Please stick to the topic of this post. Other topics are covered by other posts here (literally thousands exist). Use the Search function to find the most relevant post and read it and its comments and this site's CommentsPolicy before posting further.

MA Rodger at 20:31 PM on 6 March 2020

Skeptical Science New Research for Week #9, 2020

swampfoxh @1,

Your question doesn't 'ring any bells' with me and the authors you mention don't seem to lead anywhere that I can see.

The 1,500 year timescale is occasionally mentioned as the time it takes the ocean waters to re-appear at the surface and so reach CO2-quilibrium with the atmosphere. That is part of what Goreau (1990) 'Balancing Atmospheric Carbon Dioxide' addresses but it is not the same as timescales for temperature equilibrium under otherwise-fixed CO2 levels.

Rohling is the lead author of Rohling et al (2009) 'Antarctic temperature and global sea level closelycoupled over the past five glacial cycles' and this does consider multi-millennial equilibrium timescales but this concerns sea level. There is a connection in that the melt-out of, say, Greenland would both impact sea level and temperature as the albedo change constitutes a slow climate feedback (see this SkS post). But over such multi-millennial timescales with Milankovitch cycles in operation, it would require more than "modest" climate forcings to be significant.

More directly addressing your question, the ice cores do show a small increase in CO2 levels over the last 8,000 years. This would provide roughly a 0.3Wm^-2 climate forcing which (slow and fast feedbacks so perhaps a sensitivity of 6ºC) could have given a total temperature rise of +0.5ºC. Yet spread over eight milennia, any residual effect today would be now miniscule.

CO2 graph 10000 years

Eclectic at 16:03 PM on 6 March 2020

It's CFCs

EGS :-

Being far from expert in this area, I should be grateful if you would explain the significance or importance of that recent study by Polvani et al.

The authors are somewhat vague in their claims, and request confirmatory studies. AFAICT their models are based on experimental infrared spectra & calculated instantaneous radiative forcings. They say that their results suggest that ODS [Ozone-Depleting Substances] provide about 20% of the GHG RF forcing over the Arctic. (This fits with past information provided on the NASA website.) Yet they state that "the precise value of ODS efficacy remains to be robustly quantified."

By area, the polar regions are only a small portion of total planetary surface, and they have even lesser importance when given a radiative weighting.

There may be some misinterpretation of the relative radiative importance of the halocarbons, since (like with the comparative weightings of CO2 and H2O vapor) it is difficult to un-tease the overlapping absorptive spectra of other GHGs.

michael sweet at 15:13 PM on 6 March 2020

It's CFCs

EGS:

A free copy of the paper you cite is here. It states

"in this paper we focus specifically on the period 1955–2005,
during which ODS concentrations grew rapidly. Over that period
the RF from ODS is estimated16 to be 0.31 Wm–2, which amounts
to nearly one-third of the RF from CO2 (1.02Wm–2), making ODS,
collectively, the second most important GHG in the latter half of
the twentieth century, as seen in Fig. 1. These facts are well established7,17 and the important contribution of ODS to global warming has previously been noted18,19" my emphasis.

It appears to me that your claims are not supported by your citation.

michael sweet at 15:03 PM on 6 March 2020

It's CFCs

EGS,

You appear to be arguing that Climate Science has severe flaws in calculations based on this paper. The paper does not make that claim. Your claim that "Nearly all the recent decline in arctic sea ice due to CFCs and tropospheric O3?" is not what the paper says. In fact the abstract says:

"when ODS are kept fixed, forced Arctic surface warming and forced sea-ice loss are only half as large as when ODS are allowed to increase" my emphasis.

The response of water vapor to added greenhouse warming from CFC's would be the same as the response to CO2. Your claims that the effect of CO2 are overestimated by the IPCC are not in the abstract of the paper, you appear to have made them up yourself.

Much of the difference between the warming we have seen since 1989 and what Hansen modeled is due to the fact that Hansen modeled CFCs increase as more than they did. The Montreal Protocol resulted in lower increases of CFCs than previously expected.

Only climate deniers claim that only CO2 affects global climate change. Climate scientists know that other gasses (including black carbon) also affect warming and the total effect of human released gasses is much greater than the effect of 415 ppm CO2 alone. The linked press release claims 82% of the increase in greenhouse gasses from 2007-2017 is from CO2. CFC's were released less in that decade than before because of the Montreal protocol.

One Planet Only Forever at 14:13 PM on 6 March 2020

The potential climate consequences of China's Belt and Roads Initiative

Re-reading the article leads me to strengthen my skepticism of the story being told, or at least be skeptical of the way it is being told.

The New Silk Road will closely-integrate Asia, Europe and Africa, and help many of the poorest regions on the planet. Done with the Sustainable Development Goals in mind it would be amazing. But even if it is done that way it is likely not what the current day American Exceptionalism Empire Builders want to see happen.

I am skeptical of Stories that make speculative claims about the behaviour of Others without including mention of their own leadership's history of actions (or inaction). Like climate science reporting, stories about the current situation and speculation about the potential future should be based on, and adequately refer to the complete current day story and the History that developed the current day.

Many of the criticisms presented in the article are speculations about how China’s leadership will behave without mentioning that those are the ways that the current wealthy and powerful, and the European Colonizers of the past, acted to develop and maintain perceptions of their superiority relative to Others.

People who are concerned about what China’s Leadership might be doing can be helpful by telling stories to Their Leadership about what should be done to be more helpful than the Chinese Leadership might be. In particular, Their Leadership could step in and Altruistically give the poorer nations Renewable Energy Systems rather than speculating about what China might be up to (and they should have started doing that decades ago).

China’s introduction of coal burning electrical generation in poorer nations could and should be clarified to indicate the failure of the supposedly more advanced nations to have already helped by donating renewable energy generation to those nations. In the 1970s the UN agreed that the supposedly most advanced nations should each dedicate 0.7% of their GDP to Official Development Assistance (ODA). And the Kyoto Accord added the obligation of the supposedly more advanced nations to help the poorer nations on climate change matters (assistance on top of the 0.7% ODA).

The USA delivers less than 0.2% ODA while expanding its military spending (and demanding that NATO nations spend at least 2% GDP on their military, without any mention of also needing to spend at least 0.7% on ODA). There is lots of capacity for the supposedly more advanced portion of the global population to be more helpful than the Chinese Leadership.

China could be choosing to behave better. They could be improving living conditions for the poorest by the quick installation of fossil fuel systems with the intent to rapidly transition them like China has been rapidly transitioning. China does not seem to suffer from the Libertarian Capitalist mental-block of believing that the potential for profit from any capital investment must be maximized – no matter how harmful the developed activity is understood to be. The Chinese leadership have proven they are able to shut down fossil fuel operations, and are willing and able to do it without compensating the investors for missing out on future benefits from the harmful activity.

The leadership of the supposedly most advanced nations, particularly the USA, have a history of failing to be helpful. They need to hear more stories that are justifiably critical of their history of actions, not stories overlooking their harmful past and speculating about how bad their current day opponents might be.

EGS at 12:33 PM on 6 March 2020

It's CFCs

1/2 of all arctic warming between 1955 and 2005 due to CFCs & N20?

1/3 of all global warming between 1955 and 2005 due to CFCs & N20?

Nearly all the recent decline in arctic sea ice due to CFCs and tropospheric O3?

Tropospheric O3 and black carbon with as much impact on global warming as all the CO2 emitted since c. 1750?

EGS at 12:25 PM on 6 March 2020

It's CFCs

Would that not be evidence that climate sensitivity to CO2 must be much lower than previously modeled? These other GHGs would presumably have the same water vapor amplification feedbacks as CO2 (as non-condensing atmospheric gasses) and produce the expected lower adiabatic lapse rates of warmer water vapor, would they not? Or does water vapor resonate more readily with the discrete wavelengths of infrared radiation emitted by vibrating CO2 molecules? Are those wavebands already saturated so that any additional CO2 emissions can’t add much more radiative heat? In other words, if CO2 is as radiatively powerful as modeled, there should have been dramatically more global warming since the onset of industrialization, especially since the 1950s when these other GHGs really began to be emitted on a very large scale.

michael sweet at 08:20 AM on 6 March 2020

It's CFCs

EGS:

From the abstract of the paper you cited:

"While the dominant role of carbon dioxide is undisputed"

The IPCC knows that there are a number of other greenhouse gasses besides CO2. Modelers have these gasses in the models. It appears to me that Polvani et al are trying to quantitate more accurately how much warming is due to gasses besides CO2. This is interesting but does not change the basic science of AGW.

swampfoxh at 07:42 AM on 6 March 2020

Skeptical Science New Research for Week #9, 2020

Can anyone refer me to the source of the idea that it takes thousands of years for the planet to reach equilibrium from the relatively modest rising "rate" of greenhouse gas levels and that the planet is still warming from the effects of 260ppm about 1,500 years ago? (not in just a few decades). I have been told that a study by Goreau in 1990 and another by Rohling in 2009 addresses this "stretched" delayed effect?

EGS at 07:27 AM on 6 March 2020

It's CFCs

In my previous post I failed to mention HFCs (a.k.a. HCFCs). They replaced CFCs with the Montreal Protocol.

The 100 year global warming potential of HCFCs (C5H2F10) was recently re-estimated to be somewhat lower than previously thought, but at 1,410 it is still over 1000 times greater per molecule than C02. https://www.sciencedirect.com/science/article/abs/pii/S0022285217301455. According to NOAA, these chemicals have been accumulating in the atmosphere at a rapid rate since 1990, with HCFC-22 and HCFC-134a above 250 and 100 pptv respectively in 2015 and increasing linearly. https://www.esrl.noaa.gov/gmd/hats/about/hfc.html

EGS at 06:46 AM on 6 March 2020

It's CFCs

Very recent work led by Lorenzo Polvani and an international team of scientists just published in January 2020 by Nature Climate Change (https://www.nature.com/articles/s41558-019-0677-4)
argues that large amounts of global and arctic warming are actually due to ozone depleting chemicals (CFCs, HFCs, other halons, and nitrous oxide [N20]), no less than 1/2 of all warming in the arctic and no less than 1/3 of all global warming between 1955 and 2005. These ozone depleting chemicals are trace gasses measured in parts per billion but have global warming potentials 100s to many 1000s of times greater than CO2. CFC-11 and CFC-12 are 19,000 and 23,000 times more radiatively efficient than CO2 per molecule. The global warming impact of methane has apparently also been underestimated, with one new study by Hmiel et al. in Nature arguing that anthropogenic CH4 releases have been 25-40% greater then previously thought (https://www.nature.com/articles/s41586-020-1991-8). Another study by Thompson et al. in Nature Climate Change from November 2019 showed that N20 emissions have been rising far more than the IPCC had assumed since 2009 (by an estimated factor of 2.3!) (https://www.nature.com/articles/s41558-019-0613-7). According to the US EPA, the global warming potential of N20 is 265-298 times greater than CO2 over a 100 year timescale (https://www.epa.gov/ghgemissions/understanding-global-warming-potentials). Tropospheric ozone (O3) is both a potent direct greenhouse gas and plays a role in the lifetime and effectiveness of other greenhouse gasses. According to research by Jim Hansen and others published in the Journal of Geophysical Research (2006), tropospheric O3 is estimated to have caused no less than 1/3 to 1/2 of the observed recent trends in arctic warming in the winter and spring, when O3 is easily transported to polar regions from lower latitude urban centers https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2005JD006348. Tropospheric O3’s direct cumulative radiative forcing when combined with fine particulates like black carbon is believed to possibly outweigh that of all the CO2 released since the beginning of the industrial era https://www.pnas.org/content/pnas/early/2010/02/02/0906548107.full.pdf. Sulphur hexaflouride (SF6) is perhaps the most potent anthropogenic greenhouse gas, and its emissions have been rising rapidly from use as an electrical insulator. Its 100 year global warming potential per molecule is estimated at 23,000 times that of C02. Its atmospheric abundance is low at 8.60 parts per trillion volume, but it is rising at a linear rate by 0.33 pptv per year and can persist in the environment for more than 1000 years. https://www.atmos-chem-phys.net/17/883/2017/acp-17-883-2017.pdf

nigelj at 13:24 PM on 5 March 2020

The potential climate consequences of China's Belt and Roads Initiative

30% of the worlds metals are recycled, particularly steel and copper. Lithium can be recycled but very little is recycled, because its not currently economic to do so. Only 9% of plastics are recycled presumably because its not economic.

If we want more recycling of those uneconomic sorts of things, government incentives would help, so we effectively will all have to contribute. From what I've read it does not require much incentive to make recycling financially viable.

In the future people will probably mine rubbish tips for old metals and other materials.

dana1981 at 08:01 AM on 5 March 2020

How much would planting 1 trillion trees slow global warming?

gws @13 - thanks good catch, correction made!

John Hartz at 06:53 AM on 5 March 2020

How much would planting 1 trillion trees slow global warming?

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