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Comments 12501 to 12550:

12501. Lachlan at 12:35 PM on 10 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Evan @11,

       I agree that it would be nice to be able to "get it over with" and rebuild, but I think that having slow increase is far, far better.  If 90% of a city is intact, then it can relocate the other 10% to higher ground.  If 10% of a city is intact, it is really hard to rebuild the other 90%.

       If a change happens over a millenium, think how many cities have the same borders a they did 1000 years ago. 

       The only drawback I see in gradual seal level rise is the "boiling frog" problem, where people don't accept the rise and keep rebuilding on the same sites after damage.

       As nigelj says, the worst case is to have rapid bursts on a long-lived underlying trend, and that the greatest technical problem is unpredictability.  (The greatest actual problem is denialism.)

12502. Lachlan at 12:25 PM on 10 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       nigelj @1

       I liked the title.  When I read it, I thought "This is something to show to people who claim all realists are alarmists".  Your concerns about misreading it are valid, but must be weighed against the benefit.

12503. nigelj at 08:27 AM on 10 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       Red Baron @9, I personally agree a carbon tax should 'ideally' fund various climate initiatives, but its just not politically saleable.This is why the proposals in America have been  for carbon  tax and 100% dividend.

       Personally I think carbon tax and dividend is quite good. Its not intended to be a socialist mechanism to redistrubte wealth, it was developed to keep the Republicans happy by not increasing government spending.

       I hasten to add I dont oppose wealth distrubution, within reason, and the carbon tax and dividend falls well within reason. 

       We could of course have a carbon tax and dividend that returns something to the public, and puts something into cimate change mitigation, and  development of soil sequestration of carbon. I have always actually favoured this approach, because it makes it attractive to the public and helps solve the issues you raise. But I dont know if it has any chance in America.

       Its important to understand carbon tax and 100% dividend cannot solve negative emissions technologies, soil carbon etc. Only government subsidies can do this, and they have to come from somewhere.

12504. One Planet Only Forever at 07:30 AM on 10 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       RedBaron @9,

       I agree that measures other than a Carbon Fee and Rebate could help more rapidly develop the required corrections.

       And I would add that the amount of the carbon fee should not be calculated. Such 'Costs of Carbon' calculations are likely to be flawed (especially if future costs get discounted, because making problems others have to suffer from or try to solve is simply unacceptable).

       The Carbon Fee simply needs to be increased until the creation of new CO2 from fossil fuel burning is terminated.

       A Carbon Fee and Dividend system does indeed 'redistribute wealth':

       • from harmful unsustainable fossil fuel related activity to helpful development of renewable energy related activity.
       • from the larger than average producers of the problem to the lower than average contributors (a shift from the more harmful to the more helpful).

       Those are actually 'corrections' of wealth distribution, not 'unjust' redistribution.

       And the wealthiest should all be leading the correction (being helpful should not be 'an option for the wealthier').

       So those additional measures could be funded by taking the Carbon Fee Rebate that would have gone to wealthier people for those other actions. Alberta has done that with their Carbon Fee and Rebate program. The rebate is not given to the higher income portion of the population.

       In addition, there could be more money to fund special actions collected by a Carbon surtax on the wealthiest (with some ability for the wealthiest to claim tax credits if they did something substantially helpful - something along the lines of what the surtax money would be targeted to achieve).

12505. RedBaron at 06:39 AM on 10 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       @8 William,

       Hansen's tax and diviend has flaws. The dividend is used to redistribute wealth instead of financing AGW mitigation. 

       So while it has good intentions, it really is more like rearranging the deck chairs on a sinking titanic.

       If you want to do a carbon tax right, in my honest opinion, you must use those funds to finance alternate energy plants like those huge wind farms, and/or pay people for the carbon sequestered long term in the soil.

12506. william5331 at 05:17 AM on 10 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       It is amazing, how much progress we have made in replacing fossil fuel from renewable sources despite the barriers put in our way.  Look at the rate of increase in the uptake of wind power, solar and electric vehicles, but it could be so much faster.  Two measures would facilitate all others.  One - get vested interest money out of politics and two, put in place Hansen's Tax and Dividend.  Work through the cause and effect of these two measures and you see it would activate the most powerful force in our socient.  Economics.  With the transfer of fossil fuel subsidies, dollar for dollar, from Fossil Fuels to renewables (possible when the politicians no longer kow tow to vested interests) it would not be worthwhile ever again to build a coal fired power station.  Look at the stumulus to the economy as the poor, receiving the dividend spend every cent to keep their heads above water.  Look at the effect on egalitarianism as the population benefits instead of the rich (as their cushy deals disappear under independent politicians). We really do need to all get behind these measures.

12507. One Planet Only Forever at 03:53 AM on 10 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       The new claims by the correction resistant likes of the Republicans are no surprise.

       People who passionately believe the fairy tale that 'decent results will only develop if everyone is freer to believe what they wish and do as they please in competitions for popularity and profitability' can be expected to:

       • claim that 'innovation in an unrestricted and unregulated marketplace is the only solution to the climate change problem'.
       • fail to acknowledge that, in spite of restricted freedoms for people in their socioeconomic-political systems, people who chose to try to get away with unsustainable and undeniably harmful activities in pursuit of popularity and profit have been rewarded. And the unjust rewarding would have been even more severe with less regulation.
       • fail to see that the poorly governed socioeconomic political system that developed the problem also enables undeserving winners to very effectively resist being corrected and resist suffering penalties for understandably incorrect pursuits of popularity and profit.
       • resist understanding that the inability to get away with harmful unsustainable activity will be the most powerful way to motivate helpful sustainable innovative developments.

       The economic reality is that the currently incorrectly developed massive climate change problem will not be solved by figuring out what price to put on the externalities of fossil fuels. The incorrect development of burning of fossil fuels needs to corrected by ending the burning of fossil fuels.

       If a socioeconomic system was starting from scratch, it could develop helpful sustainable activity if:

       • there was rigorous monitoring of the potential for harm from any activity in the competitions for popularity and profit (competitions for perceptions of superiority relative to others).
       • and any activity discovered to be potential harmful was effectively limited until an investigation is completed to determine if there indeed is harm being done (the activity potentially fully shut down if the risk of harm was severe enough). And if the investigation concludes that no harm is done then the activity can be returned to a status of full freedom in the rigorously monitored competitions for popularity and profit.

       Harmful unsustainable externalities would not be allowed in the system. The impacts would need to be completely neutralized at the time of their production. They could be neutralized by the producer as part of their cost of production. Or they could be neutralized communally, with the required funding obtained through fees from all parties associated with the production of the harm. And the communal action would neutralize the impact as it was produced (no imposition of the problem on future generations, not even on next year's population).

       And that understanding exposes that trying to calculate a 'cost for carbon' is incorrect. Production of additional CO2 needs to be terminated, not just be reduced to the degree that a 'calculated price' would reduce it. And the recent impacts also need to be corrected for, meaning getting today's people to pay to remove some of the previously created CO2 (and pay to help the already negatively impacted people).
       The developed socioeconomic-political systems clearly developed significant incorrect activities because it was not correctly operating or governed. The needed 'cost on carbon' today would include the cost to effectively fully neutralize 'new production of CO2 today'. That means the cost of actually doing something today that really counter-acts a production of new CO2, like fully capturing the new CO2 as it is produced, or an equal amount, and processing it in a way that is harmless and sustainable.

       Even that corrective action misses a very important required corrective cost, the cost of removing the excess CO2 that people incorrectly profited from producing. It is arguable that all fossil fuel created CO2 since the mid 1800s would need to be paid to be removed by the descendants of those who benefited from that activity. However, I would accept that it is only practical to collect the costs of removing new CO2 that was created during a period like the past 30 years. Even that correction would require some complex forensic accounting to back-tax the undeserved wealth obtained through those 30 years. So that effort should be limited to the biggest recipients of undeserved wealth during that period (meaning accepting that some of the incorrect actions through the past 30 years will not be paid to be corrected by the ones who incorrectly benefited - the middle and lower income portions of the population would not be made to pay).

       That understanding of the required correction appears to be understood by the Republicans when they mention that going back into the past is not part of their 'desired solution'. They likely know they deliberately pushed to maximize their benefit from the burning of fossil fuels, including efforts to promote (propagandize) misunderstandings that were 'helpful to their harmful pursuits'.

       The likes of the Republicans appear to understand exactly what the problem is and its correct solution. They appear to really dislike the idea of being correctly corrected. And they are not interested in seeing the socioeconomic-political system corrected to end the potential development of other new 'innovative incorrect attempts to obtain popularity or personal benefit' they may come up with in their efforts to resist being effectively corrected.

12508. SirCharles at 00:04 AM on 10 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       2019 must be the year of attention. Name the crisis for what it is, a climate crisis. => https://tinyurl.com/CallTheCrisis

       The oncoming decade is DECISIVE whether our planet will remain below 2°C warming or not.

       

       => Global warming will happen faster than we think

       => That’s how fast the carbon clock is ticking

12509. MA Rodger at 23:47 PM on 9 January 2019
       CO2 effect is saturated
       

       Golly!! More complexity being considered.

       The tropopause is a temperature thing. The tropopause height drops at night, it drops through winter and it drops greatly with latitude towards the poles. The emissions height is a pressure thing (as well as a wavelength thing). Averaged across the globe, there are parts of the CO2 emissions band that have an emissions height up in the stratosphere, and an increase in CO2 concentrations (& thus the emissions height) will thus see wider wavelengths with emission heights up in the stratosphere. A rising stratosphere emissions height sees an increase in emissions temperature which would counteract part of the the otherwise full CO2 AGW effect. But with rising CO2, there will also be more wavelengths becoming significant to CO2 absorption, for instance the two compound bands at roughly 10 microns.

       As for the poles, these are small in area relative to the tropics and emit much less radiation from the surface (which can be absorbed by CO2) being colder. The tropopause at the poles drops to ~250mbar from ~100mbar in the tropics, so 2.5x the atmosphere above it with CO2 content. So at the poles the balance between above/below the tropopause emissions height will be greatly slanted towards stratosphere, at the poles relative to the tropics. But averaged over the globe, the poles are a small part of the equasion. It is all latitudes that are averaged out to give the logarithmic relationship between CO2 and CO2 forcing, a relationship which stands (from memory) up to 1,200ppm.

       Beyond that, the reference linked @489 is reporting that the CO2 forcing would be greater than logorithmic above 1,200ppm. Thus the rise of CO2 emissions heights for more wavelengths into the stratosphere would not see an end to CO2-powered AGW.

12510. Eclectic at 23:10 PM on 9 January 2019
       CO2 effect is saturated
       

       LTO @496 ,

       I commented (@495) because I was surprised that you (@494) were giving the impression that you thought the escape/emission altitude (for 15um IR) was in the stratosphere at some latitudes.

       The tropopause is a temperature- & weather-related concept.   OTOH, the 15um photon "escape" (for CO2 emission) is dependent on absolute CO2 density ~ and of course also dependent on temperature of "local" air which energizes the CO2 molecules to emit a sufficient energy flux to achieve the appropriate contribution to cooling the planet.   (The "altitude" you are interested in is not an ultra-thin single altitude [for any particular latitude] but is a weighted average).   The emission is from a fuzzy band (of altitude), so we mustn't oversimplify too far.

12511. michael sweet at 22:34 PM on 9 January 2019
       CO2 effect is saturated
       

       Philippe,

       Thank you for the references.

       I have noticed that it is becoming harder to find direct answers to some basic questions because they were answered so long ago.

12512. michael sweet at 22:31 PM on 9 January 2019
       CO2 effect is saturated
       

       LTO,

       I am not an expert on the tropopause but I doubt that the escape altitude will move into the stratosphere to a significant amount (I do not have a reference for that opinion).

       In the poles where the stratosphere is lowest the troposphere is very cold.  That lowers the escape altitude so that the escape altitude is still below the stratosphere (we discussed that the escape altitude varies across the planet from the tropics to the poles).  Perhaps Science of Doom can answer this question.

       These detailed questions are secondary to how the basic greenhouse effect works. 

        Keep in mind that the description of the greenhouse we have discussed is a description of some of the most important basic features of a very complex phenomenon. Many additional complications exist. If it were simple to evaluate the error bars on climate sensitivity would not be so large.

12513. LTO at 22:31 PM on 9 January 2019
       CO2 effect is saturated
       

       Hi Eclectic, it doesn't seem to me like you've correctly understood the figures quoted earlier (or my post@494), but others may have a different view. Why do you think the altitude of emission must always remain in the troposphere?

12514. Eclectic at 21:45 PM on 9 January 2019
       CO2 effect is saturated
       

       LTO @494 ,

       there are worrisome ambiguities in your comments.

       The "tropopause" is a very different concept from the "escape altitude i.e.  emission altitude".  For CO2 that altitude is dependent on the absolute density of CO2, while the tropopause is a temperature-related concept.  If I have correctly understood the figures quoted earlier, the [CO2] altitude you are interested in does always remain in the troposphere (not the stratosphere).

12515. LTO at 11:19 AM on 9 January 2019
       CO2 effect is saturated
       

       Thanks all, very useful. MA: that sounds like it would be extremely helpful for me and others.

       The point on many contributing phenomena is the key one - not just the existence of the phenomena, but how quantitatively significant it is. This no doubt varies with co2 concentration, and easily leads to confusion. The current understanding I have is that the most significant co2-induced warming mechanism (which is the one most people know about - re-radiation of IR photons to the surface) is indeed saturated at much lower co2 concs, and it is other effects that are purported to combine to trap significant amounts of energy in the troposphere. Once comfortable on this point, the point on energy balance is a given.

       One really interesting point that has come up is what happens when the altitude of emission is in the stratosphere. I understand that the tropopause varies between about 9 and 17 km, while co2 concs are relatively homogeneous across the globe, therefore the altitude of emission at ~10 km is already in the stratosphere around thr poles. it would seem that increasing co2 concs will, by raising the altitude of emission, progressively increase the proportion of the atmosphere in which this is happening. Will this offset troposphere warming effects to some extent?

12516. Evan at 05:16 AM on 9 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       nigelj@4 I agree completely. Individuals must start to act now on their own. Personal action should incentivize action because politicians will, to some degree, follow the lead of their constituents. But even if they don't, we must act. To solve the problem requires all individuals, organizations, and governments pulling as hard as we all can. Anything less than an all-out effort by everyone will likely fall short. We know this from the science, but nobody says it because of how unlikely it is to happen.

       Keep pushing the button for personal action and keep talking to your friends, neighbors, and family.

12517. nigelj at 05:08 AM on 9 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       Its also a false dichotomy to say its either government action, or individual action.

12518. nigelj at 05:04 AM on 9 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       Suggesting its either innovation or regulation is an obvious false dichotomy. We not only need technically inventive solutions (and we already have some) we need some pressure from regulation, subsidies or carbon taxes to force the scaling up of the solutions.

       The tragedy of the commons is empirical and historical fact and means market forces alone wont fix the problem, or will be painfully slow.

       The Ozone hole problem wasn't fixed by market forces alone. It used a cap and trade scheme to force the phase down of the flourocarbons. Without this we would without doubt still have an ozone hole.

12519. Philippe Chantreau at 04:53 AM on 9 January 2019
       CO2 effect is saturated
       

       The links are in the notes below and take you to the RC threads, where Ray Pierrhumbert did most of the initial comments. In fact, I don't know that anything recently discussed above is not adequately addressed in the notes right here below the comments, where there are many good links.

       http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/

       Part 2 is more interesting from the technical point of view, especially the extra absorbtion in the wings of the spectrum.

       http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument-part-ii/

       This is old news. The RC posts are almost 12 years old. It has all been worked out with the highest level of precision in HITRAN. The appropriate physics are in the models. It is not an area of very active research or debate. HITRAN was pretty much as far it was worth going with it, from any practical point of view.

12520. Evan at 03:21 AM on 9 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       It is time that we all collectively, as individuals, start to ramp down our emissions.

       We cannot wait for governments to tell us what we already know we need to do.

       The time for individual as well as government action is here.

12521. Alexandre at 03:16 AM on 9 January 2019
       Republicans call for 'innovation' to tackle climate change, but it's not magic
       

       Is it safe to say GW is not a Chinese conspiracy anymore?

       Moderator Response:

       [DB] It never was.

12522. MA Rodger at 01:02 AM on 9 January 2019
       CO2 effect is saturated
       

       michael sweet @391,

       I cannot fault what you say. Particularly, that "there are many phenomena that contribute to the greenhouse effect" is one of the difficulties in setting out a succinct statement of how it operates. Yet the simple energy balance is an overriding principle - if energy-out is different from energy-in, there has to be consequences, in the present case a period of global warming. The point with this aspect of AGW is that it is more than "settled", it is cast in concrete! All that people are lacking is an explanation appropriate for their needs.

       I have been putting a bit of thought on a journey to introduce these GHG mechanisms in a way I've not seen before. I'm hoping it may be useful to folk like LTO. I've not quite routed out that journey yet, but it is looking useful.

12523. michael sweet at 22:12 PM on 8 January 2019
       CO2 effect is saturated
       

       Chris Colose is a scientist who studies Climate Change who used to write sometimes for SkS.  He wrote a description of the greenhouse effect here.  His sumary states:

       "So…review: Because of energy balance, the planet must get rid to space as much energy as it receives from the sun. Averaged over the Earth, taking into account the albedo and geometry, this is about 240 W m-2. In the absence of an atmosphere, this flux of radiation is lost by the surface by \sigma T^{4}_{s}. With an atmosphere, this flux of radiation is allowed to emanate from upper, colder layers of the atmosphere, say on average at some altitude H. Increasing greenhouse gases increases the altitude of H, a height in the atmosphere which depends on wavelength, and characterizes a level of mean emission to space. Because the atmosphere is now emitting from colder levels of the atmosphere, the OLR has decreased, and the result is that the planet must warm to re-establish radiative equilibrium."

       I think my description is similar to his.  His summary is more technical and those who want to increase their knowledge of the greenhouse might want to read it.

       Apparently I mistook line broadening and pressure broadening.  Line broadening is important for the greenhouse on Earth.  Both these effects, and many others, contribute to the magnitude of the greenhouse effect.  If we double the concentration of CO2, the CO2 will directly cause heating of about 1C.  Some of that will be due to line broadening.  Feedbacks from other causes like increased water vapor and changes in clouds will contribute additional heating.  The feedbacks are difficult to calculate exactly but if the climate sensitivity is 3.0C (about midrange in the estimates) they will contribute 2C.

       Philippe Chantreau: can you link Gavin Schmidt's comments, I could not find them at Realclimate.

       As I said above, there are many phenomena that contribute to the greenhouse effect.  Different scientists sometimes emphasize different phenomena as important.  All these effects together make the greenhouse effect.

12524. Jonas at 20:29 PM on 8 January 2019
       2018 in Review: a recap of the Skeptical Science year
       

       PS: Thanks for the translation and sorry for the additional work, maybe I should have written in english, but beyond expression thanks, I wanted to hint to the international audience and the excellent translations that I also often link to (e.g. the guide to skepticism, debunking handbook, posts ..).

12525. RickG at 08:42 AM on 8 January 2019
       Skeptical Science takes the Pro-Truth-Pledge
       

       I think this type of approach is the key to getting people to understand the importance of fact checking and actuatly doing it.  I would also suggest the importance of addressing the content of what people say, not the person saying it.  That is, criticize (in a friendly way) the comment, not the commenter.

12526. scaddenp at 07:39 AM on 8 January 2019
       Models are unreliable
       

       I am not sure his series amounts to a "critique". He states "Climate models are the best tools we have for estimating the future climate state."

       and

       "There are lots of papers written by climate scientists on the difficult subject of evaluating climate models. They do some things well. They do some things badly. Different models get different results. Sometimes widely different results."

       No arguments there.

12527. nigelj at 05:55 AM on 8 January 2019
       Skeptical Science takes the Pro-Truth-Pledge
       

       This is such good advice. Sad in a way people need reminding.

       I stumbled on a so called science website, complete with advertisements for viagra and a book on the illuminati, and no list of the academic qualifications of its authors. Obviously the website could be completely ignored as unreliable. You have to filter out things that are a waste of time.

       One thing on verifying truth and intelligent opinion. Look for inconsistencies because these are the sign of poor quality thinking and a lack of intelligence. 

       I wonder if science has been just a little unlucky lately, and its just a temporary thing. We have had the climate gate emails where phrasing of certain statements created a bad impression, a mistake in one of the IPCC reports, the science community has revised its views on saturated fats, there have been a few other things that create the erroneous impression science has got things badly wrong. Of course if you look at the specifics, and put it in context its all nothing of consequence.

       Yet this has coincided with globalisation causing some problems, another apparent failure of experts, (it isnt) and the development of the internet and social media which turbo charges the exchange of conspiracy theory nonsense.

       I would say the net result is some well meaning ordinary people jump to the wrong conclusion that "elites cant be trusted". Its so frustrating because if anything expert knowledge is better than ever before!

       I hope sanity will prevail, and it will all blow over.

12528. nigelj at 05:05 AM on 8 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       johnthepainter @12 the original article didn't say the antarctic wouldn't collapse, it just shifted the time frame forward from by the end of this century to around 2200 - 2300. 

12529. nigelj at 04:50 AM on 8 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Evan @11 yes true it would be better to get the worst of it out of the way relatively quickly, provided we  knew the exact extent of sea level rise so we could rebuild behind  the danger zone confidently. But we will never have that certainty. The most likely outcome is we will get the worst of both worlds, long slow sea level rise with unpredictable shorter periods of rapid sea level rise embedded in this. 

       I dont envy the people trying to understand it and model it. Its not as if we can build full size glaciers and do experiments with them.

       Anyway all I know is our climate agency did graphics of the impact of 500 and 1000mm on our coastal cities and the impacts were larger than I suspected. It's hard judging sea level rise just by visually looking at a beach, its so easy to underestimate it. Cheers.

12530. johnthepainter at 04:42 AM on 8 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       What I'm wondering is how we can reconcile the conclusion of this study with the following one, reported December 18: "Discovery of recent Antarctic ice sheet collapse raises fears of a new global flood" https://www.sciencemag.org/news/2018/12/discovery-recent-antarctic-ice-sheet-collapse-raises-fears-new-global-flood?fbclid=IwAR2jMO7SgRVG4Hy7vTY3zaqi66sI2543COyiAiaIB2ej3vUvyMS5W3PgRgM

12531. VeryTallGuy at 04:41 AM on 8 January 2019
       Models are unreliable
       

       The excellent "Science of Doom" has a critique of your debunk. 

       Someone from SKS may wish to engage.   SoD is generally an excellent site for true scepticism. 

       https://scienceofdoom.com/2019/01/06/opinions-and-perspectives-5-climate-models-and-consensus-myths/

12532. jef12506 at 01:30 AM on 8 January 2019
       2019 SkS Weekly Climate Change & Global Warming Digest #1
       

       I hope everything will be OK.

12533. Evan at 01:13 AM on 8 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       nigelj@10 Here is another perspective. The way we deal with hurricanes is that we try to get everybody back from the shore and out of the way. We let the hurricane do its damage, then we clean up the mess and move everybody back (I mean no disrespect for those who suffer during hurricanes, just trying to summarize).

       We seem to take comfort if we can convince ourselves that the sea level rise due to ice loss will be slow. How do we do that with sea level rise that occurs over millenia? It would almost be better if sea level rise happened fast (like a Hurricane) and we got it over with quickly so that we had something like a single, focused event to deal with. Slow sea level rise might actually be harder to deal with than rapid sea level rise.

       I think the only thing that matters is continually monitoring all of the world's ice so that we can improve ice-loss forecasting. We need to budget for this from now on just as we budget for tsunami and hurricane monitoring systems.

12534. Philippe Chantreau at 00:31 AM on 8 January 2019
       CO2 effect is saturated
       

       I recall Gavin Schmidt going at length over this at RC and saying basically the same thing: the absorbtion in the "wings" is where the additional watts/sq.m happen as concentration goes up. It adds up significantly. This may even figure still in the "Saturated gassy argument" posts linked below the thread.

12535. MA Rodger at 20:27 PM on 7 January 2019
       CO2 effect is saturated
       

       LTO @486,

       I'm conscious that directly answering some of your queries would lead toward some rather incongruous implications with complex explanations required to sort them out. So I'm torn between simply answering #486, going back to first principles as an explanation or introducing a mathematical model into the mix. Haven't decided which yet.

       But I will pitch in with (1).

       michael sweet @487 mixes up the broadening of the CO2 dip in the IR spectrum (most important) and pressure broadening (not important). These are two different phenomena.

       The 15 micron wave band absorbed by CO2 is flanked by weaker bands which result from spinning CO2 molecules. Spin being a quantum process, there are only certain speeds of spin that can happen, resulting in the graph below (I assume it is for 1 atm).

       

       It is the strenghtening in these flanking bands that broadens the CO2 IR dip.

       But you will also note there is a small probability of absorption at wavelengths between the seperate bands. This is the pressure broadening which is a big effect on Venus with its 90bar atmosphere.

       As for your actual question, the effect of this broadening of the CO2 dip with an increase 400-to-800ppm relative to a 280-to-400ppm increase (=100). I think, as a component of a logorithmic ratio of 194/100, it would possibly be something like 400/100. By 800ppm, the emissions height for the central part of the band is increasingly in the stratosphere and so acts as a cooling mechanism counteracting much of the warming through the strengthened absorption at the edges of the CO2 dip. You may find Zhong & Haigh (2013) 'The greenhouse effect and carbon dioxide' Figure 5b a useful reference.

12536. nigelj at 16:11 PM on 7 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Evan @9, thank's for the video link. Given this is a climate expert talking about more than 5 metres sea level rise per century, I agree he cannot be simply dismissed. Shame the video was so short.

       Basically this is how I have approached the sea level rise  issue, fwiw. I have been aware for quite some time  of claims of 5 metres sea level rise per century versus the 1 metre IPCC estimate. Its hard for me to know who to believe short of cracking open a textbook or two. My own instincts fwiw have always been that the IPCC have been too conservative in their estimates, but I try to avoid confirmation bias, and catastrophic mindset thinking, so I looked at the historical record for guidance.  This is something that is happened, it does not rely on " ifs, buts and maybes" and pages of differential equations.

       The historical record does have periods of multi metre sea level rise per century, associated with ice sheet destabilsation. They appear to be around 2 - 3 metres per century for several centuries. So that is what I would see as a very strong possibility. 

       Here's another thought. I design infrastructure. Obviously the 200mm sea level rise last century is not too problematic. Its unlikely to devastate anything and is easy to design for and it was reasonably constant. Get up towards 500mm  and we have serious problems. Florida is already in this territory. It threatens existing infrastructure and making planning for the future difficult. Much land would just have to be put off limits.

       At one metre and even assuming its constant over time, building is a big problem. It would be absurd building foundations to cope. Huge areas of land would simply have to be put off limits for development.

       Now we have this scenario that it "could" be more than  one metre, who knows, perhaps two metres, or more than five metres. I dont even think it matters too much which, because a) it is all going to lead to huge loss of coastal land and b) the unpredicatbility of it all makes design impossible. 

12537. Evan at 14:00 PM on 7 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Riduna@8, thanks for the links. I take it seriously when people like James Hansen and Richard Alley talk multi-meter sea-level rise this century. nigelj was citing a background rate that is low multimeter due to historical precedence, and I realize that some of the best researchers are talking 5m or more. I cannot see that anything we will do will change the conclusion that it is time to start building coastal defenses where it makes sense, and time to start retreating where it does not make sense. In that light I found it interesting that there are already places where the retreat has started, even if climate change is not specifically identifed as the reason for the retreat.

12538. Riduna at 13:22 PM on 7 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Evan

       In 2018 I wrote an article There Will Be Consequences in which I cited work by Dr. Hansen and some leading glaciologists showing that under certain conditions mass loss from the polar ice caps could produce sea level rise of >5m. within a century.

       The likelihood of multi-metre sea level rise this century is seen as inevitable by many experts in the field. While some may reject that conclusion, they must do so in the light of increasing loss of ice from the Greenland Ice Shelf, Dr Rignots assessment of Antarctic instability and Hansen et al 2016.

       We may naïvely take comfort from those who espouse sea level rise of <1m. this century (5AR) but the evidence is compelling that without sustained reduction in greenhouse gas loading and emissions, we are very likely to be assured of multi-metre sea level rise in the latter part of this century.

12539. Tom Dayton at 11:39 AM on 7 January 2019
       Sea level rise is exaggerated
       

       AFT: Try https://sealevelrise.org/states/florida 

12540. scaddenp at 11:35 AM on 7 January 2019
       CO2 measurements are suspect
       

       billev - perhaps you are unaware of this satellite and its mission? There are several ways to determine what the increase in CO2 can be attributed to from carbon mass balance (we know pretty accurately how much FF is burned), O2 depletion, changing carbon isotope composition (FF has no C14), ocean pH. In fact nature is so far mopping up about half our emissions. More here.

12541. scaddenp at 11:25 AM on 7 January 2019
       Sea level rise is exaggerated
       

       I think Miami is already struggling with sealevel rise. Cant help with Houston Ship Channel sorry.

12542. michael sweet at 10:47 AM on 7 January 2019
       CO2 effect is saturated
       

       LTO:

       I found a Boltzmann Equation calculator on line (Google)

       It finds 239.8 W/m2 at 255 K and only 228.7W/m2 at 252K.  That means the Earth heats up faster than if the difference was only 1W/m2 but in the end the temperature at the escape altitude must increase to 255K so all the energy is emitted.

12543. michael sweet at 10:27 AM on 7 January 2019
       CO2 effect is saturated
       

       LTO,

       SkS is always happy to help those who want to learn the science.

       1) My understanding is that line broadening is a very small effect on Earth.  It is important on Venus.  It is not necessary to understand line broadening to get the basic greenhouse effect.

       2)  CO2 molecules emit a variety of radiation lines with15 micron being the most important.  The number of photons emitted by a section of the atmosphere (with a great many CO2 molecules in it) is determined by the black body equation.  Most of the CO2 molecules that absorb a photon coming up from below transfer the energy of the photon to other molecules in the air through collisions.  They do not re-emit the photon they absorbed.

       There is always a population of excited CO2 molecules that can emit a photon.  These molecules are excited by collisions with other molecules.  The size of this population is determined by the black body equation.  When it is hotter there are more molecules that are excited and more photons emitted.  When cooler less excited molecules, less photons.  The number of photons increases with Temperature to the fourth power.  The population of excited molecules is the important idea, not individual molecules.

       3) Let us imagine the escape altitude is 10.00 km and the Earth is at equilibrium.  Exactly the same amount of energy is emitted from the molecules at the escape altitude as is absorbed by the Earth (the energy comes from the Sun and is primarily absorbed on the surface).  The Earth receives 240 W/m2 and emits 240 W/m2.  The Earth is at a stable temperature.   The temperature at the escape altitude is 255.0K.  

       Someone adds 1,000 gigatons of CO2 to the atmosphere.  This causes the CO2 concentration to double.  This causes the escape altitude to increase to 10.50 km (500 meters). 

       The temperature of the atmosphere decreases with height according to the lapse rate (6C per km).  The temperature at the new altitude is only 252.0K (255 - [0.5km x 6C/km]).  Because it is colder less energy is emitted from the Earth (the amount can be calculated using the Boltzman equation.  It takes me a long time to calculate with this equation.).  For the purpose of discussion let us say at the new altitude only 239 W/m2 is emitted.

       The Earth is no longer at equilibrium.  It is absorbing 1 W/m2.  It starts to heat up.  The temperature at the escape altitude must increase to 255.0K in order for the Earth to emit 240W/m2 again. (There are some complications like a small increase in surface area that do not matter). 

       The atmosphere always has a lapse rate of 6C/km.  Since the temperature at 10.30 km has increased 3.0C the rest of the atmosphere also increases.  The lapse rate is a measured physical property so it must be applied.

       I do not understand your question about energy.  Most of the absorbed energy is transferred to the surrounding atmosphere.  That is how energy reaches the escape altitude and is emitted to space.

       The main effect is sometimes in the eye of the beholder.  I think the main effect is to  increase the temperature of the atmosphere.  That occurs because CO2 (and other greenhouse gases) absorb upwelling IR radiation and slow the emission of energy into space.  Both re-radiating energy back to the surface and heating the surrounding air are important.  The most important effect is increasing the escape altitude.

       4) The maintenance of the lapse rate in the atmosphere is complex (scientists who study the lapse rate understand how it works).  See this article for background information (found using Google).  Convection is involved but there are other factors.

       When we say the escape altitude is 10 km that is an average over the entire Earth: Tropics to Arctic, night and day (a few wavelengths escape from the surface).  The escape altitude is not the same everywhere on Earth.  In the Tropics it is higher than in the Arctic.  The lapse rate is an average property of the entire atmosphere, individual storms or other phenomena can violate the lapse rate (and the escape altitude) for periods of time.

       I recommend you accept the lapse rate and escape altitude on faith while you learn how the greenhouse effect works.  After you understand the basics you can add other effects that you are interested in.  Line broadening, convection, heat transfer by phase changes, clouds and other effects all occur in the atmosphere and alter the greenhouse effect.  Climate models have to deal with all these effects but they do not alter the basics.

12544. AFT17170 at 07:47 AM on 7 January 2019
       Sea level rise is exaggerated
       

       I encounter some extreme fringe RWNJ deniers on various investor sites. They literally don't care if the West Coast or Northeast have issues with SLR "because Democrats live there" (no, I'm not kidding). So I would like to put it in terms that they might care about. At approximately what year does SLR become "a problem" for Florida (that big swing state needed to win elections)? The Houston Ship Channel (which would be supremely ironic)? Has there been any science done at that kind of level?

12545. rcass at 06:28 AM on 7 January 2019
       Other planets are warming
       

       What amazes me about this discussion is the absense of any explicit mention of the earth's moon. The moon has been monitored for decades. It has more or less the same spatial position with regard to the sun as the earth and it has no atmosphere. In other words, it provides the perfect 'control' to assess whether earth is warming due to solar or atmospheric causes. Yet t is almost impossible to obtain an online plot of the moon's average temperatures over time - I've tried. If the moon's averages are stable or declining - out of synch with temperatures on earth - that obviously and clearly settles the argument. Skeptics talk about Mars and Pluto, where there is insufficient data. They at least appreciate that this kind of data, if reliable, is persuasive. Why do not climate change believers produce reliable plots of the moon's temperature averages against time. They are very fond of plotting earth temperature's against time. Why is this blindingly obvious 'crucial' experimental comparison never discussed?

12546. Evan at 06:25 AM on 7 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       nigelj@6, thanks for your thoughts. I've seen a lot of this material and agree with your analysis. We are talking varying shades of bad.

       Have you seen Richard Alley's short video clip where he says (not predicting) that 15-20' this century is possible? Here is an article in Rolling Stones that contains Richard Alley's video clip.

       Needless to say Richard Alley knows this stuff better than any of us, and he is a seasoned scientist, not given to making exaggerated claims. His message is sobering. But we all agree, even if he is wrong, it is still time to prepare. So here is a feel-good PBS story about a town that is taking the right steps, right now, to prepare for what is coming.

12547. nigelj at 05:02 AM on 7 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Evan @5, as far as I can figure out The IPCC currently predict 1 metre of sea level rise per century (worst case scenario) spread out over many centuries and based on medium to high climate sensitivity. If we burn all fossil fuels we are talking 30 metres plus of sea level rise but over a lengthy period.

       But some of us think they are being too conservative and that it could be more than 1 metre per century at least for a period of time. Maybe not by 2100 but soon after this

       Anyway  I would think 2 metres per century for maybe 5 centuries for example 'would' fall into the categorisation of a quick pulse! And it would be devastating for infrastructure.

       I was simply trying to get a handle on what has happened in the past known with some certainty, and that is 2 metres per century as far as I can tell. 

       However I would definitely agree we cannot rule out more than 2 metres. J Hansen has written a paper somewhere finding that 5 metres per century is possible based on physics and modelling, but many worst case factors have to coincide for this to happen.

       I do not know nearly enough physics really, but I know warming is looking like a quadratic curve, so you would expect melting of ice and expansion of sea water to follow this, and this suggests about 1 metre of sea level rise per century over many centuries. However the wild card is ice sheet destabilisation, where glaciers speed up, or the face of ice sheets starts to collapse. This looks like it would cause a step change in a quadratic curve. Glaciers would however come up against limiting facor of friction. The article suggests the face of ice sheets could collapse rapidly from undercutting and the possibility of 4 metres per century for a couple of centuries at least perhaps until things reach a new equilibrium.

       2 metres per century. 4 metres per century. All bad.

12548. Philippe Chantreau at 03:32 AM on 7 January 2019
       2nd law of thermodynamics contradicts greenhouse theory
       

       AFT, anyone who thinks seriously about it undertands that thermodynamics are not violated. This argument is just part of larger campaign undertaken by some actors because they know where the morally defensible position is and that people will in their majority adopt the morally right position if there is no doubt about it.

       The depth of the denial is compounded by numerous factors. Some scientists, like G&T, are unscrupulous enough to write such nonsense. The general population is science illiterate and innumerate enough to buy into it. The ambient attitude that anyone is free to have whatever opinion they choose is stretched to the point that it implies said opinion has validity. The overall anti elite and anti intellectual sentiment has been cultivated by crooks purely for the fostering of their financial interest.

       There is little to gain by arguing with those who go for the 2nd law argument; they are ready to cling to any straw, no matter how feeble and likely won't be convinced by any level of reasoning or evidence. Look how long this thread is. Waddle in it if you want, it's saddening. Almost 1500 post devoted to the least valid "skeptic" argument of all. It says something.

12549. Evan at 01:39 AM on 7 January 2019
       2019 SkS Weekly Climate Change & Global Warming News Roundup #1
       

       Thanks for the clarification nigelj@4.

       I assume you've seen Fig. 1 in the paper by Alley et. al. (2005) where they present a graph of sea level vs. CO₂ concentration. Using a climate sensitivity of 3C/doubling CO2, their graph works out to about 12m/1C warming, at least for the first 2C of warming or so. If we assume that we stabilize at 2C, that implies 24m of sea-level rise. At 2m/century that's 1200 years.

       The engineer in me says that given how rapidly we've warmed the planet, that we will get a sizable chunk of that 24m much, much sooner than using 2m over 1200 years. I'm not disagreeing with your analysis nigelj, but rather noting that we might get a quick pulse that then settles down into a long tail that approximates 2m/century, because we are causing a warming pulse that represents more of an impulse to the system than what we expect happened during deglaciation cycles.

       And of course this assumes that we stabilize at 2C.

12550. AFT17170 at 23:06 PM on 6 January 2019
       2nd law of thermodynamics contradicts greenhouse theory
       

       I'm fairly new to this site and just catching up on a lot of articles and comment streams. Is this myth still used? The way I explain it to laymen is...

       The CO2 greenhouse effect was discovered in the 1890's. Much of its fundamental underpinnings were discovered and confirmed with Cold War era military research. So I find it exceptionally hard to believe that this theory was studied for ~90 years before the existence of the IPCC and nobody noticed that it violated basic laws of physics.

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