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Phil at 01:21 AM on 15 February 2014Discussing global warming: why does this have to be so hard?
mgardiner @40
Yes I agree it would be tricky; the scientist would need to be impartial (and sound it too) and it would be clear that he was reporting the politicians statement against the published scientific literature.
The discussion that funglestrumpet referred to (embedded in a page here) concludes with a "discussion" about whether the heat uptake by the ocean that is responsible for the "pause" in atmospheric temperature rise is measured or speculation - it would be nice if someone, on air, could have referred to a paper that did report the measurements, perhaps with a comment along the lines of "If Lord Lawson, or his advisors, thinks there is flaw in this paper, he would do climate science a favour by submitting his reasoning as a peer-reviewed scientific paper"
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Jim Eager at 00:40 AM on 15 February 2014How we know the greenhouse effect isn't saturated
Richard McGuire, the cold layers in the upper atmosphere stop impeding the escape of heat energy radiated from the surface simply because the density of CO2* falls below the threshold that insures that a photon will more likely be absorbed rather than continue to space unimpeded. Since that altitude is colder than the surface, less energy is radiated to space than is emitted by the surface, so the entire atmosphere below that altitude warms until outgoing energy matches incoming energy.
Adding more CO2 makes little direct difference at the surface, but it raises the altitude where CO2 radiates to space, and since that higher altitude is colder, the entire atmosphere below that altitude will warm still more until outgoing energy once again matches incoming energy.
*H2O is simply not a factor at the altitude where CO2 radiates to space as H2O is almost non-existant, having dropped below the concentration of CO2 between 6 and 8 km up, and fallen to only 3-4 ppm at the tropopause. However, as the atmosphere warms it will hold more H2O, thus raising the altitude where H2O radiates directly to space in wavelengths not absorbed by CO2, which will cause still more warming of the atmosphere below that altitude. This is known as the water vapour feedback.
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Markoh at 00:14 AM on 15 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
HK @ 83
Thanks for that. It makes sense. I am not an expert by any means, but I do know from non-climate modelling that the assumptions into the model are as important as the results out.
Good point about the accelerated ice loss. Suggests the earth is more effective/has more mechanisms for transporting heat to the cold reaches than models anticipated.
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Alexandre at 00:02 AM on 15 February 2014Discussing global warming: why does this have to be so hard?
I did not grasp the hypotheses where we can be lucky enough as to have AGW only as a "minor inconvenience". Even the lower end sensitivity means reaching more than 2ºC warming, even if after 2100 - specially if we have in mind that there's no credible policy proposal today of leaving any fosil fuel unburnt underground.
The article should make it clear that mitigation is necessary even if we're lucky enough to have a 1.5 ºC sensitivity - which is very unlikely.
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Bob Loblaw at 23:38 PM on 14 February 2014Australia’s hottest year was no freak event: humans caused it
barry:
KR has mentioned relative humidity (RH). While it has its place in humidity measurement, it is not an absolute quantity (the hint comes from the use of "relative" in the title), and misses out some key components of water vapour in the atmosphere.
The question is "relative to what?", and the answer is "the saturation humidity at the current temperature". The Clausius-Clapeyron relation tells us the saturation quantity as a function of temperature - it's roughly exponential, with higher values at higher temperatures. A relative humidity of 65% means that the absolute humidity is 65% of the saturation value at the current temperature.
Humidity can be measured in several related combinations of units that aren't "relative":
- vapour pressure (partial pressure of the water vapour gas)
- specific humidity (ratio, weight of water vapour to weight of dry air)
- absolute humidity (ratio, weight of water vapour to weight of moist air)
- dew point (temperature at which the current absolute humidity equals the saturation value)
Now, to get back to the cloud issue:
- warmer air can hold more water vapour before it reaches saturation
- air that isn't saturated needs to be cooled to the saturation point before clouds can form
in comparing two masses of air, the one that is "warmer and more moist" may reach saturation at a higher, lower, or the same temperature, depending on how much warmer and how much wetter (and this also depends on where along the exponential Clausius-Clapeyron curve you are).
In weather/climate, the three common ways of cooling air to form clouds all involve adiabatic cooling: as air rises, the pressure drops, and cooling occurs. The three ways of getting air to rise are:
- free convection (heating from the ground, heated air rises through overlying cooler air, due to density differences)
- push the air up over a mountain (orographic precipitation)
- push warm, moist air up over cold dense air (along fronts between air masses. Happens in cyclonic storms.)
So, if the air becomes more moist (in absolute terms), we also need to know if it is warmer or cooler. Let's take one example where the air is further from the saturation point. You can get a combination of:
- clouds won't form (doesn't cool enough as it rises - or in other words, doesn't rise enough)
- clouds form at a greater height
- clouds form a a similar hieght, but in a different form
Same options (in reverse) if the air is closer to saturation.
In summary, yes it is complex, and this is why cloud feedbacks are difficult to estimate wrt climate change. All evidence so far is that cloud feedback effects are small, however (globally-averaged).
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Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Markoh @76:
Honestly, I’m not a model expert, so I don’t know how much deep ocean warming they have predicted in the future. If they have predicted less deep ocean warming than we are seeing now and this pattern continues, it will certainly reduce the expected SLR from thermal expansion.
But it’s also worth noting that the models have missed the accelerated ice loss from Greenland and Antarctica. The annual contribution to SLR is now between 1 and 1.5 millimetre per year from Greenland (figure 56 in the link) and maybe about 0.5 millimetres from Antarctica (360 gigatonnes of ice = 1 mm). Add the melting mountain glaciers, and we’ll find that melting land ice is now the dominant cause of the SLR.
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Markoh at 23:26 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Michael Sweet @79
i ask a question and you respond with insults, which is unacceptable. However moving forward, you made statements of how models work. Is this knowledge from modelling you have personally done? If not can you please cite a source for the explanation?
Moderator Response:[JH] What is unacceptable is your mischaracterization of responses to you. Please cease and desist.
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ubrew12 at 23:23 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
mgardner@21: Sorry I took so long to get back to you. I guess, succinctly, what I was saying is there are two kinds of people these days: those who point to debt, and those who point to climate debt. The success of the climate obfuscation movement is the idea that you're being unpatriotic to think you can point to both. It's one or the other, pick a side. Since you never know who you are talking to anymore, CC is one of those subjects about which "silence is the better part of valor". And, of course, silence works for the fossils industry: The Silence of the Lambs.
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mgardner at 23:15 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
Phil@39
This is an interesting suggestion, but then you would have the claim that the scientist is not offering an impartial assessment, and you would have to have a scientist 'from the other side' as well, and then you would end up with the same problem, since scientists 'on the other side' tend to use the same approach as the politicians.
I'm just going to repeat the point I made earlier-- it's about what we in the USA call "playing to the base".
Scientists play to their own base; they get approval by being detailed, adhering to the rules, using language correctly, articulating any potential contradiction to the point of appearing equivocal, and so on.
Politicians do best when they can use simple slogans and emotive language, as you say.
And in this case, I would have to conclude that one 'side' is all about style and group identity, not substance. I am puzzled that many with scientific training ignore certain simple facts that point to this. How is it that, in the USA at least, there is this very strong correlation between climate skepticism, evolution skepticism, and a particular constellation of social/economic/political claims. There is no logical connection among these things, so what do they have in common?
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Bob Loblaw at 23:06 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
KR:
Thanks for the correction on Tamino's model.
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Bob Loblaw at 23:05 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
If Klapper really thinks that two different data sets are equivalent because the slope of the linear regression is the same, then perhaps he should review Anscombe's Quartet - four different data sets that have identical (to a certain precision);
- mean X and mean Y
- standard deviations (or variance) of X and Y
- same linear regression (slope and intercept)
- same correlation coefficient
...so, from the point of view of several common statistical tests, the four data sets might be thought of as "the same".
Yet when you graph them, you get (from the Wikipedia page linked to above):
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chriskoz at 23:03 PM on 14 February 2014How we know the greenhouse effect isn't saturated
Thanks Glenn & jg for the simplest possible explanation of the essence of GHE. I would not imagine such explanation be possible as the more i'm learning about GHE the less easy it becomes, as the grasping of many aspects of physics is required.
Your last three paragraphs do capture the essence of GHE from the planetary energy balance perspective. But on top of that, the average person or denier might ask: what does such effect has to do with supposed increase of surface temperature everyone is fearfully talking about? The answer is: as the 'action' moves higher, the temperature profile of the atmosphere must adjusts according to the temperature lapse rate. You have to refresh your knowledge about lapse rate (dry and wet) in order to understand why such adjustment is happening. Just as you have to recall the adiabatic processes in order to know why the air pressure and temperature decrease with altitude. Also you have to be aware why permanent gases like CO2 are "well mixed" while H2O precipitates at tropopause. Those basic processes are not explained in this article because no one seems to be denying them (although few years back, someone in US Congress was speculating that "excess CO2 will stay near ground because it's heavier than rest of gases", so even such basic high school topic sometimes requires debunking).
I don't want to discuss details of planetary response to GHG forcing: that's a separate topic. I just wanted to show a nice animation from RC, that captures the situation like 1000 words:
From there, you can now clearly see that a property of constant lapse rate - the slope of the blue line - in the atmosphere (more or less true in the first approximation) ensures that the increased temperature near the top of troposphere is transfered all the way back to the ground, resulting in GW as we the ground creatures, experience.
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Phil at 21:43 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
funglestrumpet @32
It is interesting (and depressing) that the BBC set up a debate between a climate scientist and a politician. Such a debate obviously places the climate scientist at a intrinsic disadvantage, since they are percieved as offering impartial expert advice in their field, and cannot therefore comment on matters like whether wind turbines are "a waste of money" or "an eyesore", or really employ emotive arguments. Lawson was placed at an advantage since he could offer unsubstantiated opinion on aspects of climate change which were outside Hoskins remit as a scientist. It would seem to me to be a much fairer approach to have two politicians debate the issue, and afterwardds have a scientist offer an impartial assessment of how the politicians views corresponded with the established science.
Another rather sad thought is that I, personally, cannot see a politician that would go head-to-head with Lawson who commands respect, Ed Davey, Lord Deben and Tim Yeo are possible candidates, but I feel the UK is badly in need of a climate change advocate. -
michael sweet at 21:26 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Scientists continualy review all their models. Your suggestion that they are not is simply false and demonstrates that you do not understand how science and models work. There is a question of how (and if) the physics in the models needs to be adjusted. Some of the models handle ocean heat well, others not so well. Scientists are trying to determine if this is because of random weather or climate. Adjustments are always made when new physics is learned.
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Richard McGuire at 21:15 PM on 14 February 2014How we know the greenhouse effect isn't saturated
The only way a myth can be debunked is if what is put up on science blogs such as this can be explained , debated and understood in the wider community. The saturation argument is a popular with climate change contrarians. I think the Real Climate "Saturated Gassy Argument" referred to @9 is well worth a read, though even there a better explanation is required as to why the cold layers in the upper atmosphere do not also impede the escape of heat energy radiated from the surface.
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denis.boarder at 20:12 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
The article is commendable, however the assumption is that we all work, and want to work, within a logical framework of rational, critical and sceptical thinking. We chose words carefully for the sake of political expedience but to what end?
Fine if we are at a dinner party, and civility is a prerequisite for not embarrassing the host, but in the wider world the dynamics of the conversation have changed. It is no longer a simple case of presenting evidence and logically debating the finer scientific points.Reasonability and patience has its limitations, even with friends. Probably has something to do with differing 'world views' ...???
I am sure there is no agenda to wreck the environment, but the motivation to maintain and extend a lifestyle pushes environmental impacts into a lower order of concern. The level of concern is perhaps inverse to the perceived value and limited by a short horizon. Strong headwinds blow against mitigation, despite, and perhaps because of an extremely muted and considered response from the scientific community. It is perhaps the time to turn off the 'impotent charm' and throw reasonableness out the window.
For all the good work going on within acedemia, and a not inconsiderable number of busy climate communicators, my perception, rightly or wrongly, is that significant will only be made once (excuse the pun) the temperature is raised.
The lead taken by Michael Mann (as one example) needs to be emulated if any real progress is to be made.
PS: To John Cook, Dana, John Abraham, Graham Readfern & Co. keep up the good work.
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Dikran Marsupial at 18:38 PM on 14 February 2014How we know the greenhouse effect isn't saturated
Richard McGuire - yes, CO2 is more effective in the upper atmosphere because the air is colder and less humid, however that is a more advanced topic than is intended to be covered in this particular article.
The argument that CO2 is saturated was first raised by Knut Angstrom in 1900, and was refuted in the forties and fifties by the work of Guy Callendar and Gilbert Plass, so the skeptic myth was busted over fifty years ago. The skeptics are rather behind the times to begin with on this one! This argument is a bit of a touchstone, a bit like the argument that the rise in atmospheric CO2 is natural; it is an indication that the "skeptic" simply can't be bothered to look into the science and find this myth was busted long ago.
There is a slightly more detailed article at RealCLimate that is well worth reading (in addition to the many others)
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barry1487 at 18:36 PM on 14 February 2014How we know the greenhouse effect isn't saturated
This remains one of the trickiest things to explain to us laypeople. Acronyms and nomenclature don't make it any easier.
Eg, the reference to 'TOA' - top of atmosphere. Unless someone is very conversant with the dynamics, then they wouldn't know if you were talking about the top of the troposphere or some place higher. Mention stratospheric cooling and one assumes that TOA refers to the upper limit of the troposphere. But mention some unnamed point where "heat is finally radiated out to space," and many people will inlcude the stratopshere, mesosphere, ionosphere - the whole of the atmosphere.
I know that the altitude of the troposphere is increasing and still have difficulty understanding which part of the atmosphere is the thinnest part where radiation finally escapes to space, and what exactly is meant by 'TOA'.
One explanation describes the atmosphere in even more discrete layers. Is the saturated layer radiating to a higher one that is less saturated (the blanket explanation)? Wouldn't more CO2 narrow the window at the highest altitude, where there should be no saturation? Or is saturation in the 15 micron band complete at all alittudes, leaving only the 'wings' of the spectral band unsaturated?
I've read the realclimate articles and dozens of others on saturation and explanations vary, seemingly contradictorily on some points. I suppose this might be because at the molecular level normal physical analogies don't quite capture the reality.
Still questing - any further clarity will be appreciated.
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Richard McGuire at 17:11 PM on 14 February 2014How we know the greenhouse effect isn't saturated
As someone without a backround in science I found the above explanation confusing. For example heat energy radiated back into space would need to pass through the high altitude cold air whether it came from near the surface or higher in the atmosphere. No explanation is given as to whether CO2 as it accumulates higher in the atmosphere is more effective at trapping heat because there is perhaps less water vapour. Which ever way I look at it I fear climate change sceptics have little to fear from this latest effort at myth busting.
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jsmith at 14:59 PM on 14 February 2014Southern sea ice is increasing
Exactly why do we need this page when we already have one called "Antarctica is gaining ice"? It seems like that page covers pretty much the same topic as this one does.
Moderator Response:[DB] This article deals specifically with sea ice in the vicinity of Antarctica. The other rebuttal deals with both land and sea-based ice.
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ubrew12 at 14:47 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
BC @22 said: "sea level rise for the last 22 years...[is] a... straight line" Physically, it should be exponential since its caused by temperature which is itself caused by CO2 and they are both exponential (i.e. all are hockey sticks). Google 'skeptical science sea level hockey stick' for evidence that it is holding to that curve. I took values from this sea level graph (1870-2010):
and eyeballed a 'best-fit' exponential function and got SLR (inches) = exp((year-1870)/57). This function gives an average rate of rise for the 20th century of 1.6mm/year, and an average rate of rise since 1990 of 3.4mm/year, so it's 'about right'. This function gives 4 feet of SLR by 2100, so it looks like my earlier posts were a bit 'alarmist'. But here's the thing: this function is based on SLR from the 20th century, which occurred almost exclusively without input from the ice sheets (that input started around 2000). This means the SLR from just ocean thermal expansion will bring 4 feet by 2100 (if this function is accurate!). Add meltwater to that and who knows where it'll end up. I don't know. More importantly, neither does the IPCC, and I think they need to communicate that uncertainty to the public because SLR can really loom as a property killer in the future.
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Markoh at 14:46 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Knapper @67
What you say about 1 data point (Pinatubu) on the middle of a linear regression not changing the trend is partially true. It will not change the gradient but will lift the overall line up or down.
However with Pinatubo the question is what effect it had on the years following 1991? It probably had an effect and thus would also change the gradient but I am unaware of any analysis quantifying the effect for what you are looking at. It probably exists.
So it is difficult to rule out Pinatubos effect without more data.
The comment by RPainting@ 70 is simply offensive name calling.
Moderator Response:[JH] Your assertion about Rob Painting's comment is patently false. Please cease playing the "victim card."
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Wol at 14:33 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
>>Moderator Response:[PS] in that spirit, please desist from terms like "denier" or "alarmist" which are inflammatory and counterproductive to a reasonable discussion. Thank you.<<
I think taking your line is actually playing from the deniers' hymn sheet: all too often they refuse to offer logical and factual arguments by falling back on semantics and the hair splitting of words.
I may have posted the below previously but it's worth repeating in this context: I have kept a log containg just some of the names that deniers have given in blogs to those who accept AGW. Perhaps calling someone a denier isn't so bad after all?
(-snip-)
Moderator Response:[DB] This is unhelpful. Inflammatory litany snipped.
[PS] Please read the comments policy. Terms like "alarmist" and "denier" do not help constructive debate. There are plenty of other places when rants are permitted.
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DSL at 14:17 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Klapper, what I'm saying is that you can swim in statistics and never get physically wet. You dismiss Pinatubo because you can make it seem to effectively disappear by running linear regression across a specific period. Does Pinatubo actually have no effect on the temperature element of climate over the next 5-10 years? Of course it doesn't! If less solar energy reaches Earth's surface, global mean surface temperature is going to drop relative to what it would have been without the decrease in solar. Further, that drop is going to alter OHC uptake, as Rob pointed out. That will further affect GMST and ocean-atmosphere dynamics. There's probably a feedback from stratospheric warming as well, though I haven't read the literature on it. Pinatubo is written into GMST in complex ways. For you to claim that "Pinatubo has no effect on the warming rate of a trend from 1978 to 2007" is for you to claim that Pinatubo effectively didn't exist where climate is concerned. If Pinatubo doesn't occur, do you think we have precisely the same GMST monthly values from 2000-2007? Do we have the same shaped annual time series? Does ENSO follow the same path post, say, 1995?
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Wol at 14:00 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
CBDunkerson: >>This just doesn't match my experience. So far as I have seen, nearly everyone who contests AGW does so on the basis of disbelieving one or more of the three 'known and not controversial' items listed in the OP.<<
I fully agree: I have not debated (actually, given the nature of the issue, that's too strong a word) with a single sceptic who goes along with Abraham's profile.I'm sure we've all come up against the same problem: the way that sceptics make completely illogical and/or false statements of "fact" and then refuse to answer the refutations and bring up yet more of the same. Many of the "facts" are spread via the "useful idiots" who have bought into the misinformation from the fossil fuel industries lock stock and barrell.
I would like to think that head to head meetings with the likes of ******* and ****** to present the factual data (complete with full references) by real climate scientists could make them more aware of the scientific case, but I'm not that naive. People like ******** and ########## do appear to actually revel in their ignorance of basic science while at the same time repeating the same old arguments that have been shown time and time again to be invalid. (Be my guest and fill in the ***s and ####s yourself.)
As a conservative myself (small "c") I like to think that I can see both sides of any position and make up my mind independently. I struggle with the fact that so many right-wing folk seem to have problems with that, and will repeat the party line right or wrong. Fox news being a classic case and comical in its approach.
I don't see any answer, and Abraham's analysis is IMO just plain wrong.
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Markoh at 13:31 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
One Planet @33
You have restated that you think return on investment needs to be ignored for developing nations to presumably build fossil fuel infrastructure for a short duration, and then replace that infrastructure as a transition to renewable energy.
I don't see how that works. Can you please elaborate on how that would work, particularly where the funding would come from given the return on investment is not there??
Specifically, who would fund this?
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One Planet Only Forever at 12:52 PM on 14 February 2014Discussing global warming: why does this have to be so hard?
CBDunkerson @ 14,
(snip) [PS] This is over the line.
Rob Honeycutt @ 16,
I agree that the reason so many people willingly accept the unjustifiable claims hey made by the likes of Imhof is that, like Imhof, they do not expect to face the consequences of how they enjoy a better life, make more money, have more comfort or get more personal pleasure.
Rob Nicholls @ 29,
I believe your heartfelt belief that all people are basically good hearted is naïve. Some people clearly are only ever interested in getting away with getting more power, money, comfort or convenience any way they can get away with.
funglestrumpet@32,Your comment points out one of the unsavory characters I suggest Rob Nicholls and others need to accept are 'out there'.
In my opinion:
'Global warming and climate change' is a sub-set of the bigger issue of the 'acceptability of continuing the fundamentally unsustainable and clearly damaging pursuit of benefit from the burning of fossil fuels'.
Developing a better understanding of aspects of the issue is important, but many people appear to seek opportunity to claim 'uncertainty’ about the larger issue that has no uncertainty by finding a way to raise a question about the minutia of a part of the larger issue. These attempts to create the impressions of 'significant uncertainty about something there is no uncertainty about' are not ‘accidental’, they are deliberate.
The extraction and burning of fossil fuels cannot be continued for very much longer, and humanity has hundreds of millions, if not billions of years, to look forward to on this amazing planet. And there are many damaging impacts from the activity, including the impacts of the accumulation of excess CO2 (in the atmosphere and the oceans). There is also major harm caused by the conflict between powerful people fighting to get more of the potential benefit for themselves. Burning fossil fuels is an incredibly damaging activity ‘all things considered’.
An acceptable use of an unsustainable and damaging activity would be to address an ‘emergency’. I would accept that ‘emerging’ economies should be allowed to use the burning of fossil fuels to more rapidly transition their entire population into sustainable economic activity. However, this would have to be a brief transient phase. The 'economic efficiency or return-on-investment needs to be excluded from determining how long the unsustainable and damaging stage is allowed to continue.
After all, any activity relying on burning fossil fuels is ultimately a damaging dead end that needs to be stopped, the sooner the better. Those economic activities simply cannot have sustained growth. And since the objective is to ‘lift the least fortunate into a sustainable better way of living’ the only ones benefiting from the burning of fossil fuels should be those who are the least fortunate. The same goes for any other unsustainable and damaging activity like the use of harmful chemicals or using up (consuming), other non-renewable resources. Everyone already ‘more fortunate’ should be ‘getting by with sustainable virtually damage free ways of living’. That is the only viable future for humanity. Anything else would be unsustainable and unacceptable.
This ‘required development to sustainable activity model’ is challenged by the fact that sustainable activities will always be less profitable and less desired than the more damaging or less sustainable activities that ‘can be gotten away with because of popular support’. The ‘profit motive’ and ‘potential popularity’ clearly cannot be allowed to determine what is acceptable…because they clearly haven’t and won’t.
So the clear facts of matter are that the basis for determining the acceptability of prolonging the burning fossil fuels cannot be if it is ‘popular and profitable in the moment’. It cannot be based on the desires of the already fortunate to continue to benefit from unsustainable and damaging activity they have ‘grown fond of getting away with benefiting from’.
The increased understanding among the global population of the unacceptable and significant impacts of excess CO2 is just one of the ways to help raise awareness of the fundamentally unsustainable and damaging ways that many among the most fortunate ‘strive to get away with for as long as they can get away with’. Discussing and debating details of sub-sets of the larger issue needs to be clearly understood to not reduce the urgency of ‘changing the minds, attitudes and actions’ of the population so that humanity actually develops a sustainable better future for all life on this amazing planet.
Moderator Response:[PS] This is on thin ice. Please read the comments policy and abide by it.
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Glenn Tamblyn at 12:50 PM on 14 February 2014How we know the greenhouse effect isn't saturated
Actually jyyh, this myth only relates to the idea that adding more CO2 can't cause much more warming.
What you are referring obliquely through you reference to the magnifying glass is the 'it's the Sun' myth
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Markoh at 12:31 PM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
HK @73
i was aware of the 10 fold difference in coefficient of thermal expansion of water at different temperatures.
Given that the models did not predict the heat going into the cold lower sections of the ocean over the last decade, caused by the trade winds, resulting in no appreciable surface temperature increase over the last decade when surface temperature increases were expected by the models, then have the models got the sea level rise predictions correct?
ie if the models didn't have that the heat was going into ocean depths over the last decade, do the models have the correct amount of heat going into the oceans in future prediction, and more importantly given the 10 fold difference in coefficient of thermal expansion, if the models predict heat going into the wrong part of the ocean the sea level rise predictions could be dramatically out?
Do the models need to be revised, if not why not?
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jyyh at 11:58 AM on 14 February 2014How we know the greenhouse effect isn't saturated
As the the myth in the article goes, the words "at the surface" could be bolded. "what of upper levels?", might a proper sceptic ask. The myth also imagines IR-radiation is the only form of energy effecting temperatures, though everyone knows (or at least could know) about the heat concentrated by a magnifying glass. -
scaddenp at 11:17 AM on 14 February 20142014 SkS Weekly News Roundup #6
Worth also pointing to the WG1 chapter "Climate models and their evaluation". (Ch 8 in AR4, ch9 in AR5). However, they do not do weather forecasting, have no skill at decadal level prediction and dont pretend to, and need to be evaluated against the robust predictions that they actually to make. More importantly, models are very important for predicting the future but not to validating AGW. A better question to ask is "are models skillful?"
However, there is a saying that "It is useless to attempt to reason a man out of a thing he was never reasoned into". Many see AGW as a challenge to their political values or their disbelief as a part of their tribal identity. Good luck changing those.
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jyyh at 11:13 AM on 14 February 2014How we know the greenhouse effect isn't saturated
yes, Tom Curtis, let's not get semantic on the words 'greenhouse gas' or 'greenhouse effect'. But I bet my explanation is better for 8-year-olds than for intentionally obtuse deniers. I also think there could be some gases that would rise the surface temperature of Venus still, so the greenhouse effect isn't saturated there either. I haven't come up with one but then I haven't particularly wanted to find out. Local concetrations of gases vary of course, but they stay the same and do not change their properties. 100% IR-absorbing material sounds like something scary from a scifi-novel, but that isn't what you said, the IR-photons can wiggle their way out of the planet between the molecules even in a 100% CO2 atmosphere.
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2014 SkS Weekly News Roundup #6
Chandra - Those truly in denial cannot be convinced; their confirmation bias prevents it. However, there is a lot to be said for pointing out such a persons errors to the others reading the discussion, people more willing to weigh the evidence presented.
In that regard I would highly recommend Raymond Pierrehumbert's presentation at the 2012 AGU Tyndall Lecture, Successful Predictions.The actual presentation starts at about 4:15 - in it Pierrehumbert discusses the many many successful predictions made about climate over the last 120 years.
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Tom Curtis at 10:00 AM on 14 February 2014How we know the greenhouse effect isn't saturated
jyhh @1, if you were being witty and making a pun, forgive my obtuseness.
If not, your argument is a non-sequitor. If CO2 absorbed at all IR wavelengths at its maximum strength, it would be saturated, even at current CO2 concentrations. That is because at maximum strength its effective altitude of emission is in the low stratosphere, which warms with altitude. Therefore increased CO2 would increase the effective altitude of emission, and hence increase the IR radiation to space.
Of course, my argument assumes hypothetically that the temperature structure of the atmosphere would remains the same in such a case. It is far from clear that that would be the case with 100% IR absorbing CO2. The hypothetical, however, is sufficient to show your argument fails logically. That is, you may be able to infer that which you wish to, but you would need far more premises to do so than you actually give.
As it happens, even with a 100% CO2 atmosphere, so long as the temperature at the effective altitude of radiation to space fell with increasing altitude, increased CO2 would result in less IR radiation to space at a given surface temperature, thereby requiring an increase in surface temperature to maintain the energy balance. That is, even 100% CO2 atmospheres need not be, and typically would not be, saturated.
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Tom Curtis at 09:50 AM on 14 February 2014How we know the greenhouse effect isn't saturated
potvinj @2, there are over 830 x 10^12 Kg of CO2 in the Earth's atmosphere (equivalent to 390 ppmv). The density of dry ice, ie, the precipitated form of CO2 is, 1,600 Kg per cubic meter. The area of the Earth is 510 x 10^12 meters squared. Consequently, if the atmospheric CO2 weref precipitated out into an even layer across the Earth's, there surface would be 1.6 Kg per square meter, or a layer 1 millimeter thick across the Earth's surface.
The question then becomes, can a layer a millimeter thick be effectively opaque to a given frequency. Could we, for example, coat a sheet of glass with a layer of paint less than a millimeter thick such that it would block out effectively all light?
Put in these terms, it is apparent that it is physically possible, and measurements have shown it is actually the case, that the atmosphere is effectively opaque to IR radiation in a limited bandwidth. This does not stop radiation of IR in that bandwidth to space, because the CO2, including CO2 above 80% of the CO2 in the atmosphere itself radiates in that bandwidth, with the radiation from the upper levels of CO2 reaching space.
The reason for the qualifier in the second bullet point is that CO2 absorbes less and less well as frequency moves from the center of the bandwidth of maximum absorption. The result is that IR radiation in those frequencies that would have previously escaped have an increasing chance of being absorbed with increased CO2. It should be noted that in the very center of the CO2 absorption band, the majority of emissions to space are from CO2 in the stratosphere, which is warmer than the upper troposphere, and warms with increased altitude. Consequently the mechanism described in the OP does not work (indeed, has the opposite effect) in the center of the absorption band. It does, however, work in the wings, so that the net effect is as described.
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Chandra at 09:47 AM on 14 February 20142014 SkS Weekly News Roundup #6
Thanks for the comments and kind advice. I'm not sure I have anything that will have any effect on the skeptic in question. Anything that refers to models just gets the response that such models are "unvalidated" and incapable of being validated. Saying that the models have forecast past events successfully is likely to be rejected as just hind-casting (with models tuned for the purpose, of course) even if the forecast was actually performed before the event. Whether the skeptic is actually unaware of the empirical data, I'm not certain. I think it is more likely that he is well aware of it but rejects any that doesn't fit his preferred tune. The "Theory and Experiment--Atmospheric Radiation" page is a useful reference for me, if not for the skeptic. Thanks. -
Klapper at 08:58 AM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
@ DSL #74:
I'm trying to figure out what your point is. I didn't throw an absurd number in the middle of anything. I'm doing linear regression, not point to point, of the SAT record. Pinatubo has no effect on the warming rate of a trend from 1978 to 2007, although I didn't think about that until Rob Painting (incorrectly) pointed out it was affecting the trend. Maybe for some periods, but not the trend I picked which was basically to show what the maximum warming rate had been in the late 20th, early 21st.
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Concerned Citizen 60025 at 08:48 AM on 14 February 2014The Oceans Warmed up Sharply in 2013: We're Going to Need a Bigger Graph
Yes, it is a shame that the total amount of ocean energy increased by 0.001% since 1998. But what exactly does that mean when we're still emerging from the Little Ice Age?
Moderator Response:[PS] % is meaningless. You can discuss little ice age here.
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Glenn Tamblyn at 08:02 AM on 14 February 2014How we know the greenhouse effect isn't saturated
potvinj
If you contrast the density of a solid surface with the density of the air there is a difference of the order of 1000's of times. Add in the proportion of GH gases in the atmosphere and the difference becomes of the order of 10's of 1,000,000's.However IR radiation from a solid surface only originates from a very thin layer right at the surface, no more than microns thick. In contrast the atmosphere is kilometers thick. So this compensates so that there are ample GH molecules to potentially intercept IR photons. We need to contrast the number of molecules in a microns thick layer of a dense material with the number in a 1000's of meters thick layer of a diffuse material.
A different way of looking at this is to take how much energy is radiated from a solid surface at a given temperature based on Planck's Law and work out how many IR photons are radiated per second by dividing that by the average energy of the individual photons.
When we do that we get a result that says there is roughly the same number of CO2 molecules in a few cubic meters of air as there are photons being radiated from a square meter of a solid surface every second. When we then remember that a GH molecule is continuously transferring energy to all the other molecules around it through collisions - each molecule in the lower atmosphere collides with other molecules billions of times per second - and thus the GH molecule can potentially engage in an abroption event millions of times a second or more.
So there are actually millions of CO2 molecules available to potentially interact with each IR photon emitted from the surface in the first meter of that photons travel. If it were based just on the probability of them meeting all the IR radiation would be absorbed within the first meter of the atmosphere.
However just because a photon and a molecule encounter each other does not automatically mean that absorption occurs. There is actually only a modest probability of an absorption event occurring. It is this that extends the distance that it takes for most IR photons to be absorbed out to typically 100's of meters.
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Tom Dayton at 07:12 AM on 14 February 20142014 SkS Weekly News Roundup #6
Chandra, your skeptic has no idea how science works, as noted by some of the responses to your comment on Science of Doom--the responses about the role of models. A thermometer is a model, so when your skeptic wholly trusts the temperature measurement from a thermometer, he/she is wholly trusting a scientific model!
He/she is shockingly unaware of the existence of the massive empirical data, too. Since he/she reads Science of Doom, please point him/her to "Theory and Experiment--Atmospheric Radiation." That post covers only a sliver of a topic, but perhaps it will be enough to convince him/her to graduate to reading the Skeptical Science post Models are Unreliable to learn about other kinds of empirical validation; please point out there is an Intermediate tabbed pane there in addition to the Basic one.
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funglestrumpet at 06:58 AM on 14 February 2014Discussing global warming: why does this have to be so hard?
If anyone doubts that there is still the need for the science community to learn debating techniques on top of the science, one has only to listen to this morning's BBC R4 Today programme (available on podcast and on Iplayer - about ten minutes from the end, give or take five minutes)
There was a debate between Sir Brian Hoskins and Lord Nigel Lawson regarding whether climate change is having a bearing on the current extreme weather events that the U.K. is experienceing. It was a tour de force by Lawson. Never one to let the facts get in the way of winning an argument, he excelled himself, even using his knowledge of the regular timing pattern of the programme to get the last word in. And what a great last word it was! One guaranteed to win over those members of the public who might be in doubt, and one that was completely and utterly untrue.
I urge anyone who might find themselves in a debate with Lawson, or those of a similar ilk, to listen to the podcast. They will then see just how easy it is to lose a debate despite having all the facts on your side.
We are never going to get meaningful action on this issue until the politicians are scared of losing their seats and that will only happen when the public are convinced of the dangers climate change poses.
Is there any chance of creating an A team for representing the science of climate change in media discussions and debates? I would be happy to contribute to a fund for them to get some media training. This morning, when Lawson tried to steer the discussion towards 'We have to keep the lights on' - a hot topic in the U.K. - and one guaranteed to burn more fossil fuels - Hoskins could have won the day by simply commenting that he would prefer the occasional blackout to having his children and grandchildren in body bags and what a pity it is that Lawson doesn't care as much for his family. But it needs training to come up with such ripostes (or 20/20 hindsigtht, as is the case with me.)
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potvinj at 06:27 AM on 14 February 2014How we know the greenhouse effect isn't saturated
I understand and agree with this post. But I have a problem with the second bullet in the introduction. I always thought that there are a lot more emitters
of IR photons (and thus more IR photons) than there are greenhouse absorbers since the rock/ground molecules are packed to higher densities than the amospheric CO2 gas molecules. So even if all the CO2 molecules present at a given time were saturated (ie excited to higher energies via IR photon absorption), the new molecules entering the atmosphere via antropogenic means would capture more of the available IR photons. This would further reduce the net IR output at the top of the atmosphere
and further heat the atmosphere near the ground. Here the atmosphere is never in balance (ie in thermal equilibrium) and this cause the heat to accumulate near the ground. Another corrolary is that the atmosphere is never completely saturated: there are always more (new) CO2 molecules being introduced to capture the yet untapped IR photons available, and this further heats the atmosphere.Is this picture correct?
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DSL at 06:19 AM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Not really, Klapper. I'm pointing out that you can throw an absurd number in the middle of a simple point-to-point linear analysis and get a conclusion that has absolutely no informational content with regards to physical reality. I should have made the series (1,1,1) and (1,4000,1).
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Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Klapper #61:
Sea level rise from thermal expansion is not an accurate proxy for ocean heat uptake without a more careful analysis.
Take a look at this graph in Wikipedia. (the water’s density for each degree from 0°C to 100°C is listed further down the page) If you convert density change to expansion you get this for some temperatures:4-5°C: +0.001%
6-7°C: +0.004%
10-11°C: +0.01%
15-16°C: +0.016%
20-21°C: +0.021%
Heating water from 10 to 11°C makes it expand ten times more than if you heat it from 4 to 5°C! So the amount of thermal expansion doesn’t only depend on how much heat is being added, but where it is added, since warm water expands more than cold. These numbers are for fresh water. Salt water continues to contract down to its freezing point, but the principle is the same.
And where has the ocean heating taken place?
If you study this and this and this graph thoroughly, you will find that a rising fraction of the heat is accumulated in the deeper and colder parts of the oceans.
With a caveat for quite uncertain pre Argo data I got this result for the fraction of the heating taking place deeper than 700 meters:1957-1994: 25%
1994-2011: 38%
2005-2013: 49%
The tendency is quite clear: More of the heat accumulation happens in the deeper, colder parts of the oceans where each unit of energy cause less thermal expansion than in the warmer, upper layers.
And finally, this graph shows that the warming in the upper 100 meters have been almost zero for the last ten years. Each unit of energy added here would produce at least 10-20 times more expansion than in the deep and cold parts of the oceans!
Conclusions:
1. You can’t translate thermal expansion to heat accumulation without knowing where the heating takes place.
2. Much of the SLR from increased melting of ice sheets in the 2000’s has been offset by decreased thermal expansion because more of the warming happens in colder water. That probably explains the apparent lack of acceleration seen here.
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william5331 at 05:59 AM on 14 February 2014Discussing global warming: why does this have to be so hard?
On other thing we know for sure from ice cores from Greenland and mud cores from El'gygytgyn is that climate has changed rather rapidly in the past and that these two sources most likely under-estimate the rapidity of the change. The Foen zone masks sudden changes in ice sheets and vegetation takes time to establish and leave pollen signals in mud cores. The deniers will be more than red faced and dispeptic if even a fraction of the predicted outcomes for climate change eventuate. We must keep being polite and calm but never holding back on the facts as they are known when explaining to them. Our demeanor is as much part of the argument as the facts. Unfortunately we need a few super Sandies to get the message across. We don't want to get the backs up of the deniers since it will just make it harder for them to back down as various disasters take place. Just as a reformed drunk is the strongest advocate against alcohol, a reformed denier will be the strongest advocate for climate change.
Moderator Response:[PS] in that spirit, please desist from terms like "denier" or "alarmist" which are inflammatory and counterproductive to a reasonable discussion. Thank you.
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Klapper at 05:56 AM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
@ Rob Painting #70:
@ DSL #71:
I think DSL is saying I am in fact correct about the trend with Pinatubo in the centre. It affects the intercept of the regression equation but not the slope.
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DSL at 05:30 AM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Shorter Klapper: LINEST(1,2,3,4,5) = LINEST(1,2,-327,4,5)
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Rob Painting at 05:01 AM on 14 February 2014Unprecedented trade wind strength is shifting global warming to the oceans, but for how much longer?
Klapper - "My 30 year 0.18C/decade trend was from 1978 to 2007 inclusive. Because Pinatubo lies right in the middle of this period, it has no leverage on the trend either way"
Now you are descending into complete nonsense. This demonstrates you cannot be taken seriously.
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howardlee at 04:38 AM on 14 February 2014The Oceans Warmed up Sharply in 2013: We're Going to Need a Bigger Graph
Rob - that's helpful, thanks. I read the Keeling et al 1995 paper. It's probing the causes of variations in the Mauna Loa record, so it's really not getting to the issue of deep ocean storage as far as I can tell.
I'm really taking the longer view of this. As you say, in the long term the ocean is storing more (via acidification). Per the work of Zeebe and others, the amount and rate of CO2 absorbtion on a global scale depends, in the long term, on the feedbacks (fast, slow) that come into play.
I see very strong parallels with past global warming events and mass extinctions (Permian, Triassic, Toarcian, Cretaceous OAEs, PETM et al). They have all been associated with huge carbon emissions, from Large Igneous Provinces (Some debate on that regarding PETM). We are releasing comparable quantities of carbon at rates that exceed LIP rates (but increasingly the timeframes of those seem to be being revised shorter...).
Basically per the work of Zeebe and others, the idea is that in those times (and today) the rates of CO2 emissions, and temperature increases, overwhelmed the short term feedbacks (biosphere, surface ocean etc), before the long term feedbacks (deep ocean, weathering, etc) could cut in to process them. Hence CO2 ramped up ever faster in the atmosphere, further accelerating warming, until you have the same symptoms of a global-warming-mass-extinction like the end Triassic or even Permian (ocean acidification, jump in global temperatures, ocean anoxia,etc). There's evidence that immediately following the Permian emissions, it was lethally hot on land and in the oceans in equatorial to tropical regions for the very early Triassic.
That's why I'm wondering if the deep ocean is cutting in already as a feedback - absorbing both CO2 and temperature on a long-term net basis rather than on a multidiecadal oscillatory basis. The deep ocean in the latest IPCC report and in the work of many others including Zeebe, is not supposed to cut in until several centuries have passed. If it's really cutting in now, after a century or two, it would bring a much larger reservoir for CO2 and heat into the equation. I'm not for a moment suggesting this makes global warming go away, only it might slow the rate of change down - a bit - in the short term (perhaps the average transit time of deep currents). BUT ONLY IF the deep ocean reservoir is currently in active CO2 exchange with the atmosphere at meaningful rates.
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Dikran Marsupial at 03:33 AM on 14 February 2014Discussing global warming: why does this have to be so hard?
While even radical "skeptics" don't want to damage the environment, I would doubt that even radical "warmists" actually want to forgo the benefits of fossil fuels either. So at the end of the day, we have to reach a compromise that uses (and spreads) the benefits of fossil fuel use, while at the same time minimising the environmental damage this will cause. There is a spectrum of opinion on where this compromise should lie. One thing is for certain though, which is that torturing the science to provide support for a socio-politico-economic argument is not the way to reach agreement on a solution to the compromise!
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