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Tristan at 20:32 PM on 14 April 20152015 SkS Weekly Digest #15
Thank you very much Tom, I appreciate you spelling it out to me.
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billthefrog at 20:24 PM on 14 April 2015Andy Lacis responds to Steve Koonin
As Tom has pointed out, when one is considering eustatic sea level rise (i.e. the rise due to more water being added to the oceans) the behaviour of the East Antarctic Ice Sheet will not simply mimic that of the Greenland Ice Sheet, the West Antarctic Ice Sheet or the Antarctic Peninsula.
The EAIS is at a much higher elevation than its smaller counterparts, and would need considerably more (and longer) planetary warming before it would even come close to melting out. Those wishing to learn a bit more might care to look at the Antarctic Glaciers website, or at the British Antarctic Survey site.
There is little meaningful argument that the Mass Balance for each of the GIS, the WAIS and the Peninsula is in negative territory. However, the EAIS may actually be accumulating ice at present, as enhanced precipitation in its central regions (thanks to the good old Clausius-Claperyon relationship) could be more than compensating for increased peripheral loss.
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Tristan at 19:58 PM on 14 April 2015CO2 limits will harm the economy
Maybe this has been talked about in the comments: Where might I find a detailed examination of the likely performance of an ETS vs Carbon Tax/Fee and Dividend?
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Tom Curtis at 18:43 PM on 14 April 20152015 SkS Weekly Digest #15
Tristan @1, similar claims have been made on SkS before, and discussed in detail. The validity of the claim depends, however, on the way it is formulated. In this case, based on IPCC AR5 figures, to counterbalance total annual anthropogenic emissions, humans need only increase total terrestial photosynthesis (ie, Gross Primary Productivity) by 8.9 GtC, or 7.24%. That is, of course, the figures for all terrestial photosynthesis, not just crop land. Taking the figures of Haberl et al (2007), that equates to increasing agricultural productivity by 57.1% of current human appropriation of net primary productivity or 107.6% of the current harvestable yield.
I don't know whether that is technically feasible, but it does not present a theoretical bar. However, that increase must be the increase in persistent biomass. Any actual crop, whether consumed by humans or as fodder for animals, returns to the atmosphere as CO2, and hence is not sequestered. The sequestration, therefore, is limited to the annual increase in standing biomass and soil biomass. Here, however, you face a problem. Based on the IPCC AR5, human activity has reduced terrestial biomass by just 30 GtC since the industrial revolution. That is, if we could manage that rate of sequestration, we would have to exceed natural levels of sequestration within 3.4 years. That figure is less the increase in biomass due to increased temperature, water, CO2 and the agricultural revolution. On an alternative measure, we would be exceeding natural levels 18.4 years (remember to convert from GtCO2 to GtC if checking the figures). Allowing for preindustrial levels, we might have 36 to 40 years of such sequestration before we reached a situation where the land simply would not hold more biomass. So, while such high rates of sequestration cannot be excluded, neither can they be maintained sufficiently to provide a long term solution.
Finally, many of the changes suggested require convesion to small scale, labour intensive farming (permaculture). The problem with that is it requires the majority of the population to be farmers. It represents a retreat back to a dark age, where we do not have sufficient resources to maintain a system of universities and scholarship, or of mass entertainment (which may be of interest to more people).
I am not suggesting that implication of the methods advocated by Savory or the Rodale institute are not worthwhile in themselves, or that they will not help. They are just not a silver bullet for global warming, and they make themselve incredible (ie, not capable of being believed) by suggesting otherwise.
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Tristan at 15:29 PM on 14 April 20152015 SkS Weekly Digest #15
I'm not quite sure where to put this, it may not be within the remit of this site. I'm just wondering if this might be an example of 'misinformation' from team environment.
"According to the Rodale Institute, small-scale farmers and pastoralists could sequester more than 100% of current annual CO2 emissions with a switch to widely available, safe and inexpensive agroecological management practices that emphasize diversity, traditional knowledge, agroforestry, landscape complexity, and water and soil management techniques, including cover cropping, composting and water harvesting."
http://www.commondreams.org/views/2015/04/13/food-farming-and-climate-change-its-bigger-everything-else
WIthout a background in ag science, I can't evaluate the truthiness of that.
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John Brookes at 15:07 PM on 14 April 2015Andy Lacis responds to Steve Koonin
Thanks for a very clear explanation.
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Tom Curtis at 14:24 PM on 14 April 2015Andy Lacis responds to Steve Koonin
mrkt @10, looking carefully at the graph in the upper right panel, it becomes clear that they show a "likely range" (68%) at 9 to 59 meters at 450 ppmv. That makes their claim of a "likely (68% confidence) long-term sea-level rise by more than 9 m above the present" true, but obscure. Ie, they are saying that the likely confidence interval, using IPCC methods of expressing confidence, has a lower limit of 9 m. From that it follows that their results show an 84% probability of at least 9 meters of sea level rise for a long term CO2 concentration of 450 ppmv.
That is not how I initially read it, so thank you for drawing attention to my error.
Looking at their likely range, over that interval, it appears evident that the upper value is so large due entirely to the limitted observations. On the assumption that increased temperatures will not cause water to refreeze, I think the lowest upper limit of the likely range at higher temperatures can also be used as a more realistic upper limit for a long term 450 ppmv concentration. That produces an adjusted likely range between 9 and 30 meters, with 30 meters representing the almost complete melt of the WAIS and GIS, with any surviving ice from those ice sheets being more than compensated for by melt of the EAIS.
bozza @11, the flat line is because while the WAIS and GIS are on the verge of melting, the EAIS is much more stable , and will mostly remain intact once the WAID and GIS have melted away with little melting other than at the fringes. Only after considerable further rise in temperature will the EAIS melt away.
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bozzza at 12:23 PM on 14 April 2015Andy Lacis responds to Steve Koonin
@ 9, I think this is surely the relevant question at the moment!
@ 7, why things flatline and/or double dip I don't know but the links should prove interesting- cheers.
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mrkt at 09:46 AM on 14 April 2015Andy Lacis responds to Steve Koonin
Tom Curtis @7: In looking closely at the graphs, it appears that a 9 meter rise corresponds to 1 std. dev. below the mean. This would imply that the chance of less than 9 meters is 16%, and the chance of more than 9 meters is 84% rather than 68%. No? Clearly not a better situation. (I do note that you are quoting the paper.)
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scaddenp at 09:38 AM on 14 April 2015Andy Lacis responds to Steve Koonin
I think it would be accurate however to say the 450ppm is incompatible with the ice-age cycle. (Didnt have ice ages when atmosphere was last at 450ppm, though there were still polar ice caps.)
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Tom Curtis at 09:02 AM on 14 April 2015Andy Lacis responds to Steve Koonin
gregcharles @5, the CO2 in the atmosphere does not reflect IR radiation back towards the Earth. Rather, it absorbs it, and then reradiates it. The difference is important, because if reflected the energy returned would be the difference between that which the surface emits (398 W/m^2) and that which escapes the atmosphere (239 W/m^2), ie 159 W/m^2. In fact, downwelling IR radiation (or back radiation) averages around 342 W/m^2 because the IR radiation from the atmosphere (figures from IPCC AR5):
The much higher back radiation is due to the air mass immediately above the Earth's surface (from which most of the back radiation originates) having a temperature very close to that at the surface. In constrast, most of the IR radiation to space comes from high in the troposphere, where the temperatures are much lower.
Further, the actual back radiation is not important to the greenhouse effect (although may be important for local weather events). That is because if the back radiation were to increase, with no change in the greenhouse effect, evaporation and sensible heat transfers would also increase to maintain a balance, and if it were to decrease, evaporation and sensible heat would also decrease. The greenhouse effect is determined by the top of atmosphere energy balance.
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Tom Curtis at 08:44 AM on 14 April 2015Andy Lacis responds to Steve Koonin
CBDunkerson @1, Bozza @2, the most recent credible data that I know of is encapsulated in this figure:
(Source)
Total melting of the ice caps is associated with a sea level rise greater than 70 meters. Ergo, from paleo data, we cannot expect that unless we have sustained CO2 concentrations of 800-1500 ppmv. From that paper (Foster and Rohling 2013), we lean that "our results imply that acceptance of a longterm 2 °C warming [CO2 between 400 and 450 ppm (46)] would mean acceptance of likely (68% confidence) long-term sea-level rise by more than 9 m above the present." That probably represents the melting of the West Antarctic Ice Sheet (WAIS), and the partial melting of the Greenland Ice Sheet (GIS), with only limited melting of the East Antarctic Ice Sheet (EAIS).
Looking at the figure, Andy Lacis may be basing his claim on van der Wal et al, 2011, except that when I actually look at van der Wal et al, the modelling shows a total loss of polar ice does not occur until a sustained temperature anomaly of plus 20 C is reached, ie, around 1600 ppmv with an Earth System Climate Sensitivity of 8 C. It appears, therefore, that Foster and Rohling have incorrectly represented van der Wal et al's results.
Aslak Grinstead gives a more detailed discussion.
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Andy Lacis responds to Steve Koonin
gregcharles - The Earth isn't in equilibrium right now, increasing ocean heat content (OHC) measures show that over the last 50 years we've averaged about a 0.6 W/m2 mbalance over that period, meaning the earth has been receiving about 240 W/m2 and radiating about 239.4 W/m2. The difference points to the (currently) unrealized warming due to thermal lag, primarily in the oceans.
The difference between the near-blackbody IR radiation at the Earths surface (~396 W/m2, IR emissivity about 0.95-0.98) and what's radiated to space (~240 W/m2) is entirely due to the radiative greenhouse effect - in essence energy isn't emitted to space until much higher altitudes (and colder) due to greenhouse gases, making the effective emissivity of the Earth in IR around 0.61. The Earth's just not as effective a radiator as a bare rock would be, and with increasing GHGs it becomes even less effective - hence a higher and higher surface temperature required to radiate the same energy to space.
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gregcharles at 07:27 AM on 14 April 2015Andy Lacis responds to Steve Koonin
I agree that 450ppm by the end of the century is an understatement. Everything I've seen suggests we'll reach that mark within the next 20 years.
I have a couple of questions about the Fourier calculations. First, the global mean temperature of 288K implying 390 W/m2 of radition, some into space and some reflected back to earth by greenhouse gasses. I'd like to know more about how that's calculated.
I also don't fully understand the near-global energy balance used as the reason earth absorbs 240 W/m2 of radiation from the sun and radiates the same amount out of the upper atmosphere. The earth isn't in equilibrium now is it? We'd still warm for quite awhile even if CO2 levels remained constant, right? Doesn't that imply we're absorbing more radiation from the sun than we're radiating back into space? I feel like I'm missing something obvious here.
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ubrew12 at 06:16 AM on 14 April 2015Andy Lacis responds to Steve Koonin
Has anyone put the basic Arrhenius/Hulburt calculation in a spreadsheet? Something where at the top you input your preferred CO2 level and at bottom it tells you how much warmer, or cooler that will be, in equilibrium, compared to pre-industrial? I understand it means breaking up the atmosphere into 200-500 nodes, each of which absorbs sunlight, radiates/convects/etc. It means assumptions are made about feedbacks (clouds, vegetation, ocean response, ice cap extent).
My point is: equilibrium sensitivity, at the level of Arrhenius or Hulburt, is just a calculation, like 2+2 =4 (indeed, for them, it was a calculation done without benefit of electronic calculators). If you can put those assumptions/calculations in a spreadsheet for anyone to see and manipulate, it reinforces the notion that this is, at base, just Math (i.e., once the Physics and Chemistry have been codified into Math). It's Math anyone sufficiently trained can do/see/appreciate.
Hence, when someone says "Doubling CO2 is no big deal" you can send them the spreadsheet and say "identify the specific location where 'no big deal' " comes out of this Math". Without the spreadsheet you're left saying "It IS a big deal. My expert says so." Leading to the response "My expert says it isn't."
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bozzza at 04:05 AM on 14 April 2015Andy Lacis responds to Steve Koonin
@1, The truth may be more along the lines of " a sustained level of 450 ppm CO2"...
Note that Dr David Mills was on youtube years ago saying the 440ppm barrier is impossible not to break... he says it is(/was) still being worked out whether or not it was possible to go over the limit and then duck back under it but the point I'm making is ---> 450 ppm is written in stone as reality!
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Composer99 at 03:07 AM on 14 April 2015Andy Lacis responds to Steve Koonin
Some housekeeping may be required, as this article is breaking the formatting of other posts on the main page (no doubt due to the preview ending in a block quote).
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CBDunkerson at 02:46 AM on 14 April 2015Andy Lacis responds to Steve Koonin
"They should also pay attention to the geological record that points to an atmospheric CO2 level of 450 ppm as being incompatible with polar ice caps..."
That figure seems much too low. 450 ppm is the most common 'target limit' to avoid the worst impacts of AGW, but I've never seen a claim that we'd eventually lose the ice caps and have corresponding 70 meter sea level rise at 450 ppm.
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billthefrog at 23:06 PM on 13 April 20152015 SkS Weekly News Roundup #15B
"... usual media hyperbole is beginning to come down on the pro AGW side"
I do love the term "pro AGW", as if it is something that many people would actually want to see happening. In common with many people, I think there is a causative relationship between ozone depletion and melanoma incidence rate. That doesn't mean I'm "pro CFCs", or that I'm "anti the Montreal Protocol".
Terms such as "pro democracy" or "pro equal rights" do tend to convey the correct impression, but "pro AGW", I rather think not.
If you are genuinely concerned about perceived press bias, it might be educational for you to have a look at the article John Mason wrote a few weeks ago concerning the reporting of certain climate/weather related events.
cheers bill f
Moderator Response:[JH] "Pro AGW" is typically shorthand for "pro AGW science".
I also presume that your admonition is directed to the journalist who wrote the article. If so, you should post your concerns on the comment thread of the article as posted on the Los Angeles Times website.
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CBDunkerson at 22:01 PM on 13 April 20152015 SkS Weekly News Roundup #15B
mjp, the article clearly states;
"California has seen droughts before with less rainfall..."
How does that constitute 'sidestepping' the severity of past droughts?
You cite the headline, but it doesn't say anything about precipitation or 'drought' in general. It says that heat records have been broken. Which is true.
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scaddenp at 13:37 PM on 13 April 2015Global warming hiatus explained and it's not good news
amhartley - I dont immediately find McGregor's source but I think you can guess it's context. You are usually interested in heat capacity in terms storage of added energy. Add energy to earth (eg increased solar output or additional GW), then the heat capacity of earth is going store energy, slowing the temperature rise. Warming from solar doesnt penetrate far into land - a few meters (ask horizontal ground source heat pump installers). Sea is different with deeper penetration but more importantly convection carries heat deeper and heat capacity is huge. Atmospheric storage is pretty minimal.
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chriskoz at 12:33 PM on 13 April 2015Global warming hiatus explained and it's not good news
scaddenp@14, Tom@16,19
Your discussion belongs to Underwater volcanoes are warming the oceans. I went there to check what SkS has to say about your last sentences (thermal insulation of the ocean depths and thermal gradient of ocean warming vs. volanic/geotermal heat) & sadly, I found this very would be useful article is empty! What happened to it?
If it's lost it should be brought back. Some mod could check it...
Otherwise it should be filled in with the results of your discussion, together with the references Tom had provided. That article is important to debunk the claims like that by Peter Carson. Anyone wants to do that?
Moderator Response:[DB] That's a topic article stub, earmarked for a future piece.
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mjp at 12:19 PM on 13 April 20152015 SkS Weekly News Roundup #15B
The completely rational story for the California drought is that worse droughts have occurred in the deep past and are possible in the future, but a warming climate will make a recurrence of similar circumstances worse in the future. Bit of a mouthful, I know.
When used in the context of the drought I find it unhelpful to see headlines like "California's new era of heat destroys all previous records".
Denial arguments play on the science papers that show worse droughts have occurred in the past. When science based articles appear to sidestep and not acknowledge that, it appears that the science is being deceptive. Doesn't help.
But this is mainstream media. I guess the upside is that usual media hyperbole is beginning to come down on the pro AGW side.
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amhartley at 11:16 AM on 13 April 2015Global warming hiatus explained and it's not good news
"About 97 per cent of all the heat capacity of the Earth is in the ocean — that's where all the energy gets stored."
Is that accurate? Should a qualifier accompany that 97%? For instance, is the denominator the earth's heat capacity within, say, 10km of the surface?
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Tom Curtis at 09:04 AM on 13 April 2015Models are unreliable
Tom Dayton @860, that Hotwhopper article is pretty damning of Roy Spencer's choices. What it does not mention was that 1983 was massively effected by the El Chichon volcano (which shows up the models), but that the effect in observed temperatures was cancelled, or more than cancelled by the 1983 El Nino in the observational record, which by some measures was stronger than the 1998 El Nino:
As ENSO fluctuations are random in time in the models, they do not coincide with observed fluctuations. The consequence is that while the volcanic signal was obscured in the observations, it was not in the models and the discrepancy between models and observations in 1983 was not coincidence. Nor was the greater relative temperature in UAH relative to HadCRUT4, as satellite temperature indexes respond more strongly to ENSO.
Spencer knows these facts. Therefore, his arbitrary choice of 1983 as the baseline year must coint as deliberate deception. He is knowingly lying with the data.
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scaddenp at 08:47 AM on 13 April 2015Global warming hiatus explained and it's not good news
Tom, I have just got to stop doing this when I get out of bed! You are correct of course.
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Timothy Chase at 08:43 AM on 13 April 20152015 SkS Weekly News Roundup #15B
Although the Bloomberg California heat chart does not appear in the tech paper, at least with respect to the unprecedented nature of the current drought, the Bloomberg article appears to going off of:
... the 2012–2014 drought stands out in the context of the last millennium. In terms of cumulative severity, it is the worst drought on record (−14.55 cumulative PDSI),more extreme than longer (4 to 9 year) droughts. Considering only drought episodes defined by at least three consecutive years all lower than −2 PDSI, only three such events occur in the last 1200 years, and 2012–2014 is the most severe of these."
Open Access: Griffin, Daniel, and Kevin J. Anchukaitis. "How unusual is the 2012–2014 California drought?." Geophysical Research Letters (2014).
http://onlinelibrary.wiley.com/doi/10.1002/2014GL062433/epdf The tech article makes clear that the reduced precipitation is by no means unprecedented, but over the past three years the higher temperatures have resulted in higher rates of evaporation that have amplified the drought such that cummulative drought severity has been unprecedented. -
Tom Curtis at 08:39 AM on 13 April 2015Global warming hiatus explained and it's not good news
scaddenp @18:
"Argh! Dont attempt this stuff when you are in massive hurry and barely awake."
I know the feeling, and good advise ;)
Running through the calculation, and using your figures we have:
3 x 10^23 Joules / 0.84 Jouls/Kelvin.gramme = 3.57 x 10^23 Kelvin.grammes
3.57 x 10^23 Kelvin.grammes/ 2790 Kelvin = 1.28 x 10^20 grammes
1.28 x 10^20 grammes / 3 grammes/cm^3 = 4.267 x 10^19 cm^3
4.267 x 10^19 cm^3 /10^15 cm^3/km^3 = 4,267 km^3 of basalt cooled from "melting point" to 10 C to generate the release the amount of energy accumulated in the ocean. That in turn works out at approx 97 km^3 per annum. That compares to the 30 km/annum estimated deposited magma globally.
You will notice the major difference between my and your working is that I divide by temperature rather than multiply, the division being necessary to get the correct units.
As an estimate, the 3800 K magma temperature is absurdly high relative to recognized values (which are closer to 1300 K from wikipedia, National Geographic, and a couple of scientific articles I read). However, you did not include the heat of fusion, nor the difference in heat capacity between magma and basalt.
Using the values from the worked example @16, we would need an additional flow of 50,025 km^3 of magma at the ocean floor (ie, not mere crust formation) to account for the increase in OHC since 1970. Even that, however, would not account for the problem of thermal insulation of the ocean depths, nor why the thermal gradient cools with depth rather than warms with depth as would be required if the major source of surface ocean heat was from the ocean floor.
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Phil at 07:57 AM on 13 April 2015Models are unreliable
Rhoowl:
Phil computers do have rounding errors, iteration problems with real numbers.
Indeed they do, which is why careful climate modeller programmers analyse their programs to ensure such errors are restricted, and the models (or their component parts) are tested to ensure they do not exert a undue influence. That they do would be obvious - a modelling program that produces results that are unduely influenced by rounding errors would give widely different results with very small changes to the input.
Input has fudge factors. I use fudge factors all the time when modeling. I enter objects that can't possibly exist just to make the program work...
Whatever you may do, it does not follow that climate modellers do it too. -
scaddenp at 05:54 AM on 13 April 2015Global warming hiatus explained and it's not good news
Argh! Dont attempt this stuff when you are in massive hurry and barely awake. I had 30E22 in head from look at OHC graph and transcribed it to exponent too. However, I didnt make typo entering into calculator and 3E11 is still the cubic kilometers. As Tom said, this has to be very thin to transfer that much energy to ocean. The main point stands: it is totally unrealistic to blame undersea volcanoes for GW.
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Rhoowl at 03:09 AM on 13 April 2015Models are unreliable
Jh I wish to reply to your comment and since it is off topic and is more personal in nature we should do this privately. My email is rhoowl at yahoo
Moderator Response:[JH] Your request has been duly noted.
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Tom Dayton at 02:54 AM on 13 April 2015Models are unreliable
Rhoowl: Your reply to my comment was not on the topic I had explained--differences between models. Since you either will not or cannot focus on a topic long enough to have an actual conversation, I'm giving up on you.
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saileshrao at 02:53 AM on 13 April 2015The history of emissions and the Great Acceleration
Thanks, sidd and andyskuce.
Howard Lee indicates that would be 340 Gt of Carbon, not CO2, for land use changes from prehistoric times to pre-industrial times.
As such, cumulatively, land use change dwarfs all the other contributors, which bodes well for the potential of land use changes to drawdown CO2 in the near future, if we put our hearts and minds to it. -
Tom Dayton at 02:49 AM on 13 April 2015Models are unreliable
Rhoowl: Spencer followed up his claim that you linked, with another claim this time about "90 models" but likewise severely flawed. Hotwhopper clearly explained Spencer's biggest...um, "mistake"...of playing loose and fast with baselines. There is also the issue of Spencer falsely giving the impression that the RSS and UAH satellite trends for the tropics are consistent, when in fact UAH for the tropics is three times lower trend than RSS, and recently RSS has been shown to be correct in the tropics and UAH wrong.
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billthefrog at 02:40 AM on 13 April 20152015 SkS Weekly News Roundup #15B
@ PC
Ah, you have unerringly spotted the fingerprint of the 66 year cycle, which proves that it was the PDO "wot dunnit".
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PhilippeChantreau at 02:11 AM on 13 April 20152015 SkS Weekly News Roundup #15B
Here's a funny thought: if I was to use fake skeptic methods with the NOAA chart of California's temps, I would cherry-pick 1949 as starting point and calculate the "trend" to the present...
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Rhoowl at 01:53 AM on 13 April 2015Models are unreliable
robp dr Roy spencer has also reviewed this his conclusion don't agree with you graph. Tristan dr spencer is a climate scientist.
http://www.drroyspencer.com/2013/06/epic-fail-73-climate-models-vs-observations-for-tropical-tropospheric-temperature/
Td I have already agreed that the scenarios spread was not an model error....there are errors in the models. I have also read the intermediate blog. What you pointed to as verification was reviewing past Enso from only 18 climate models. What About the other climate models. This appears to be a weak verification. He only matced the trend an not absolute values. I reviewed Steve easterbrook material. Much of what he professes is that science twist need to aek to the public in general terms so it is more understandible. Much of what he said didn't address the issues I am presenting.
leto I never claimed that the modelers do not have skill or infallibilty
Quite the opposite actually. The losing argument was started by someone else previously. Perhaps this was out of line.
Phil computers do have rounding errors, iteration problems with real numbers. Input has fudge factors. Is use fudge factors all the time when modeling. I enter objects that can't possibly exist just to make the program work...
after further reading about about the water co2 interaction it became clear that a grid resolution of 100km x 100km is too coarse to property model the cloud co2 interaction. The material is too anisotropic for that resolution. Zhou zhang bao and liu wrote a paper suggesting that grid resolution Be 1x1 mm. To properly model turbulence.. In the atmosphere. Obviously this would be an impossible task
Moderator Response:[JH] Either English is not your first language, or you do not take the time to proof read what you have keyed in prior to hitting the "Submit" button. Either way, parts of your comment are nonsensical. In addition, some of your statements insult the intelligence of other commenters. If you keep going down this path, your future postings may be summarily deleted.
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billthefrog at 01:34 AM on 13 April 2015Global warming hiatus explained and it's not good news
3 x 1030 joules?????
As scaddenp refers to 3x1023 J in comment #14, then 3x1030 J in #15, I think we can safely assume there has been a typo.
Unless, of course, there was a sudden increase in OHC of 2.9999997x1030 joules in the space of approximately 22 minutes. (In which case, I think we would have noticed.)
Glad to see I'm not the only one that does typos.
cheers bill f ;-)
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Phil at 21:48 PM on 12 April 2015Models are unreliable
And two more ...
3. Hoffmann seems to think that global temperatures are inputs to GCM. This is just factually wrong
4. He makes the usual "denier" mistake of equating the atmospheric temperature record with the "global" temperature record (i.e he ignores 93% of the energy imbalance) -
Phil at 20:41 PM on 12 April 2015Models are unreliable
@851
The blog post by Dr Hoffmann is wrong in so many ways. Here are just two points from it.
1. The illustration of rounding errors in computer programs would only be relevant if the errors have a systematic bias (i.e. they all rounded up or all rounded down). As Hoffmann's output shows they don't; the rounding errors are randomly signed and therefore will tend to cancel each other out, both within an individual run and between runs.
2. The discussion about modelling individual molecules in the atmosphere/planet is ludicrous; bulk matter has well defined properties that can be determined experimentally and used in a model without recourse to modelling individual molecules. We didn't know, or model, the individual atoms of the Apollo 11 space rocket, but that didn't affect our ability to predict its behaviour.
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grindupBaker at 17:13 PM on 12 April 2015The global warming 'pause' is more politics than science
Here's my analysis based on an LSQ fit to an RSS graph I saw on WUWT site (unclear to me whether they were saying it was Monckton or Knappenberger-Michaels LSQ fit):
1996/10-2014/10 = 0.0 degrees/century (18 years 1 mo. = 217 months)
WUWT Monckton(?) LSQ fit with comment <I paraphrase> exactly zero warming.
1999/02-2014/10 = 1.2 degrees/ century (15 years 9 mo. = 189 months)
*more recent* my well-estimated eyeballed fit *on the very same WUWT graph* for this later period.
Thus, Monckton (I think it is) shows clearly that "global warming" increased just 16 years ago.
Not only that but the fun part now: 1.2 degrees later warming trend / 0.0 degree earlier warming trend = infinity so the Monckton (?) analysis *shows an infinite increase of "global warming" just 16 years ago*.I'm like that other bunch, Monckton and that, I hugely prefer fun & games to actual work.
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sidd at 12:58 PM on 12 April 2015The history of emissions and the Great Acceleration
In particular table 3 in ruddiman(2013) estimates 320-343 gigaton pre1850 carbon emissions
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sidd at 12:42 PM on 12 April 2015The history of emissions and the Great Acceleration
sailesh rao asked:
"What is an estimate of the CO2 emissions due to land use changes from the start of the agricultural revolution, say 8000BC to 1750?"
See Ruddiman(2013) doi:10.1146/annurev-earth-050212-123944 or his recent book "Earth Transformed"
sidd
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Leto at 09:44 AM on 12 April 2015Models are unreliable
Rhoowl wrote,
"you have to understand the the people who are writing and operating the programs for computer models are not climate scientists."
Producing a useful model of anything is 99% based on understanding the domain you are modelling, and 1% putting some code together. The idea that a non-climatologist who knows about programming is particularly well-positioned to comment on the success or otherwise of a climate model is nonsense. The idea that climate science has a lack of intelligent people versed in both the necessary domain knowledge and the coding skill is also nonsense. Sure, you mustn't assume that the climate modellers are infallible, but your starting assumption should be that the people trying to educate you on this site know much more about this than you or some programmer.
"btw..you only win the argument if you convince the other person that they are wrong."
This is probably the silliest comment I have ever read on this site. For a start, you are wrong if you see this exchange as a contest people are trying to win. The people responding to you are trying to educate you, and if you refuse to be educated that is a reflection on you, not on the validity of their responses. I see no evidence that anyone has failed to understand your points (which have all been discussed before anyway), but I see plenty of evidence that you have not actually stopped to consider what you are being told. Remainingly stubbornly ignorant and then calling that result a win or a draw is simply foolish.
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Tom Curtis at 09:24 AM on 12 April 2015Global warming hiatus explained and it's not good news
scaddenp @15, I do not understand why you are using 3 x 10^30 Joules as your target, given that it is 10 million times the heat increase in the ocean since 1970.
Anyway, in trying to check your numbers I came across a worked example by Ass Prof Leslie Sonder at Dartmouth College. This area falls close enough to her area of specialization that I suspect she has made no blunders in the basic calculation, but am quite happy for others to point out blunders so that we can correct the example.
In any event, she calculates that 2 x 10^13 Kg per annum of new crust is formed by mid-oceanic ridges. That represents 6.67 x 10^9 cubic meters, or 6.67 cubic kilometers, or 22.23% of estimated global magmatic deposition.
She also calculates an energy release of 4 x 10^19 Joules per annum, or less than 0.008% of the average annual energy accumulation in the ocean since 1970.
Several things should be noted about this. First, the magma deposition as new crust of a given year does not all occur at the center of the mid-ocean ridge. Rather, extrusion form pillow basalts at the surface (0.5 km thick according to wikipedia), which because they cooled in water, cool rapidly. Below that, however, are sheeted dike complexes (1.5 km thick) which cool beneath the layer of pillowed basalt, and hence slowly. Beneath that again are Gabbro and layered ultramafic rocks (5 km thick) which, because of its depth below the sea floor, cools very slowly. The process of formation appears like this:
(Source)
Because the vast majority of the solidified magma is not at the surface, it cools slowly releasing its heat gradually over time. This does not mean less heat is released in any given year, because heat is still be ing released from previous years. It does mean the heat is not all released at the center of the mid-ocean ridge by volcanism. The vast majority of it is released later by diffusion through the sea floor. Hence the wide bands of increased geothermal heat surrounding each mid-ocean ridge.
It also means that the majority of the rock does not cool to abyssal water temperatures. Indeed, the rock immediately above the mantle is near the melting point of the rock, with temperatures declining approximately linearly as it approaches the ocean floor. In other words, Sonder's estimate is likely an over estimate. Put another way, 0.008% of recent annual OHC increase is an upper limit of the heat released by cooling magmas at the mid-oceanic ridges. Further, the process of that release ensures that it is near constant over time so that it cannot be a significant contributor to any change in OHC.
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Andy Skuce at 09:08 AM on 12 April 2015The history of emissions and the Great Acceleration
eksommer @18
You are correct that stacked graphs can be misleading. So, here are annual emissions and cumulative emissions graphs, unstacked. There are things that jump out of these graphs that are not obvious in the ones I presented. Thanks for the suggestion.
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Andy Skuce at 09:02 AM on 12 April 2015The history of emissions and the Great Acceleration
mdenison @19
Here is a plot showing year-to-year changes in the emissions rates. The blue line jumps around a lot, so I applied a 10 year trailing filter (ie, the 2010 figure is the average of 2001 to 2010).
There seems to be a jump after about 1950 where the annual rate of increase in emissions is roughly 400-500 million tonnes of CO2 per year. Before 1950, the change was 0-200, roughly speaking. I think that's a real step change.
Now, you might argue that what matters is not the actual growth rate but the percentage rate of growth, You would be right, an economy growing steadily at 2% per year would grow faster in dollar terms the bigger it got.
Let's look at some curve fits, before and after 1950.
I fitted an exponential curve to emissions between 1850 and 1950 and extrapolated it to 2010. I think it's obvious that this would have under estimated growth in emissions for the next 60 years. The last curve in my post showed a linear rather than exponential extrapolation, which assumption, you are right, did exaggerate the effect of the Great Acceleration. But I think it's clear that the Great Acceleration is still a real phenomenon.
For the 1951-2010 period, I found a linear function fitted best. Although I just argued that growth should ideally be exponential rather than linear, I think that applies to the economy, but not necessarily to emissions. There have been improvements in the efficiency of fossil-fuel usage and, although there is an undoubted correlation between fossil-fuel use and economic growth, increasing fossil-fuel combustion has not been the only factor driving the economy.
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scaddenp at 07:18 AM on 12 April 2015Global warming hiatus explained and it's not good news
Lets run some numbers shall we. Specific heat of basalt is 0.84J/gK. Assume is deposited very thinly and so can cool from 2800C to 10C in decades. To get a change of 3E30 in OHC from this basaltic lava cooling we need 3E30*2790/0.84 g of lava. With a basalt density of 3.0, that would translate into an increased volcanic outflow of about 3E11 cubic kilometers of basalt, or around 8E9 cubic kilometers per year, 8E8 Mt pinatuba per year. I think we would have noticed.
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scaddenp at 06:56 AM on 12 April 2015Global warming hiatus explained and it's not good news
"[El Nino, for example, by itself releases 10 to 20 cu.km of lava near the Eats pacific Rise, let alone that released elsewhere. This is yet to be shown there.]"
Can we have a cite for evidence of this please. Especially change in volcanic output between el nino and la nina?
Also, Ocean heat content has increased by 3E23J since 1970. Entirely consistant with CO2 increase. Most of this heat accumulation in top 700m with gradual warming in top 2000m, nothing much happening in depth (where you claim the heat is coming from). Furthermore the spatial distribution of this heat accummulation is in no way correlated volcanic ridges. Heat transfer between ocean and atmosphere is also entirely consistant with El nino warming.
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Tom Dayton at 03:27 AM on 12 April 2015Models are unreliable
Rhoowl claimed "the cmip5 models produce a wide range of results with a large error. the models are off what real world temperatures indicate. just looking cmip5 ar4 model graphs compare to real world temperature it appears that the models are more than two standard deviations off."
Multiple people have explained to you that your particular interpretation of the model results as "error" is incorrect. It appears that you continue to refuse to read explanations of what the model results actually are, and what the models actually are. To start with, you absolutely must read the Intermediate version of this "How Reliable Are Climate Models?" post. When a bunch of people on SkS tell you that you don't understand something, it is your responsibility to make at least the effort to read all of the original post on which you are commenting; some posts have Basic, Intermediate, and Advanced tabbed panes. If you don't trust what those blog posts say, I applaud you for your skepticism as long as you then read the peer reviewed original publications that those posts cite.
One source of variability in GCMs' results is differences in the models' constructions, not just their parameters. The CMIP5 ensemble of models is just that--multiple models, created by multiple people using different approaches. Those differences in models' constructions are not weaknesses! They are intentional--think of them as replications of experimental setups. Robust "replication" does not mean just rerunning an experiment with exactly the same setup. Instead it means running an experiment differently as long as, in principle, the results should be the same. Using differences in experiment construction and running is a test of whether the orginal experiment's results really were due to the posited phenomena or were due to otherwise uninteresting quirks in the experiment. Likewise, having differently constructed climate models safeguards against any one model's results being due to quirks in that particular model.
A good place to start learning about verification & validation (V&V) of climate models is at Steve Easterbrook's blog Serendipity. Steve is a computer scientist and engineer who used to be the chief scientist at NASA's independent V&V center, now is a professor, and does climate research. He has a good recent video of a TED talk (you should read the text surrounding that video on his blog), a short but good description of V&V, and a short description of massive and thorough comparisons of the outputs of 24 climate models. You would benefit from reading other posts of his that you can find by using his blog's Search field to look for "verification" or "validation."
Also useful for you to read is Tamsin Edwards's series of four short blog posts the links to which are near the top of her post Possible Futures.
Of course the bottom line is whether all those different models' results are the same. But "the same" does not mean "exactly the same." There is no absolute definition of "the same." Not 1 in 10,000. Not 2 standard deviations. Not 20%. This is true not just in climatology, but in every field. All models are wrong, but some are useful. For example, if you are trying to discover whether a drug helps an illness, and every experiment testing that shows it does not help, then it doesn't matter that some experiments show it makes no difference and some show it makes the illness worse. For the purpose of those experiments, the unanimous, sensible conclusion is that you should not give that drug to anyone with that illness.
It is necessary to define "the same" climate model results as "similar enough to suit the purpose to which these models' results are being put." But that's a topic for a future comment. First please address, narrowly, what I've written here.
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