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Climate Change Commitment II

Filed under: — gavin @ 2 June 2010 - (Español)

A couple of months ago, we discussed a short paper by Matthews and Weaver on the ‘climate change commitment’ – how much change are we going to see purely because of previous emissions. In my write up, I contrasted the results in M&W (assuming zero CO2 emissions from now on) with a constant concentration scenario (roughly equivalent to an immediate cut of 70% in CO2 emissions), however, as a few people pointed out in the comments, this exclusive focus on CO2 is a little artificial.


I have elsewhere been a big advocate of paying attention to the multi-faceted nature of the anthropogenic emissions (including aerosols and radiatively and chemically active short-lived species), both because that gives a more useful assessment of what it is that we are doing that drives climate change, and also because it is vital information for judging the effectiveness of any proposed policy for a suite of public issues (climate, air pollution, public health etc.). Thus, I shouldn’t have neglected to include these other factors in discussions of the climate change commitment.

Luckily, some estimates do exist in the literature of what happens if we ceased all human emissions of climatically important factors. One such estimate is from Hare and Meinshausen (2006), whose results are illustrated here:

The curve (1) is the result for zero emissions of all of the anthropogenic inputs (in this case, CO2, CH4, N2O, CFCs, SO2, CO, VOCs and NOx). The conclusion is that, in the absence of any human emissions, the expectation would be for quite a sharp warming with elevated temperatures lasting almost until 2050. The reason is that the reflective aerosols (sulphates) decrease in abundance very quickly and so their cooling effect is removed faster than the warming impact of the well-mixed GHGs disappears.

This calculation is done with a somewhat simplified model, and so it might be a little different with a more state-of-the-art ESM (for instance, including more aerosol species like black carbon and a more complete interaction between the chemistry and aerosol species), but the basic result is likely to be robust.

Obviously, this is not a realistic scenario for anything that could really happen, but it does illustrate a couple of points that are relevant for policy. Firstly, the full emissions profile of any particular activity or sector needs to be considered – exclusively focusing on CO2 might give a misleading picture of the climate impact. Secondly, timescales are important. The shorter the time horizon, the larger the impact of short-lived species (aerosols, ozone, etc.). However, the short-lived species provide both warming and cooling effects and the balance between them will vary depending on the activity. Good initial targets for policy measures to reduce emissions might therefore be those where both the short and long-lived components increase warming.


727 Responses to “Climate Change Commitment II”

  1. 201

    #176 Rod B

    Arrhenius was pooh-poohed by one or two scientists? until the scientific argument countervailing his theory could be pooh-poohed, which was around 1904/6, at which time there was no more pooh-poohing of Arrhenius. I could be wrong, I am going from memory on that.


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  2. 202
    Gilles says:

    BPL: Ever hear of “detrending?”

    ehhhm … using detrended correlation to extrapolate long term trends? weird idea…

    the correlation between growth rate and temperature is doubtful from the beginning, starting from a dimensional analysis (you guys seem to have a background in physical sciences good enough to agree on the importance of dimensional analysis…). A growth rate has the dimension of time^(-1) : actually the inverse of a doubling time. Sorry for the misprint in previous post, the doubling time is actually 70/k = 100 ln2 /k and not 35 , 35 yrs is the doubling time for the popular 2% growth rate.
    So correlating growth rate with temperature generates a weird quantity of dimension “time. temperature” ^{-1} . What is a “time*temperature” physically? no idea. Of course correlating anything A against anything B allows always to construct a mathematical quantity of dimension A.B-1 , but it may not be physically meaningful – just dependent on particular conditions for which you have computed the correlation.

    Note that the growth rate is just the SPEED at which you grow – meaning that you aren’t saying anything on the possible limits on GDP itself. You just apply a growth rate during a certain time , and of course the result after this time will depend on the growth rate… assuming that it continues indefinitely , i.e. there is no physical limit to the growth.

    Well, this could well be a thought of economists, but I’m sure that most of you would be reluctant to admit there isn’t any limit on growth ;). But note again that giving a correlation between growth rate and temperature doesn’t give any constraint on this limit, it says basically that temperature will limit the rate , but not the accessible GDP level. So complaining about the “low growth rate” means actually that you think that the best thing is to grow as fast as possible and reach as soon as possible the limit. Are you SURE that you’re actually thinking that ?

    So a more meaningful quantity would be a limiting GDP as a function of temperature – does it exist, independently of FF consumption? very doubtful.

    On the opposite, the correlation I’m claiming is between GDP it self (NOT growth rate !) and FF consumption. The same reasoning leads to consider a quantity whose dimension is “$/kJ” “value per unit energy”. Does it make sense? of course YES. value is in some way related to the amount of work you need to produce things, and the amount of work is correlated with energy (correlated doesn’t mean strictly proportional, of course). So it makes sense to correlate GDP with FF consumption, even if the correlation is not perfect. in the same spirit, it makes sense to wonder if reducing FF use can be done without restraining in anyway GDP. This can probably be partly done improving efficiency, but this is not a NATURAL thing , and once you have improved the best you can the efficiency, you will be forced to admit that decreasing FF will much probably result in a decrease of GDP – and changing the index will probably not give much different results. So it is much more natural to question the influence of FF consumption than that of temperature on GDP – acting like it doesn’t matter at all is much likely totally bogus.

  3. 203
    Rod B says:

    Bob (Sphaerica) (183), I don’t disagree with anything you say (I admitted I wasn’t sure if I was citing Benjamin correctly) except the one tiny piece about me putting the word “irrefutable” in people’s mouths. You skipped or forgot a couple of posts.

    Ray Ladbury (184), O.K., as far as it goes. But you’re skimming over a couple of significant points. #1, the correlation between temp and GDP has no point nor value added. I can find a correlation between GW and piracy. So what? #2, what about Greenland? Or are you just (cherry) picking a extremely limited scenario in time (and probably scope) to try to imply a point?

  4. 204

    #200–John:

    There was initial enthusiasm for Arrhenius’ theories, but he already had lots of scientific enemies due to his highly controversial primary research focus–the development of electrolytic chemistry–which won him one of the first Nobel Chemistry prizes. It was at this time that <a href="http://hubpages.com/hub/Global-warming-science-press-and-storms&quot; rel="nofollow"Nils Ekholm–a friend and sometime collaborator of Arrhenius–wrote his synoptic paper on climate and CO2.

    Then a controversy with the younger Angstrom developed–this was the genesis of the “saturated gassy argument” (as it was called on an RC post on the topic.) Angstrom won the controversy in the short term; the saturation of CO2’s IR absorption was pretty much the accepted wisdom until 1938, when Guy Callendar took a fresh look at the new spectroscopic results obtained in the intervening 20+ years. That’s really when the science started being taken more seriously again; Callendar’s efforts culminated in the work by Revelle & Suess, Plass, Keeling and others in the 50’s; in many cases the work was helped by the International Geophysical Year in (mostly) ’58–a whole lot of good data got gathered!

    I already posted links to my Callendar article upthread; Arrhenius is discussed here.

    Original papers by Arrhenius, Callendar, and others on climate science are available here:

    http://wiki.nsdl.org/index.php/PALE:ClassicArticles/GlobalWarming

  5. 205
  6. 206
  7. 207

    OK, why that’s not working I don’t know. (“Alas, poor preview function, I knew (and appreciated) it well. . .”)

    Arrhenius link in the clear:

    http://hubpages.com/hub/Global-Warming-Science-And-The-Dawn-Of-Flight

  8. 208
    Rod B says:

    John P. Reisman (OSS Foundation), et al, from Spencer Weart (very first paragraph in History): “… Svante Arrhenius calculated that emissions from human industry might someday bring a global warming. Other scientists dismissed his idea as faulty. In 1938, G.S. Callendar argued that the level of carbon dioxide was climbing and raising global temperature, but most scientists found his arguments implausible. It was almost by chance that a few researchers in the 1950s discovered that global warming truly was possible.”

  9. 209
    John Pollack says:

    Doug @ 167 Thanks. I’m basically in agreement with you that we’re going to be seeing more and longer excursions into extreme heat episodes, and I appreciate your reference to the article. I looked up the original, but it was paywalled, so I confess to only reading the abstract, and saving $10.

    I do have some significant concerns about the way the article portrays the issue of extreme heat. From my perspective as a weather forecaster, it is not surprising that wet bulb temperatures don’t (generally) exceed 31C, unlike the PNAS abstract expressing surprise. That’s due to the extreme vertical instability that I mentioned earlier.

    The brunt of the issue is that the response of the atmosphere to increased moisture, and higher dew points, is extremely nonlinear. The ability of the atmosphere to hold water vapor, and potential energy, increases nearly exponentially with rising temperature. Really high dew points tend to create huge thunderstorms and floods.

    IMHO, models, including both GCMs and forecasting models, don’t do a very good job with this. They have trouble partitioning excess energy between increased temperatures and increased evaporation. They also have trouble with vertical stability. For this reason, while I certainly accept AGW, I don’t trust the regional details. But that’s a separate thread, and I’ll wait until it’s more relevant. I also realize that I could be creamed by some dedicated modelers who will bury me with details. For those people – I know you are working hard and doing your best! I’m talking from the perspective of a forecaster, not a denier.

  10. 210
    Edward Greisch says:

    To all those who are debating genetic engineering of crops:
    1. GW doesn’t simply raise the temperature. It changes the weather in unpredictable ways and not at all uniformly. Right here, the last 2.5 years have seemed cooler because of the extra rain, but other places have gotten less rain. The rain has come at the wrong times. We can’t do a 1 year or 2 year or 5 year weather forecast, but that is what farmers need. These super-long term weather forecasts have to be local, so there have to be a lot of them.
    2. Farmers keep growing the same thing regardless of the need to change crops. They don’t know how to grow a different crop. It takes experience. It takes many years to switch to an unfamiliar crop.
    3. The genetic engineers need stable goals at least, and a lot more time than electronics engineers. How do you expect them to design one plant to grow in ANY climate?
    4. You are all discussing very small changes in the climate as if the region of stability were very large. The region of relative stability is very small. If we leave it, there is no coming back. Once the climate is out of our control, it is out of our control effectively forever. Once the climate has changed enough, the farmers can grow nothing. Civilization falls very quickly, as in about a day once there is no food in the grocery store. We have about a month of food in storage. Only 1 person in 10,000 survives a typical collapse, but that is a rough average and supposes that the collapse covers only a small area. For somebody to survive, there has to be a refuge to go to that is within reach, but not easy reach. This time, the collapse will be global and there will be no refuge, so we go extinct. [Mars would be the right distance away, but Mars is dead and unlikely to be revivable.]

    Genetic engineering of crops cannot save us no matter how good the genetic engineers are. The only way we can avoid extinction is to prevent the climate from changing. It doesn’t matter who or what we attribute the change to, we still have to prevent the climate from changing. We have to commit our civilization to putting the total CO2 equivalent back to the way it was before the Industrial Revolution. Even if we put the total CO2 equivalent back to 280 ppm, enough ice is likely to melt in the mean time to cause major disruptions.

  11. 211
    Doug Bostrom says:

    Stealing a term from Spencer Weart, on the “Saturated Gassy Argument” front the CO2-emanating blowhard Chris Monckton makes an appearance at Skeptical Science to hurl threats at John Abraham, who had the temerity to reply to Monckton’s squeals of protest at being outed.

    Abraham’s reply to Monckton can be found here at Skeptical Science, along with Monckton’s meta-meta throwdown of the usual sternly worded letter to Abraham’s university.

    Obviously Abraham’s comprehensive treatment of Monckton has struck a nerve, as well it should. No more free travel, adulation? Could be.

  12. 212
    Completely Fed Up says:

    “#1, the correlation between temp and GDP has no point nor value added. I can find a correlation between GW and piracy. So what”

    So when you or Gilles complain that GDP goes up when temperatures rise, we know you’re wrong.

    PS it’s funny how you’re all over causation being sine qua non of discussion when you’re using it to avoid being wrong.

  13. 213

    Rod 176: Up to beyond 1900 climate science (as specifically practiced by Arrhenius et al) was pretty much ignored, and often pooh-poohed, by the mainstream.

    BPL: Prove it.

  14. 214

    Gilles 202,

    It is ABSOLUTELY IRRELEVANT what the units of the two series being correlated are. The mass of main sequence stars is highly correlated with their luminosity. One is measured in kilograms, the other in watts. Real economic growth is highly correlated with changes in unemployment. One is measured in dollars per year, the other in employees.

  15. 215
    Dr Nick Bone says:

    It’s good to see this discussed again on Real Climate.

    Following the previous post, I put together a multi-part analysis looking at the long-term commitment from present emissions. The results were rather sobering, as it seems that after allowing for slow feedbacks we’ve already done a lot of long-term damage. See:
    here and here .

    Brief recap:
    Stage 1: CO2 levels in the atmosphere start declining. After some initial bumpiness (due to the effect of sulphates dropping out), temperature stays at approximately today’s level or falls slightly.

    Stage 2: CO2 stops falling, because there is a portion (20-25%) of our emissions which is persistent for thousands of years. CO2 bottoms out at around 335ppm. Temperature rises owing to fast-feedbacks (Charney sensitivity) for that level are around 0.75 degrees C above pre-industrial, roughly where we are today.

    Stage 3: Slow albedo feedbacks also kick in (Earth System Sensitivity). A slow warming resumes, leading to an additional 0.75 degrees or so over the next few centuries. But we also see a temperature-dependent CO2 response, with CO2 levels slowly rising again. This increased CO2 causes a bit more warming, which causes a bit more CO2, and so on, but in a convergent series.

    Stage 4: CO2 levels converge back up to around today’s levels (370-400ppm), and the temperature to around 2.5 to 3 degrees above pre-industrial levels. The Greenland and West Antarctic ice-sheets have gone. Part of the East Antarctic ice-sheet has gone too. Earth resembles the Pliocene.

    Stage 5: Our persistent CO2 finally drops out of the atmosphere after maybe 100,000 years. Milankovich cycles resume, and eventually ice sheets grow again.

    I haven’t seen anyone pick this apart, but feel free to do so if it’s seriously wrong.

  16. 216
    Ray Ladbury says:

    I think the responses of Rod B and Gilles to the data on GDP vs. Temperature are revealing. Now when some of us are confronted with data that runs counter to our prejudices, we respond by trying to find out more about the data. Rod B. and Gilles first reaction is to attack the data and the person who brought it to their attention.

    Gilles spews a line of absurdities that makes it clear he hasn’t even bothered to look at the data long enough to understand what it is about. Dimensional analysis? Dude, you don’t have a clue.

    Now, Rod B. has hung around us a bit more, so his argument is at least not absolute bullshit. He points out quite correctly that correlation is not causation. However, while this is true, there are plenty of studies that find plausible mechanisms–and these Rod simply chooses to ignore.

    I guess that is the difference beteween someone who wants to understand and someone who merely wants to argue. The latter do neither particularly well.

  17. 217
    Gilles says:

    “The mass of main sequence stars is highly correlated with their luminosity. One is measured in kilograms, the other in watts. Real economic growth is highly correlated with changes in unemployment. One is measured in dollars per year, the other in employees.”

    True, but there is a fundamental reason why there is a correlation between mass and luminosity of the stars – meaning that you can actually construct a “luminosity per unit mass ” (actually per unit mass^3 since luminosity scales more like M^3) from fundamental constants.

    http://en.wikipedia.org/wiki/Mass–luminosity_relation

    For economic growth , you’re wrong : it is measured by its RELATIVE (or logarithmic) increase, so the unit is yr^-1, not $.yr^-1. There is no $ in growth (there are in GDP). And rate of unemployment is dimensionless. So the correlation lets a dimension “time” in the constant- it is an interesting question to ask why a “time” appears naturally in economy , and why a growth of “a few % per year” appears to be optimal -meaning a doubling time of a few decades. I suspect that it has to do with the life expectancy of human race : ” a good” growth is a growth improving sensitively the life of average workers during their work time , around 30 years, but without changing it too rapidly. So there is actually a “fiducial” time in economy – the work time of an average worker.

    It’s interesting to remark that it is exactly the same criterion that limits the growth, since it can not exceed a relatively small number of doubling times. So the unavoidable conclusion is that the “good” growth of a few % per year cannot be sustained during more than a relatively small number of generations – that have already largely passed of course.

  18. 218

    #176, 212–

    There was an ongoing effort in the late 19th century to try and understand how and why the Ice Ages could have occurred. (There was also an explosion of understanding of the essentials of meteorology.)

    These researches, IM(unscholarly!)O at least, form the roots of modern climate science.

    So I wouldn’t agree–based upon what I’ve read so far–that climate science was ignored prior to 1900, as Rod says. Rather, it was developing rapidly. I’d also perhaps quibble that no-one had done climate science quite like Arrhenius before 1896! See:

    http://www.gustavholmberg.com/tomrum/wp-content/uploads/2008/04/tempestselektronisk.pdf

    This paper has more to say about Ekholm that Arrhenius, but note the section on the “cosmological style” of science practiced by the “Stockholm school,” as opposed to the old-guard Swedish “science establishment.”

  19. 219
    Gilles says:

    RL #216 : I’m afraid you didn’t catch completely my point. I didn’t deny that there could be some correlation between GDP and temperature in some countries. There can be also correlation of GDP with the presence of cod fish or the organization of soccer championships. I said that I doubt very much that is it a universal correlation that can be extrapolated ad libitum – actually it seems restricted to poor and hot countries, and the causes can be easily understood. There is probably some optimal local temperature for agriculture – very hot or very cold climate are not so good. So for countries whose economy are relying mainly on agriculture AND that lie at low latitude, warming is probably not good. Note however that it appears to be the opposite for northern countries in the Middle Age, since they probably lie above the optimal latitudes – so it is by no way a universal law, as I said.
    But the main point is that most obviously, industrial countries burning a lot of FF are essentially insensitive to temperatures, which can be here again easily understood. So of course advocating cutting all FF consumption to avoid some warming could have be very strong effects – but not the expected ones.

  20. 220
    Nick Gotts says:

    For all those extolling the power of crop breeding, I recently attended a talk by Prof. Peter Gregory, head of the Scottish Crop Research Institute. He was much less sanguine than you are, particularly about rice, where the rate of yield improvement has slowed considerably in the last couple of decades. At the same time, the number of varieties of each crop in use has fallen, increasing the risk of disastrous disease outbreaks.
    Nor have GM crops, as yet, fulfilled the promises of “feeding the world” the likes of Monsanto make. Yes, crop research is essential, and useful, but it’s also limited in what it can achieve, expensive and uncertain: not a panacea.

  21. 221
    Septic Matthew says:

    198, Completely Fed Up: Remind us of the particular technology and where its record is proven, will you?

    Crop breeding. It has been proven all over the world.

  22. 222
    Completely Fed Up says:

    “Crop breeding. It has been proven all over the world.”

    And so you can get from a wolfhound to a chihuahua in 20 generations?

    You can get from plains grasses to the heavy head of midwest american wheat in 20 years?

    No, no you can’t.

    And may I refer you back to an earlier statement:

    #158:

    How do you know that plant breeding will be successful? After all, there’s been marginal land for food production and calls for more food production for decades, yet these plant breeding processes don’t seem to have solved the problem there.

    So how has it proven itself for increasing yields and negating things like drought and floods and pauperisation of soils, matching to new pest and invasive species in the time scale of Anthropogenic Climate Change?

    It hasn’t.

    It hasn’t proven to work over the timescales nor over the severity of the change required.

    You’re pointing to a horse drawn cart and saying it’s a drag racer and saying that the horse drawn chariots of the ancient world proves it.

  23. 223

    #219–

    Funny, the corresponding point (frequently put to Gilles), was that the correlation between fossil fuel use and GDP was not likely to be robust over different technological regimes. . . somehow that logic, so sturdily resisted then, is embraced now.

  24. 224
    JCH says:

    Has crop breeding – drought-resistant plants – diminished desert area all over the world?

  25. 225

    #204 Kevin McKinney #208 Rod B

    Thanks for the refresher. Not sure which cabinet in my mind the 1904/6 came from. Thinking about it, that might be when the next argument was presented against Arrhenius? So, it was probably a combination of Plass/Revelle/Keeling that ended the Pooh-poohing I suppose. But 1950’s covers that pretty well. Callendar did a good job of bringing attention to the potentials again.

    Rod B, then I’m not sure why this was brought up? My point though possibly out of context is why worry about what was pooh-poohed, when we now know that the pooh-pooh is no longer relevant to current understanding?


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  26. 226
    Didactylos says:

    “Completely Fed Up”

    Please go away and check your “facts”.

    Dwarf wheat was bred in just 16 years. Bred using traditional (if accelerated) crossbreeding techniques.

    The doberman pinscher was bred from a few other breeds of dog in just 35 years.

    When you attack a falsehood for false reasons, you only look silly. And you look really, really silly, right now – particularly since you failed completely when it came to basic things like reading the reference I gave you. For the love of all that is holy, stop showering us with your ignorance.

    Every time you say something silly and unsubstantiated (and wrong), you make it harder for others to make serious points about the risks of a changing climate.

    What do you do now? First of all, what you *don’t* do. You don’t attack the messenger. You don’t insist that you are right, and dig yourself into a bigger hole. You don’t pretend you were saying something else and insist *that* was right.

    Instead, you spend a little time reading about selective breeding, crossbreeding and artificial selection. Note that the number of generations required for backcrossing is typically in single digits. Then, find a productive use for your new knowledge.

  27. 227
    Thomas says:

    Anon Cowar @199. Looks like a pretty good reply. You obviously know more about teh subject than I.

    So do you think global food production will be sufficient in the next few decades? I am particularly concerned that a lot of current and near past production was largely due to the mining of fossil water. Many of these aquifers won’t support anything near current withdrawal levels for much longer.

  28. 228
    Ray Ladbury says:

    Septic Matthew,
    My objection is not to crop breeding, but rather to invoking it–or any technology–as a panacea. There are limits to what we can breed a crop to do.

  29. 229

    203 (Rod B.)

    You skipped or forgot a couple of posts.

    Yes, and no. I didn’t see how often the word was used, but I went back and looked and it was still never used at all in the way that you implied it was. You said:

    Giving scenarios “irrefutable” exact numbers is silly if not preposterous — that’s what I’m fussing about.

    The problem here is that you tied the word “irrefutable” to the words “exact numbers,” when that was never done. The term “irrefutable” was tied to the idea of an inverse correlation between GDP and temperature only, never to specific numbers quantifying that correlation. So by exaggerating the original claim by cobbling together separate aspects of the argument, you make it sound implausible.

    In effect, you construct a strawman from what people have actually said, by making it sound like they said something else, which you can then refute.

    Stop making stuff up.

  30. 230
    Edward Greisch says:

    Dr Nick Bone: Thanks. I needed a breath of science. [I’m skipping Gilles’s comments.]
    Your second “here” doesn’t work. Your starting point is: we cease CO2 production abruptly now, which is optimistic. You say Pliocene-like, as in the time 5.332 Ma to 1.806 Ma when primitive humans developed, would be the hottest. We should be able to hack the Pliocene after enormous disruptions and loss of population, if we survive. But survival would be very much in doubt because starving humans would eat so many species to extinction in the mean time. It would be an horrendously impoverished new Pliocene. There might be nothing left to eat.

    You think 2.5 to 3 degrees C more will not kick the methane hydrates into melting along with the tundra peat bogs, causing a PETM type rise of 6 degrees C or more?
    http://en.wikipedia.org/wiki/Paleocene–Eocene_Thermal_Maximum
    That would be a total of 9 degrees C or more if we get a PETM spike. But our PETM spike might be bigger because the methane hydrate “gun” is “fully loaded” this time. I forgot where I saw that. The PETM spike adds methane-air explosions to the list of activated kill mechanisms. 9 to 12 degrees C of GW is outside the range at which humans have ever existed. I have listed kill mechanisms earlier under this article.

    OK, I’m glad you are optimistic . How do we avoid the PETM-type spike other than by mining and burning the methane hydrates and sequestering the CO2? Mining methane hydrates would be a delicate operation since they are sensitive to triggering release. You must be saying their trigger temperature is higher than I thought it was. But somewhere I read about methane bubbles in the Arctic ocean already. Yes, I am interested in this topic. I would like to hear more about it. I agree that we need to “suck CO2 out of the atmosphere” for a while.

  31. 231
    Gilles says:

    #219 : since i don’t know any “technological regime” in the modern sense that doesn’t make a massive use of FF , I consider your assertion as self-contradictory, since the correlation is already there from the beginning (in the very definition of “technological regime”) . There hasn’t be anywhere anytime any developed country without FF, and I know no fact showing it is possible.

  32. 232
    Ron R. says:

    As the Sun Awakens, NASA Keeps a Wary Eye on Space Weather

    http://science.nasa.gov/science-news/science-at-nasa/2010/04jun_swef/

    Combine a solar maximum with a big El Nino and it could get hot…

  33. 233
    Completely Fed Up says:

    “Dwarf wheat was bred in just 16 years. Bred using traditional (if accelerated) crossbreeding techniques.”

    And dwarf wheat is what we need if we change the climate?

    No.

    Please check your facts for relevancy. Especially if you’re touting a dumb idea.

    Quote:

    “Dwarfing

    Dwarfing is an important agronomic quality for wheat; dwarf plants produce thick stems. The cultivars Borlaug worked with had tall, thin stalks. Taller wheat grasses better compete for sunlight, but tend to collapse under the weight of the extra grain”

    Yeah, that’s exactly what we need to have to make wheat like less rain…

  34. 234
    Completely Fed Up says:

    “Dwarf wheat was bred in just 16 years. Bred using traditional (if accelerated) crossbreeding techniques.”

    And dwarf wheat is what we need if we change the climate?

    No.

    Please check your facts for relevancy. Especially if you’re touting a dumb idea.

    Quote (from Wikipedia):

    “Dwarfing

    Dwarfing is an important agronomic quality for wheat; dwarf plants produce thick stems. The cultivars Borlaug worked with had tall, thin stalks. Taller wheat grasses better compete for sunlight, but tend to collapse under the weight of the extra grain”

    Yeah, that’s exactly what we need to have to make wheat like less rain…

  35. 235
    Richard Steckis says:

    222
    Completely Fed Up says:
    6 June 2010 at 4:58 PM

    ““Crop breeding. It has been proven all over the world.”

    And so you can get from a wolfhound to a chihuahua in 20 generations?

    You can get from plains grasses to the heavy head of midwest american wheat in 20 years?

    No, no you can’t.”

    You will never get wheat from American plains grasses. This is because wheats such as bread wheat is a hybrid of three grasses from the Caucasian Mesopotamian regions (hexaploid). Other varieties may be from a single species (diploid) and tetraploid (hybrids of two species.

  36. 236

    Gilles 217,

    You’re quite right, I got the economic units wrong (shame on me, a former econ minor!). On the stellar mass-luminosity relationship, the units of the two are still different, and BTW, the relation is nowhere that I am aware of L proportionate to M to the 3rd. For high-mass main sequence stars the exponent is normally around 4-5; for red dwarfs it is around 2.6.

    My point stands–the units are irrelevant.

    Let’s take a numerical example. Let there be a series, X, measured in watts per square meter, and another, Y, measured in kilograms per second. The Pearson product-moment correlation coefficient is defined as

    r = sxy / sqrt(sx2 sy2)

    where the s terms are reduced sums of squares, or sums of squared deviations, for the product of x and y and the squares thereof, respectively.

    The sum of x^2 terms would be in W^2 m^-4, and the sum of y^2 terms would be in kg^2 s^-2.

    Their product would be in W kg m^-2 s^-2.

    Let us assume
    sxy = 50 W kg m^-2 s^-2
    sx2 = 80 W^2 m^-4
    sy2 = 90 kg^2 s^-2

    For Pearson’s r, we then have

    r =

    50 W kg m^-2 s^-2
    ———————————
    sqrt[(80 W^2 m^-4)(90 kg^2 s^-2)]

    Clearly, the answer is about 0.6035 and is dimensionless. The product-moment units must cancel out with the units of the denominator terms.

  37. 237

    Oops! The units on the product moment should have been W kg m^-2 s^-1, of course, not s^-2. My bad!

    Damn, I want preview…

  38. 238

    Gilles 219: I didn’t deny that there could be some correlation between GDP and temperature in some countries. There can be also correlation of GDP with the presence of cod fish or the organization of soccer championships. I said that I doubt very much that is it a universal correlation that can be extrapolated ad libitum – actually it seems restricted to poor and hot countries, and the causes can be easily understood.

    BPL: So stop saying GDP grows with temperature. Whatever the causal link or lack thereof, the correlation is negative–not positive.

  39. 239
    Bill says:

    Re #210 Edward says ” The only way we can avoid extinction is to prevent the climate from changing. It doesn’t matter who or what we attribute the change to, we still have to prevent the climate from changing. We have to commit our civilization to putting the total CO2 equivalent back to the way it was before the Industrial Revolution. Even if we put the total CO2 equivalent back to 280 ppm, enough ice is likely to melt in the mean time to cause major disruptions.”

    How do you propose to achieve this in practice ?

  40. 240
    Ray Ladbury says:

    Didactylos,
    I don’t think anyone questions the tremendous success and utility of breeding techniques or of genetic modification. The problem comes when one blithely assumes that they will be adequate in the face of any environmental challenge–and particularly when the challenge may not represent a single trend, but rather increased variability. This is further compounded by the fact that we only have a dim inkling of what climate change will mean for regional climates.

  41. 241
    Ray Ladbury says:

    No, Gilles, your one and only point is actually quite easy to catch. You think human civilization is impossible without high consumption of fossil fuels. That is the only thing you’ve had to say since you appeared last year. You’ve had over half a year to make that point, and you’ve been less than convincing.

    Now, given that fossil fuels are a finite resource, and that their consumption poses all sorts of strategic and environmental risks, I hope you will forgive those of us who want to look to what a society might look like once we move beyond fossil fuels.

  42. 242
    Anonymous Coward says:

    Thomas (#199),
    I don’t know very much. But I know the system isn’t set up to provide the best nutrition for the maximum number of people or for sustainability. Depending on how you look at it, production is insufficient already. And there are sustainability concerns as well obviously. But, depending on your metric, there’s much potential for improvements.
    As I see it, the main problem is not a resource bottleneck but rather the lack of incentives to produce for social needs and the lack of global governance. To address the issue you raised, there isn’t a technical reason why human nutrition should require so much (or even any) fossil water.
    There aren’t a whole lot of people professionally concerned with food security considering how important it is. Historically, governments have been more often concerned with squeezing the agricultural sector and it shows. You’ve got food riots and fertilizer riots while grain is being used to power SUVs. A simple change such as higher prices for essential human foods would reorient global agriculture towards feeding people but how are dispossessed consumers supposed to pay for this? The sustainability issue is trickier. As with GHG emissions, there are few incentives for producers to take the commons into account and no one is being held responsible for the predictable result. There’s no simple fix.

  43. 243

    #231–

    Ludicrous. If you equate “technology” with FF use, you will of course conclude that ceasing to rely on FF will kill technology.

    Of course, there was a time when such thinking was applied to reliance on the horse.

  44. 244
    Nick Gotts says:

    No, Gilles, your one and only point is actually quite easy to catch. You think human civilization is impossible without high consumption of fossil fuels. That is the only thing you’ve had to say since you appeared last year. – Ray Ladbury

    Not quite, Ray. He’s also been making the point that we should take no measures whatever to limit their use, because… well, admittedly, why we shouldn’t has never been clear.

  45. 245
    Rod B says:

    BPL says, “Rod 176: Up to beyond 1900 climate science (as specifically practiced by Arrhenius et al) was pretty much ignored, and often pooh-poohed, by the mainstream.

    BPL: Prove it.”

    You likely already have, but read Kevin McKinney’s #204 and my quote from Spencer Weart in #208.

  46. 246
    Rod B says:

    Ray Ladbury, when I point out your silly meaningless correlation and your devoid implication, why is it me that is just arguing and you that is “understanding the science”?

  47. 247
    Rod B says:

    John P. Reisman (OSS Foundation), I challenged a very minor but bothersome point — the hyperbolic claim that AGW was a “mature science” even before 1900.

  48. 248
    Rod B says:

    BPL (238) et al, you can really analyze the be-Jesus out of basic nonsense. Higher temps can increase GDP. Or not. They can decrease GDP. Or not. I can find constrained scenarios with correlations for all four examples (though you seem to claim in #238 that only the 3rd example holds.) But the scope of the entire correlation is so small as to make it meaningless. I can find a negative correlation between CO2 and global temperature that lasts for (a few) years. What does this mean?

  49. 249

    Gilles 231: There hasn’t be anywhere anytime any developed country without FF

    BPL: As of 1850 or so, there hadn’t been anywhere anytime any developed country without whale oil.

    As of 1970, there hadn’t been anywhere anytime any developed country without typewriters.

    Need I go on? That we’ve needed fossil fuels in the past does NOT prove we need it in the future. Technologies change. We don’t drive traps and carriages. We don’t scrape laundry over washboards. Our armies don’t carry swords or shields. Hell, nobody uses DOS any more.

  50. 250

    Rod 245,

    I think you’re conflating “AGW theory” with “climate science.”


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