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Comments 46551 to 46600:

46551. CBDunkerson at 21:49 PM on 9 April 2013
       It's the sun
       

       Chris wrote: "Those who cite CO2 as the only culprit in weather change..."

       No such people exist. As should be clear from the original article, the Sun does have a major impact on weather and climate. It just demonstrably is not responsible for the current unprecedented warming. Volcanoes, ENSO fluctuations, greenhouse gases other than CO2, aerosols, clouds, and many other factors which influence climate are discussed in detail in various posts on this site.

       However, the factor currently undergoing the biggest change is clearly the atmospheric CO2 level. We can look at every other factor and see that it has changed by a few percent at most... atmospheric CO2 is up by more than 40% in the past ~150 years. That's a profound change at a rate vastly greater than anything we have ever seen in nature. Ditto the corresponding increase in temperature. We've got two shockingly fast global increases occuring in tandem and basic physics tells us that increasing CO2 must cause increasing temperatures... yet somehow people keep insisting that we ignore the obvious primary issue and concentrate on anything and everything else.

       Why is that?

46552. Chris Eastaughffe at 20:57 PM on 9 April 2013
       It's the sun
       

       Perhaps we are asking the wrong questions, or looking for a simple correlation?

       The nexus may not be a direct link nor logarithmic progression.  It may be that a number of factors must align, or a threshhold be reached, before the effect of sunspot activity, volcanic activity or other factors have more than a negligable effect on the weather - this would perhaps be best demonstrated by research into unusual tornado events in winter, in the US.  It was suspected the link related to El Nino/La Nina events.  This, and swings in the jet stream related to it, were eventually established once the right question was found.  This is not a simple correlation but rather that a cluster of severe torandoes must be identified, rather than simply that a tornado occured, before the effect is identified (movement of the jetstream, spinning up the severe tornados, related to the El Nino/La Nina winds changes), and a correlation established.

       This information was there for all to see but not found until the right question was asked.

       Those who cite unusual weather events as proof are puting the cart before the horse, and ignoring the fact that weather prediction is an evolving science without absolutes. 

       Those who cite CO2 as the only culprit in weather change are again ignoring the fact that our models to date have failed to predict temperature and weather movements with a reasonable degree of accuracy.

46553. ajki at 19:59 PM on 9 April 2013
       The History of Climate Science
       

       Very nice and to the point.

       May I suggest to enrich the text with links to the studies, articles or abstracts?

       SkS has most of the needed links right here.

       (A special thank you goes to BaerbelW for the german translation)

46554. chriskoz at 19:33 PM on 9 April 2013
       The History of Climate Science
       

       John,

       Your jargon is not understandable to me at all. You could as well speak Welsh :)

       But the evidence of "weathering lasting just ten thousand [years]" is very much interesting (if you translate it to non-professional English) and hopeful that the geo processes that we need desperately in XXI century can be sped up.

46555. scaddenp at 12:06 PM on 9 April 2013
       The Fool's Gold of Current Climate
       

       The Matthews and Solomon paper appears to depend on the earlier Matthews and Caldeira paper. However, as far as I can see neither this nor the earlier Matthews and Weaver paper dealt with effects of aerosol reduction which must surely also accompany emissions.

       On the other hand, that paper references Montenegro et al 2007 which surely gives lie to those who think CO2 levels in the atmosphere are short-lived.

46556. Andy Skuce at 11:22 AM on 9 April 2013
       The Fool's Gold of Current Climate
       

       I have a post in the works (out later this week) that will discuss the recent Matthews and Solomon paper in Science and which refers to the MacDougall et al paper on permafrost that Icarus mentioned. I did a blogpost a few months ago on that paper. Figure 3 from that post is similar to Figure 3 in the MacDougall paper and I have reproduced it below.

       

       Figure 3. Showing the atmospheric concentration of CO2 following a shutdown of human emissions in 2013(left) and, after following DEP 8.5 for 39 years, a shutdown in 2050 (right). The dotted blue line shows the results at a climate sensitivity of 3.0°C and the upper and lower lines 4.5° and 2.0° respectively. Selected and modified from Figure S8 in the Supplementary Information.

46557. scaddenp at 09:34 AM on 9 April 2013
       Trillions of Dollars are Pumped into our Fossil Fuel Addiction Every Year
       

       " the retail price increase may be proportionally more than the tax increase."

       I find that very unlikely. An increase in bulk energy (crude oil, electricity generation) usually comes to retail as less. If all middle men are working to fixed margins, then retail go up precisely by same percent. In practise, industries would be extremely lucky to be able to sell on fixed margins.

       The set up under discussion is a 100% rebate scheme so let's discuss that rather an alternative which I agree you would not want. In this scheme, your income after tax increases. If you spend less than average joe on carbon, then you are better off not worse. The obvious way to improve your income is to look around for ways to pay less carbon tax than average joe because then you become even better off. So an energy company that sell to you with no carbon tax will get your business. They get more market share so that is what provides the incentive.

       Actually in an unfair carbon tax, where only say 70% is rebated, there is actually an even bigger incentive to get your energy from sources with no carbon tax.

       If live in a country where the reality is that people vote right-wing into power, then you have to also find climate change solutions that the right wing can live with.

46558. Tom Curtis at 09:28 AM on 9 April 2013
       Trillions of Dollars are Pumped into our Fossil Fuel Addiction Every Year
       

       gaillardia @17:

       1)  Introducing a carbon tax or emissions trading scheme will set a higher mean retail price for energy.

       2)  That means that corporations that can deliver energy with less carbon production will pocket more of that retail price, and hence will have an incentive to reduce carbon emissions by switching energy production from coal to gas, or from coal to renewables.

       3)  It will also mean there is a greater incentive for private individuals to independently source their energy needs by installing their own renewable energy capacity.

       4) It also means that private individuals will have a greater incentive to conserve energy, ie, by installing better insulation and running their heater/air conditioner at a lower rate, or by turning down (or up in hot climates) the thermostat slightly, or by turning of electronic equipment at the wall when not in use.  Conservative estimates show that households can reduce power consumption by at least 10% by these means, which would make them slightly better of even without a rebate.

       5)  Finally, it would mean the savings on power from installing insulation or renewable power would likely exceed the interest payments on the loan taken out to do either or both of the above (if you don't have the ready cash).  So it is not true that you won't have the extra money to change consumption habits provided that those changes reduce your energy bills.

       The most fundamental point is that your claims amount to the claim that market mechanisms cannot efficiently adapt to changes in prices.  If true, we had better switch to socialism because the efficiency of free markets is premised on the ability of markets to adapt to price signals.  That is why it has been conservative economists who have proposed and pushed the use of pricing mechanisms rather than regulation to control carbon emissions.

       Of course, the evidence is that markets do adapt efficiently to price changes.  

46559. gaillardia at 09:09 AM on 9 April 2013
       Trillions of Dollars are Pumped into our Fossil Fuel Addiction Every Year
       

       scaddenp at 06:07 AM on 7 April, 2013

       gaillardia - how can you claim - "my income and everyone else's won't change (assuming a %100 rebate)" The 100% rebate idea means you get back the tax money. You can get more than your fair share if you less carbon than average. That gives companies a serious incentive to build low carbon infrastructure.

       The idea that tax money is used by government to improve infrastructure unfortunately is an anethema to the right who do not trust government (with some justification ) to do this efficiently.

       
       Sequence:

       1. Carbon tax is levied on energy company.

       2. Energy company raises price by amount of tax, at least.

       3. Middlemen and retailers raise their prices also, and since they frequently do this on a percentage basis, not by amount of expenses or some other real quantity, the retail price increase may be proportionally more than the tax increase.

       4.  Best case scenario:  Because of the additional tax, I pay more for the product, by an amount equal to (not more than, see #3) that product's share of the tax.

       5.  The tax is rebated to me, maybe at %100, but I've already spent that money paying for the tax.

       6. My income has not changed, in fact there's a good chance it will go down a little.  I have no additional disposable income to buy anything, let alone something as expensive as a personal renewable energy system.

       7. This scheme merely cycles more money, with greater opportunity for energy companies to skim off the top.  They don't care that more dollars are cycling through the system, as long as their net profit is maintained (They don't care that some individuals might get a bigger rebate, and some might get less.  That makes no difference).  They have no incentive to change.

       We need systemic change, yesterday.  We have to do it as a society, all together, or it won't happen.  Let's take the tax money and build what we need the way that it's actually possible, by pooling the money to buy the big systemic changes:  better-designed communities, mass transit, and renewable energy infrastructure.

       I know the right thinks it's anathema.  They think taxes are anathema.  That problem must be confronted, since it won't go away by waiting for it to go.

       Waiting for the market is waiting for purposefully ignorant grifters to see the light.

        

46560. Jonas at 06:56 AM on 9 April 2013
       Food Security - What Security?
       

       Agnostic @ 23: Randers says: "The global population will peak around 8 billion people in 2040", see ca. 10:40, link to video starts at 9:50: http://www.youtube.com/watch?feature=player_detailpage&v=8qDy0jHo_DQ#t=590s I know this is not mainstream and I can't judge it, but it's interesting and it's a report to the club of Rome ... . See also http://www.2052.info , where you can also find the spreadsheet with the data to run your own forecasts, depending on the parameters. Just FYI.

        

46561. dana1981 at 05:23 AM on 9 April 2013
       Land Surface Warming Confirmed Independently Without Land Station Data
       

       keith @1 - indeed, Anderson is the 'natural thermometers' reference in the 5th bullet at the end of the post.

46562. keithpickering at 02:26 AM on 9 April 2013
       Land Surface Warming Confirmed Independently Without Land Station Data
       

       Also worth mentioning is the recent paper by Anderson et.al. 2013, which extends proxy temperature records forward to 1980. The Anderson data also nicely confirm thermometer records' accuracy; at 20-year smoothing, Anderson and HADCRUT4 are virtually indistinguishable from 1920 forward.

46563. Daniel J. Andrews at 01:54 AM on 9 April 2013
       The History of Climate Science
       

       This is good! I find myself forgetting some of the historical details, and this is the perfect refresher (the picture graphs alone are good memory aids). Weart's book is great, but if I have limited time, I tend not to check it out unless it is a "need to know" for a reply I'm working on. This article and the graphic timeline will make it so much easier to double-check myself (and certainly replaces my scribbed notes based on the info gleaned from Wearts book). Thank you. 

46564. Joel_Huberman at 01:23 AM on 9 April 2013
       The History of Climate Science
       

       In the third paragraph of the section "1930s: Hulburt and Callendar", the word "slated" is obviously a mistake. Perhaps the intended word is "slanted"?

46565. DSL at 23:21 PM on 8 April 2013
       Sportsmen’s and Anglers’ Views Highlighted in New ‘This Is Not Cool’ Video
       

       Bill, that highlights one of the great unknowns about the consequences of rapid warming on top of an interglacial.  We don't have a good analogue for the rapid transmutation of the biosphere in the post-glacial regions.  The dis-integration and trans-integration of species is, even as an 'issue', largely ignored by the general public living in developed areas.  The typical response I see when a relevant article does happen to be published in mainstream press is "See how goofy they are?  They blame everything on global warming."   

46566. Bob Lacatena at 22:43 PM on 8 April 2013
       Food Security - What Security?
       

       DSL,

       I was going to say it, but I say it so often I get tired, but yes, I think that Hadley Cell expansion, in and of itself, is one of the major expressions of climate change, and perhaps the one with the greatest human impact.

       Hadley cell expansion means the desertification of otherwise heavily populated and mostly arable land.  Most of the deserts of the world are defined by their position within the Hadley cells (the Mojave, Arabian, Sahara, all of the Australian deserts, etc.).  But they are often bounded by heavily populated and farmed regions.

       The expansion of the Hadley Cells will mean the desertification of otherwise useful land in Texas, Oklahoma, Spain, Italy and many other parts of the world.

       Imagine a world where southern, or even all of, Spain and Italy are deserts.  Imagine refugees leaving Texas and Oklahoma for "greener pastures."

       That's a sad thought.

       

46567. CBDunkerson at 21:50 PM on 8 April 2013
       The Fool's Gold of Current Climate
       

       Icarus, we know that human industry emits about 30 billion tons of CO2 per year and that the atmospheric content of CO2 is increasing by about 15 billion tons (2 ppm) per year. Thus, we know that natural sinks are removing about 15 billion tons more than natural sources are emitting. If human emissions suddenly dropped to zero natural sinks still take about 15 billion tons (2 ppm) out per year... at first. That would rate would decline as the atmospheric and ocean surface carbon levels came into equilibrium. This kind of decline can be seen in the red line of graph A of Andy Skuce's post #29 above.

       The alternate view, as with the MacDougall paper, is that we will soon see a shift in the balance between natural sources and natural sinks as permafrost and other sources release long held carbon. If that does happen then atmospheric CO2 levels might remain raised, or even continue to increase, even without human emissions. There is still a great deal of debate about the temperature at which this shift in natural emissions vs sinks would take place and how large an impact it would have. As you note, MacDougall seems to predict that we have already passed the point at which natural emissions will grow to offset natural sinks. If true then we're looking at a 'best case scenario' (i.e. immediate zero human CO2 emissions) matching the blue line in charts A & C from Andy Skuce... with level atmospheric CO2, temperatures would continue slowly rising for centuries.

       However, that difference between 'flat' temperatures if atmospheric CO2 levels fall and slowly rising temperatures if atmospheric CO2 remains stable is relatively insignificant in comparison to the real danger... which is the currently upward rocketing temperatures as atmospheric CO2 levels climb. The sooner we get to 'flat' atmospheric CO2 levels the better. If we can then go further and actually decrease atmospheric CO2 that'd be good to, but we have got to stop the level from increasing ASAP.

46568. Icarus at 21:08 PM on 8 April 2013
       The Fool's Gold of Current Climate
       

       "Significant contribution to climate warming from the permafrost carbon feedback" – Andrew H. MacDougall, Christopher A. Avis & Andrew J. Weaver.

       In figure 3, the paper suggests that even with a hypothetical complete cessation of anthropogenic CO2 and sulphate emissions in the year 2013, atmospheric CO2 would not fall by more than about 10ppm for hundreds of years, if climate sensitivity is ~3C per doubling. That seems very worrying if true – doesn’t it mean that they expect permafrost carbon release to have offset all natural carbon sinks within the next decade or two? The usual scenario is that land and ocean sinks would quickly start to draw down atmospheric CO2 if we stopped emitting it (e.g. in the ‘Climate change commitments’ RealClimate article from 2010).

46569. BillEverett at 15:05 PM on 8 April 2013
       Sportsmen’s and Anglers’ Views Highlighted in New ‘This Is Not Cool’ Video
       

       Posted on a friend's blog 16 June 2010: "The massive environmental upheaval caused by global warming in the pine and spruce forest of Idaho and Montana is stunning. The forest is dieing. Pine Beetle and Spruce Moths are unchecked by the long frosts of winter. The result is hundreds perhaps thousands square miles of dead and dieing forests. There is the loss of the wood and timber...the water holding of the trees, the air purification, the oxygen generation but, more.... The millions of pine and spruce needles in the waters have changed the PH of the lakes and streams. The water born insect life is gone. Three different streams, three hoops set out for three days each ... less than 20 insects collected where there should have been thousands. Breeding salmon seen but no fry, no first or second year fish, no trout, no white fish, no suckers...the streams are dead.

       "Sorry my mind is still struggling with the facts and unsure as to how I will deal with those who say my truth is lies. Will they come walk the streams, roll the rocks, hang the hoops, count the insects, float the rivers and prove me wrong or will they simply move their mouths in denial? I was unable to write this last summer and do not know what I can do this year."

46570. DSL at 13:09 PM on 8 April 2013
       Food Security - What Security?
       

       Johanson & Fu (2009) might be worth looking at as well re things drying up.  From the abstract:

       "Observations show that the Hadley cell has widened by about 2°–5° since 1979. This widening and the concomitant poleward displacement of the subtropical dry zones may be accompanied by large-scale drying near 30°N and 30°S. Such drying poses a risk to inhabitants of these regions who are accustomed to established rainfall patterns."

       Others . . .
       Hoerling et al. (2012):

       "The land area surrounding the Mediterranean Sea has experienced 10 of the 12 driest winters since 1902 in just the last 20 years. A change in wintertime Mediterranean precipitation toward drier conditions has likely occurred over 1902–2010 whose magnitude cannot be reconciled with internal variability alone. Anthropogenic greenhouse gas and aerosol forcing are key attributable factors for this increased drying, though the external signal explains only half of the drying magnitude. Furthermore, sea surface temperature (SST) forcing during 1902–2010 likely played an important role in the observed Mediterranean drying, and the externally forced drying signal likely also occurs through an SST change signal."

       and Seager & Naik (2012)

        

46571. villabolo at 13:00 PM on 8 April 2013
       Food Security - What Security?
       

       Agnostic @23

       There is actually an entire industry catering to survivalists that supplies bulk grain packaged in either nitrogen packed cans (almost gallon size) or food grade mylar bags with oxygen absorbers inside 5 gallon buckets.

       Dry grains packed in nitrogen have a 20-30 year shelf life. Those packed in plastic buckets have anywhere from 3-10 years shelf life.

       I myself had a quarter ton worth of hard red winter wheat in the gallon sized cans. The cost comes out at about a dollar per pound of grain.

46572. Riduna at 11:39 AM on 8 April 2013
       Food Security - What Security?
       

       Glen Tamblyn @ 7 … The most obvious effects of ocean warming are on fish habitat (eg coral reefs) and fish physiology – forcing fish to move further north or south of the equator, which is why I gave it a mention. It also leads to accelerated melting of ice, reduced albedo, rising sea levels, loss of permafrost, carbon emissions and a whole host of nasties not considered here.

       Ainsworth et al (2011) point to the effects on biodiversity of ocean warming in their regional study of the NW Pacific. Pratchett et al (2011) also have some interesting stuff on the effects of ocean warming on seaweed and fish habitat and heaps of references to other material.

46573. Riduna at 09:59 AM on 8 April 2013
       Food Security - What Security?
       

       Ivoryorange @ 17 … Good point. Desertification could well result from global warming induced climate change, such as persistent drought. I have not read much on this topic and I am surprised that very little on the subject is available on SkS. Both need rectifying.

       Moderator Response:

       [DB] Desertification is an emergent outcome of a warming world, as is an intensification of the hydrological cycle.  For the former, see this post.  IIRC, Rob Painting has a forthcoming post on the latter.

46574. Riduna at 09:42 AM on 8 April 2013
       Food Security - What Security?
       

       Jonas @ 3 … Thanks for the reference on population which shows a mid-range estimate of 9.3 billion by 2050, not inconsistent with an estimate of 10 billion by 2065. Even if we assume global population does not exceed 9 billion by 2100 (unlikely), can we assume that they will all be adequately fed and housed? Can human ingenuity in the sphere of genetics produce food plants able to cope with a rapidly changing, less predictable and more extreme climate?

       Villabolo @ 5 … That’s a novel idea, canned wheat – very expensive but not very practical since it would involve transporting grain to a “cannery” The problem is how to store millions of tonnes of various grains to cover shortages arising from crop losses caused by severe climate events, grain losses due to insect and rodent predation and transport delay due to infrastructure damage. This already cause significant grain losses but nowhere near as large as those likely to occur as the effects of global warming increase.

46575. Tom Curtis at 09:38 AM on 8 April 2013
       The two epochs of Marcott and the Wheelchair
       

       scaddenp @58, the temperature increase in the 20th century has been matched by an approx 2.2 C increase in temperatures at the GISP2 site, only 1.5 C of which is captured in the ice core record (Kobashi et al, 2011).  For comparison, the 8.2 Kya trough was approximately 3 C in the nearby Aggasizz-Renland core.

       And contrary to KR, it does not show up in the Marcott reconstruction.  Indeed, direct comparison with the data from the SI spreadsheet shows that at the time fo the dip, the reconstructed temperature is rising from a low point at 8.31 Kya to a high point at 8.05 Kya.  The 8.2 (technically 8.17 in the Agassiz-Renland data) trough is at best matched by a 0.01 C inflection in that rise.

       If the -1.5 C excursion at 8.25 Kya of the Dome C record was in reality the same event, this is possibly a global temperature excursion greater than 0.9 C.  The 80 year differnce in time matches 1 SD of temporal error in the A-R record and 0.5 SD in the Dome C record so allignment in reality is certainly within the bounds of possibility.  Indeed, it is probably that they, and similar troughs in the 50 odd proxies with data points in that interval align in at least one realization of the reconstruction, but with that many proxies, allignment across all would be rare so that such allignments would be washed out by the majority of realizations in which there is no alignment.

46576. Tom Dayton at 08:51 AM on 8 April 2013
       Food Security - What Security?
       

       Steve Easterbrook summarized a recent lecture by Damon Matthews on the consequences of reductions of emissions.  (Hat tip to somebody in some comment here on SkS a while ago who brought this up, but I dunno who.)

46577. DSL at 07:17 AM on 8 April 2013
       The History of Climate Science
       

       Oh - the graphic!  Snort.  Thanks, jg.

46578. DSL at 07:16 AM on 8 April 2013
       The History of Climate Science
       

       Thanks, John (and jg?).  While I appreciate very much Spencer Weart's work, it's nice to have a shorter version and a nice timeline graphic.  I'll be using this out in the trenches.

46579. scaddenp at 07:11 AM on 8 April 2013
       Food Security - What Security?
       

       Ray, can you be more specific about your reference for "half life of CO2 at around 5-50 years" please. I cant find it. It looks rather like a statement of CO2 has short residence time myth.

       For actual studies of what will happen to climate under constant emissions, or zero emissions, (ie what are we committed to already) see Hare and Meinshausen (2006) and Matthews and Weaver 2010.

46580. Tom Dayton at 05:48 AM on 8 April 2013
       Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
       

       Thanks, Rob! Based on your clues I found it. Sombody should add it to this SkS post, at least in the Further Reading section....

       I need it to respond to a comment on the recent Economist article.

46581. Rob Painting at 05:03 AM on 8 April 2013
       Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
       

       Tom. IIRC, a commenter ,CTG at Hot Topic NZ, uploaded something similar to what you describe. Had a silder bar so you could make adjustments too. Ask Gareth at Hot Topic. 

46582. Tom Dayton at 04:49 AM on 8 April 2013
       Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????
       

       Does anybody know where I can find a graph of atmospheric global temperature with all possible 10-year trend lines drawn on top of it?  I thought I'd seen it on SkS or Tamino's site, but I've Googled my brains out to no avail. 

46583. villabolo at 04:00 AM on 8 April 2013
       Food Security - What Security?
       

       Even if CO2 levels even out or drop what about the delayed warmth "in the pipeline". I understand that is supposed to be 1F in the next 30 years.

       Also, if industries stop consuming energy in large amounts then the sulfur emissions will drop. Those emissions reflect light therefore there will be even more warming. I understand that would be over 1F.

       We're already at 1.4 globally and more in the Arctic.

46584. Albatross at 03:52 AM on 8 April 2013
       The History of Climate Science
       

       John and jg,

       An excellent summary and superb effort. This, IMHO, is a must read by anyone new to this field, or educators looking for a resource for classes.  The excellent graphics will no doubt be a popular and effective way of distilling the text/history. 

46585. Phil at 01:56 AM on 8 April 2013
       Food Security - What Security?
       

       Ray,

       
       I think you are veering off topic , so I'll be brief.

       The Greenhouse effect is approximately proportionate with CO2 concentration. Stablise the level of CO2 in the atmosphere and the GHE stablises too, at the new global temperature. This stablisation doesn't happen immeadiately due to thermal inertia (so whenever we do eventually stabilise CO2 levels, there will be a bit more "warming in the pipeline")

       The lower the level we stabilise on, the less disruption to civilisation and the natural world.

       As Glenn states, reverting to pre-industrial CO2 levels (and hence a climate similar to the last few thousand years) will take in the order of 1000 years. At least we are not aware of any natural process that will rapidly draw CO2 out of atmosphere.

       I cannot read Moguitar7's mind, my view is broadly with Glenn's assertion that a decreasing population would, at best, stabilise CO2 levels. The proviso I mentioned @15 does suggest a mechanism by which population decreases whilst anthropogenic emissions continue.

       Note that for CO2 levels to rise, you only need net CO2 emission to continue, if the amount of CO2 emitted year-on-year decreases, CO2 levels are still rising; you only stabilise CO2 levels when the anthropogenic contribution is zero (in other words the CO2 from last year doesn't disappear)

46586. Ray at 00:26 AM on 8 April 2013
       Food Security - What Security?
       

       Apologies Glen and Phil for not stating this earlier, Moguitar7 specifies AGW which as far as I know specifically means anthropogenic global warming. So if the anthropogenic component is diminishing geometrically as Moguitar7 asserts and which part of the population is diminishing is not specified, what component is causing an exponential rise in AGW? Surely in the face of a rapid decline in population CO2 levels would stabilise even if not fall, so, as Moguitar 7 asserts what would cause an exponential rise, not just a rise, in AGW?  Surely it must be something other than the anthropogenic component.

46587. Ivoryorange at 00:14 AM on 8 April 2013
       Food Security - What Security?
       

       Hi, what about increased desertification for your list of impacts resulting in lower yields?

       Did I read somewhere (a while back) that a warmer world will lead to increased evaporation from soils? If so, then our industrial agricultural, which results in dead soils, is going to lead to significant erosion and desertification, even in developed countries.

       I'm under the impression tthat organic and biodynamic methods could help buffer this because these methods produce living soils that can hold more moisture and can better adapt to changing conditions. I've seen studies that show equivialant yields from both methods with fruits and vegetables, but I'm not sure that these methods are sufficient for larger grain and maize crops.

       Matt

46588. Ray at 23:50 PM on 7 April 2013
       Food Security - What Security?
       

       Glen and Phil

        

       If what you say is correct then stabilising CO2 levels at say 400ppm, which is what it is suggested could help ameliorate if not avert AGW makes no sense.  According to your arguments it seems that AGW will increase in the presence of a stable CO2 level.  The IPCC have given the half life of CO2 at around 5-50 years. so presumably levels would graudally fall.  And Glen why would the poulation of the developed world crash rather than that of the developing world?  For a start the population of the developed world is less than that of the developing world and the developed world has more resources on which to call than does the developing world.  Look at the current situation where the developed world  is often asked to provide food aid to the developing world.  It certainly isn't the other way round.so your argument seems to fly in the face of reality

46589. John Mason at 21:03 PM on 7 April 2013
       The History of Climate Science
       

       @ Chriskoz #2 - These are important points, although the piece above is primarily an historical resource. I think this aspect of the carbon cycle deserves a post all of its own. As my SkS colleagues know I'm a geologist specialising in mineralogy, I've probably just volunteered myself to do this!

       You are right about the timescales involved with these major weathering cycles. Herabouts (Mid Wales) there are remnants of deep tropical terrestrial weathering (most was removed by glacial erosion in the Quaternary). Around the old lead-mines of the area, highly evolved secondary lead mineral assemblages occur in considerable amounts in association with remnants of this weathering (it leaves normally slate-grey metasediments bulk-leached to pinkish and buff shades). Post Quaternary secondary lead mineral assemblages occur in a slate-grey metasediment matrix in areas where the bulk-weathered material is now absent: the mineralisation is typically found in small amounts of non-equilibrium assemblages - perhaps just what might be expected for a weathering lasting just ten thousand, as opposed to tens of millions, of years. I'll stop rambling now!!

46590. Phil at 21:03 PM on 7 April 2013
       Food Security - What Security?
       

        

       Glenn Tamblyn:
       

       but what would crash with any crashing of population levels would be the rate of CO2 emissions

       Doesn't this assume that the crash in population levels would happen in the developed world ? (which produces most of the CO2 emissions). Surely food security issues are faced by the subsection of the world population that produce practically zero net emissions. Which, of course, makes Rays point @13 even less correct.
       

46591. chriskoz at 20:34 PM on 7 April 2013
       The History of Climate Science
       

       The article does not mention an important deail: the rock weathering climate "thermostat" is very slow to react. It works on a timescale of at least 100ky. Up to 500ky is required for Urey reaction to fully respond to an impulse forcing such as anthopo CO2.

       CO2 dissolves in the oceans much quicker (on 100-1000y timescale) but that carbon still stays within AO system and may degass back into A. The amount of CO2 that can be dissolved is limited (as oceans themselves are limitted), and Henry's law dictates that it won't be absorbed entirely. The AOCM models quantify that in a case of a proposed C cycle disturbance of ~1000GT, some 10-15% of that C must stay as CO2 and wait for rock weathering (100-500ky) to be removed out of the system. That's virtual eternity, even on the timescale of homo sapiens as a species. That point should be stressed to pre-bunk the ignorant interpretations - "no worries - the Earth's thermostat will take care of the climate" - of this article.

       It's also worth mentioning that rock weathering is too slow to signifficantly react on the Milankovic forcings of 100ky timescale, therfore we do not hear about "rock weathering influences on glacial cycles" in the literature.

       The setting of rock weathering thermostat is influenced, on still longer timescale of My, the plate techtonics. In fact, the rock weathering has been used as explanation of temp changes in Cenozoic (64my). Early part of Cenozoic (Paleoce-Eocene) have been hot because India was running like crazy accross the ocean from antarctica to Asia at 25mm/y - therefore triggering more volcanic activity with no change in weathering - more CO2 produced. When India finally smashed against Tibet giving rise to Himalayas - triggering increased rock weathering - more CO2 absorbed in climate cooled down to today's glacial cycles. This is very interesting science, although it must be admitted is based on far less certain prerequisites (i.e. plate techtonics) than the science of e.g. radiative forcing or Charney sensitivity. However, it is rarely challenged by today's "sceptics" - simply because it's not inconvenient - even opposite - it is actually convenient to claim ignorant nonsense ala "little warmer ain't bad because it was far more warmer few My ago".

46592. Glenn Tamblyn at 19:02 PM on 7 April 2013
       Food Security - What Security?
       

       Ray

       I'm not sure I agree with all of Moguitar7 argument but what would crash with any crashing of population levels would be the rate of CO2 emissions, not CO2 levels. Any decline in CO2 levels requires first a major drop in the rate of CO2 emissions and then the time needed for the chemistry of the Carbon Cycle to then draw down CO2 levels. A part of that will happen within years to decades due to equlibration with the ocean. After that we are looking at centuries to millenia for other geo-chemical processes to sequester remaining CO2.

       If natural feedbacks in the Carbon cycle occur due to higher temperatures - permafrost melt which has already started, destruction of some of the major carbon sinks in the form of rainforests, etc - then the starting point before any slow drawdown begins may be much higher than current CO2 levels.

46593. Ray at 18:15 PM on 7 April 2013
       Food Security - What Security?
       

       Moguitar7 I can't follow your reasoning.   If as you say, the population "will be crashing geometrically while AGW increases exponentially" what will be driving this exponentional increase in AGW?  Presumambly  not CO2 as levels surely will be falling geomentrically in line with the geometric crashing of the population.  

46594. bill4344 at 18:08 PM on 7 April 2013
       The History of Climate Science
       

       Good work! I like the graphics; and the rising CO2 trace is a nice touch.

46595. MA Rodger at 17:26 PM on 7 April 2013
       Making Sense of Sensitivity … and Keeping It in Perspective
       

       Engineer @113.

       Restating the message of Sphaerica @114 - I would mention that the Stephan-Boltzmann equation yields a cubic relationship as it is the derivitive being used:-

       ΔT = ΔF/4σT^3

       
       As T is in Kelvin, even what would be a big change for earth's climate results in a small theoretical change in the T^3 term - eg 255 °K +/- 5 °K would result in a theoretical 5% change in sensitivity.

       The big changes in sensitivity, as described @114, comes not from the physics but from the climate system. When temperature change is large, when our planet is pushed towards becoming a 'snowball' or a 'steamed doughnut,' that is when sensitvity really starts to change in value. Hansen & Sato 2012 (discussed by SkSci here) show sensitivity more than doubling for such extremes.

46596. moguitar7 at 15:50 PM on 7 April 2013
       Food Security - What Security?
       

       There are 3 billion people getting 60% of their protein from the oceans which will be depleted between 2035 and 50.  Aquifer depletion circa 2040 will vastly reduce yields, -83% in affected areas.  Soil salination from river water irrigation will also take out a good chunk as will soil micronutrient depletion from lack of organics.  Citification will take more land and so will desertification.  Then high priced oil and petro chemicals will affect prices, yields, and distribution, while its AGW will increase losses to crop failures from a number of reasons by climate fluctuation beyond historic.  Adding them all up we get a realistic figure of being only able to feed between 3 and 4.5 billion just before 2050.  An increasing death rate from a poor world economy will slow down population gain and by mid century it will be crashing geometrically while AGW increases exponentially.  Then in 3-500 years it will really get worse.  AETM and the finish of the Sixth Great Extinction.   Preventable in the 20th century to very early this century.  With nothing really sufficient being implemented, humanity is probably out of time to stop the Juggernaut of Ecocide.

46597. scaddenp at 14:00 PM on 7 April 2013
       The two epochs of Marcott and the Wheelchair
       

       I think I will have to stop being lazy and dig out the data. 0.9C is a global average. For individual proxies (eg greenland), the change in temperature at the same location is much higher than 0.9. So when looking at individual proxies, a spike should be based on comparing the 20C change in temp at that location with the proxy. Eg for greenland, how common are spikes of 1.6C on a centennial scale?

46598. scaddenp at 11:55 AM on 7 April 2013
       Making Sense of Sensitivity … and Keeping It in Perspective
       

       Engineer - models have to be verified. The physics and the numeric methods are both complex. You can run the models for past conditions of the earth and get a climate sensitivity from the model. You can also determine number empirically just as you illustrated given DelthF and DeltaT. You have confidence that your estimates of climate sensitivity are good if both the model-determined sensitivity and emperically-determined sensitvity match reasonably well. For emperical determinations, you are assuming a linear relation but model dont. It just turns out from models that the relationship is close enough to linear for a relatively small change in deltaT. As said in earlier post, it would not remain that way for very large changes.

       It appears that there is no possibility of a "runaway" greenhouse on earth (the oceans boil) without a hotter sun which will happen some time in the deep future. However, in that situation, the change in sensitivity to increasing deltaF because seriously non-linear,

46599. Bob Lacatena at 07:55 AM on 7 April 2013
       Making Sense of Sensitivity … and Keeping It in Perspective
       

       engineer,

       wikipedia.... bleh.  It's good for some things, as an introduction to concepts, but I wouldn't for a minute use it to learn real climate science.

       Stefan-Boltzmann... not for small values of ∆T.  For example, the energy received by the Earth from the sun (approx 239 W/m2) translates to a temperature of 255˚K.  Here's a graph of the relationship (temperature at the bottom) for temperatures near those at the surface of the earth.  Notice that it is for all intents and purposes, in that small range, linear.

       

       "Empirically" means from data, from observations.  Again, follow the links I already gave you and look at how they do it by measuring the response of global temperatures to a major volcanic eruption (effectively reducing solar input by a measurable amount), or by studying the transition from the last glacial as in the example given by wikipedia.

       The fact that it is linear (or near linear) is almost required.  Without a linear relationship you'd too easily get a runaway effect, or a climate so stable that it would not demonstrate the volatility that we see in climate in the history of the earth.  Another way to look at it is due to the fact that the Earth's climate (normally, naturally) never varies by all that much over short periods of time (where short equals thousands or tens of thousands of years).  There's just not much room for anything but something that is for all intents and purposes linear.

       To repeat, while the climate sensitivity is from physical mechanisms, none of these are so simple as to be modeled with very simple mathematics.  The melting of the ice sheets, the browning of the Amazon, natural changes in CO₂, etc., etc., are all complex natural processes.  There's just no way to mathematically derive climate sensitivity short of the (clever) variety of methods used, including observations, paleoclimate data, and models.  Again... follow the links, and read up on feedbacks.

46600. Matt Fitzpatrick at 07:50 AM on 7 April 2013
       Food Security - What Security?
       

       @villabolo#4

       Sorry, looks like I haven't kept up to date on that story. The bill, in amended form, was passed into law on August 1, 2012. As amended, it no longer forces the state coastal agency to predict sea level rise based only on past trends. Instead, it prevents the state from predicting sea level rise altogether, until July 1, 2016, and requires the state to study the costs and benefits of the sea level rise regulations which, until 2016, it's not allowed to make. Until 2016, local officials can approve coastal developments using any predictions they like.

       Gannon, Patrick (01-Aug-2012). "Sea-level rise bill becomes law." Star-News (Wilmington, NC).

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