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Tom Curtis at 10:25 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Let's put some figures on Killian @11.
Between 1850 and 2008, cumulative emissions due to Land Use Change represented 32.8% of all anthropogenic emissions. Part of that comes from intensive animal husbandary and the expansion of rice paddies rather than deforestation, but we will ignore that. If follows that complete reforestation to 1850 levels will draw down around 36 ppmv of CO2. That could be approximately doubled by reforesting to, essentially, tenth century levels, ie, by returning Europe to the once verdant forest it was.
That is the total of the draw down that could be managed by "sustainable" means. Counting a switch to permaculture is not an additional draw down. A permaculture garden stores substantially less carbon per acre than does a forest, so any acreage set aside for permaculture reduces that total draw down. Never-the-less, it must be considered technically feasible to draw down CO2 as Killian suggests. The total draw down would reduce the CO2 concentration to approx 310 ppmv, with equilbriation of the partial pressure of CO2 in the ocean over the next two centuries drawing that down further to abotu 285-290 ppmv. Problem solved!
What is missing from this analysis is how we are going to feed the population once all of the world's arable lands have been returned to forest.
As pointed out by William, permaculture is labour intensive. So much so that feeding a population by permaculture is not feasible unless every familly has its own permaculture garden. With the labour hours of all famillies dedicated to just feeding themselves, there is no excess labour for such luxuries as geting an education, publishing books or newpapers, manufacturing any electronic equipment (including radios) having a civic life, and a democratic governance, long distant transport, long distance communications except by courier, or a population of the Earth greater than about 1 billion.
The great danger of global warming is primarilly that it will create conditions that will result in the collapse of world trade. Failing that, it may cause deaths in the millions but our civilization will struggle on. With the collapse of world trade, however, we will face deaths in the billions from war, starvation and disease.
Killian's solution to that threat is to embrace the threat as the solution.
My opinion is different. I think if we are going to be forced back into another dark age; we should at least put up a fight.
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Doug Hutcheson at 09:47 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Wyoming @ 18, you said:
If we continue BAU we will have a collapse due to climate change/fuel supply issues, if we don't continue BAU we have collapse because only BAU can supply the food requirements of 7 going on 9 billion people.
I have never seen our dilemma so succinctly expressed. Everything comes back to the fact that there are simply too many of us.
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Doug Hutcheson at 09:23 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Ger @ 9, can you clarify what you mean by "torrefact"and "torrefaction"? Google suggests it is from the Spanish "torrefacto", which refers to the roasting of coffee beans. I presume torrefaction is a process for roasting or burning biomass, but I have never encountered the word before.
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scaddenp at 07:22 AM on 21 April 2013Record snowfall disproves global warming
dvaytw - in very general terms, the Clausius–Clapeyron relationship between temperature and water vapour is known from mid-19th C. Issues with precipitation were flagged in Ch 4 of WGII of the IPCC FAR 1990. Beyond the broad picture however, regional climate prediction was not possible then (and remains a considerable challenge now -see for instance here) and so perhaps you ask the source of the their claim for drier winters?
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GordoMukWA at 06:03 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Scenario #1 in Limits To Growth, the equivalent of the "no policy" of current MIT prof's, looked to the long-term consequences of "poisoning the planet" and the global population's decline from starvation due to those various poisons in our seas, soils, food water, air and us. Here in Puget Sound we are already seeing those consequences in our shellfish industries, salmon unable to spawn in their natal streams,& first-born Orca dying from the toxins concentrated in their mother's milk. The continuing leak of radioactivity from the Fukushima Daiichi nuclear power plant crisis hasn't reached us in significant amounts yet, but prognosticaters report it is enroute. How many streams, lakes and rivers are uncontaminated? None around here or other parts of this continent. Folks who live in the Niger River delta have seen their life expectancy rates reduced from 65 to 45. Contaminated breast milk is being reported in subsistence cultures all over the world. Without our pollution, yes, survival of the species 200 years from now might be possible. Getting there seems unlikely - unless, of course, you have a mustard seed.
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william5331 at 05:26 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Paradigm changes can occur incredibly rapidly when they get going. Look at our nearly smoke free indore environment and the change from horses to cars. However, to really change the world opinion on the use of fossil fuels to an extent that it will lead to action and will overcome vested interests, it will take a high impact disaster. Sandy, the disappearance of the Arctic ice and such events are not enough. We need, for instance, a complete failure of northern hemisphere crops due to a clear, demostrable lurch northward in the climate zones. Unfortunately (or fortunately, depending on your point of view) it will be too late for many of us. Massive starvations have occured again and again in the past but they have been localized. Think Ireland, for instance. We have had a little hint of crop failure in Russia in 2010 and the USA in 2012 but they will only be seen as signs in hindsite. If indeed the modern fertile crescent (Russia, Canada and the USA) fail, starvation will be global. It will be too late for Most of us. The following link is interesting. Guy is pretty far out there but he gives a good list of possible tipping points.
http://guymcpherson.com/2013/01/climate-change-summary-and-update/
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Wyoming at 04:24 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
CBD,
I think we are in violent agreement as they say. I say the general non-scientific reader will likely misunderstand the structure of the language used by the authors and reach the wrong conclusion. You say that the " foolish people might reason that we can continue letting the temperature rise and 'just stop emitting when things get bad'." I think we are talking about the same people, in a slightly different way, and coming to the same conclusion.
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Wyoming at 04:19 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Killian,
I think you have a misunderstanding regarding sustainable agriculture techniques and permaculture in particular. Some background, after I retired from my engineering career I owned and operated an organic farming operation for a number of years. I have spent a lot of time learning about farming, sustainable practices and such particular issues as permaculture and biodynamic practices.
I have no issues with any of the attempts to develop sustainable farming practices and think it is a worthy goal. However, one has to keep in mind that these techniques are knowledge that we need people to develop and preserve for future needs as they have no fundamental ability to sustain our current population levels and complex civilization. Our extremely complex civilization and some 7 billion plus population is the direct result of our forebear's having obtained access to vast amounts of fossil fuels. One leads to the other and this has been well researched and documented.
Almost all global food production, in percentage terms, is based upon heavy dependency on fossil fuels, be it from building the machinery used in farming and transporting food, storing food, making fertilizer, pesticides, fungicides and herbicides, etc. This reliance is not limited to 'industrial agriculture' but also applies to almost 100% of organic production as well. The amount of global food production from human/animal only labor food production is very small. And ramping up human/animal production to levels sufficient to support our current population/civilizational complexity is mathematically impossible. This is the dilemma of being in overshoot or past our global carrying capacity. If we continue BAU we will have a collapse due to climate change/fuel supply issues, if we don't continue BAU we have collapse because only BAU can supply the food requirements of 7 going on 9 billion people.
Take some time to research permaculture production levels per human hour of labor. It will shock you. There is a good reason that before the introduction of industrial farming techniques and access to cheap fossil fuel some 98% of the population were farmers. When only human and animal labor is used it is very difficult for a farmer to reliably grow more food than he, his family and his animals (a plow horse is a tractor that runs on bio-fuel) need for their own use. There is no avoiding having some years when you produce less than you need to consume. This is why starvation was common in older times and is common in places where subsistence farming is still practiced. Now think about trying to supplant our current system of food production and supply for a city like Phoenix, Sao Paulo, Cairo, Moscow, Beijing, Hong Kong, Los Angeles, New York, etc. Pretty hard to solve that problem. And if you are planting vast acreages to forest like you mention it is wise to keep in mind that by definition you are covering arable land in forest that your sustainable farmers will need to be growing crops upon. You will need to be using every square inch of ground while you are trying to maintain the population levels if you are using sustainable techniques.
There are a host of things we all must do to avert total disaster and there are no simple solutions. We absolutely have to cut GHG emissions, we must become much more efficient in our use of fuels, we must develop alternative energies, we must learn to live more simply and consume less, but most important of all things (and by far the hardest) is that we must find a way to dramatically reduce population levels as fast as possible. If we do not find a way to agree to cut population levels beyond the very slow decline in global growth rates( which indicate a maxing of population near 9 billion around mid-century) there is no possible solution to our above dilemma. We will just run into a brick wall.
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CBDunkerson at 03:24 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Wyoming wrote: "I think that a significant percentage of the readers (not even counting the Deniers,) on initial reading of the post, would come to the conclusion that all we have to do is wait until the rising levels of CO2 have resulted in conditions which are at our limits of tolerance and then we stop emmisions and all is going to be ok."
Except that the point the article actually makes is that rather than 'everything being ok' in such a scenario, what it would actually mean is that "conditions which are at our limits of tolerance" would then persist for hundreds of years.
Seems like a bad plan.
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Killian at 03:13 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Sorry, here are the Seattle Food Forest links:
http://www.seattle.gov/parks/projects/jefferson/food_forest.htm
http://www.takepart.com/article/2012/02/21/its-not-fairytale-seattle-build-nations-first-food-forest
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Killian at 03:10 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Moderator, I stated clearly my awareness of the 30-year lag with regard to the climate system. What I have said flies in the face of nothing, you simply don't know of these exceedingly simple ways to return to pre-industrial levels of GHG's.
As I said, it is yet a tiny percentage of people who look at the energy, resource and climate issues we have in a fully holistic manner, yet, no discussion of any of these issues is meaningful without discussing all of them. So long as we continue to attempt to discuss them seperately we will continue to fail to make meaningful changes in policies.
People, seriously, if you think you understand what's going on yet look only at the climate science or tech-based solutions... egad.
You can start with Rodale, which is a study that looked at, though they don't use the term, applying permaculture design principles to farming. Basically what most of you might think of as no-till farming.
Rodale Institute 30-year comparative Study of Farming Methods.
Tainter video (1 of 7, the rest are also available.) Diminishing Returns on Complexity
Jared Diamond on Choosing to Simplify
Hansen, et al.
An essay on Hansen's strategies
Willie Smits: Rebuild a Rainforest, Grow a Commmunity
Food Forest process
Seattle Food Forest
Yacouba: Stopping The Desert
Green deserts?Moderator Response:[DB] And again, none of what you furnish for support deals with ocean acidification and the basic chemistry of seawater. If humans manage to somehow initiate the drawdown of atmospheric CO2, the oceans will simply start spitting back out what they have under duress absorbed. So your goal of returning atmospheric CO2 below 300 ppm target remains an elusive and unrealized goal.
If you wish to explore that further, take it to the Physical Chemistry of Carbon Dioxide Absorption thread, and the followup Seawater Equilibria thread, where that is more appropriately discussed.
Further, please note that Youtube videos, while useful, generally do not constitute scientifically reliable evidence in a science-based forum such as this. Much more credence is given to the primary literature published in peer-reviewed, reputable journals.
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Wyoming at 02:52 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
I must admit that when I started reading this post my first reaction was 'WHAT!'. After carefully reading through it 2 times my reaction was "Ok, that, guess, is technically right. But what a way to misstakenly try to accomplish the stated goal of trying to forestall inaction on the part of people because they have the wrong impressions about the answers to the 2 posed questions.
I think that a significant percentage of the readers (not even counting the Deniers,) on initial reading of the post, would come to the conclusion that all we have to do is wait until the rising levels of CO2 have resulted in conditions which are at our limits of tolerance and then we stop emmisions and all is going to be ok. The Deniers of course would twist the language of the post towards their arguments with no trouble at all.
In frank words, I think the way this post went about explaining the science completely misunderstands how most people comprehend what they sort of read and will result in exactly the opposite of what the authors intended. They better hope that the general public is not reading this.
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John Hartz at 01:14 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
@Killian #11:
Please provide citations for the numerous claims that you have made. Thank you.
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Karellen at 01:10 AM on 21 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
@TomCurtis #25:
the key point is that a confidence bound is a line that the observed value is expected to fall below a certain percentage of the time
*click*! Yup, that's all I needed. Thanks!
(BTW, what is up with the stupid edit box on this site, and it's inability to let me copy/paste text into it? Whenever I try, I just get "undefined".)
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CapeCondor at 01:10 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Agree with comment from CB@2. As human inertia will not rapidly decline and temps will continue to rise, will not climate inertia pick up on its own with declining albedo and increasing defrosting of the perma frost.
Thinking beyond zero human GHG emissions, might we also focus on planetary recovery, even in small gradual steps?
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Killian at 01:09 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
I can't believe people - everyone - gets this so wrong. Of course Climate Change is reversible. At least the process is. While some of th effects will be hard to reverse as bioregions change, if we act quickly enough that the bases of these zones are still intact, these will also revert. To the extent some changes are permanenet, adaptation will be possible.
The key issue is how longit takes to start reversing and get back to pre-industrial levels of CO2. That will ultimately determine how much ecosystems are impacted before we can cool the planet. It should be obvious to all that returning GHGs to pre-industrial levels will, in fact, cause the planet to cool over time. The approximate 30-year lag is the largest obstacle. It would take, in the absolute best case, 20 years to draw down CO2 to preindustrial levels, but more realistically closer to 50 since, well, human beings are largely idiots. That means we're looking at roughly 20 to 75 years of additional warming before reaching a level where a relative cooling would take place, with relatively less heat retained a GHG levels fall.Far too many people still don't understand the full systemic nature of this. Even without AGW we still have to simplify society due to resource constraints and the instabilities that come with that and diminishing returns to complexity. (See J. Tainter.) Once a society has reached a level where the resource base has been overshot there are two essential options: deceiving itself into believing it can overcome Nature with technology and/or bigger mo‘ai and the magical thinking that comes from both. The fact our economy is based on mythology is what has basically gotten us to this point, being based in a non-mathematical realities that do not even consider physical limits. This cannot go on. A resource-based economy, steady-state is not only a good idea for management of resources, it's absolutley necessary to avoid a collapsed society. This is a choice that is unavoidable. (See J. Diamond.)
Such an economy requires localization based on bio-regional management of resources. Natural systems and resources will become far more a part of the materials we use. Natural building, virtually no cars, mass transit for the far less movement we will be doing, etc. A huge change will be a natural system of localized food production using regenerative methods, which are based in natural organizational principles. (See permaculture, 30-year Rodale study, Alan Savory, etc.) And this is the first leg of our carbon draw down. According to the Rodale study, very large amounts of carbon can be sequestered in soils, which is where it needs to be anyway. This has addtional positive effects such as mitigating flooding, reducing run-off into water systems and eliminating chemical runoff which is the primary cause of eutrophication. We can even green desert regions with this methodolgy and potentially choose to shape the hydrological cycle.
The second leg of this is reforestation and aforestation. 40% of the dry weight of trees is carbon. Rebuilding lost forest ecosystems alone will draw down huge amounts of carbon based on estimates from Hansen, et al. I don't recal lthe number, but it is a minimum of 50 ppm, potentially double that. Adding to this a key element to a localized and highly resilient food system, Food Forests, would have hte same, but accelerated, effect given Food Forests are actively managed and accumulate carbon faster than a natural process of getting to an apex forest system. Whereas a prairie to forest process can take centuries, or more, reforestation, aforestation and food forests can reach apex in mere decades, and be essentially established within 7 years, particularly a Food Forest.
These processes alone can get us to negative accumulation with no changes to our economic system. Add in a full shift to a localized, largely de-industrialized economic and social system with "renewable" (renewables are dependent on FFs, so are not truly renewable, yet) energy and we mazimize this even more be reducing the load we are putting into the atmosphere by 80 - 90 percent.
In other words, those who call AGW irreversible are bdly incorrect and it is extremely dangerous to keep repeating this defeatist mantra. While it is not intentionally defeatist, it may as well be. Designing sysems depends on initial conditions and a needs analysis. This must have a realistic understanding of the resource base. But if you are convinced we will be living in a radically different world because we cannot draws down carbon, your planning will be skewed to adaptation rather than mitigation and will allow massive amounts of current resources to be lost altogether or squandered on trying to survive an avoidable future.
The only reason to believe AGW is irreversible is to believe only long, slow natural feedbacks will draw it down. This is blatantly incorrect and is somethiung we need to stop repeating. Fast feedback, human-engineered, natural systems can get us back to < 300 ppm CO2 in mere decades.Moderator Response:[DB] Please provide proof citations for your claims, especially this one:
Fast feedback, human-engineered, natural systems can get us back to < 300 ppm CO2 in mere decades.
As that flies in the face of established oceanic chemistry.
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Ferran P. Vilar at 00:35 AM on 21 April 2013Global Warming: Not Reversible, But Stoppable
Andy,
Are you sure the climate system doesn't have any inertia? This is a general feature of system dynamics. Doesn't the ocean act as an accumulator, as a capacitor in a circuit? What, then, is the meaning of "at equilibrium"?
After a pulse of CO2, "about 40 percent of the equilibrium response is obtained within five years. This quick response is due to the small effective inertia of continents, but warming over continents is limited by exchange of continental and marine air masses. Even after a century only 60 percent of the equilibrium response has been achieved. Nearly full response requires a millennium." (Hansen, 2008, Earth's Energy Imbalance and Implications). I don't think Hansen refers to the socioeconomic system... I may have some misunderstanding here-
Could you please clarify this for me?
Thank you
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Ger at 19:38 PM on 20 April 2013Global Warming: Not Reversible, But Stoppable
@villalob#3, biochar would reduce or delay emittance for a 42 to 100 years. For USA only (based on 1999 figures) one would to torrefact 13,530,208,333 metric tons to replace the coal fired electricity. Pure biomass residues dry matter weight.
Slightly more efficient approach is to do the torrefaction of the biomass and gassify an amount to produce high hydrogen containing syngas, helped by solar assisted steam generation (ISCC,IGCC combination). Capture the CO2 during cleaning of syngas and use in controlled (greenhouse) environment to boost plant productivity.
Even capturing CO2 of coal would help right away and can be executed right away. Of course to use the CO2 in plantgrow stimulation not for enhanced oil recover methods.
Anyway stop emitting of CO2
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dvaytw at 18:35 PM on 20 April 2013Record snowfall disproves global warming
Deniers I've argued with about this claim that this is a "post prediction" in that scientists were earlier saying we should expect warmer and drier witners. Can someone provide me articles dis-proving this claim?
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climateadj at 11:46 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Damon Matthew's figure 1c doesn't seem to resemble what I recall seeing with regard to the 1% to 2x CMIP3 ensemble. IIRC the temperature deceleration after stabilzation is much quicker. Given that the actual growth has been much slower than a 1% growth, the deceleration should be even flatter. Shouldn't it?
Regards, AJ
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CBDunkerson at 07:56 AM on 20 April 2013Climate's changed before
In conversation I actually enjoy this kind of misleading statement;
Denier: 'You know, climate has changed before.......'
Me: 'Good point! The link between past CO2 changes and past climate changes gives us a clear idea of what to expect with our current CO2 emissions.'
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Tom Dayton at 06:19 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Well, heck, you're right, Dana! Maybe Andy could add a link to that post to his post?
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Robert Marston at 05:31 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Hat tip?
Excellent article clairifying the science. I think the key issue as in the linked article and your above post is to make certain that people understand warming is mostly stoppable, but not reversible.
Moderator Response:[AS] Thanks for the link to that article, which I hadn't previously seen. I made it clickable.
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dana1981 at 05:25 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Tom @4 - sounds like you're asking for this post, no?
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rockytom at 03:40 AM on 20 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
KR #8 To give credit where credit is due, the two different clocks analogy is based on Einstein's Special Theory of Relativity from the following paper "ON THE ELECTRODYNAMICS OF MOVING BODIES" By A. Einstein, June 30, 1905.
Moderator Response:[DB] Hyperlinked paper.
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Bob Loblaw at 03:32 AM on 20 April 2013Climate's changed before
Phil:
Yet another "advantage" of not stating the implied argument is that it leaves the imagination of the listener free to come up with any number of arguments. I was going to phrase that as "possible arguments", but then I realized that they don't even need to be possible - at least in a real sense. As long as the listener thinks they are "possible", then the speaker has sown the seeds of doubt.
Twenty listeners can come up with 20 mutually-exclusive implied arguments, and as long as nobody goes into detail everyone is happy (except for the scientists and policy people that actually want to examine the logic, validity, and strength of the argument).
As you say, getting the person to explicitly state the argument, rather than leaving it implied, allows you to examine it properly. Unfortunately, you often end up playing whack-a-mole as the fake skeptic refuses to provide a proper argument, and keeps saying "that's not what I meant" as you cycle through the possibilities and explain why they are wrong.
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Tom Dayton at 02:55 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Thank you for this post! I've been needing to point to something like this.
Next we need a post that shows why the uncertainty about sensitivity is irrelevant to our need to take significant action immediately. In a business as usual scenario:
1. Here are five versions of graph C--one for each of the sensitivities 1.5, 2, 3, 4, 4.5.
2. The consequent temperatures in each of those five graphs are sufficiently bad that it is far more cost effective to prevent than to purely adapt.
I guess we first need a peer reviewed paper for item 1.
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villabolo at 02:42 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Is it not possible to use biochar on an industrial scale to reduce C02 levels? If it were to take a hundred years to reabsorb the CO2 to preindustrial levels it would be worth the effort.
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shoyemore at 02:03 AM on 20 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
Dave123,
I tried to address this in #21. Lewis claim is that his transformations of the data and the parameter space renders his prior distributions objective, and makes his results tightly constrained. I lack the experience to pass judgment, but I am sure somebody can. From earlier discussions, James Annan (who also uses Bayesian methods, as do many climate scientists) has previously said he sees nothing wrong with Lewis' methods. Perhaps the best person to look at it might be Andrew Gelman, a well-known Bayesian statistician at Columbia U, author of many books, who blogs here:
http://andrewgelman.com/
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CBDunkerson at 01:57 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Excellent article. Even people who have paid attention to the science often have trouble with these details, so it is good to have a clear summation. The only point I might have stressed more is that the bit about warming stopping when human CO2 emissions do is conditional on how high the temperature goes. Currently it is true. At some future higher temperature permafrost and/or methane hydrates may be releasing enough greenhouse gases that atmospheric levels and temperatures continue rising even without further human emissions. This is alluded to in the 'Wrinkles' section, but is one of the major reasons action is needed now. Otherwise, foolish people might reason that we can continue letting the temperature rise and 'just stop emitting when things get bad'. Even in the best case that would mean we'd be stuck with the 'bad' conditions for hundreds of years, but it could also put us past the point where carbon feedbacks kick in and things do keep getting worse no matter what we do.
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From Peru at 01:38 AM on 20 April 2013Global Warming: Not Reversible, But Stoppable
Two things:
1)The link to the PDF is broken. Please help!
2) What about the "warming in the pipeline" caused not by the current global radiative imbalance, but by the masking of part of the greenhouse forcing by short-lived, man-made cooling aerosols(the so-called "global dimming")? They have masked nearly half of the CO2 forcing, and have very brief lifetimes, unlike CO2 and the other greehouse gases.
Moderator Response:[AS] 1) Could you let me know which link is broken? 2) The aerosol issue was discussed briefly in the "Wrinkles" sub-section. I understand that Matthews has a paper "in the pipeline" addressing aerosols and non-CO2 GHGs, but I haven't seen it.
[DB] The source paper PDF is here.
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citizenschallenge at 00:41 AM on 20 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
Thank you Rob for that excellent article.
Good enough to Repost:
http://whatsupwiththatwatts.blogspot.com/2013/04/examining-david-roses-no-warming-daily.html
Thank you SkepticalScience.com for your generous Reposting policy !
Peter
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Dave123 at 00:02 AM on 20 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
I'm not following this closely, but the implication is that Nic Lewis is a known climate contrarian. This would make his exercise, laudable admittedly for peer review publication, an excercise in motivated reasoning. Now admittedly there are good reasons to try to find out how you can create low ECS estimates. Determining what ECS is most sensitive to would seem a sensible procedure. But the question of biases built into Bayesian priors, the ability to skew the results as a result of those choices coming from a prior advocacy position sets a Bayesian prior of its own: Will a contrarian cherry pick to get a desireable result? Wouldn't past history with Watts and crew suggest that the Bayesian prior for this would be a strong "Yes"? Will Bayesian priors selected by a contrarian be likely to face questioning by Climate Hawks? Undoubtedly the prior here is a strong yes also.
So, as part of any exposition on this, should we be looking to experimental determinations rather simply allowing people to make prior estimates? (When I retire I'm really going to have to take some refresher stat classes)
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Kevin C at 21:42 PM on 19 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
OK, this question has finally puched me into what I've been meaning to do for a long time, and get my simple response function model online.
With this you can vary the strength of the different forcings and see how that affects the fit to 20thC climate, the TCR and the RCP projections, as well as a few other things. You can also see the effect of switching between GISS and Potsdam forcings.
While on defaults the model gives a very similar result to CMIP-5 projections, that proves nothing. Try switching to the Potsdam forcings and you get a smaller response. Try doubling the Black Carbon term (in line with the recent study) and you get a yet smaller term. The main take-home is that while current forcing can explain 20thC climate, the forcing are sufficiently uncertain that this doesn't allow us to very significantly constrain future climate change.
A few notes:
1. I don't think the Potsdam forcings include the 2nd aerosol indirect effect. You can try multiplying it by 1.5 to compensate.
2. Hansen's aerosol forcing is larger than most.
3. I've rushed this out, there may well be mistakes.
4. Start date is fixed at 1880, so not directly comparable.
See what you can do with it.
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Phil at 19:51 PM on 19 April 2013Climate's changed before
I think one of the "strengths" of this argument (from the Denialist point of view) is that there are actually two possible implied arguments. One is (as others have pointed out above) is
Climate has changed before [naturally and so the current instance of climate change must be natural too]
The second is this
Climate has changed before [and "the planet" survived that and so will survive the current climate change, irrespective of how its caused]
I've put the incorrect implication in []. The first case is a failure of logic, the second case mis-identifies both the risk of climate change, and what "taking action" on GHG emissions seeks to accomplish.
So when responding to the simple statement "Climate's changed before", you can't be sure which one of these two arguments is being implied, if you rebute one the other can still be thought to be valid, if you try and rebute both it can get very involved.
Perhaps this helps explains why, as an argument, it is so popular with contrarians.
A final thought: It seems to me that as soon as the implied arguments are stated, the flaws in them are very obvious, and this, together with the fact that the prima-face statement is true and uncontestible, explains why the implied arguments are always just that - implied - which is why SKS haven't found a quote to adorn this acticle that exposes the real myth(s)
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Dikran Marsupial at 17:29 PM on 19 April 2013Models are unreliable
@bouke The current policy decision to do nothing [and it is a policy decision] is not based on the projections of sea ice extent, so you did dodge the question.
I'm sorry, I have better things to do with my time than engage in evasive rhetorical discussions. If you want to demonstrate that is not what you are trying to do, then give a cogent explanation of how sea ice extent projections support the policy decision to do nothing. The models clearly indicate that sea ice extent is diminishing and that we will see effectively ice free summers on a timescale relevant to human lives, so even though they underestimate the rate of ice loss, the clearly argue that we should do something, not do nothing.
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DSL at 13:47 PM on 19 April 2013Climate's changed before
So the answer to your first question is "What's wrong is that Lindzen actually wrote it."
In other words, Lindzen thinks you're stupid or at the very least simply ignorant, and willingly so. If you said to him "Duh! What's your point?" he'd probably bluster a little and then show you some really cool graphs.
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DSL at 13:43 PM on 19 April 2013Climate's changed before
No. There's nothing wrong with the information itself. The myth occurs when the information is voiced--made public. I'd bet you that in 99.99% of the cases in which those facts are strung together and published, the person doing the stringing is attempting to make an implied argument that since climate has changed before without rapid accumulation of atmospheric CO2, and therefore the current climate change is not the result of human CO2 emissions. I've engaged with at least 400-500 people on comment streams using this very implied argument.
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scaddenp at 13:41 PM on 19 April 2013Climate's changed before
Mark, "the climate has changed" before is mostly used to imply that humans arent responsible for current warming and/or that past changes are unforced. As a skeptic argument, it is framed as an excuse to do nothing. In the source where the quote came from, Lindzen tries to touch both bases, along with an a priori assumption that climate sensitivity is low. He has been trying to find some plausible reason for low sensitivity without much success so far. If you want to get down to real myths, then I guess you have to look at what logical step follows from "climate has changed before" but for many, this somehow seems to be enough.
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Tom Curtis at 13:32 PM on 19 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
Karellen @21,
the key point is that a confidence bound is a line that the observed value is expected to fall below a certain percentage of the time. The confidence interval is then the interval between the lower and upper confidence bounds.
Thus, the way to read the uncertainty interval is that, for the lower bound (5%), the observed value is expected to fall below that value 5% of the time. The upper (95%) bound is the limit such that the observed value is expected to fall below that value 95% of the time. Similarly you can have 25% and 75% bounds, which the observed value would be expected to fall below 25% and 75% of the time respectively. The predicted value (the central line) is in fact just the 50% confidence bound, ie, the line that the observed value is expected to fall below 50% of the time. You will also sometimes come across 33% and 66% confidence intervals, which the observed value is expected to fall below respectively 33% and 66% of the time.
When the observed values minus the predicted value, which is called the residual, is normally distributed the confidence interval is often expressed in terms of Standard Deviations (SD), or Standard Error (SE). With a normally distribued residual, the two SD confidence interval is approximately a 95% confidence interval, ie, the lower bound is such that the observed value is expected to fall below it 2.5% of the time and the upper value is expected to fall below it 97.5% of the time. For the one Standard Deviation (or Standard Error) confidence intervals, the lower bound is such that the observed value is expected to fall below it approximately 16% of the time, while the observed value is expected to fall below the upper bound approximetely 84% of the time. These bounds are often designated by the mathematical symbol for a Standard Deviation, ie, a lower case greek letter sigma (σ) which is eqivalent to "s" in the English alphabet. Likewise it will sometime be reffered to simply as one or two "sigma".
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Mark Bahner at 13:02 PM on 19 April 2013Climate's changed before
Mark @345 - there's nothing directly wrong with 'the skeptic argument' as articulated by Lindzen here.
So the "#1 global warming myth" is not really a myth at all...?
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engineer8516 at 11:08 AM on 19 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
I should add that the 5-95% uncertainty range is the dark red region and lighter red region combined.
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engineer8516 at 11:06 AM on 19 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
@ karellen
The 25-75% uncertainty range, means that the actual temperature is expected to be within that range 50% of the time (75-25=50). The 5-95% uncertainty range means that the actual temperature is expected to be within that range 90% of the time (95-5=90).
Another way to think about it is that the actual temperature has a 50% probability of landing in the dark red region and a 90% probability of landing in the red or lighter red region.
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Tristan at 10:57 AM on 19 April 2013The anthropogenic global warming rate: Is it steady for the last 100 years?
Nice work DS
I couldn't even show her the difference between a negative temperature trend and 'statistically significant cooling'.
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Don9000 at 10:38 AM on 19 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
Karellen@21
My layman's understanding is that the uncertainty ranges are also called "confidence intervals." The 5-95% range is saying that the value being tracked will fall within the wider band 95% of the time. Similarly, the 25-75% uncertainty range is saying that there is a 75% confidence that the value will fall within the narrower band. I'm sure someone with more technical expertise will chime in with a better explanation. That said, between you and me and everyone else, I would like to see the Climate Science Glossary under the Resources tab get a bit better about explaining this kind of thing. -
Karellen at 09:36 AM on 19 April 2013Global Warming is Accelerating, but it's Still Groundhog Day at the Daily Mail
Sorry if I'm being stupid here, but I don't understand how the uncertainty ranges on figure 3 are supposed to work.
At the blue line, the average value looks to be (approx) +0.6°, with the "25-75% uncertainty range" going from +0.5 to +0.7, and "5-95% uncertainty range" going from +0.3 to +0.9.
So, the outer band is both more uncertain (95% > 75%) *and* less uncertain (5% < 25%) than the inner band? That doesn't make any sense to me.
Surely if your average value is +0.6, you might be 50% certain that the value will be between +0.5 and +0.7, and 90% certain that the value will be between +0.3 and +0.9. But that would make your inner band "50-100% uncertain" (0-50% certain), not 25-75%, and your outer band "10-50% uncertain" (50-90% certain), not 5-95%.
I mean, I'm pretty sure I understand what the graph is telling me. I think the graph, and the bands, make sense. It's just the labelling that I can't figure out. The Y axis is measuring temperature, not certainty. Certainty is an expected deviation from a value, with zero uncertainty being zero deviation. Zero uncertainty is not as far as you can go below the expected value, it *is* the expected value.
Isn't it?
Clearly, everyone else has no problem with this graph, and is reading it differently from me, but presumably you're all reading it the same way as each other. Therefore, the most obvious conclusion is that I'm the one reading it wrong. But how?
Can someone please tell me which angle I need to tilt my head at, in order to look at this in the right way so it actually makes sense for me?
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K.a.r.S.t.e.N at 07:52 AM on 19 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
Thanks Tom!
In order to be more transparent, I uploaded the principal figure from Lewis 2013 (Fig 3). It shows the posterior PDFs in comparison with Forest et al. 2006 (which I erroneously referred to as Forster et al. 2006 in #14):
Figure caption: "Marginal posterior PDFs for the three climate system parameters by diagnostics employed, method used and either upper-air diagnostic EOF truncation parameter (panels a, b and c) or surface diagnostic EOF truncation parameter (panels d, e and f). Panels a, b and c use the F06 diagnostics; panels d, e, and f use revised surface and deep-ocean diagnostics, and no upper-air diagnostic. Panels show marginal posterior PDFs for, from the top, Seq (ECS), Kv (effective vertical deep-ocean diffusivity) and Faer (total aerosol forcing). In panels a, b and c, the solid red lines show marginal PDFs using the new objective Bayesian method and kua=12 (number of EOFs for upper air (ua) and surface (sfc) diagnostics), while marginal PDFs using the F06 method are shown at kua=12 (solid green lines) and at kua=14, as used in F06, (dashed blue lines) , and the dotted black lines show the published F06 PDFs. In panels d, e and f, marginal PDFs using the new objective Bayesian method are shown with ksfc=16 (solid red lines) and ksfc=14 (dotted blue lines), while corresponding marginal PDFs using the F06 method are shown with respectively solid green and dotted black lines. The box plots indicate boundaries, to the nearest fine grid value, for the percentiles 5–95 (vertical bar at ends), 25–75 (box-ends), and 50 (vertical bar in box). Parameter ranges are given by plot boundaries."
His prior assumptions for Seq, Kv and Faer are: 0.5 to 15 K, 0 to 64 cm2/s, -1.5 to 0.5 W/m2.
He explicitly states that: "Faer represents net forcing (direct and indirect) during the 1980s relative to pre-1860 levels, and implicitly includes omitted forcings with patterns similar to those of sulfate aerosols." As aerosol forcing seems the most constrained parameter, I wonder what a small shift in the prior to a more plausible range of -1.5 to 0.0 W/m2 would do to the final results. Given that the F06 aerosol forcing mode isn't too far off the one in Lewis 2013, it seems that the method is very sensitive to the prior choice. I might very well be wrong in this regard.
Note that there the paper comes with Supporting Information, which isn't available yet.
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BBD at 07:03 AM on 19 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
Much to ponder.
Without going so far as to suggest that this study is intended as a distratction, there is no doubt that it will be used as such in the 'debate'.
Perhaps this bears repeating:
Albatross #9 gives the best synopsis in my view - the meta-estimate of ECS is still stubbornly in the 2.5-3C range, and I somehow doubt if we will even pin it down more accurately. Deniers are just arguing the decimal points, as Professor Scott Denning told the Heartland Institute in 2011, but of course they did not listen then either.
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bouke at 07:02 AM on 19 April 2013Models are unreliable
@Dikran
- You asked "Exactly what are the policy decisions that are being made based on predictions of SSIE?".
- I answered "The current policy decision is to do nothing".
- You stated "it is a pity that you dodged my question".
- I stated "perhaps we disagree on what constitutes a policy decision"
- You stated "I agree that "do nothing" is a policy decision, nothing I wrote suggests otherwise."
The only way I could reconcile (3) with (2) was if you didn't consider doing nothing a policy decision. That's where (4) came from.
Essentially the point is that for Arctic sea ice extent, the observations tell you what is happening, the models predict that the Arctic sea ice will last longer than the observations suggest to the extent that we know that their projections are wrong, and hence nobody should be taking them sufficiently seriously as a basis for policy.
Now you think that they do have an effect on policy, but do you have any evidence to support that?
The entire purpose of the IPCC is to inform policymakers. The IPCC's AR5 draft mostly discusses models and their projections. If you think that the projections of those models are wrong, why are these projections in AR5?
Anyway, this is the last post by me on this matter. I will read answers but won't post more. Except for CBDunkersons link, the discussion here hasn't been very useful for me and I doubt that will change.
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Tom Curtis at 06:40 AM on 19 April 2013Climate Sensitivity Single Study Syndrome, Nic Lewis Edition
Dana @22 & 23, the mode (unlike other parameters) is easilly estimated from the PDF shown in Fig 6 a. Using a pixel count, I can confirm the estimate of 1.6 C for the mode of the main analysis.
Contrary to your main article, this is not "simply a misrepresentation" of Aldrin et al. It is misleading in that he does not point out the difference between the modal value and the central estimate commonly quoted for the IPCC, and that they are not directly comparable. However, it is not incorrect on any matter of fact. That is, the modal value of Aldrin et al is the value Lewis quotes, and he does specify that it is the modal value he is citing. Consequently, as it stands, your section on "Misrepresenting Aldrin" is more misleading than is Lewis' citation of Aldrin.
Further, Aldrin et al do not exclude cloud and aerosol effects in general. The nine forcings included in the main analysis are specified as:
"long-lived greenhouse gases (CO2, CH4, N2O and halocarbons), tropospheric ozone, stratospheric ozone, stratospheric H2O, the direct aerosol effect, the cloud albedo effect (indirect aerosol effect), surface albedo because of land use changes, solar radiation and volcanoes".
(My emphasis)
Aldrin et al do exclude cloud lifetime effects from the main analysis and other cloud effects (ie, other than the aerosol indirect effect and cloud life time effects) from all analyses. As these are not defined as forcings in the IPCC AR4, they may or may not be included in other estimates of climate sensitivity. De facto, they will be included in purely observational estimates, but their inclusion in model based estimates (or hybrid estimates such as Lewis 2013) may well be doubtfull.
For what it is worth, by eyeball, inclusion of a cloud lifetime effect of -0.25 W/m^2 lifts Aldrin's modal estimate of climate sensitivity to about 1.8 C, and including a feedback of -0.5 W/m^2 lifts it to about 2.2 C. Aldrin et al cite confidence interval for the effect of -0 to -1.5 C from Isaksen et al (2009), and from consulting the figures for Isaksen et al (it is pay walled), the mean estimate is about -0.3 W/m^2.
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