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Comments 128451 to 128500:

128451. HumanityRules at 10:13 AM on 23 October 2009
        What does past climate change tell us?
        @Chris #25 In response 1. False Logic Medical clinics are meagre and have no drugs not because of global warning. Infrastructure is poor not because of global warning. People earning next to nothing not because of global warming. Child mortality is not because of global warming. These are the real problems I am concerned with now. There is no false logic in worrying about real issues rather than being alarmist about future problems. I thought it was a fact that that region of the world does produce sufficient food to feed itself and has the potential to produce more it's the complicated (and screwed) relationship it has with the global economy that has kept that region in the state its in. Nothing about it's past, present or future climate. 2Crocidile tears I have no problem with your first paragraph, I totally agree. I've been an active anti-imperialist most of my adult life. But I don't see the jump of going from blaming the west and it's institutions to giving them cheap solar panels. Imperialism has thru the ages changed but it has always been morally justified. The civilizing of the savage argument came to look out-dated and racist after the war but during the 19th centuary was absolutely mainstream, as you say the more recent IMF/world bank form of fiscal imperialism played on the protection of the african people from their corrupt leaders. My worry is the next moral reasoning for western control of the poor will be environmental protection. It does appear one country is breaking the mould in Africa. China is doing what has never really been done investing in infrastructure. It's big, dirty and has a high carbon footprint but it has the potentially of shifting some african countries into the industrialized world. Many african commentators see this as preferrable to either western conservative fiscal control or western liberal charity. You can give african villages free solar panels. I aspire to see them have everything we have, and more.
128452. WeatherRusty at 07:38 AM on 23 October 2009
        Working out climate sensitivity
        djb95054, Increased ocean temperature absolutely increases the amount of radiation emitted by the oceans. According to the Stephan-Boltzmann Law the energy emitted across all wavelengths by a black body increases as the 4th power of the temperature. A portion of this is lost directly to space out what is called the infrared window where greenhouse gases do not intercept the radiation, while a much larger portion is absorbed by the atmosphere. Thus, warmer ocean's maintain a warmer lower atmosphere which expands due to the added warmth. The layer of emissivity, where Earth's effective temperature of 255K is met, reaches to greater height where the radiation balance between incoming and outgoing radiation is attained, no extra energy is lost from there. So, most of the additional energy emitted by a warmer surface (oceans) goes to warming the atmosphere to higher temperature, while an increased but much smaller amount is lost out the atmospheric infrared window.
128453. Riccardo at 07:00 AM on 23 October 2009
        How do we know CO2 is causing warming?
        Henry Pool, you have to consider the different wavelength range in the two cases. In the visible range (sunlight coming in) the CO2 effect is definitely negligible, there's no significant absorption nor scattering. No cooling, as you call it. As for the radiation coming from the earth surface (infrared going out), there's no significant scattering as well but there's absorption (at certain characteristic frequencies). Again, no cooling. More generally, as in the case of aerosol, you can have a net cooling effect due to the combined effect of absorption and scattering. But this is a much more complicated matter and infact is the biggest single contribution to the uncertainty in the estimates of the total net forcing.
128454. djb95054 at 06:02 AM on 23 October 2009
        Working out climate sensitivity
        What about the latest study by Lindzen/Choi (see http://climaterealists.com/index.php?id=3932) that pegs sensitivity at .5 degrees C? Is there any validity to the theory that increased ocean temperatures increases the amount of radiation that is lost to space?
        Response: Increased ocean temperatures do increase the amount of radiation lost to space - if the Earth is in positive energy imbalance, the planet will accumulate heat, oceans will warm, the earth will radiate more energy to space until it approaches radiative equilibrium again. This is discussed in more detail in the Climate Time Lag post.
128455. shawnhet at 05:48 AM on 23 October 2009
        How we know global warming is still happening
        Chris, all of the issues involved are massively complex, so it is easy to find people on different sides of any issue. If you want to assume that anyone who agrees with you must be right and anyone who disagrees with you wrong, that's fine. The fact remains that many people feel that PDO shifts have the capacity to accelerate or deccelerate the warming trends. If this is true, then the fact that there are (essentially)two PDO warming periods and one PDO cooling period in the last 100 years must reduce the anthro contribution to warming. One does not have to accept that the PDO can change the rate of warming, of course, but this leads to its own problems (like the anomalous jump in temperatures in ~1976). It is widely supported including by Josh Willis(who is no stranger to ideas of OHC). There are other comparisons one could make of course, to try and guage the natural component of climate change. Comparing the temperature now to the temperature at the height of MWP or comparison of temp change(or sea level increase) from 1800-1900 and 1900-2000 or of the rate of temp change from 1910-1945(the previous positive PDO period) to the 1976-2000 period). "These observations are not surprising shawnet; the movement of waters around the world simply cannot “magic” heat generation, even if they can redistribute this due to long term oscillatory shifts in currents. " The movement of water may not be able to generate heat, but it will definitely allow it to be dissipated and radiated more or less efficiently. Think about it.
128456. Henry Pool at 05:17 AM on 23 October 2009
        How do we know CO2 is causing warming?
        Yes Riccardo!- I am glad you understand. I am talking about both directions. The cooling is coming from the top to the bottom, the warming is going from the bottom to the top, or rather, from the bottom up back to the bottom - i.e. the greenhouse effect!! Your argument that carbon dioxide is a "small particle" surely applies both ways. i.e. both for earth and the sun. I therefore would like to see the actual figures or measurements from experiments -do you have them? What is the nett result of the cooling and the warming effect of CO2??
128457. Steve L at 04:28 AM on 23 October 2009
        What does past climate change tell us?
        I'd like to respond to Humanity Rules. First, I don't think we need cheerleaders on a science blog. That's a comment on your net name, but it's also a comment on your attack on John Cook. You say that in 17, John "hold up the Sub-saharan life as the way forward for humanity". I don't think he does any such thing. I think he merely points out that human population by itself doesn't increase CO2 content of the atmosphere -- that requires liberation of fossil carbon (as Ricardo makes clearer in 22). It's really very simple: CO2 added to the biosphere = (human population) x (environmental consumption per capita) x (CO2 emissions per unit of environmental consumption). So you could say that CO2 added to the biosphere = (N x E x C). To limit increases in atmospheric CO2, it doesn't matter if you manage to reduce population (N) by 20%, per capita consumption (E) by 20%, or CO2 required to provide that consumption (C) by 20%. If you hold the other two components constant, then you end up with a 20% overall reduction. But, one must be aware that these components interact in a complex manner, and focusing on one of them (especially a difficult one, like population) will likely not result in the CO2 limitation one might have simply imagined (China's population didn't stop growing via one-child policy; their CO2 production went up greatly at the same time). Nobody here is advocating "back to the stone age" policies, so please leave that rhetoric at home.
128458. chris at 04:18 AM on 23 October 2009
        How we know global warming is still happening
        come on shawnet. You've just been demonstrating that one can fabricate the pretence of a "debate" by saying "stuff" for which there isn't any evidence! In fact there actually isn't much scientific debate about the attribution of natural and anthropogenic factors to 20th century and contemporary warming....the scientific evidence from a number of different analyses (see for example my post #76) indicates that the natural contribution is small and the anthropogenic contribution is large. I prefer to follow the science on these issues. Your "simple argument" is meaningless, isn't it, without recourse to evidence. There has been significant scientific investigation of the contribution of ocean current regime shifts on the 20th century temperature trend. The evidence indicates that the nett effect is unlikely to have been much above zero, despite the fact that these effects have likely modulated the time course of warming significantly. For example Swanson et al, who have addressed this exact question, find that while ocean current effects have modulated the pattern of 20th century temperature, the nett warming contribution has been negligible (well below 0.1 oC). Lean and Rind (cited in my post above) find much the same. These observations are not surprising shawnet; the movement of waters around the world simply cannot “magic” heat generation, even if they can redistribute this due to long term oscillatory shifts in currents. Swanson KL, Sugihara G, Tsonis AA (2009) Long-term natural variability and 20th century climate change Proc. Natl. Acad. Sci. USA 106, 16120-16123 Rather than use a form of Aristotelian syllogism where you choose the conclusion you desire and bind this into a “logical” “argument” based on false premises (the Shaviv chap you keep referring to does this too), it really does help to look at the evidence. Apart from the abundant science that informs us of these issues, I find it rather compelling that even though we’re apparently within a cooling ENSO regime (your PDO shift which your hopeful guess gives “0.2-0.25 oC” of cooling), and the sun is smack at the bottom of a rather extended solar minimum (which according to your mate Shaviv should give a highly amplified cooling!), we’ve had the warmest September on record [*] and the second warmest June-July-August on record [**]. Of course one can’t draw major conclusions from short time periods, but our current global temperatures are well above the 1990’s average [*,**]. So where’s the marked cooling that your (and Shaviv’s) syllogism is attempting to trick us with? [*] http://www.cru.uea.ac.uk/cru/data/temperature/crutem3vgl.txt [**] http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt
128459. Steve L at 03:47 AM on 23 October 2009
        Working out climate sensitivity
        The caption for Fig 1 is confusing: how could the thicker bars represent higher integrated probability than the thin bars (which cover a broader range)? Surely it's the narrower range that is "likely" and the broader range that is "very likely". I also find interesting the circles for the most likely value. Instrumental record, last millenium proxy, and combined lines of evidence are less than 3 Celsius; only general circulation models indicate more. So it's hard to see why the IPCC point estimate is 3 C rather than, say, 2.8 C (like for "combined lines of evidence"). Finally, it's interesting to see that "expert elicitation" gives exactly the same likely range as IPCC (I don't really see how they would differ) while surely with several estimates producing similar ranges the confidence in that range should increase (and thus the narrow bar for "combined lines"). And finally, er, really finally, I think we must be over 384 ppm in CO2 equivalents now. Just CO2 was 385 ppm http://tinyurl.com/yz783a9 so I imagine adding anthropogenic methane and such would push us to ... maybe 395?
        Response: The caption for Fig 1 was confusing because it was wrong - I've updated the text, swapping thicker and thinner. Thanks for pointing that out.
128460. chris at 03:22 AM on 23 October 2009
        What does past climate change tell us?
        HumanityRules, there's a strong dose of false logic combined with crocodile tears in the sorts of argument you are presenting. I’m not saying they necessarily apply to yours specifically, but they hint in that direction! 1. False logic. Large parts of sub-Saharan Africa are (and will continue to be) regions of the world that are most susceptible to the effects of global warming. It's established that the effects of global warming has produced increasing drought in these regions, and as warming progresses the region of reduced precipitation will spread Northwards and Southwards from the mid latitude bands already suffering from drought [*]. The global areas classified as "severely dry" by the Palmer Drought Severity Index (PDSI) more than doubled from 12% to 30% in the period 1970-2002 with surface warming as the dominant cause post-1980 [**]. This is the major cause of current, and near and medium-term food limitation that is the source of much of the problems in these and other areas in the middle latitude bands of the earth. The notion that this situation can be eased by beefing up the carbon footprint of these populations (and similarly low-carbon footprint populations elsewhere) is simply fallacious. What these increasingly drought-ridden regions need is a reduction in global warming. The obvious means of addressing this problem is to make a large investment in providing sustainable energy for these people, while we do the same for ourselves. This has to happen sometime (our civilizations are untenable into the future on the centennial timescale without this), and it should be happening with increasing urgency now (it is to some extent). [*] Zhang XB, Zwiers FW, Hegerl GC, et al. (2007) Detection of human influence on twentieth-century precipitation trends Nature 448, 461-465 [**] Dai AG, Trenberth KE, Qian TT (2004) A global dataset of Palmer Drought Severity Index for 1870-2002: Relationship with soil moisture and effects of surface warming J. Hydrometeorology 5, 1117-1130 2. Crocodile Tears One wonders where the concern for sub-Saharan Africa has suddenly sprung from! During the past 40-odd years this part of the world has suffered enormously from economic mismanagement a large extent of which was perpetrated by Western governments in support of their own economic advantage, largely in relation to extraction of raw materials. This encompassed major political interference in support of despotic or otherwise compliant leaders, and imposition of severely unfavourable trade and social conditions by the IMF/World Bank in which economic assistance was built around a system of enforced restructuring involving easing access of Western corporations to commodities and infrastructure, and dismantling of social structures. The World Bank ultimately admitted that it had caused huge social damage through these policies. That's happened and it can't be easily undone. However if we are truly concerned about those people (rather than using them for convenient hand-wringing in fallacious arguments to avoid doing anything about global warming), then we should address the problem directly. For example, cheap solar panels of the sort that China can producing in large amounts could be distributed, so villages could power fridges to keep medicines and run basic systems to power educational facilities and peripherals and so on. Major efforts to make local use of the abundant solar power in the central latitudes for more widespread industrial and social applications could be promoted. Properly planned programmes for sustainable biofuel generation in the so-far drought-free regions south of the equator could be developed…and so on. The notion that the well-being of populations can only be improved through burning fossil fuels is not only wrong...it's an admission of an essential futility of future progress.
128461. Kevinb3 at 03:15 AM on 23 October 2009
        What does past climate change tell us?
        Thanks Philippe, So we're now moving into the cooling phase of the Milankovitch cycle correct?
128462. Philippe Chantreau at 03:00 AM on 23 October 2009
        What does past climate change tell us?
        Kevin, if anything the Earth would be cooling, if left only Milankovitch cycles. That would be a slow process though, leading to cold conditions within 25 to 50000 years.
128463. Riccardo at 02:59 AM on 23 October 2009
        How do we know CO2 is causing warming?
        Henry Pool, my reasoning was upside down, the IR radiation leaving the earth surface. Instead, you're are talking about scattering of visible light from the sun, a completely different issue. No problem about Copenhagen, we can go safely. Scattering is a old and well known phenomenon. The intensity of the scattered light depends on the size of the partiicle and CO2 is quite small; on the contrary, water vapour tends to form liquid droplets (or ice crystals) which are several order of magnitude bigger than a single molecule. Hence droplets suspended in air scatter incoming sunlight much more efficiently than CO2 molecules, the latter being negligible. As a take away message, don't think scientists (and i'm not one of them) are not smart enough to account for the known physics.
128464. Riccardo at 02:31 AM on 23 October 2009
        What does past climate change tell us?
        batsvensson, luckly the CO2 we release with respiration does not come from fossile carbon ;)
128465. Riccardo at 02:29 AM on 23 October 2009
        What does past climate change tell us?
        RSVP, i'm sure you know the per capita emissions in poor country, what you say has not been confronted with reality. And it's worse than that, in what even in poor countries there are rich and the industrial system is much less efficient than ours (compare emission per unit GDP). And yes, global ecology is definitely a luxury as well as the possibility to plan a relatively far future. But this points in the very same direction, it's not over-population but over-consumption.
128466. Kevinb3 at 01:41 AM on 23 October 2009
        What does past climate change tell us?
        As a non scientist I read your comments with great interest and would like to ask what many of you would consider rather basic question I'm sure. Another article I read on Skeptical Science dealt with Milankovitch cycles - how increased temperature causes CO2 rise. http://www.skepticalscience.com/co2-lags-temperature.htm So relative to this blogs emphasis of past change I would like to propose a hypothetical and hear your thoughts. The question: If we humans were not here, thus not pumping out C02, and when considering the Milankovitch cycles, would temperatures still be rising, albeit at a bit slower rate? As a non scientist I'm having a hard time quantifying what I've read, that warming started again in the late 19th century following the little ice age. Did the earth basically shrug off the short term effects of the little ice age during this period to begin its relentless march towards warming because of the Milankovitch cycle? If so, I would assume we humans are just juicing this effect now, but that it started before we contributed much C02? If this is the case, I would be curious hearing a hypothesis looking into the future of the difference where sea levels would be without humans versus with humans. Excuse my layman thinking!
128467. HumanityRules at 00:57 AM on 23 October 2009
        Empirical evidence that humans are causing global warming
        Correction to above "The clearest fig to my mind is Figure 3 from chen 2007"
128468. HumanityRules at 00:56 AM on 23 October 2009
        Empirical evidence that humans are causing global warming
        I also got a question about the (Harries 2001, Griggs 2004, Chen 2007) papers on radiation observations. The clearest fig to my mind is Figure 3. This figure is a subtraction 1970 radiation from 2006 data. I see the drip (negative values) in radiation at the wavelength for CO2 so energy at that wavelength is being retained more in 2006 compared to 1970. But I see positive readings at other wavelengths. My understanding would be that relatively more energy is being lost from the earth at those wavelengths in 2006 compared to 1970. Why is it possible to ignore the the energy at these different wavelengths and only focus on the wavelengths associated with CO2?
128469. RSVP at 00:47 AM on 23 October 2009
        What does past climate change tell us?
        "...poor people emit enormously less CO2 than rich" You probably will find your "poor" closer to template climates for starters. And for however closer they may be, they tend to burn and destroy more forests per capita than anyone on the planet. This does not make industrialized nations any less guilty, however, if anything is going to help us get through this it is science and technology. And to contrast human values, historically, one of the strongest incentives to having more children in these "poorer" countries is tied to a desire for more hands in the fields, while "global ecology" (if it even registers on the mental radar) is some strange luxury of the rich. Monboit's thesis is kin to the concept of the "nobel savage" of the 18 and 19 centuries.
128470. HumanityRules at 00:46 AM on 23 October 2009
        Empirical evidence that humans are causing global warming
        I can't find the "earth total heat content Figure 3 in (murphy 2009) are you referring to the paper "An observationally based energy balance for the Earth since 1950"?
        Response: Yes, the data from my Figure 3 (Earth's Total Heat Content) comes from the energy storage element of Figure 6b in "An observationally based energy balance for the Earth since 1950" (Murphy 2009). Dan Murphy very generously sent me his data.
128471. dopeydoctorjohn at 00:25 AM on 23 October 2009
        The growing divide between climate scientists and public opinion
        I discussed on the "there is no consensus" debate that the Doran paper comes to an invalid conclusion comparing the earth scientists views to that of the general public because the question asked of the earth scientists in the Doran survey was substantially different to the question asked of the general public in the Gallup poll. Undoubtedly most scientists in the field agree with the current dominant paradigm. Undoubtedly some do not. Sometimes the majority are wrong; but usually not. However, the Doran study is seriously flawed and tries to exaggerate the degree of consensus that exists. Because it does this clumsily and amateurishly, and is easily exposed with a little further research and thought, it actually undermines (rather than firms) belief in the consensus. There must be better "consensus" papers around than this. Regarding the extent to which there is a cultural dimension to science, I believe Kuhn's work was highly influential and some of the posters might like to have a look at it http://en.wikipedia.org/wiki/The_Structure_of_Scientific_Revolutions
128472. Henry Pool at 00:10 AM on 23 October 2009
        How do we know CO2 is causing warming?
        Yes, I am talking about the the radiation from the sun hitting on the carbon dioxide. A large portion of that radiation must be scattered away to outer space. You can observe same effect if you stand in the sun (here in Africa) - you will notice that the heat coming directly at you from the sun definitely decreases as the humidity increases. You can feel it. So, the same observation must be true for carbon dioxide. At all levels of the atmosphere. Notice (from the graphs) that at quite a few points the water vapor and carbon dioxide work together to keep us cool. I don't understand how we can go to Copenhagen with this and nobody studied what the nett effect is of the cooling and warming caused by the carbon dioxide. How do we know for sure that the warming effect is bigger if nobody did some experimentation on this? I don't think that temperature and pressure (have to)come into this at all? The CO2 is diffused in the air, therefore you can see it behaves the same as does oxygen.It keeps us cool (during daytime, 12 hours per day) and it keeps us a bit warmer (all of the time) but what is the nett effect?
128473. batsvensson at 23:56 PM on 22 October 2009
        Empirical evidence that humans are causing global warming
        The OP claims that the if "Humans are raising CO2 levels" and "CO2 traps heat" and "our planet is accumulating heat" then the conclusion "human are causing global warming" must be taken under seriously considerations. The OP proves the premises, and then states the conclusion. But does that mean the conclusion is true? Not necessarily. Why? Because it is also equal true to that the conclusion from "If apples are fruits and there is no air on the moon and Mondays comes after Sunday then the moon is made of cheese" is true as well. That implication, plus an infinite many other implications of the same type, has exactly the same logical structure as the implication the OP has proven to be true. So what is wrong with the conclusion which the OP has present? First of all, the premises is only based on observational fact that are true, therefore the conclusion follow as a necessity but it doesn’t say anything about weather the conclusion is correct or not. Secondly the implication contains hidden assumptions, which turns out to be implications as well, which are assumed to be true – therefore unless this can be shown to be true the conclusion must be regarded as postulated by the OP. The hidden assumed condition is the strong statement "CO2 drive temperature changes". The question to ask is: did or did not the OP address this assumed statement? My answer to that question will be that the OP failed to address this assumed statement. The OP address a weaker a form of the strong statement that can be formulated as "CO2 level follows changes in temperature". The weaker form is very interesting because it makes us able to formulate testable hypothesis of the form "If CO2 level changes then temperature will change accordingly" which under certain condition is the same as the statement "CO2 drive temperature changes" as implication also are causal relation. Formulated this way we realize why the statement "CO2 drive temperature changes" is a much stronger statement than "CO2 level follows changes in temperature", this because the strong statement is in fact a law, while the weaker statement "CO2 level follows changes in temperature" is simply a matter of observing measurements. Now, if we can show this stronger statement, the law, to be true, then it will follow from the evidence that the conclusion ‘humans causes global warming’ according to empirical data (observations) is in fact correct. However the OP never shows this but stop at the weaker statement. Why the OP has decided to exclude the stronger statement from the article remains a mystery to me. But just because the OP has decided to exclude it, the OP is guilty of having jumped to the conclusion that human causes global warming
128474. batsvensson at 23:21 PM on 22 October 2009
        What does past climate change tell us?
        "we have to work pretty hard to send 29 gigatonnes of CO2 into the atmosphere every year." Only by breathing humans releases approximately 2 gigatonnes of CO2 every year into the atmosphere. (The calculation is based on that one(1) human release about 1 kg of CO2 per day)
128475. HumanityRules at 23:18 PM on 22 October 2009
        What does past climate change tell us?
        Response: The point is to address the argument that it's increasing population that is causing increasing CO2 emissions. On the contrary, the cause is over-consumption more than over-population. If we're going to hit CO2 emissions, best to be pointing in the right direction. You didn't answer the point I made you you hold up the Sub-saharan life as the way forward for humanity. Along with empty bellies, disease, illiteracy and wasted potential they also have a small carbon footprints. Well done the sub-saharan africans. Humanity isn't just about a head count its about a quality of life which requires consumption. Briefly forget about emission and think about the life of the people you are talking about.
128476. Spencer Weart at 21:24 PM on 22 October 2009
        Comparing CO2 emissions to CO2 levels
        You DO need to include deforestation and other "land use" emissions, which are clearly not present in your dataset. Note that your curve shows some rise of atmospheric CO2 in the 18th-19th century before industrial emissions became strong. This is due to the deforestation of North America and other regions. All this is well covered by the work of William Ruddiman (for references, look him up in Wikipedia). By the way, Ruddiman's work is even more important for cumulative methane emissions.
128477. Riccardo at 20:41 PM on 22 October 2009
        How do we know CO2 is causing warming?
        @Henry Pool I'm a little bit confused by what you call the cooling effect of CO2. Do you refer to the part of the radiation that is re-emitted toward space after absorption? If this is what you mean, the point is that the process of absorption and re-emission happens through the whole atmosphere, true, but at very different temperatures and pressures going from the surface up. At some point (altitude), the radiation will escape to space and it's the temperature and pressure at this point that matters for the energy balance.
128478. Riccardo at 20:00 PM on 22 October 2009
        What does past climate change tell us?
        @RSVP "What I dont understand is how the "non-skeptics" somehow think it is possible to lower CO2 contamination without addressing population growth and the other sources of global warming?" If i get your thoght right, i think you should focus a little bit more. Given that poor people emit enormously less CO2 than rich, the question should be how can they improve their condition without a catastrophic increase of GHGs? This point is made clear and addressed in the UNDP Human Development Report 2008. This little step will change the view that the problem is population by itself, the raw number. And also again underline that the problem is global as global has to be the solution.
128479. RSVP at 19:02 PM on 22 October 2009
        What does past climate change tell us?
        Reply to HumanityRules I am in agreement with you, which I will explain, however, you have confused my point with content added by "Response". In fact it was "cbrock" who originally cites Monbiot. I agree with you in that I do not see Monbiot as being correct in, as you imply, holding up some of the worst living conditions as the way forward. On the contrary, my assessment is that the only viable solution is to work on curbing population. What I dont understand is how the "non-skeptics" somehow think it is possible to lower CO2 contamination without addressing population growth and the other sources of global warming?? What do they think got the CO2 contamination to these levels in the first place? And to be quibbling about who exactly is responsible is hypocritical when you consider the extended influence of the globalized economy. Aside from CO2, isnt it clear that there is no energy delivery system that does not pollute heat directly in some form or another, starting with nuclear energy??? Example http://en.wikipedia.org/wiki/Heat_engine And getting real... behind every solar cell, there is a automobile in a chip plant parking lot used everyday for a 25 mile commute. Behind every wind farm, there are trucks (as you read this) used in transport and maintenance burning diesel. ETC. Getting back to my original point. I wasnt addressing man-made global warming. I was referring to the historical data that indicates potential for global warming or cooling whether man-made or not. And the fact that so many people live on the fringes of habitable terrain. ------------------------ By the way, in the news yesterday, an AP article terms greenhouse gasses as "global-warming gases"... fait accompli. http://www.google.com/hostednews/ap/article/ALeqM5jZFyOvC-Hn8ZRKlbw2eJKukIRmHAD9BFKLT00
128480. HumanityRules at 16:07 PM on 22 October 2009
        What does past climate change tell us?
        @ RSVP You include this "Monbiot: "A paper published yesterday in the journal Environment and Urbanization shows that the places where population has been growing fastest are those in which carbon dioxide has been growing most slowly, and vice versa. Between 1980 and 2005, for example, Sub-Saharan Africa produced 18.5% of the world’s population growth and just 2.4% of the growth in CO2. North America turned out 4% of the extra people, but 14% of the extra emissions." I'm not sure what point you are trying to make. That population can expand ith limited impact on CO2 levels? Sub-Saharan Africa has just about the worst living condition for human being than any place on earth. Life expectancy, child mortality, education, infrastructure I could go on and on and on. It seems you (or more accurately Monbiot) are holding these people up as examples to us all. You want all of us to have quality of life similar to sub-saharan africans? I'd prefer to fight for an improvement in their quality of life and the inevitable increase in their carbon footprint than champion extreme poverty as some way forward. Unpleasant decadence from privileged western liberals
        Response: The point is to address the argument that it's increasing population that is causing increasing CO2 emissions. On the contrary, the cause is over-consumption more than over-population. If we're going to hit CO2 emissions, best to be pointing in the right direction.
128481. HumanityRules at 15:45 PM on 22 October 2009
        What does past climate change tell us?
        There seems to be a leap in this article that is unexplained and leaving me confused. Many things can absorb the suns energy and many things can reflect the suns energy and maybe the amount of energy from the sun can vary. And maybe the way processes (currents, continents, winds) move that energy around the global alters things. You show an equation, very sciencey. Then make the comment "The most common way of describing climate sensitivity is how much global temperature would change if CO2 is doubled." and from then on it seems everything is explainable by CO2 levels. I don't get that last jump. Just because some people simplify the process down to CO2 levels doesn't mean that CO2 is the main cause. Or have other factors been corrected for? How would you know albedo, volcanic activity, cloud cover, ocean currents etc for this whole period? Few other things. 1) So there was a Medieval Warm Period? Because I thought this was expunged from history by Mann as an inconvinient truth. 2) "Hegerl 2006 looks at global temperatures spanning both periods, using 4 different temperature reconstructions." Isn't it northern semishpere temperature not global temperature in that publication?
        Response: In its most fundamental terms, climate sensitivity means "if climate experienced a radiative forcing of 3.7 Wm^-2, global temperatures would rise 3°C". This is the case whether the radiative forcing came from CO2, methane, solar variations, changes in albedo, etc. Or more accurately, all those factors added together.
        
        CO2 is not the only driver of climate. When you add them all together, then you have the net radiative forcing that is driving climate. I've gone back and tweaked the wording of that paragraph, hopefully clarifying the language somewhat. In fact, I'm currently working on a post coincidentally titled "CO2 is not the only driver of climate" :-)
        
        The main controversy with the Medieval Warming Period is whether it was global or a regional phenomenon. However, bickering over how widespread the MWP was underlies the irony of arguing about past climate change. If, as skeptics say, the MWP was a global phenomenon and temperature change was greater than currently thought, that would mean climate is more sensitive than previously thought. Hence the climate reaction to current CO2 radiative forcing would be even larger.
        
        Re Hergerl 2006, you're right, it did use NH reconstructions, not global. Thanks for spotting that, I've updated the post.
128482. Alberta Clipper at 15:22 PM on 22 October 2009
        How do we know CO2 is causing warming?
        Co2 is not CO2. Co2 is molecular cobalt (Co). Why didn't the moderator pick up on that?
128483. Henry Pool at 14:43 PM on 22 October 2009
        How do we know CO2 is causing warming?
        It appears no one ever seemed to have come up with the thought that carbon dioxide also causes cooling. I did not receive an answer to my question at post 67.perhaps I still get an answer. But I doubt it. It seems everyone forgot to look at the cooling aspect. In my view, especially with CO2, the way for radiation from the top to the bottom is the same as for the bottom to the top because the CO2 is almost 100%diffused into the air, so this question is and must be relevant. Why did no one ask it before? The cooling does not happen just in the upper air, it happens anywhere. I am busy carefully analyzing the graphs that I posted at 67, and all in all, it looks to me pretty much evens up, In other words: the cooling effect might in fact be just as much as the warming effect. If you enlarge it big enough you will notice that there are a few small gaps caused in the sun’s radiation which is due in part to the two absorptions of carbon dioxide between 2 and 3 um. It seems to me that the spectral intensity at the 4-5 um absorption is pretty much the same for both the sun and earth, although it is probably not on the same scale. But let us say this cancels each other out, more or less. It seems there is a small corner of radiation not being emitted by earth due to the CO2 absorption, at 14 um. (note that water is also absorbing here). This is the warming effect. Without someone doing some experimental testing, I think it will be difficult to quantify which is the biggest: the cooling or the warming. But if you ask me, it looks to me that the nett effect is or will be close to zero
128484. Philippe Chantreau at 11:04 AM on 22 October 2009
        How do we know CO2 is causing warming?
        TS, all the science used by the IPCC is done "outside" of the organization. You say you like the science papers presented in this site. Did it occur to you that most of them are part of the body of science used by the IPCC in its work?
128485. shawnhet at 09:54 AM on 22 October 2009
        How we know global warming is still happening
        Chris, are you really unaware that there is substantial debate in how much natural contribution there has been to warming over the last century? What was the temperature increase from 1800-1900? IAC, I'll give a very simple argument here. The PDO shift which happens every 30 or so years has been claimed by many people to be able to cancel out the current rate of global warming, which means that the current rate of GW should be approx. equal to the cooling rate of a negative PDO(and, by extension the warming rate of a positive PDO). From that logic, we had two warming PDOs and one cooling one btw 1900-2000, we end up with PDO shift accounting for btw 0.2-0.25 C of your 0.8-0.9C in the last hundred years. If you then add your **separate** heating of 0.1C you reference above, you end up reasonably close to my 0.5C. Cheers, :)
128486. chris at 09:03 AM on 22 October 2009
        How we know global warming is still happening
        Not really Shawnhet. You can't just make things up according to your preference. The attribution of natural contributions to 20th century warming has been addressed empirically and analytically and simply doesn't accord with your unattributed assertions. You really need to address the science; we do notice when you try to sneak completely unfounded assertions into your messages! So for example the most recent analyses of natural and anthropogenic contributions to 20th century warming indicate that very little was from natural variation. J. L. Lean and D. H. Rind (2008) How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006 Geophys. Res. Lett. 35, L18701 Which indicates that the natural contribution to warming in the period 1889-2006 was around 0.12 oC (0.002oC per decade ENSO; -0.001 pd volcanic; 0.007 pd solar). Nothing like your hopeful guess of 50%! A similar conclusion results from the recent analysis of Schmidt and Benestad: Benestad RE and Schmidt GA (2009) Solar trends and global warming J. Geophys. Res. 114, D14101 who determine a solar contribution of 7% for 20th century warming with a slight cooling contribution since 1980, in line with quite a bit of other research on this subject. And while natural variations resulted in significant modulation of 20th century warming its nett contribution was near zero (around 0.1 oC or less): Swanson KL, Sugihara G, Tsonis AA (2009) Long-term natural variability and 20th century climate change Proc. Natl. Acad. Sci. USA 106, 16120-16123 And so on. The science simply doesn’t support your assertions shawnhet, and so your arguments about climate sensitivity are based on a false premise (or wishful thinking perhaps). Notice that your comment about where we are with respect to forcing from doubling of CO2 is not relevant without considering the inertias in the climate system that delay the full temperature response to that forcing. The abundant data on climate sensitivity that indicates a sensitivity near 3 oC per doubling is consistent with the major anthropogenic warming of the 20th century, as indicated by attribution studies as I’ve just indicated, and with modelling which has been rather successful in predicting the greenhouse-induced warming since the mid-1980’s. In fact the modelling is actually consistent with a climate sensitivity somewhat higher than 3 oC. J. Hansen et al. (2006) Global temperature change Proc. Natl. Acad. Sci. USA 103, 14288-14293 If the science from a number of different methodologies indicates that the climate sensitivity is near 3 oC, I don’t think one can gainsay this by unattributed assertions and argumentation that is demonstrably incorrect. It’s best to address the science on these issues. R. Knutti and G. C. Hegerl (2008) The equilibrium sensitivity of the Earth's temperature to radiation changes Nature Geoscience 1, 735-743
128487. canbanjo at 08:54 AM on 22 October 2009
        The growing divide between climate scientists and public opinion
        The most convincing book i've read is 'without the hot air' by david j mackay. its on line free http://www.withouthotair.com/ but i bought it after reading one chapter. it focuses on how much energy everyone uses (rather than climate change) and how much energy is available renewables / nuclear / fossil fuels, it really focus's the mind on the reality of humankind's predicament whether forced by climate change or declining fossil fuels. it is an example of how to make something huge and complicated understandable. no surprise david mackay has recently been appointed as chief scientist at the (British) department of Energy and Climate Change (http://news.bbc.co.uk/1/hi/sci/tech/8283909.stm). Politicians must be relieved to have a scientist able to summarise the reality of what is going on. brilliant. puts other scientists, journalists and politicians to shame. i'm not saying the content is not to be challenged - it is the method of delivery. numbers not adjectives!
128488. shawnhet at 08:38 AM on 22 October 2009
        What does past climate change tell us?
        Chris:"1. The sub-set of tide guage measurements he used show a marked modulation with the solar cycle that isn't seen in the globally averaged sea level analysis. The fact that the satellite measure is short doesn’t discount the fact that it doesn’t show the marked solar cycle modulation; after all one only needs the satellite measures through one solar cycle to assess whether the globally averaged sea level shows the marked solar cycle modulation seen in the sub-set of continental margin-biased records…it doesn’t. The data is in the Church et al. reference I cited above – see their Figure 3." Ok, well I haven't read the original Douglas paper, so I can't really comment here at the moment, perhaps you are right and they are improperly chosen for the purpose. As to the Church paper and the lack of solar cycle trend: Are you just eyeballing it and guess-timating or do you have an actual reference here? I think drawing this conclusion is much more complicated than that. 3. The third problem also relates to the OHC (ocean heat content) measures. Shaviv has to apply a number of corrections to remove “noise” like ENSO modulation of upper OHC, and after all of the corrections are made the correlation with the solar cycle is low as he states (see (2) above). What Shaviv doesn’t seem to have done is to remove the influence of volcanic eruptions, which is important in analyzing solar cycle related effects on OHC since for two of the 5 cycles (or 6; it’s not clear from Shaviv’s paper) analyzed, the volcanic forcing happens to be in phase with the solar cycle. This will produce a spurious “amplification” of any apparent solar effects that is not, in fact, related to solar effects. This has been pointed out by Lean and Rind in their recent analysis of attributions to 20th century warming (see section 4 on page 4 of their paper): Thanks for this. It does appear to be a flaw in Shaviv's paper. It would be interesting to see it redone with volcanic corrections made(if in fact they weren't done). IAC, I still tend to think that the amplification factor will still be there when appropriate adjustments were made. It is pretty clear the solar signal has been much more strongly evident in its climate effects than its raw forcing value might suggest. It is pretty hard to imagine Herschel in 1801 being able to detect 0.1% change in solar radiation if that's all there was to it. Cheers, :)
128489. TruthSeeker at 08:26 AM on 22 October 2009
        How do we know CO2 is causing warming?
        Philippe Chantreau, "This statement by Truth Seeker: "I have found the UN to be a horribly corrupt organization" is totally meaningless and bad rethoric ... How relevant is it?" It is relevant in that I don't accept IPCC (UN) as being an organization of Scientist, rather they are a political organization (and a relatively corrupt one at that) with policy agenda. Their call for action has my highest suspicions, and I look to real science (done outside of this organization) for evidence of the truth. The thing I like about this site is that most of the arguments and evidence I find here meet that qualification.
        Response: If you read the IPCC reports, you'll see they're basically just a summary of all the peer reviewed scientific literature. It reads like a science textbook (a rather dry one) and its conclusions are conservative. I often use the AR4 as a starting point to lead me to what papers are out there. I strongly recommend reading the IPCC Fourth Assessment Report - you will learn a lot about all the research that's out there.
128490. TruthSeeker at 08:21 AM on 22 October 2009
        How do we know CO2 is causing warming?
        Steve L, you made the comment "but for one theory to supplant another, it must explain/predict more than the incumbent theory." This is true, however usually theory's have a basic ability to predict. I have seen much with regards to the correlation between Temperature and CO2, but the predictions on how temperature will change with increasing CO2 concentrations have been horribly in accurate. So, until the temperature / co2 models get some degree of credibility, it's difficult to accept the premises that CO2 is the culprit for the increase in temps.
128491. shawnhet at 07:43 AM on 22 October 2009
        How we know global warming is still happening
        Chris, sure if you only look at things from your POV, then they will appear to line up, the way you have outlined them. However, there are other ways of analyzing the evidence, I don't really like addressing the same points on two different threads so I will leave most of your post there. "(iii) we've had around 0.8-0.9 oC of warming during the last 100 years. That's entirely consistent with a climate sensitivity near 3 oC of warming per doubling of atmospheric CO2, and it's rather difficult to take seriously your notion that we might have "only ~0.5C of anthropogenic warming over the next century" with a negative cloud feedback. After all where has this supposed "negative cloud feedback" been for the last 100 years?" We may have had 0.8-0.9C of warming over the last 100 years, but some of that has probably been due to natural fluctuations. The increase up to 1940 is pretty close to the increase since 1940. It is therefore pretty reasonable to say that somewhere around 1/2 of the total increase was natural. That brings the amount of anthropogenic increase up around the 0.5C mark which is pretty much consistent with a no net feedback response to CO2 forcing, which is basically my opinion. "(iv) We've already seen that we don't need a positive cloud feedback to give us well over 2 oC of warming during rhe next 100 years, and that there isn't any evidence of a negative cloud feedback." In fact, I think that if most GCMs included negative cloud feedback the sensitivity to a CO2 doubling would be under the 2.0C mark. see here. (Don't forget that we are already ~ halfway to a forcing from double CO2). ftp://eos.atmos.washington.edu/pub/breth/papers/2006/SPGRL.pdf For the record, I haven't been able to get past the paywall on the Clements paper. It looks interesting, but I have a suspicion that it treats all variation to clouds as a feedback and doesn't allow for the possibility that cloudiness can be independently forced(which would obviously have temperature effects). Cheers, :)
128492. TruthSeeker at 07:18 AM on 22 October 2009
        How do we know CO2 is causing warming?
        John, I still have some questions regarding you response to TP100 [ Response: Theory says more CO2 will trap more heat leading to global warming. Now we have observations that quantitatively confirm this. I think you have done a good job of this, but I haven't seen solid indication of the magnitude of impact (how much temperature increase can we expect with the next incremental increase in ppm concentration.) This is important to the debate, because policy is being decided based on very "scary" scenarios that this magnitude is great, but I haven't seen any science on this.
128493. chris at 05:52 AM on 22 October 2009
        What does past climate change tell us?
        Yes there's a number of reasons for being skeptical of Shaviv's study that you cite, shawnet: 1. The sub-set of tide guage measurements he used show a marked modulation with the solar cycle that isn't seen in the globally averaged sea level analysis. The fact that the satellite measure is short doesn’t discount the fact that it doesn’t show the marked solar cycle modulation; after all one only needs the satellite measures through one solar cycle to assess whether the globally averaged sea level shows the marked solar cycle modulation seen in the sub-set of continental margin-biased records…it doesn’t. The data is in the Church et al. reference I cited above – see their Figure 3. 2. This obviously leads to a problem with this measure of apparent “amplification”, and has a knock on effect with the rest of the analyses, since if this part of the analysis is likely wrong due to the bias described in (1), the agreement with the other analyses suggests that the others might also be spurious. This is particularly the case considering the fact that Shaviv’s apparent “correlations” between ocean heat content (OHC) and solar cycle is poor. So in fact the tide guage analysis actually plays a dominant role in Shaviv’s paper. As Shaviv states (see section 3.2): “Given the relatively small correlation coefficient and modest significance, it is worthwhile to corroborate the existence of the large heat flux variations using an independent data set. We thus turn to analyze tide gauge data measuring sea-level variations.” And: “Note that the relatively low correlation coefficient between the OHC and solar signals may seem somewhat suspicious” (page 10) 3. The third problem also relates to the OHC (ocean heat content) measures. Shaviv has to apply a number of corrections to remove “noise” like ENSO modulation of upper OHC, and after all of the corrections are made the correlation with the solar cycle is low as he states (see (2) above). What Shaviv doesn’t seem to have done is to remove the influence of volcanic eruptions, which is important in analyzing solar cycle related effects on OHC since for two of the 5 cycles (or 6; it’s not clear from Shaviv’s paper) analyzed, the volcanic forcing happens to be in phase with the solar cycle. This will produce a spurious “amplification” of any apparent solar effects that is not, in fact, related to solar effects. This has been pointed out by Lean and Rind in their recent analysis of attributions to 20th century warming (see section 4 on page 4 of their paper): J. L. Lean and D. H. Rind (2008) How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006 Geophys. Res. Lett. 35, L18701
128494. shawnhet at 04:01 AM on 22 October 2009
        What does past climate change tell us?
        Chris:"Whether or not the warming effect of solar activity is "amplified" or is "increased by a positive feedback" is immaterial to the question of climate sensitivity, unless one considers that there is something "special" about the forcing from solar activity that doesn't apply to other forcings." Well, clearly there is a lot different about solar activity than other sorts of forcings. Solar energy heats the oceans directly, it is composed of many different wavelengths of energy and it is correlated with other phenomena. IAC, in this context an amplification means an increased forcing. "And one has to be a little careful in taking Shaviv's analysis at face value, due, amongst other things, to his selection of data sets. For example much of his analysis is based on a set of tide guage records of Douglas (1997), which shows a marked cyclic variation of local sea level that matches the solar cycle. However, this doesn't match the globally averaged sea level variation, especially the satellite-derived record which doesn’t show a marked variation with the solar cycle" Well, given that the tide guage data set is only one of three that demonstrate the same basic magnitude of solar cycle response, the totality of the date is fairly suggestive. IAC, do you have a reference for your claim that the satellite measurements don't show a marked solar cycle response? It does not appear to be the Church reference. and regardless, satellite measurements of sea level seem much too short to reach such a conclusion(less than two complete solar cycles along with a likely PDO regime shift since satellite measurement began). You potentially make a good point about placement of the tide guages though. Cheers, :)
128495. Philippe Chantreau at 03:19 AM on 22 October 2009
        How do we know CO2 is causing warming?
        Henry pool, from the way you wprd it, I can't be sure, but I believe that what you're describing is mainly seen in the stratosphere. I recall that the Iacono and Clough (1995) paper is considered a seminal paper on the subject.
128496. RSVP at 02:00 AM on 22 October 2009
        What does past climate change tell us?
        cbrock I just read Monbiot's essay. It is a bit off topic because I was not focussing on CO2. I was implying that the negative effects of Global Warming or and Ice Age (whether man-made or not, and whether the time scale for disaster is 100, 1000, or 10,000 years) seem to indicate that there is less habitable space than one might initially suppose. In other words, even if mankind were able to supress absolutely all forms of pollution (which is nearly impossible), the natural fluctuations of global temperatures would at some point catch up with us and eat away many of the areas of the Earth that are now inhabited. It is easier to imagine (although maybe I am too optimistic here) human migrations on a less populated planet than one that is maxed-out as is the current situation. Please see: http://en.wikipedia.org/wiki/Waterworld for further reference.
128497. dopeydoctorjohn at 01:51 AM on 22 October 2009
        The growing divide between climate scientists and public opinion
        I discussed on the "there is no consensus" debate that the Doran paper comes to an invalid conclusion comparing the earth scientists views to that of the general public because the question asked of the earth scientists in the Doran survey was substantially different to the question asked of the general public in the Gallup poll. Undoubtedly most scientists in the field agree with the current dominant paradigm. Undoubtedly some do not. Sometimes the majority are wrong; but usually not. However, the Doran study is seriously flawed and tries to exaggerate the degree of consensus that exists. Because it does this clumsily and amateurishly, and is easily exposed with a little further research and thought, it actually undermines (rather than firms) belief in the consensus. There must be better "consensus" papers around than this. Regarding the extent to which there is a cultural dimension to science, I believe Kuhn's work was highly influential and some of the posters might like to have a look at it http://en.wikipedia.org/wiki/The_Structure_of_Scientific_Revolutions
128498. cbrock at 00:46 AM on 22 October 2009
        What does past climate change tell us?
        At the risk of moving a bit off-topic, I'll respond to RSVP: I think you are right that in the long term, human population is a huge concern regarding all sorts of environmental abuse and resource consumption. But for now, let's put the blame firmly where it belongs: in the hands of the industrialized societies, whose extreme per capita consumption has led to the current situation with greenhouse gases and the measured temperature increases to date and the potential increases to come. An interesting, if perhaps overwrought, discussion of this issue can be found on George Monbiot's site at http://www.monbiot.com/archives/2009/09/29/the-population-myth/. While most population increases are occurring in the less-developed nations, it is the industrialized nations, and the growth-at-all-costs economic model that we have espoused, that have led to the current levels of greenhouse gases in the atmosphere.
128499. RSVP at 20:03 PM on 21 October 2009
        What does past climate change tell us?
        I am dizzy. So the logic goes that since climate is demonstrably susceptible to change, it is easy for humans to affect change. Furthermore, by correlating the recent temperature rise with a doubling of CO2, it is possible to deduce the leverage and scale of this influence. '''''''''''''''''''''' Getting practical How productive is it to be focussing on a symptom, when the real cause and problem is overpopulation? You wouldnt have as much CO2 to begin with if there were simply less people around. Anyone bother to correlate CO2 with population growth? Curbing population will not only lower CO2 emissions, it will also give people a chance for surviving (and with less pain) the fall out of global warming. I'm sure the CO2 proponents admit that CO2 is not the only man-made factor that is contributing to global warming. And again, even if GW were completely caused by nature, the remedy for humans would be the same. Decrease population.
        Response: To answer your first section:

        1. "since climate is demonstrably susceptible to change, it is easy for humans to affect change" - well, I don't know if it's easy, we have to work pretty hard to send 29 gigatonnes of CO2 into the atmosphere every year. But the basic point is true - past climate change shows how sensitive climate is to radiative forcing - therefore it will be sensitive to the radiative forcing from CO2
        2. "by correlating the recent temperature rise with a doubling of CO2, it is possible to deduce the leverage and scale of this influence" - no, not the case. We deduce the scale of CO2 influence by calculating the radiative forcing from CO2. This is worked out using line-by-line radiative transfer codes. This result is then verified by direct observations of satellites and surface measurements which quantify the amount of longwave radiation that CO2 has sent back to the Earth's surface.

        "Has anyone bothered to correlate CO2 with population growth?" Yes, in fact, to quote Monbiot: "A paper published yesterday in the journal Environment and Urbanization shows that the places where population has been growing fastest are those in which carbon dioxide has been growing most slowly, and vice versa. Between 1980 and 2005, for example, Sub-Saharan Africa produced 18.5% of the world’s population growth and just 2.4% of the growth in CO2. North America turned out 4% of the extra people, but 14% of the extra emissions."
128500. TallDave at 11:17 AM on 21 October 2009
        Antarctica is gaining ice
        Seriously? A graph from 2002? That's just silly. By moving the range a couple points in either direction you could get a trend going any way you want. Meanwhile, there's a 20-year graph that confirms Antarctica appears to be gaining mass: http://www.gsfc.nasa.gov/topstory/20020820southseaice.html
        Response: Note: the rebuttal above has been updated since this comment was posted, incorporating later references and clarifying that sea ice and land ice are two separate phenomena. Antarctica is losing land ice at an accelerating rate. Sea ice around Antarctica is increasing. The reasons for sea ice increasing in a warming Southern Ocean are complex and described in detail above.

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