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Comments 43651 to 43700:

43651. Joel-Snape at 00:36 AM on 13 July 2013
       Empirical evidence that humans are causing global warming
       

       This is a nice and simple explanation of the greenhouse effect in action. The effective blackbody temperature of Earth when applying the Stefan-Boltzmann law is -18 or 255K and its observed temperature is 15C or 288K representing a temperature-disparity of 33K. This amounts to a huge 'radiative forcing' by the atmospheric greenhouse. in fact it amounts to 150.35W/sq.m. The idea that CO2's forcing is "small" I guess depends on your definition of `small'. Doubling atmospheric CO2 is enough to produce a radiative forcing of 3.7W/sq. thanks to thousands of line-by-line spectural computations by HITRAN, which even prominent climate skeptics such as Lindzen and Spence acknowledge is true and wholly. 3.7Wsq.m would result in an atmospheric warming of about 1.2C, with the rest accounted for by positive feedbacks inherent in the climate-system. This imples that CO2's direct warming would only need to be amplified by a mere 0.8C by feedbacks to take us to 2C, which is apparently dangerous territory for some scientists. I think skeptics such as the Sky Dragon Slayers could learn thing or two about the greenhouse with the Moon/Earth comparison. Spencer's illuminating saucepan anology and cooked chicken as a way of conceptually proving the existence of the radiative greenhouse effect is probably one of the best I've come across. You guys should do a similar thing.

43652. Tom Curtis at 22:00 PM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       Videre @66:

       1)  To a first approximation, all energy on Earth comes from the Sun.  That energy is then reradiated to space as thermal radiation (IR).  The surface temperature required to balance the incoming energy depends on:

       a)  The amount of energy from the sun which is reflected (albedo);

       b)  The level in the atmosphere from which energy is radiated to space (the greenhouse effect); and

       c)  The distribution of heat on the Earth's surface.

       The albedo is controlled by the presence and latitudes of snow and ice, the prevalence of clouds and by the prevalence of different types of vegetation.  The natural greenhouse effect is controlled by the four major naturally occuring greenhouse gases, ie, H2O, CO2, O3 and CH4.  The distribution of heat is controlled by the arrangement of the continents and milankovitch cycles.  Variation of any of these factors can result in a change in the Top Of Atmosphere (TOA) energy balance, and hence of the surface temperature.  In the face of that, saying that "its just weird that more energy was getting into the atmosphere at various times in the past even before the CO2 levels rose" is, quite frankly, silly.

       As it happens, climate scientists have a pretty good idea as to what caused increased warming durring glacial epochs (change in the distribution of heat due to milankovitch cycles, which drove changes in albedo and CO2 and CH4 concentrations as a feedback).  They also have a good idea of what those factors would be doing now without human intervention.  Specifically, the milankovitch cycle would be cooling the Earth, driving an increase in ice and snow, and a reduction in CO2 and CH4 concentration as a feedback.

       2)  The entire basis of your second point seems to be the assumption that if increased CO2 traps more heat through the greenhouse effect, then it must over ride all other influences on the Earth's temperature so that countervailing factors cannot result in cooling.  Or, to take a specific example, the fact that the CO2 forcing was sufficient for a 6.5 C increase in surface temperature 400 million years ago, would mean (by your logic) the fact that the sun was about 10% cooler that could not possible prevent that increase.  

       3)  We do not know that the current CO2 increase is anthropogenic by measuring all natural fluxes and finding a shortfall.  Rather, we have measured the human addition ot CO2 in the atmosphere, and found that less is staying in the atmosphere than we put there.  It follows that nature is taking the shortfall out of the atmosphere.  So, the error bars on our measurement of natural fluxes is irrelevant, because the error bars on our measurement of anthropogenic emissions are sufficiently small as to leave no doubt.  IF you wish to learn, you need to stop constructing straw man versions of purported scientific arguments, and address the actual arguments used by scientists.

       4)  From table 2.12 of IPCC AR4, the sum of all forcings exluding long lived greenhouse gases is  -1.24.   The forcing from long lived greenhouse gases is 2.63, leaving a net forcing of 1.39 W/m^2 (just slightly greater than that of CO2 alone).  CO2 is the largest single forcing, and the only anthropogenic forcing agent with a duration greater than a century.  No other single forcing agent has even half the effect of CO2.  Consequently your claim that, "it looks like the CO2 forcing is kind of small compared to the other effects" is pure bunkum.

       On all four points it strikes me that you are not an earnest seeker after the truth of the matter, but somebody looking for any fact to twist out of context to avoid accepting the science.  You are doing this before you even understand the science, and the result merely makes you look foolish. 

43653. chriskoz at 20:17 PM on 12 July 2013
       2013 SkS Weekly News Roundup #28A
       

       Depending on your stance on fracking (called Coal Seem Gas down under) you may welcome or dislike this news:

       Sydney water catchment fracking ruled out for now

       Clearly, people who pushed for creation of new Dharawal National Park had this in mind. Not a word about impact on CO2 pollution though: CSG is better than coal but still bad, IMO.

43654. Videre at 18:07 PM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       Thanks for the help. I guess I was trying to keep my focus on this thread and just looking at the data.

       Scaddenp, I am sorry for coming back to this thread, but it was the moderator who directed me to those other threads as having the answers to my questions about this thread, but when I read the other threads, I just had more questions about this thread so I just posted my observations from those other threads into this thread where it was relevant. I am really trying to get a handle on the maint points of this thread and the information given in this thread.

       So if I go down the main points in the summing part at the bottom of the thread with my questions I get something like this:

       1. More energy is remaining in the atmosphere. See here when he sent me to the geological pages and the energy balance it looks like more energy has come into the atmosphere lots of times, I think one of the threads says it was astronomical changes like orbits and the sun. So it just looks like there are a lot of things that have and can cause more energy to be in the atmosphere. I mean when he directed me to the CO2 lagging thread, its just weird that more energy was getting into the atmosphere at various times in the past even before the CO2 levels rose.

       2. The next is the mechanism by which energy can be trapped in the atmosphere. I guess this makes sense as being a mechanism that can do it, but then the lag problem crops up again because if CO2 lags temperature then it just seems something else traps energy too to start the temperature going up. And I guess if the greenhouse effect traps the energy, while it might not go runaway, if it was high in the millions of years past and still the temperature went down and up and down then is there something else going on too that either gets rid of heat and traps it? Its just weird that if the greenhouse effect traps energy that it wouldn’t just keep trapping energy in the past. The other thing about trapping the energy came up when I looked at the fourth point below.

       3. The next one is CO2 increasing 50% in the past 150 years. When the moderator told me to look at the history and I had already looked at the data over millions of years,   i think it went back to about 60 Ma, which I thought meant 60 million  years, there were a lot of ups and downs,  not just going up like doubling like Glenn said. Plus if the ocean temperature is going up and CO2 was going up because of the less solubility of CO2 in water I guess that could explain the CO2 rising now too, like it might have millions of years ago. It made it even worse when I looked at the CO2 balance thread the moderator directed me to where I saw those other ins and outs of CO2 were like about 10 or 20 times as big as the fossil fuel burning and land use. I know scaddemp said those much bigger CO2 sources were more or less balanced, but I thought error bars on measurements in climate science must be like 5 or 10 percent or even larger sometimes and that just a few percent of those big numbers would be a lot larger than the fossil fuel burning contribution to CO2.

       4. So the last one I wondered about too, and it is about the energy being trapped in the atmosphere is exactly the energy captured by CO2. So I looked at the link to the conference poster of Evans in 2006 and it had the radiation measurements for all the greenhouse gases but it took out water and wasn’t a peer reviewed paper so I looked at the IPCC last out report, I think its called AR4, which came out in 2007, after the Evans poster. On page 141 in Chapter 2 there’s a Table 2.1 that shows the CO2 radiative forcing in 2005 was 1.66 W/m2 and all the other gases, not CO2, add up to about 0.77 W/m2 so CO2 is about 63% of the total of those gasses. But water still wasn’t in there so I looked on page 204 still in Chapter 2 at the Table 2.12, which gives all the radiative forcings. A lot of them are negative, like ozone and aerosols and all, so if I add up all the negative ones (a big one is the cloud albedo effect) I got negative forcings of -2.1 W/m2 and adding up the total of the positive ones, not CO2, I got a positive 1.35 W/m2. The uncertainties are pretty big on the numbers too so these numbers have intervals around them like a factor of two. So what confused me is that it looks like the CO2 forcing is kind of small compared to the other effects. Just the negative ones look like they can cancel out the CO2 effect. It just seemed weird that so many other effects are going on but somehow it’s for sure that CO2 is the dominant thing.

       So anyway, I just wanted to look at the post and the information in it and try to understand the main points, which I thought were all about the empirical evidence that humans are causing global warming by increasing CO2, but wound up having a lot of questions. Sorry if I crossed the threads but I thought they all related to this one, plus I think the moderator pointed some of them out to me as helping understand this thread.

43655. Glenn Tamblyn at 17:29 PM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       Videre

       I would second Rob Honeycutt's comment.

       Also, to help clarify your thinking, you talk about 'millions of years'. Be clearer in your own mind what time scale you are thinking about because different factors have different significance over scales of millions of years, 10's of millions and 100's of millions.

       For example, over very large time scales 10's to 100's of millions of years, one needs to take account of the fact that the Sun wasn't as hot in the past and that higher CO2 concentrations in the past approximately compensate for this. Roughly speaking, every 150-200 million years that we look back in time, CO2 levels need to double, just to compensate for the cooler Sun.

43656. Rob Honeycutt at 10:28 AM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       Videre...   You're asking good questions.  Just don't make the mistake of thinking that just because you're coming up with questions that there are no answers.

       All too often I've seen folks coming to comment on SkS asking many similar such questions thinking they're somehow figuring out "problems" with climate science.  Nothing could be further from the truth.

       What they are figuring out is that climate is a very complex area of science.  This is also science that dates back to the 1820's and has been very intensely researched for many decades.  Greenhouse gas theory is on equal footing with evolution, relativity and germ theory.  That we are warming the planet through the combustion of fossil fuels is settled science.  As with all theories there are areas we don't yet completely understand.  Those areas we don't fully understand are highly unlikely to change the aspects of climate science that have been long settled.

       You'd do well to spend some time reading through all the relevant posts here on SkS.  And if the posts don't answer your questions fully, feel free to click through to the actual scientific research.  Almost every article on this site has direct links to the relevant peer reviewed research.

       Remember, most scientific research is being done by people who have dedicated their lives and careers to understanding the areas they're researching.  When you come upon something that doesn't make sense to you, that means you're just coming upon something you don't yet understand, and need to understand better.  

       If you do find things that just aren't making sense to you, as scaddenp said, post a comment in the section of the relevant article.  We all keep track of current comments, so your question won't get lost.

43657. scaddenp at 09:51 AM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       Videre - it would be better if you put your questions in the relevant thread. Very very briefly (and if you have more then PLEASE respond in the right place):

       - natural flows in and out are very large, but also more or less balanced. FF is changing that. If you messed significantly with natural flows, you would be trouble fast.

       - CO2 and methane respond to change in temperature regardless of cause of change. They magnify (over very long time scales) any other forcing that changes temperature. Water vapour does same but more or less instantly. However, the feedback is not a runaway (k<<1) so equilibrium is reached. (see here for detail if you dont understand).

43658. Videre at 09:17 AM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       That’s great, thanks. I looked at the Global Carbon Cycle link. That’s really great. What I don’t understand is that all the other parts of the carbon cycle, like the vegetation and land and the oceans and rock weathering are more than10 times the size of the fossil fuel and land use source, and I guess if they only changed like 5 or 10% they could either decrease or increase the CO2 as much as the fossil fuel burning. So if its just the fossil fuel that makes all the difference, then do we need to assume that all those other much bigger effects are staying constant within a few percent?

        

       Thanks for the link to the CO2 lag link too, but now I am more confused. It says that the initial rise in temperature was caused by astronomical things and then the ocean temperatures rose and CO2 then rose because it is less soluble in oceans if the temperature is higher. I guess that makes sense. But then does that mean that all those million years ago the same thing was going on? And I guess if the CO2 got released after the temperature went up in those long ago times and then started heating things up, I guess I don’t understand what stopped it. The other thing I guess is if the temperatures started going up and caused the CO2 to go up, how do we know that is not what’s happening now. I mean the ocean temperatures look like they are going up. How do we know, I mean from the data, that the CO2 rise in the atmosphere isn’t being caused by the rise in ocean temperature. I guess the other thing is if CO2 lagged temperatures in the past and then the greenhouse effect kicked things up a notch, so it should just keep going up. But if I look at the upper graph on the link, it looks like the temperature went up and then down a lot of times in the past 400 thousand years. So what I don’t get is, if the greenhouse effect kicks in and heats things up, then more CO2 gets released from the oceans, then more greenhouse effect kicks in, it seems like it should just keep going up and up? Or is there something else going on that is causing the temperatures to go up and down in thos 400 thousand years?  And i guess if there was something else going and we dont know what it was, how do we know its not going on now?  

       Thanks for the info on plant and animal species. I guess I was most curious about the cause effect relation between CO2, temperature, and other climate factors.

43659. mandas at 08:53 AM on 12 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       Chrisoz @9

       Thanks for that.  I didn't know the best place to post it, and I am happy for the mods to delete it.  I just wanted to bring it to John Cook's attention.

43660. Tom Dayton at 08:39 AM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       Videre, regarding your question #1:  No one has claimed that 400 ppm or 1,000 ppm of CO2 are bad for life in general.  But all individual species have evolved to thrive in certain environments, including a certain range of CO2 levels.  When any aspect of their environment changes "slightly" and/or "slowly," individual animals and plants might be able to cope, and even if individuals cannot cope, their species might be able to evolve to cope.  But if some aspects of their environment change "too much" and/or "too fast," individual animals cannot cope well or at all, and species cannot evolve fast enough to avoid extinction.  Making the whole thing even more precarious are the interdependencies of plant and animal species.  If just one species' numbers fall, or if their characteristics or behavior change, a large number of other species can be affected even to the point of extinction.  The big problem for us and all other current life is that CO2 is rising so fast that many species cannot evolve or move or otherwise adapt fast enough to the temperature and other climate changes, or to the ocean chemistry changes.  For some examples, see the post It's Not Bad, and be sure to read all three tabbed panes (Basic, Intermediate, and Advanced).

       Regarding increased CO2 increasing plant growth and using less water:  Yes, there are some benefits at some levels of CO2 increase for some plants.  But it is not a uniform benefit across all levels of CO2 or plants.  And increased growth of crops often means the extra growth goes into of the parts of the plants that humans don't use, such as woody stalks of plants whose leaves and fruit we eat.  More importantly, increased CO2 does not come by itself; it causes climate changes such as increased temperature and changed precipitation patterns, and ocean acidification that detrimentally affects fish, coral, and even vast numbers of microscopic creatures on which other creatures in the food pyramid depend.

43661. william5331 at 06:39 AM on 12 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       Fair enough Mr Kraut-hammer.  You don't beleive in climate change so forget climate change.  Look at the damage you are doing to your country which has nothing to do with climate change.

       http://mtkass.blogspot.co.nz/2010/10/forget-climate-change.html

43662. tcflood at 05:42 AM on 12 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       chriskoz @8:

       Krauthammer is one of a dozen or so ultra-right-wing appologists that we can all name who can be depended on to faithfully ignore facts to spout thier wingnuttery. Such people are not worth the space at SkS.

43663. Videre at 05:34 AM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       This is good information. One thing I am trying to understand. If I look at the current understanding of CO2 levels over millions of years, reconstructed by a variety of methods like ice cores, plant stomata, and geochemistry, all put together, it looks like the levels of CO2 went up and down a lot and were way higher in the past than they were now, like 1000 or 1500 ppm. A recent paper on it is at

       http://ajsonline.org/content/311/1/63.short

       but there are lots of other papers like that too. So what I am curious about is

       1) During a lot of those times millions of years ago, the earth was fairly lush and had a lot of flora and fauna, and I guess evolution was taking place. I think man is supposed to have evolved about then.  But if 400 ppm or 1000 ppm are bad for life, why was there so much life going on then? I mean even now there’s a lot of stuff being published about how trees and plants and other flora are using water better, growing faster and things like that, for example the USDA just said trees are using water a lot better at

       http://www.nrs.fs.fed.us/news/release/trees-water-atmospheric-co2

       2) The CO2 levels went up and down a lot it looks like over millions of years so. I guess that means that a lot of natural processes affect CO2 levels? Or is it just man that does it? I mean what was making the CO2 go up and down for all those past millions of years?

       Just curious.  Thanks for your reply.

        

       Moderator Response:

       [TD] Excellent questions.  For answers to your question 2, see the post How do human CO2 emissions compare to natural CO2 emissions? (after you read the Basic tab, click and read the Intermediate tab) and the post Understanding the long-term carbon-cycle: weathering of rocks - a vitally important carbon-sink.

       For one specific example, see CO2 lags temperature - what does it mean?

43664. John Hartz at 00:36 AM on 12 July 2013
       Empirical evidence that humans are causing global warming
       

       @Terranova #48:

       My satement about the rapidity of climate change being generated by mankind's activities is based upon a body of science very nicely articulated by Gavin Schmidt and Joshua Wolfe in their book, Climate Change: Picturing the Science, W.W. Norton Company Ltd, 2009.

       Here's what they say: 

       “Over eight glacial cycles in 650,000 years, global temperature and the amount of CO2 in the atmosphere have gone hand in hand. When temperatures are high, so are CO2 amounts and vice versa. This obvious connection is part of a coupled system in which changes in climate affect CO2 levels, and CO2 levels also change climate. The pacing of these cycles is set by variations in the Earth’s orbit, but their magnitude is strongly affected by greenhouse gas changes and the waxing and waning of the ice sheets.

       “Despite these large natural CO2 variations, atmospheric CO2 variations remained relatively stable over the 12,000 years from the end of the last ice age to the dawn of the industrial era, varying between 260 and 280 ppm. Methane, too, was stable during this period varying from 0.6 to 0.7 ppm. These trace-gas concentrations are well known from analyzing air bubbles trapped in ancient snowfall. This relative stability came to an abrupt end with the onset of the industrial era. At that point, we started transferring to the atmosphere carbon that had been stored in underground reservoirs for millions of years. These modern increases have occurred in a geologic blink of the eye, dwarfing the rate of increase coming out of the last ice age. Plotted on the same graph as the ice age change, the industrial era increases look like vertical lines.”

43665. Paul D at 21:31 PM on 11 July 2013
       The Consensus Project self-rating data now available
       

       Yeah Tom.I realised after posting the comment that i was going for the earliest point where there was a clash, rather than the most recent.

       I have added some more graphs to the TCP datavisualisation that show the accumulation over the years since 1991. It's currently being tested.

43666. c.change at 20:18 PM on 11 July 2013
       Climate Change Denial now available as Kindle ebook
       

       Thanks chriskoz. Great idea.

43667. chriskoz at 19:48 PM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       mandas@7,

       A news like yours belongs to SkS Weekly Digest or SkS Weekly News Roundup threads. Please post it there (and mods should delete it from here together with my comment herein) thanks.

43668. chriskoz at 18:56 PM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       It'e worth mention the little fact that before 2012 election, Krauthammer predicted that the election would be “very close” with Mitt Romney winning the popular vote by “about half a point & Electoral College probably a very narrow margin".

       We know know, by  comparing to e.g. Nate Silver, that Krauthammer "prediction" had nothing to do with scientific polling & binomial distribution analysis but rather with unrealistic wishful thinking.

       Krauthammersince addmitted his prediction was incorrect but is still claiming that " that "Obama won but has no mandate." (source). So, in his illusionary world of "no presitential mandate", the only appropriate thing is to negate and deny what Obama says. I rest my point. It'w worthless to spend any more time listening to that man's comments.

43669. Rob Honeycutt at 16:33 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Terranova @48...  "You cannot dismiss the contribution of water vapor."

       Definitely not dismissing it in the least.  I'm just saying that for the purposes of understanding what human factors of impacting changes in global temperature, the fact that WV is not on the spectral graph has no bearing on the point being discussed.

43670. Rob Honeycutt at 16:27 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       William...   "Where I live, H2O is a very long lived gas."

       Your comments demonstrate a fundamental lack of understanding of the physics being discussed.  WV is not a long lived gas, and as has be stated by others here, is also a condensing gas.  CO2, CH4, etc. are all long lived non-condensing gases in our atmosphere.

       Think about it this way.  What is the WV content of the atmosphere where you are when the temperature goes below zero C?

43671. mandas at 14:13 PM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       John

       I know this is off topic, so I apologise for that.  But I had to provide this link to this thread at WUWT.  The conspiracy theorists are out in force today: http://wattsupwiththat.com/2013/07/10/macquarie-university-responds-to-murry-salby-termination-issue/#comment-1361244

43672. Philippe Chantreau at 13:08 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Jason says " If humanity was busily attempting to artifically cause global warming by increasing atmospheric H2O levels, it would fail,"

       True but it's ironic that we kinda are attempting to do just that. Burning hydrocarbons can be summarized by the simplified relation: CH + O2 ---> CO2 + H2O.

       So we do release large amounts of water vapor in the atmosphere through the combining of atmospheric oxygen with fossil hydrogen. As I recall, the decrease in atmospheric oxygen has even been observed.

       So, William, even if your argument had any validity in physics (which it doesn't), it would constitute even more of a reason to decrease fossil hydrocarbon consumption.

43673. DSL at 13:06 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       John @ 20: "Problem is that when those events occurred in the past, they gnerally occurred over a geological time scale."

       Terranova @ 48: "JH at 20: prove that statment. No models, but proof."

       Here you go, Terranova: http://tinyurl.com/l5wz6zc

       Ask a broad question, get a broad answer.  Did you want John to do your thinking as well?  Btw, science is not going to provide you with proof for a positive hypothesis.  Perhaps you meant "evidence."  If you want absolute certainty, go find a priest.

43674. DSL at 12:55 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       William Haas, you seem to think that where you live is isolated from the rest of the climate system.  Are you sure you want to claim that dropping CO2 completely from the atmosphere would have no appreciable effect on your local water vapor concentration?  H2O is a powerful greenhouse gas, but it's also a fast feedback--not a forcing.  It responds very quickly to other forcings.  Its residence time makes it unable to produce any climate-scale trend in global energy storage (not even close).  It follows GHG forcing (rising rapidly).  It follows solar forcing (flat or falling for fifty years).  Harp on WV all you want, but it doesn't do the driving.

43675. JasonB at 12:55 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       William,

       One other point:

       H2O does not need any other greenhouse gas to exist in the atmosphere in order to provide its greenhouse gas effect.

       That's actually not true. With no CO2, the earth would freeze into a snowball and at low enough temperatures there will be no H2O in the atmosphere. The reason the earth escaped snowball earth situations in the past was because CO2 and methane released from vocanoes was not being taken up by rock weathering (due to the rock being covered in ice) allowing the concentrations to reach high enough levels that the greenhouse effect could melt the ice. The transitions between snowball earth and hothouse earth can't be explained without those other greenhouse gasses.

       So while H2O provides over half of the total greenhouse effect currently, it only does so thanks to the other greenhouse gasses. Again with the turbo analogy: no matter how powerful a turbo is, it has exactly zero effect when the car is switched off. Drive at 200 km/h and it could well be causing the engine to produce more than twice as much power as an equivalent engine without a turbo, but it's still dependent on the accelerator to do its job.

43676. JasonB at 12:47 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       William,

       The fact that H2O levels are high where you live is really missing the point. How long would an artifically induced change in those levels last?

       The answer is "a few weeks". If humanity was busily attempting to artifically cause global warming by increasing atmospheric H2O levels, it would fail, because any extra beyond what the atmosphere can carry will simply precipitate out. To increase H2O levels long term requires increasing the temperature, which is exactly how H2O acts as a feedback to warming by CO2.

       Contast this with CO2. It will take thousands of years for an increase in CO2 levels to revent naturally. During that entire time, the greenhouse effect is enhanced.

       As I mentioned before, H2O is the turbo, CO2 is the accelerator. Travelling at 200 km/h the turbo is probably responsible for quite a lot of the engine's power output, but that doesn't change the fact that the turbo is still a slave to the accelerator and it's the accelerator that's responsible. Nobody's ignoring H2O, we're just focussing on what actually matters when it comes to driving climate change.

43677. William Haas at 12:30 PM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Honeycutt #47, Thank you for reading my post and commenting.  Where I live, H2O is a very long lived gas.  It is always there in very abundant quantity.  An individual molecule may leave the atmosphere but it is always replaced by another one,  H2O is the primary greenhouse gas and has a whole slew of LWIR absorption bands  H2O does not need any other greenhouse gas to exist in the atmosphere in order to provide its greenhouse gas effect.  H2O is the weather maker.  Ignoring it leaves a big whole in the argument.  "Dwarfs all other greenhouse gasses" cannot be inferred from the chart because the greenhouse gas that is responsible for most of the greenhouse effect was filtered out of the chart.

       Moderator Response:

       [GPW]: William, there are a few other points I'd like to make about water vapour (UK spelling). CO2 is now a precursor of warming, WV is a function of it. CO2 is well-mixed globally, WV is not. The residence time of CO2 is centuries or even millennia; the residence time of WV is days or weeks.

       We humans are not directly adding WV to the atmosphere (although it increases through chemical reaction and increased evaporation). We are adding CO2, methane etc. And finally, the reason WV was left out was explained by DSL earlier (thanks DSL), and in the paper from which the graph was obtained (post #10). I'll repeat the extract of the paper once more:

       From the paper: "The contribution of water vapour to the increase in greenhouse radiation has not been included since it is a part of the natural climate feedback. There is some argument to suggest that tropospheric water vapour has already increased by several percent; hence, the corresponding flux contribution may need to be included, but this effect is beyond the scope of current models."  

43678. Tom Curtis at 11:42 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Terranova @48, from forcings alone, we expect 3.7  Wm^-2K^-1.  That is, for each one degree C increase in temperature, we expect a 3.7 W/m^2 increase in outgoing radiation.    The observed ratio is 0.75 Wm-2K-1, the difference being the net effect of all fast feedbacks, including the water vapour feedback, so my calculation already includes water vapour.  It does not include slow feedbacks such as glacial melt so the final equilibrium response will be greater than that indicated by the calculation, although it will take centuries and possibly millenium to reach that equilibrium response.   

43679. JasonB at 11:41 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Terranova,

       You cannot dismiss the contribution of water vapor.

       I wouldn't dream of it, water vapour is a significant feedback that approximately doubles the warming effect that increased CO2 would have on its own.

       But pointing it out in this context is like a driver complaining to the cop who just pulled him over for speeding that it's the turbo's fault that he was going so fast and not the position of his foot on the accelerator.

43680. Terranova at 11:12 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Rob at 47

       TC at 46

       William at 45 made a point that is valid, and not moot.  You cannot dismiss the contribution of water vapor.  

       Mind you, I do not disagree that human actions have contributed to increased CO2 in the atmosphere, and the increased CO2 has led to some increase in temperature.

       And, JH at 20: prove that statment.  No models, but proof.

43681. Rob Honeycutt at 10:23 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       William @45...   Being that WV (which you're referring to) is not a long lived gas, it responds to the forcing from these other gases.  So, your point is moot.  Including WV doesn't change the accuracy of the statement.

43682. Tom Curtis at 09:48 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       eklectikus @33, from 1900, total forcings have increased by approximately 1.56 W/m^2.  The current TOA energy imbalance is approximately 0.63 W/m^2 meaning there has been an increase in outgoing radiation of 1.2 W/m^2 due to increased temperatures of about 0.7 C over the twentieth century.  Therefore, each degree C of increased temperature results in about  1.32.  That means it would take a  2.8 C increase in temperature to compensate for a doubling of CO2.  It would also take a 1.35 degree increase to compensate for the increase in CO2 forcing since 1970.

       It is not that there is no empirical evidence.  It is that some people are eclectic about the evidence they will look at.

43683. Tom Curtis at 09:23 AM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       I detest the moral bankruptcy of the argument that China is emitting more than the US, so the US need to nothing.  In fact, the Chinese individually (ie, per head of population) are emitting much less than US citizens individually.  Therefore it is incumbent on US citizens individually to reduce their emissions more than Chinese citizens individually; and on the governments of the respective nations, as agents of the people, to assist them in doing so.  Ignoring the per capita emissions tacitly endorses the claim that US citizens are entitled to a greater share of world resources (in this case energy resources) than Chinese citizens as a matter of policy.  Hence the moral bankruptcy of the argument.

       Not only is the argument morally bankrupt, it is also entirely hypocritical.  No supporter of the argument would endorse a global agreement on CO2 emissions which entitled Tuvalu or Monaco to the same national emissions as the US.  Doing so would limit the US to 0.5% of global emissions, compared to their current 18.5%.  They would undoubtedly reject such an arrangement as unjust based on differences in population; thereby rejecting the uniform application of the principle they want to apply to China to excuse their excess emissions.

       Somebody who trots out that argument deserves nothing but contempt. 

43684. Tom Curtis at 09:11 AM on 11 July 2013
       The Consensus Project self-rating data now available
       

       Paul D @10, based on the interactive history, in the decade from 1961 to 1970, 20% of papers with a position where skeptical.  While still a majority opinion, that suggests acceptance of AGW was hardly a consensus at that stage.  Further, despite the evident overwhelming majority of papers endorsing the consensus from 1990, evidence from other sources suggest the consensus among scientists did not form until after 1995 and possibly not till after the Third Assessment report.  It is very evident, however, that once the number of studies per decade started increasing, the consensus formed very rapidly.

43685. Don9000 at 09:01 AM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       men. Oops.

43686. Don9000 at 08:59 AM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       The media outlets that carry such columns are in effect aiding and abetting the deniers. Krauthammer and George Will are two similar peas in the same pod when it comes to global warming denial. I take comfort that they are both old me.

43687. Tom Curtis at 08:04 AM on 11 July 2013
       The Consensus Project self-rating data now available
       

       dana @9, the claim that "skeptics" are "more likely to pretend to endorse it in the abstract while claiming they rejected it in the full paper" is not supported by Poptech' sample.  One of Poptech's sample (Scaffeta) outrageously misrepresents the nature of the scientific consensus so that he can falsely claim an error in the abstract rating.  Shaviv's abstract, however, concludes:

       " Subject to the above caveats and those described in the text, the CRF/climate link therefore implies that the increased solar luminosity and reduced CRF over the previous century should have contributed a warming of 0.47 ± 0.19°K, while the rest should be mainly attributed to anthropogenic causes. Without any effect of cosmic rays, the increase in solar luminosity would correspond to an increased temperature of 0.16 ± 0.04°K."

       The increase over the 20th century was 0.7 K, so the paper attributes greater than 50% of warming to natural causes under an assumption the authors are willing to entertain. That indicates the paper should be rated (IMO) as at most a 5 (implicitly rejects), and certainly not, as it was actually rated, at 2 (Explicitly endorses).

       In like manner, Idsos' abstract describes the impact of enhanced growth on the seasonal cycle in CO2 and should probably (and at most) have been rated neutral, but was actually rated 3 (implicitly endorses).

       These two examples represent genuine mistakes.  Of course, Poptech has only found two genuine errors from among a very large number of abstracts rated as endorsing the consensus.  As always, he avoids mentioning the denominator.

43688. William Haas at 07:13 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       The statement: " But the spike for CO2 on the left dwarfs all the other greenhouse gases, and tells us something very important: most of the energy being trapped in the atmosphere corresponds exactly to the wavelength of energy captured by CO2." is wrong because the primary greenhouse gas in our atmosphere was not included.

43689. Paul D at 06:41 AM on 11 July 2013
       The Consensus Project self-rating data now available
       

       Nichol@5

       "How far would you need to go back to the time when there was still a reasonable controversy over climate change among climate scientists?"

       Try the An Interactive History of Climate Science gizmo.

       I suggest about 1900 or 1901 and the Angstrom/Arrhenius disagreement.

        

        

43690. James Madison at 04:47 AM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       ahh, I see, beer is not just for breakfast anymore, eh?

       If this is what one understands after reading the Krauthammer piece, then, well, one will never understand why climate change and its solutions are not taken seriously by the majority.

43691. Eclectikus at 04:24 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       #43 Amen.

43692. Dikran Marsupial at 04:22 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Eclectikus, there are "skeptics" who claim that there is no such thing as the greenhouse effect, for example "Atmospheric "greenhouse forcing" does not warm the planet, never has and never will. In fact, the very idea that there is a greenhouse effect in our atmosphere is absurd.".  So while skeptics are generally letting go of climate myths such as "there is no empirical evidence" one by one, there is still a need to deal with these myths for the sake of those who have heard them from the misguided and want to hear the other side of the story.

       Please do not further disrupt the discussion of the science by trying to hold an off-topic meta discussion about what the site should be for.  SkS has been around for a while, and a fair bit of thought has gone into who the intended audience actually is, and which arguments ought to be addressed.

        

43693. Eclectikus at 04:03 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Thanks heb0 #40. I'm an old reader of this blog, and just wanted to point out what I pointed out. In this case it's more like to tell my mechanic that the spark plug that he put to my car was secondhand. Question of nuances.

43694. Eclectikus at 03:54 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       DSL #37
       I understand that there is people with no background in Science, and that they form their opinion on the debate based on their political bias, but I did not know that this site was dedicated to those people, in fact, I'm pretty sure that that kind of people do not read these entries, and in the rare event that they stumble upon them, they will understand nothing. So if it comes to send a message, I think is better that the message be correct, and in someway to imply that skeptics discusses the anthropogenic CO2 causes some warming is fallacious. The dispute comes in how much warming, not in ellemental physics.

       Of course there has been a lot of improvement over the last years, in Climatology, and in all... but still we are in the first stadiums in terms of empiric verification, probably (surely) is not a scientists fault, is by the very nature of this Science. So a minimum of caution on predictions should be compulsory.

       If there were evidence of catastrophic character of the case, there would be no discussion, no one can be interested in destroying a planet or its inhabitants / customers. And use weather events of the present and the recent past does not seem very tight to the scientific method.

       Thanks for the link, I leave it as homework for tonight.

43695. heb0 at 03:29 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       @Eclectikus - The style of presentation of this website is to address specific myths about global warming. You're bringing up questions that this article doesn't claim to address and then comaplining whenever they aren't answered in it. A bit like throwing a fit at your local mechanic's shop because they don't stock croquet sets.
       
       If you're interested, there are other articles on this site that address the questions you're asking:
       
       

       • "It's Not Bad"
         
       • A Comprehensive Review of the Causes of Global Warming
43696. ajki at 03:15 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       In addition to the ASRB network [MeteoSwiss] reference @38 it may be useful to mention a very short and recently published overview [free access!] on the current status of measurements of radiation profiles by Philipona:

       Philipona, R., A. Kräuchi, and E. Brocard (2012)
       Solar and thermal radiation profiles and radiative forcing measured through the atmosphere
       Geophys. Res. Lett., 39, L13806, doi:10.1029/2012GL052087

43697. ajki at 02:57 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       bouke @26: I always thought it was too difficult to measure this accurately enough. Could you provide a reference to this?

       The "classic" reference would be:

       Philipona, R., B. Dürr, C. Marty, A. Ohmura, and M. Wild (2004)
       Radiative forcing - measured at Earth's surface - corroborate the increasing greenhouse effect
       Geophys. Res. Lett., 31, L03202, doi:10.1029/2003GL018765.

43698. DSL at 02:52 AM on 11 July 2013
       Empirical evidence that humans are causing global warming
       

       Eclectikus, "we" know it, but I talk with people every day who confidently claim that human CO2 does not contribute to global warming, and in fact that it's all a hoax.  This website is aimed partially at those people and partially at the people who are lying to to the claimers.

       I disagree on the no progress in thrity years claim.  Articulating the strength of the various forcings has come a very long way in thirty years.  You're going to have a hard time arguing that the last thirty years' worth of sensitivity, feedback, and modeling work has all been redundant and pointless.

       "catastrophic" as you define it is no definition.  All you're saying is "well, catastrophic as other people use and define it."  What does "catastrophic global warming" mean to you?

       Sure, CO2 concentrations are important for life at both ends of the ppm range.  Yet pushing the extremes of that range is not what the current problem is all about.  Within the context of rapid climate change via anthropogenic global warming, discussing the extreme ends of the range is irrelevant--basically a red herring made of straw.  Discussing the effect of the likely range of change on plant life is relevant.  

43699. ubrew12 at 02:32 AM on 11 July 2013
       Charles Krauthammer's flat-earther global warming folly
       

       Krauthammer is worried about the cost of transitioning to renewables because of "the problematic nature of contradictory data."  Is that like the data presented by weapons inspectors before the U.S. invasion to find Iraqi WMD?  The data that there WERE no WMD?  April22nd is now celebrated as 'Krauthammer Day', when he opined: "Hans Blix had five months to find weapons. He found nothing. We’ve had five weeks. Come back to me in five months. If we haven’t found any, we will have a credibility problem." uhh... ok...

       http://crookedtimber.org/2010/04/22/have-a-blessed-charles-krauthammer-day/

       And what did Krauthammer learn after spending $3 trillion in Iraq to obtain zero WMD? In 2004, he opined "we should have invaded Iran"!!  It should be obvious that 'the problematic nature of contradictory data' has never bothered Krauthammer before, and does not now.

       Krauthammer: "I’m not against a global pact to reduce CO2. Indeed, I favor it."  I like these 'standard disclaimer' lines at the end his piece.  As in: "The science on global warming isn't sufficient to do anything about CO2  ...  except a GLOBAL PACT REDUCING IT!!"  (by force of American military might, perchance?  What's not to love, for a neocon like Krauthammer?). 

43700. dana1981 at 01:57 AM on 11 July 2013
       The Consensus Project self-rating data now available
       

       Not only is Poptech's sample of 7 much smaller than our author self-rating sample of 1,200 (and over 2,100 papers), but his sample is biased toward "skeptics" who are more likely to reject the consensus, and also apparently more likely to pretend to endorse it in the abstract while claiming they rejected it in the full paper.  Not exactly a compelling argument against our paper and conclusions.

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