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Comments 127301 to 127350:

127301. pekka.lehtikoski at 16:08 PM on 11 October 2009
        Human CO2 is a tiny % of CO2 emissions
        This is a very good article, and it and comments answered to some of my questions. I hope you would post this content also in Wikipedia's [Carbon cycle] article, and link the article in wikipedia back to this page.
127302. Tom Dayton at 15:46 PM on 11 October 2009
        How do we know CO2 is causing warming?
        RE: #24 RSVP and #25 my reply: Look in the green box immediately above this Comments section. There our host John Cook has supplied a link to an extensive collection of literature on the laboratory measurements of CO2 absorption properties.
127303. pekka.lehtikoski at 14:28 PM on 11 October 2009
        A broader view of sea level rise
        Raising sea level seems almost a fact, and measurements appear good. But does this have any connection to global warming theory?
        Response: By "global warming theory", I assume you mean the notion that humans are causing global warming (also known as anthropogenic global warming or AGW). What does rising sea levels prove? It tells us that the planet is warming. We know this because the two major contributors to rising sea levels are thermal expansion (warming oceans) and melting land ice/glaciers.
        
        Does rising sea levels prove that mankind is causing global warming? No. The reason we know we're causing global warming is because we're raising CO2 levels and CO2 traps heat which leads to the planet accumulating heat.
127304. pekka.lehtikoski at 13:32 PM on 11 October 2009
        Is Antarctic ice melting or growing?
        The noise in ice mass data graphs compared to length of time period is poor. With this data the regression line can point to any direction, depending on selection of start end end dates, and calculated confidence in result will be 0. Besides I could find no significant correlation to NASA's temperature data. If you used better data, please include link. BR Pekka Lehtikoski
127305. Robbo the Yobbo at 13:11 PM on 11 October 2009
        How do we know CO2 is causing warming?
        I will add a couple of additional sources that address decadal climate variation – by Dr Syun Akasofu and Professor Ole Humlum. http://wattsupwiththat.com/2009/03/20/dr-syun-akasofu-on-ipccs-forecast-accuracy/ - a reasonable summary http://www.iarc.uaf.edu/people/indiv/iarc_all_staff.php?photo=sakasofu - home page of Dr Akasofu http://www.climate4you.com/ - home page for Prof. Humlum The planet isn’t currently warming and the IPCC is a political stuff up rather than a credible scientific oganisation.
127306. JohnMashey at 13:10 PM on 11 October 2009
        How we know global warming is happening, Part 2
        Nice article John, and the new website design is terrific. Thanks so much (and you should advertise, or if you did I missed it). All: see IPCC WG I, Section 5.2.2.3,Implications for Earth's Heat Balance, p.8 of the PDF, an especially Figure 5.4, which has a great chart that shows the heat takeup of various Earth elements, with error bars. Of course, there is newer data,but this is a great, an publicly-accessible summary, an that one chart eliminates a lot of silliness. Volcanoes aren't there, because undersea volcanoes are essentially irrelevant: they just don't produce enough heat to be interesting. Of course, big surface volcanoes cane relevant, but only when (like Pinataubo), they send enough sulfate aerosols high enough to cool the Earth. "Undersea volcanoes" are what I'd call M2 memes propagated by the usual blogs to confuse the unwwary. I.e., to see that they are wrong, you need to know just a little bit of climate science. (John: maybe it's worth augmenting your volcanoe discussion with a bit about undersea volcanoes, if you don't want to give that it's own item.
        Response: New website design? You haven't been here in a while, have you, John?
        
        Are you sure that link to the IPCC report is correct? If you have links to data on undersea volcanoes, please do post them - would be much appreciated.
127307. Robbo the Yobbo at 12:14 PM on 11 October 2009
        How do we know CO2 is causing warming?
        The essential question is not whether greenhouse gases are greenhouse gases – but to what extent they interact with myriad other factors to influence global climate. Ocean heat content has plateaued. The OHC page at the NODC shows the latest update. http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/index.html Schuckmann et al may indeed show a slight increase in OHC to 2000m – with everyone else showing slight cooling to slight warming to 700m. Talk about cherry picking. With a reduction in TSI since 2000 (http://www.pmodwrc.ch/pmod.php?topic=tsi/composite /SolarConstant) and a 1% increase in Earth albedo over the same period (http://www.bbso.njit.edu/Research/EarthShine/) – it would be very surprising if there were much warming going on. Schuckmann et al may need to revise their depth integrating or areal averaging algorithms. TSI will increase over the upward arm of the current 11 year cycle – but the longer term trend is downward. One should anticipate significant variability in ocean heat content – it is blindingly evident in the record of the recent past and ocean heat content must continue to be variable. Natural climate variability should be anticipated on 20 to 30 year – and longer - timescales. You continue to argue that natural variability is evident as an explanation for short term cooling – but continue to be non specific about what drives variability in the earth’s heat budget. I quote from NASA’s SORCE pages. ‘The Sun and Global Warming Of the many trends that appear to cause fluctuations in the Sun’s energy, those that last decades to centuries are the most likely to have a measurable impact on the Earth’s climate in the foreseeable future. Many researchers believe the steady rise in sunspots and faculae since the late seventeenth century may be responsible for as much as half of the 0.6 degrees of global warming over the last 110 years (IPCC, 2001). Since pre-industrial times, it’s thought that the Sun has given rise to a global heating similar to that caused by the increase of carbon dioxide in the atmosphere. If the past is any indication of things to come, solar cycles may play a role in future global warming.’ http://earthobservatory.nasa.gov/Features/SORCE/sorce_04.php Before you suggest that TSI peaked in 1958 – look at the TSI reconstructions in this report for AR4 from the British Met Office. Better yet - read the whole report. This should include the section on possible amplifying mechanisms for subtle solar variations. http://www.metoffice.gov.uk/publications/HCTN/HCTN_62.pdf It is very odd indeed you can insist on feedbacks for greenhouse gases – but want to ignore the feedbacks for solar variations. For example an increase in TSI and temperature leads to an increase in water vapour in the atmosphere. The same feedback as carbon dioxide – but with several others thrown in as well. While there is still considerable doubt on the exact values of TSI and TSI changes over time – the SST changes observed directly and as a result of interactions with global hydrology are reasonably conclusive. We are looking at natural variability producing a cooling influence for 20 to 30 years from 2000. The question of whether this is ‘warming interrupted’ – e.g. realclimate, Keenlyside, Swanson and Tsonis and Mojib Latiff – or something else entirely is not answerable at this time. However, from a number of lines of evidence – anthropogenic warming is at most 50% of what is claimed by global warming activists. Activists such as yourselves are continuing to promote alarmism. You need to develop a more nuanced understanding and a less dogmatic approach.
        Response: How is it cherry picking when you're including MORE data (down to 2000 metres as opposed to only down to 700 metres). As you say, with a reduction in solar activity since 2000, if the oceans are still retaining heat at a rate of 0.77 ± 0.11 Wm⁻², there is obviously some other cause besides solar variations causing the energy imbalance. And considering we have satellite and surface measurements giving empirical confirmation of an amplified greenhouse effect, it's not surprising at all.
        
        Regarding positive feedbacks, these apply to any sort of warming whether they be CO2 warming or solar warming. And there is always the possibility that there are other feedbacks unique to solar variations (eg - changes to ozone in the stratosphere, cosmic ray modulation of clouds). But if solar activity does have a greater effect on climate than generally thought, then what does that say about the current situation where oceans are showing a strong warming trend simultaneous to the sun cooling to it's lowest levels in a century?
127308. shawnhet at 09:37 AM on 11 October 2009
        Are humans too insignificant to affect global climate?
        The paper referencing my above claim that the Earth has become 6% greener is Climate-Driven Increase in Global Terrestrial Net Primary Production from 1982-1999. Nemani et al. Also, above I made a typo above ... which have rather larger impacts on CO2 should read "...which have rather larger imapcts on plant growth". Cheers, :)
127309. shawnhet at 09:26 AM on 11 October 2009
        Are humans too insignificant to affect global climate?
        Philippe, I would actually agree that CO2 is a minor factor compared to water and nutrients, but the point about constraints is that they matter **on the margins**. Imagine a plant could grow at speed S1 if it has N amounts of nutrients and W of water and C of CO2. The same plant, however, could grow at S2, if it had 2N, 2W and 2C, however, if it has 2N, 2W and 1C, it will only grow at speed S1. IAC, this point is moot, as a warming planet also has more water vapor in the air and more precipitation which have rather larger impacts on CO2. David Horton: If CO2 isn't good for plants, why do greenhouses pump it in? That one simple question will put all your silliness in context. People whose livelihood depend on growing plants quickly disagree with you about the benefits of CO2. Put simply, plants get carbon from the air and if the air has less carbon in it, a plant has to move a greater amount of air through its system to grow *when everything else is equal*. Calling something "denialist" doesn't address whether it is true. Also, your common sense idea that the Earth is getting less green is not science. I will try to find the reference that demonstrates how it is in error. Cheers, :)
127310. shawnhet at 09:10 AM on 11 October 2009
        How we know global warming is still happening
        WeatherRusty, I'm confused. Don't you agree that condensing water is a primary constituent of clouds? Doesn't it follow then, that more condensing water makes it easier for clouds to become larger and thicker? Aren't the clouds in the tropics thicker and deeper than clouds in other parts of the world? OTOH, to require that there is positive cloud feedback requires that it becomes *harder* to condense sufficient moisture out of the air to form a cloud of size X as that air becomes more moist. Chris, THanks for the CLement paper, I'll take a look at it. Cheers, :)
127311. David Horton at 07:57 AM on 11 October 2009
        Are humans too insignificant to affect global climate?
        Philippe, I commend your patience and politeness in dealing with the denialists on this blog. You are a better man than I. But the comment at #16 above could serve as a text book case of denialism in action. Mr Het believes the coal industry propaganda that CO2 is a "nutrient" and good for you. He plucks from somewhere, anywhere, who knows, perhaps just a figure made up by a denialist on another blog, the nonsense "6% increase in plant life on Earth over the last 20+ years". Who knows what this even purports to mean, as you pint out, but given the continued land clearing activities in Indonesia, the Amazon, Australia and elsewhere, common sense alone would tell you that "vegetation cover" of the planet is continuing to decrease. In addition we know that the effects of drought are both causing the loss of more vegetation and putting forests under stress so that they can absorb less CO2. Mr Het either knows none of this, or cares less, but he has wasted your time, and mine, and helped to fill up another thread with rubbish, hoping, no doubt that some other gullible person somewhere will pick up the "6%" pseudo data and run with it elsewhere. On John's next post our other resident denialists are up to the same tricks "water vapour" "CO2 saturation" "ocean absorption" "Nuclear tests(!)" and calls for "laboratory experiments". Again, they have no idea what these things mean, they are just random noise injected into a thread to try to stop the clear explanations of data provided by John being accepted by readers. Next thread they will be back again either with the same non-points or with other pieces of foolishness ("submarine volcanoes" "cosmic rays"). I am dealing with a plague of mice at present. I catch one, put it outside, catch another next day, put it outside, and on, and on. Doesn't matter how many mice I catch, they just seem to keep coming. Almost makes me think they have some way of multiplying faster than I can catch them. Just like denialists, except they have caused far more serious damage than a few mice..
127312. chris at 07:49 AM on 11 October 2009
        How we know global warming is still happening
        Re #58 Shawnet. The evidence supports the expectation from basic physics encapsulated in models that the atmosphere retains a roughly constant relative humidity as it warms [*] Also, the evidence indicates that a warming world doesn’t mean more clouds; in fact observational evidence from the Pacific indicates that cloud cover may decrease in a warming world. That’s the conclusion from a study just published in Science [**] [*] Dessler, A. E. et al. (2008), Water-vapor climate feedback inferred from climate fluctuations, 2003–2008 Geophys. Res. Lett., 35, L20704 Abstract: Between 2003 and 2008, the global-average surface temperature of the Earth varied by 0.6°C. We analyze here the response of tropospheric water vapor to these variations. Height-resolved measurements of specific humidity (q) and relative humidity (RH) are obtained from NASA's satellite-borne Atmospheric Infrared Sounder (AIRS). Over most of the troposphere, q increased with increasing global-average surface temperature, although some regions showed the opposite response. RH increased in some regions and decreased in others, with the global average remaining nearly constant at most altitudes. The water-vapor feedback implied by these observations is strongly positive, with an average magnitude of λ q = 2.04 W/m2/K, similar to that simulated by climate models. The magnitude is similar to that obtained if the atmosphere maintained constant RH everywhere. [**] A. C. Clement et al. (2009) Observational and Model Evidence for Positive Low-Level Cloud Feedback Science 325, 460 – 464. Abstract: Feedbacks involving low-level clouds remain a primary cause of uncertainty in global climate model projections. This issue was addressed by examining changes in low-level clouds over the Northeast Pacific in observations and climate models. Decadal fluctuations were identified in multiple, independent cloud data sets, and changes in cloud cover appeared to be linked to changes in both local temperature structure and large-scale circulation. This observational analysis further indicated that clouds act as a positive feedback in this region on decadal time scales. The observed relationships between cloud cover and regional meteorological conditions provide a more complete way of testing the realism of the cloud simulation in current-generation climate models. The only model that passed this test simulated a reduction in cloud cover over much of the Pacific when greenhouse gases were increased, providing modeling evidence for a positive low-level cloud feedback.
127313. Tom Dayton at 05:43 AM on 11 October 2009
        How do we know CO2 is causing warming?
        RSVP, lab experiments of the type you describe (actually, much better designed than the one you described) have been done for more than 150 years. They are now done even in high school science classes.
127314. RSVP at 04:53 AM on 11 October 2009
        How do we know CO2 is causing warming?
        I find Lorezo's remarks refreshing. It seems like a lot of money has been spent around testing the effects of CO2 on the Earth's atmosphere, but has anything like the following lab work been performed? That is, experimentation to show how CO2 actually impedes the COOLING of an object, and demonstrate that recycled heat is not getting around CO2 at other IR wavelenghts? In terms of a thought (or actual) experiment this might involve an elongated and sealed glass tube, (perhaps a few meters long) insulated thermically everywhere except on one end. At the base, inside the tube, a heating element would be used for heating a radiative plate wired with sensors that allow monitoring temperature over time. The opposite (non-insulated) tube ending would protrude into a cool dark chamber where the heat radiation is absorbed. For experiments, the tube would be filled with air having controlled amounts of CO2. The heating element would be switched on to leave the temperature of the plate at some specific elevated value. It would then be switched off to allow the plate to cool. The data of interest would be the TIME it takes for the plate to cool for the different levels of CO2. Indications that cooling actually take longer for higher levels of CO2 would be consistent with the idea that CO2 plays a significant role in global warming. If cooling times, however, were not found to be affected by CO2 concentrations, either CO2 is saturating energetically as mentioned by Lorenzo, or heat is returning to the plate and being emitted at other IR wavelengths.
127315. chris at 03:54 AM on 11 October 2009
        There is no consensus
        re #171, neil the evidence indicates that there has been substantial acceleration in glacier mass loss since the 1970s. A detailed study of Alpine glaciers was published by the World Glacier Monitoring Service in Zurich a couple of years ago: Haeberli W et al. (2007) Integrated monitoring of mountain glaciers as key indicators of global climate change: the European Alps Annals of Glaciology 46,150-160 Abstract: The internationally recommended multi-level strategy for monitoring mountain glaciers is illustrated using the example of the European Alps, where especially dense information has been available through historical times. This strategy combines in situ measurements (mass balance, length change) with remote sensing (inventories) and numerical modelling. It helps to bridge the gap between detailed local process-oriented studies and global coverage. Since the 1980s, mass balances have become increasingly negative, with values close to -1 m w.e. a(-1) during the first 5 years of the 21 st century. The hot, dry summer of 2003 alone caused a record mean loss of 2.45 m w.e., roughly 50% above the previous record loss in 1998, more than three times the average between 1980 and 2000 and an order of magnitude more than characteristic long-term averages since the end of the Little Ice Age and other extended periods of glacier shrinkage during the past 2000 years. It can be estimated that glaciers in the European Alps lost about half their total volume (roughly 0.5% a(-1)) between 1850 and around 1975, another 25% (or 11% a(-1)) of the remaining amount between 1975 and 2000, and an additional 10-15% (or 2-3% a(-1)) in the first 5 years of this century. And this analysis of glacier mass balance has recently been extended to a worldwide set of glaciers in which mass balance of 228 glaciers with full or partial records back to the 1940’s has been analyzed. This also indicates that after a relative lull in net glacier mass balance in the period around 1960 to 1975 there had been a marked acceleration in glacier mass balance loss. Zemp, M. et al. (2009) Six decades of glacier mass-balance observations: a review of the worldwide monitoring network Annals of Glaciology 50, 101-111 e.g the the authors state that the 30 reference glaciers where there are high quality continuous records show “an accelerated thinning, with mean annual ice loss of 0.14 m w.e. (1976-85), 0.25 m w.e. (1986-95) and 0.58 m w.e. (1996-2005)…. So the loss of glacier mass balance certainly seems to have increased rather markedly since the 1970’s. A brief account of this can be found here: http://www.sciencedaily.com/releases/2009/01/090129090002.htm Likewise, analysis of the Greenland and Antarctic ice sheets indicates a continued acceleration of mass balance loss: e.g. Velicogna, I. (2009), Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE Geophys. Res. Lett. in press “We find that during this time period [April 2002 and February 2009] the mass loss of ice sheets is not constant, but accelerating with time, i.e. that the GRACE observations are better represented by a quadratic trend rather than a linear one, implying that the ice sheets contribution to sea level becomes larger with time. In Greenland, the mass loss increased from 137 Gt (gigatonnes)/yr in 2002-2003 to 286 Gt/yr in 2007-2009, i.e. an acceleration of -30 +/- 11 Gt/yr^2 in 2002-2009. In Antarctica the mass loss increased from 104 Gt/yr in 2002-2006 to 246 Gt/yr in 2006-2009, i.e. an acceleration of -26 +/- 14 Gt/yr^2 in 2002-2009. There aren't any press releases for this study yet I think, but related work is decribed here: http://www.sciencedaily.com/releases/2008/11/081129094609.htm http://www.sciencedaily.com/releases/2009/06/090612092741.htm
127316. Philippe Chantreau at 02:35 AM on 11 October 2009
        How do we know CO2 is causing warming?
        Thingadonta, you seem to suggest that the oceans could somehow selectively absorb IR in the same bands as GH gases, so as to mimic the GH effect. How exactly would that be physically accomplished? Furthermore, the Philipona and Evans papers examine downward LW radiation, how would increased ocean absorbtion lead to increased downward radiation?
127317. Ari Jokimäki at 01:44 AM on 11 October 2009
        How do we know CO2 is causing warming?
        #19. LorenzoG said: "O2, N2, H2O all radiate at different wavelengths than CO2, and your chart above doesn't even cover two of the H2O bands. Unless you analyze the total energy exchange by the Earth on all wavelengths you can't begin to come to any conclusions." If there is a measured difference in CO2 bands (such as the one measured by Harries et al. in their few studies), possible differences in H2O bands don't change that, the CO2 difference remains the same. "The three primary IR absorption peaks of CO2 only cover about 8% of the infrared band, so CO2 is transparent to 92% of infrared energy." Which also doesn't take away anything from CO2 absorption. Nobody is claiming that CO2 absorbs whole of infrared band. "The Philipona paper mentioned above indicates a 1.8W/m2 increase in energy being radiated towards the ground. The sun sends ~1,000W/m2 at the equator. The increase described by Philipona is 0.18% of the sun's output. Can you prove that there has not been 1/5 of 1% variance in the sun's output over the last 34 years?" The 1.8 W/(m^2) number in Philipona et al. is for downward longwave radiation, but the number you give for the sun is for total sunlight, not only for longwave band. Try again.
127318. jshore at 01:32 AM on 11 October 2009
        Scientists can't even predict weather
        An analogy that I like to make is to the seasonal cycle. For example, if I told you that I could predict with confidence the weather here in Rochester for a day three weeks hence, you would correctly laugh at me. However, if I told you that I could predict with confidence that the average temperature for next January will be roughly 40 F colder than it was in July, I don't think you would give me much of an argument. It is also worth noting that the chaotic behavior of the weather can be tested with the numerical weather prediction and climate models. For example, a numerical weather prediction model will give a specific weather prediction for a day 3 weeks hence, but if you run it again with just small perturbations to the initial conditions, the prediction will be very different. (Actually, such running of ensembles with perturbed initial conditions now plays an important role in weather forecasting, at least for the period out beyond a few days.) On the other hand, I assume that such a model will give a reasonable prediction for the climate in January relative to July and the basic features will not be sensitive to the initial conditions. Likewise, with a particular climate model, perturbed initial conditions result in differences in the "jiggles" of the global temperature but when run out for 100 years, the different realizations all predict roughly the same overall amount of warming. This is true because the warming that occurs is governed by the fundamental issue of radiative balance between the earth, sun, and space. (Admittedly, because of feedback effects, determining how that radiative balance plays out is not easy...but it does not seem to be sensitive to small perturbations in initial conditions.)
127319. Philippe Chantreau at 18:36 PM on 10 October 2009
        How do we know CO2 is causing warming?
        Lorenzo, the Max Planck Institute TSI reconstruction shows a variance of about 0.8 w/m2 since 1885 (0.2 w/m2 on Earth surface), no net increase over the past 35 years. That reconstruction uses an 11 year average that removes the variations from the solar cycle. Both PMOD and ACRIM show cyclic variations no greater than roughly 2w/m2 (no trend over the observation period), which translate into a surface forcing +/- 0.5 w/m2. We're talking total irradiance here, not the IR part. Considering how small TSI changes are and considering how much of TSI is in the IR spectrum and at which wave lengths, I'm wondering how your question #4 can make sense.
127320. Philippe Chantreau at 16:17 PM on 10 October 2009
        Are humans too insignificant to affect global climate?
        Increased CO2 is such a minor factor compared to water availability and nutrients, it's not even worth considering from a practical point of view. Water vapor itself is also very minor. Changes in rain patterns associated to the climate changes brought by increased CO2 are much more likely to affect plants than the level of CO2 itself. We're not talking about a greenhouse or lab where every single parameter can be finely controlled here. Availability of liquid water and nutrients are the real important things. Ther rest is nit picking. I'd like to see the reference on that increase in plant life study, especially to see if there is any attribution to possible causes in the increase. I'm also wondering what exactly is meant by "increase." I believe that land use changes are more likely than any other factor to yield that kind result. I seriously doubt that "CO2 fertilization" (an abuse of language really) can be that effective.
127321. Tom Dayton at 15:16 PM on 10 October 2009
        How do we know CO2 is causing warming?
        LorenzoG wrote in #19: "2.) Doubling the CO2 level in the atmosphere will not result in any more energy being trapped in the atmosphere because ALL OF IT IS ALREADY ABSORBED." That myth is ancient--as in the turn of the 19th century to the 20th century. See A Saturated Gassy Argument.
127322. WeatherRusty at 13:13 PM on 10 October 2009
        How we know global warming is still happening
        shawnhet, "Cloud formation depends on RH, but also on the specific humidity. The more water in air, the thicker and deeper will be the clouds that form *once that air cools sufficiently*. There will be more water condensed out of air cooling from 16C to 15C (when everything else is equal) than air cooling from 15C to 14C. If everything else were really equal, then this should lead to correspondingly higher amount of clouds." Why is that? At a given specific humidity the relative humidity will depend upon the saturation vapor pressure and that in turn is dependent on temperature. The higher the temperature the greater the saturation vapor pressure and lower the RH at a given specific humidity. The GCM's indicate that as global average temperature rises so does specific humidity in such a way that RH remains nearly constant (Clausius-Clapeyron relation) or maybe a bit lower. The tendency to form clouds begins at around 70% RH no matter the temperature or specific humidity. You are correct that more water can potentially be condensed out at higher specific humidities where clouds do form, but this relates to precipitable water within the column of atmosphere (because the water load is greater), not necessarily to the tendency for cloud formation.
127323. Philippe Chantreau at 12:05 PM on 10 October 2009
        Are humans too insignificant to affect global climate?
        Increased CO2 is such a minor factor compared to water availability and nutrients, it's not even worth considering from a practical point of view. Water vapor itself is also very minor. Changes in rain patterns associated to the climate changes brought by increased CO2 are much more likely to affect plants than the level of CO2 itself. We're not talking about a greenhouse or lab where every single parameter can be finely controlled here. Availability of liquid water and nutrients are the real important things. Ther rest is nit picking. I'd like to see the reference on that increase in plant life study, especially to see if there is any attribution to possible causes in the increase. I'm also wondering what exactly is meant by "increase." I believe that land use changes are more likely than any other factor to yield that kind result. I seriously doubt that "CO2 fertilization" (an abuse of language really) can be that effective.
127324. LorenzoG at 09:14 AM on 10 October 2009
        How do we know CO2 is causing warming?
        This article ignores basic science. 1.) OK, so a CO2 absorbs a photon of infrared. The only ways that molecule can de-energize to be ready for the next photon is to conduct heat away through impact with another molecule, or to re-radiate it out at the same frequency. Either it does one of these or all CO2 molecules will soon reach saturation and be unable to absorb more infrared. If it conducts it to another molecule then that molecule will either conduct it away again or re-radiate the photon, BUT AT THAT MOLECULE'S WAVELENGTHS, not CO2's. O2, N2, H2O all radiate at different wavelengths than CO2, and your chart above doesn't even cover two of the H2O bands. Unless you analyze the total energy exchange by the Earth on all wavelengths you can't begin to come to any conclusions. 2.) Dr. Heinz Hug's work suggests that CO2 is such a good absorber of infrared energy that it absorbs 100% of IR radiated from the ground at your 650/cm region within 10 meters of the ground. Doubling the CO2 level in the atmosphere will not result in any more energy being trapped in the atmosphere because ALL OF IT IS ALREADY ABSORBED. You won't get twice the heating from doubling the CO2 concentration because there is none left to absorb at that wavelength. 3.) The three primary IR absorption peaks of CO2 only cover about 8% of the infrared band, so CO2 is transparent to 92% of infrared energy. 4.) The Philipona paper mentioned above indicates a 1.8W/m2 increase in energy being radiated towards the ground. The sun sends ~1,000W/m2 at the equator. The increase described by Philipona is 0.18% of the sun's output. Can you prove that there has not been 1/5 of 1% variance in the sun's output over the last 34 years?
        Response: If the CO2 effect was saturated, then increasing CO2 would lead to no change in the greenhouse effect. As satellite measurements (Harries 2001, Griggs 2004, Chen 2007) and surface measurements (Philipona 2004, Evans 2006) all find an enhanced greenhouse effect at the CO2 and CH4 bands, this is empirical confirmation that the CO2 effect is not saturated.
        
        Note that hotter objects emit radiation at shorter wavelengths. Hence the sun emits shortwave radiation while the earth emits longwave radiation. This is the basis of the greenhouse effect - shortwave radiation from the sun passes through the atmosphere, warms the earth which then emits longwave radiation back out to space. This longwave radiation is absorbed by greenhouse gases. The enhanced greenhouse effect observed by the papers listed above are at longwave wavelengths, not shortwave. It's basic science.
127325. shawnhet at 08:47 AM on 10 October 2009
        Are humans too insignificant to affect global climate?
        The fact is, that plant growth has a number of constraints on it and if you relax a constraint then growth will increase, unless there is another constraint that is blocking it. If the plant is primarily constrained by the amount of liquid water it is exposed to(or the nature of the soil it is sitting in), then adding more CO2 will not help it grow. However, for the plants that are(currently) constrained by the speed/efficiency they can remove carbon from the air, then increasing CO2 will help them grow. This is why commercial greenhouses routinely pump massive levels of CO2 into their structures(they are designed to relax as many constraints on plant growth as possible). Clearly, some plants, in their current environments would grow faster(and, hence bigger) if they had access to more CO2. Further, this is compounded by the fact that warming temps will also yield more WV which also makes it easier from plants to grow, on average. IIRC, this effect has been measured from space, and there has been something approximating 6% increase in plant life on Earth over the last 20+ years. Cheers, :)
127326. shawnhet at 08:28 AM on 10 October 2009
        How we know global warming is still happening
        WeatherRusty:"It is not a given that there are more clouds in a generally warmer environment. Cloud formation depends very much on relative humidity and also the availability of lift within the atmosphere, warm moist air must rise and cool to near it's dew point. A product of all climate simulations is a near constant relative humidity as the climate warms. Look at the tropics and near tropics today. Most cloud formation is convective in nature and where this is the result of daytime heating the clouds dissipate at night. The tropics receive the vast majority of solar radiation but cloudiness does not prevent that region from being the warmest on Earth. If the climate zones and jet streams are shifted poleward in a warming world why would the dynamics be any different in their displaced positions?" Cloud formation depends on RH, but also on the specific humidity. The more water in air, the thicker and deeper will be the clouds that form *once that air cools sufficiently*. There will be more water condensed out of air cooling from 16C to 15C (when everything else is equal) than air cooling from 15C to 14C. If everything else were really equal, then this should lead to correspondingly higher amount of clouds. The fact that clouds form quickly and easily in the tropics doesn't prevent them form being the hottest place on Earth(on average), but it does help prevent them from getting as hot as land at the same latitude (during the day). Further, it is not a given that RH is, in fact, a constant either. Cheers, :)
127327. Alexandre at 04:11 AM on 10 October 2009
        How we know global warming is happening, Part 2
        The ocean heat content graph still has some amount of noise in it. I wonder if the total global heat content would be a more monotonic line, since the planet is steadily taking up more heat over time.
127328. dopeydoctorjohn at 02:25 AM on 10 October 2009
        There is no consensus
        Doran then compares this result with a response from the general public......disingenuously. He quotes a Gallup poll that "suggests that only 58% of the general public would answer yes to our question 2." However, if one cares to check the reference, the question asked of the general public was whether they thought human activities OR natural forces were driving climate change. To answer "yes", they had to think not just that human activities were "a" significant factor, but "THE" significant factor driving warming. A climate scientist thinking human activities contribute 1% to warming answers the survey question "Yes" Joe Bloggs, thinking that human activities contribute 49% to warming answers his respective Gallop question "No". Doran knows this, but compares them on the same graph anyway, and concludes that climate scientists need to "spread the word" more enthusiastically. And this website swallows it hook line and sinker.
127329. dopeydoctorjohn at 02:07 AM on 10 October 2009
        There is no consensus
        Didn't Doran design this question in order for it to be almost impossible to answer "no" to? Didn't he do that in order to generate the highest "yes" answer % possible, in order to create a paper purporting to demonstrate a consensus in excess of the "real" consensus that may exist? Didn't Doran fail to follow up on non-responders? Didn't Doran select out, for special attention, not necessarily the most knowledgeable (why not select out PhDs, or professors, specifically?) but specifically those most likely, undoubtedly, to agree with the premise of his question, and then did he not ask the most inclusive, weakly-framed question possible, just to generate this mighty figure of 97.4%
127330. dopeydoctorjohn at 02:01 AM on 10 October 2009
        There is no consensus
        Doran asked these climate scientists this question: "Do you think human activity is a significant contributing factor in changing mean global temperatures?" 1) "A" factor, not "The only" factor. Not even "the most". 2) What does a climate understand by the word "significant"? In medicine, a relationship is said to be significant if there is a less than 5% chance that it can be explained as random. If sample sizes are large enough, "highly significant" relationships can be calculated that actually mean zip to any given individual. If a given subject is important enough, a 1% contribution to it may be significant. Schizophrenia affects just 1% of the population: anyone think it is an insignificant illness? 1% of the US population lives in Chicago City: is Chicago's contribution to America insignificant? So if human activity contributes 1% to global warming, and if a climate scientist lives and breathes climate, he or she would have to say that 1% contribution is significant, no?
127331. dopeydoctorjohn at 01:41 AM on 10 October 2009
        There is no consensus
        97.4% is an awfully consensus-like number. Practically unanimous. But there are two parts to a fraction or, in this case, a percentage Numerator; and denominator Let's look at the denominator They are "those who listed climate sci- ence as their area of expertise and who also have published more than 50% of their recent peer-reviewed papers on the subject of climate change (79 individu- als in total)." Hmmm. 1) If your gut feeling, after finishing your B.Sc., was that the climate wasn't changing, would you study climate change? Probably not. You'd be thinking it would be pretty boring, because you'd be not expecting it to change. If your gut feeling, after finishing your B.Sc., was that AGW threatened mankind, would you study climate change? You betcha! Here's your chance to save the world AND get the girl! 2) If a climate scientist is doing research on climate change, and he or she finds no change occuring, do we think it is still going to get published? Publication bias in clinical research The Lancet, Volume 337, Issue 8746, Pages 867-872 So doesn't that mean published research, and therefore published researchers, must be biased to those reporting change? 3) When we are talking about "the subject of climate change", isn't it understood that we are usually talking about AGW? 4) SO, that impressive number 97.4% tells us that 97.4% of climate scientists studying climate change and publishing primarily on climate change believe in.......climate change. Exploring the denominator renders the numerator much less impressive. Is that a statistic, or a tautology?
127332. dopeydoctorjohn at 01:07 AM on 10 October 2009
        There is no consensus
        In Australia, if a doctor A thinks another doctor B is impaired to the point of being a danger to society, then doctor A must report doctor B to the Medical Board Medical Practice Amendment Act 2008 (NSW) (Section 71A) If 90% of Earth scientists think the world is at threat from climate change, and 10% of their colleagues are going around unable to agree even on warming, shouldn't the 90% move to get the 10% dismissed? Or, isn't it actually quite that "cut and dried", even amongst Earth scientists?
127333. dopeydoctorjohn at 00:56 AM on 10 October 2009
        There is no consensus
        Doran's survey population included "more than 90%" PhDs and 7% Masters degrees in earth sciences. They were asked: "When compared with pre-1800s levels, do you think that mean global temperatures have generally risen,fallen,or remained relatively constant?" 90% said "risen". Everyone here would be pretty sure as to why that answer would have been given. But, as we all know, truth isn't a democracy. so..what about the other 10%? Here are 300+ PhDs and Master's degreed folk who don't even think warming has occurred. Wouldn't it be good to know their reasoning?
127334. dopeydoctorjohn at 00:45 AM on 10 October 2009
        There is no consensus
        Does anyone think the opinions of the 7111 non-responders might be different to the opinions of the responders? I Googled "Non-response bias" (under the Scholar listings) and found oodles of studies on the subject. It seems to be particularly important when the subject matter is controversial. Like climate change. It seems that if a researcher is keen to know what the surveyed group really think, the researcher will do a followup small randomised study from the target group to try to demonstrate no statisticlly significant difference between the thoughts of the survey responders and the non-responders. Can anyone see where Doran did this?
127335. dopeydoctorjohn at 00:21 AM on 10 October 2009
        There is no consensus
        Hi John. Great site!! Extremely helpful from both sides I know diddly-squat about the environment, so all I can do is ask questions. Regarding the Doran 2009 study, so extensively quoted above, it is written "The authors surveyed 3146 earth scientists" but when I look at the actual link I find 10257 earth scientists were surveyed, and only 3146 responded. So, really, if you survey 10257 earth scientists and ask them "Do you think human activity is a significant contributing factor in changing mean global temperatures?" you find (10257-3146=) 7111 don't find 2 minutes to answer your survey. If I were an Earth Scientist and I thought global warming was about to destroy the planet, I'd be pretty keen to get the message out. I'd find 2 minutes to answer an "up to 9" question survey to help get the message out. Especially if I thought the survey was going to get as much publicity as this Doran study. Why do you think those 7111 Earth Scientists didn't answer the survey?
127336. Frank Schnabel at 21:53 PM on 9 October 2009
        Temp record is unreliable
        Greeting all, When some outfit like Hadley or GISS offers an estimate of the global mean temp for a given year, do they present along with it an error estimate? e.g. In 2008 the average temp was 25 degrees C + or - 5 degrees. Seems like they would have to, given all that goes into coming up with an estimate. How do they assess the range of error, and how much confidence can we place on such estimates? cordially Frank
127337. thingadonta at 20:23 PM on 9 October 2009
        How do we know CO2 is causing warming?
        "What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as CO2 and methane (CH4) absorb energy." This is a better post than most i have seen here (with a bit of history and hard physics), but i wonder what the radiation band absorption spectra would look like if the oceans were also absorbing radiation wavelengths due to eg less clouds over the oceans?, rather than c02/ch4 doing it?? Just a thought.
127338. Philippe Chantreau at 15:57 PM on 9 October 2009
        How do we know CO2 is causing warming?
        WR, I believe that Chris is right. In short, if a feedback induces a change lower than the one that caused the feedback itself, then there will be no runaway. The system is inherently stable.
127339. neilperth at 14:13 PM on 9 October 2009
        There is no consensus
        Chris, I am aware that there are many proxies which can be used to give rough estimates of temperature in the past. I agree that the climate has been warming at least since the start of the 20th century. The Earth's climate can warm and cool over time due to natural factors. My quest for the "truth" centres on finding out: 1) How much of the recent warming is due to man-made CO2 emissions. 2)Is warming necessarily a bad thing. 3) If man-made CO2 emissions are a contributing factor, what can be done to lower the emissions in a way that will have a DEMONSTRABLE effect in reducing temperature increases in the future - maybe having more nuclear power stations would be the way to go. aww However, with regard to your claim that temperature increase since 1850 " most likely already had an anthropogenic component", is it not true that the IPCC climate models can replicate temperature trends prior to around 1970 simply using natural forcings. Also, from the graphs I have seen, there has been no general increase in the rate of recession of glaciers since 1970.
127340. Thermoguy at 09:28 AM on 9 October 2009
        Is the U.S. Surface Temperature Record Reliable?
        Recording the temperatures on the surface of the planet aren't accurate and do not reflect the true participation of urban heat islands related to global warming. Global warming means there is a source of heat atmospherically. Here is a link to advanced temperature work to isolate the cause of urban heat islands. Look at the amount of heat generated in September. http://www.youtube.com/watch?v=1EmBQcXr6ng
        Response: The source of atmospheric heat has been determined empirically by both satellites and surface measurements of longwave radiation to come from greenhouse gases trapping more heat that would otherwise have radiated back out to space. As for urban heat island, see this research into the effect of urban heat island effect on temperature records.
127341. chris at 05:54 AM on 9 October 2009
        There is no consensus
        neil, you're changing the subject and arguing about something that isn't what my post (#157) was about. I was pointing out that there are quite a few different temperature scales and that these yield a rather consistent interpretation of 20th century warming. No one is arguing that glacier retreat is solely due to enhanced anthropogenic greenhouse forcing. The point is that one can use glacier extent and its temporal variation as a crude "thermometer", and this analysis gives a temporal variation in earth temperature consistent with that determined by analysis of direct measures.. Note that glacier advance due to the so-called Little Ice Age had more or less stopped by around 1800, and the slow retreat from around 1850 most likely already had an anthropogenic component. After all, the preindustrial atmospheric CO2 levels of around 280 ppm, were ncreased through the 19th century to 300 ppm by 1900 and by 320 ppm by 1960. That increase in atmospheric CO2 should give a warming near 0.4 oC within the best estimate of the climate sensitivity (around 3 oC per doubling of atmospheric CO2). And this is consistent with analysis of attributions of 20th century warming. One simply can't reproduce 20th century warming without including this very significant anthropogenic contribution. An example of this attributional analysis can be found elsewhere on John Cooks site: http://www.skepticalscience.com/climate-models.htm
127342. jshore at 05:21 AM on 9 October 2009
        Scientists can't even predict weather
        An analogy that I like to make is to the seasonal cycle. For example, if I told you that I could predict with confidence the weather here in Rochester for a day three weeks hence, you would correctly laugh at me. However, if I told you that I could predict with confidence that the average temperature for next January will be roughly 40 F colder than it was in July, I don't think you would give me much of an argument. It is also worth noting that the chaotic behavior of the weather can be tested with the numerical weather prediction and climate models. For example, a numerical weather prediction model will give a specific weather prediction for a day 3 weeks hence, but if you run it again with just small perturbations to the initial conditions, the prediction will be very different. (Actually, such running of ensembles with perturbed initial conditions now plays an important role in weather forecasting, at least for the period out beyond a few days.) On the other hand, I assume that such a model will give a reasonable prediction for the climate in January relative to July and the basic features will not be sensitive to the initial conditions. Likewise, with a particular climate model, perturbed initial conditions result in differences in the "jiggles" of the global temperature but when run out for 100 years, the different realizations all predict roughly the same overall amount of warming. This is true because the warming that occurs is governed by the fundamental issue of radiative balance between the earth, sun, and space. (Admittedly, because of feedback effects, determining how that radiative balance plays out is not easy...but it does not seem to be sensitive to small perturbations in initial conditions.)
127343. chris at 03:28 AM on 9 October 2009
        How do we know CO2 is causing warming?
        WeatherRusty, I thnk the answer is simply that the water vapour response to increased atmospheric warming is small enough that its additional forcing results in a temperature rise that is quite a bit smaller than the temperature rise that induced it. The water vapour feedback applies to anything that enhances (or reduces, of course) the atmospheric temperature. So if the sun became a bit brighter such that the direct atmospheric warming was 1 oC, and the resulting water vapour feedback adds an additional x of additional warming then the total warming from the solar enhancement + water vapour feedback is something like 1 + x + x^2 + x^3 + x^4 ... which is 1/(1-x). So if the water vapour response to a 1 oC warming is 0.5 oC then the total warming when everything comes to equilibrium is 1/(1-0.5) = 2 oC. The same argument applies for the enhancement of atmospheric CO2 concentrations. If the atmospheric CO2 concentrations rise by an amount giving a 1 oC of warming then the water vapour feedback will result in a total warming of 1/(1-x). In some ways it's better to describe the feedback as an "amplification" to avoid the connotation with a "runaway" positive feedback.
127344. dopeydoctorjohn at 00:50 AM on 9 October 2009
        Less than half of published scientists endorse global warming
        Quietman Your link on post 5 should be added to the consensus thread where it may get more attention. It's a great link! Cheers
127345. WeatherRusty at 00:40 AM on 9 October 2009
        How do we know CO2 is causing warming?
        Can anyone explain why the positive feedback involving water vapor is not a runaway condition? More water vapor=increased warmth=more water vapor=increased warmth etc....etc..... I would start with the fact that water vapor is not a well mixed gas. What would happen if a magic wand where waved and water vapor concentration were approximately the same everywhere such as is the case with CO2?
127346. WeatherRusty at 00:11 AM on 9 October 2009
        How do we know CO2 is causing warming?
        RSVP, Very simply in response to post #13, the greenhouse effect slows the loss of out going thermal radiation both day and night. A stronger greenhouse effect results in warmer nights, the energy of which is carried over the the next day. The atmosphere radiates energy all night long, thus preventing a drastic drop in surface temperature, especially over land, in the absence of sunshine. The energy input of the previous day is not totally "discharged" at night as you assert, it only slowly trickles out due the the atmospheric greenhouse effect. Adding greenhouse gases slows the loss even more.
127347. RSVP at 23:32 PM on 8 October 2009
        How do we know CO2 is causing warming?
        Aside from the heat directly released, just as CO2 plays a role as a catalyst in global warming, underground nuke testing may have upset Earths hotspots. Why not. The non skeptics arent concerned with this however, even if it were true. All they want to do is ramrod the idea that CO2 is doing everything. This paper for instance "proves" that CO2 is responsible for global warming, since more IR energy around a band of CO2 IR emission is now greater as compared to 25 years ago. If the data is good, about all it proves is that there is more CO2, which we already know. The data is insufficient because even if more heat is being trapped during the day due to CO2, it is the stored energetic carry-over from one day to the next that matters. (Night and winter has an important role in global cooling, yet never mentioned in these discussions.) Energy stored in land and sea. If the total conditions during the 24 hr cycle are enough to "discharge" the energy, even if you have an instantaneous increase in heat retention from CO2, (as is typically illustrated in greenhouse energy budget diagrams), about all you can say is that CO2 makes it hotter during the day (and under specific conditions). That is a lot different from saying that CO2 is the main cause of global warming. Never mind the possibility that you allude to about nuclear testing. Never mind the possibility that air pollution causes more clouds, and clouds as any farmer knows keeps things generally warmer. The concept that CO2 is doing everything however has been institutionalized, and opening up people's minds on the subject appears about as difficult as getting rid of excess CO2 itself.
        Response: This is not the first time you've raised the strawman argument that we claim "CO2 is doing everything". It is not - I've even posted a reply to your previous comments to clarify that CO2 is just one of several anthropogenic forcings - it just happens to be the most dominant forcing and of all the positive forcings, it's bigger than the others combined:
        
        
        
        The studies above also confirm the amplified greenhouse effect from methane but as there is much less methane in the air than CO2, it's radiative forcing is much smaller. Any comments repeating this strawman argument will be deleted.
127348. neilperth at 21:05 PM on 8 October 2009
        Sea level rise is exaggerated
        A recent ( June 2009 ) scientific paper by Cliff Ollier of the School of Earth and Environment, The University of Western Australia, states as follows : Abstract: Graphs of sea level for twelve locations in the southwest Pacific show stable sea level for about ten years over the region. The data are compared with results from elsewhere, all of which suggest that any rise of global sea level is negligible. The Darwin theory of coral formation, and subsidence ideas for guyots would suggest that we should see more land subsidence, and apparent sea level rise, than is actually occurring. Sea level studies have not been carried out for very long, but they can indicate major tectonic components such as isostatic rebound in Scandinavia. Attempts to manipulate the data by modelling to show alarming rates of sea level rise (associated with alleged global warming) are not supported by primary regional or global data. Even those places frequently said to be in grave danger of drowning, such as the Maldives.
127349. hyrax at 17:17 PM on 8 October 2009
        How do we know CO2 is causing warming?
        Has there been any studies of nuclear weapon testing's impact? There only has been a ban of nuclear testing after 1993. I read there was one nuclear test every nine days prior.
127350. Ari Jokimäki at 16:47 PM on 8 October 2009
        How do we know CO2 is causing warming?
        As someone who only has limited access to full contents of papers, I thank you for giving us a peek at the Harries et al. (2001). It's too bad we don't have much papers like Evans & Puckrin (2006) who measure the change in DLR by each gas. A new paper by Wang & Liang (2009) mentions the possible reason why we don't have much of them: "While surface shortwave radiation has long been measured globally [Gilgen and Ohmura, 1999], Ld is not conventionally observed due to the higher cost of pyrgeometers used for Ld measurement, and more difficult challenges of instrument calibration and quality control [Enz et al., 1975; Udo, 2000; Sridhar and Elliott, 2002; Duarte et al., 2006]." (Ld being the surface downward longwave radiation.) http://www.agu.org/pubs/crossref/2009/2009JD011800.shtml

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