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Phila at 16:35 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Whilst much is made of how high CO2 levels may rise to, there seems to be little mention made of how much the water vapour levels will rise and whether there is an ultimate limit. Little mention where? Climate scientists have addressed this issue at length, repeatedly. See Water vapor is the most powerful greenhouse gas, just for starters. It's one thing to disagree with a specific scientific arguments on water vapor, but to act as though it's being downplayed or ignored is kind of absurd, especially for a longtime commenter on this site. In my experience, there are in fact very few "skeptical" arguments and very few uncertainties of which "little mention" has been made by climate scientists. -
Marcus at 16:11 PM on 30 June 2010Perth forum on climate change: all the gory details
My counter to the "CO2 is just the result of the MWP lag" would be this-"where does all the excess CO2 come from?" If you look at the Ice Cores that show the various Milankovitch Cycle driven Glacial & Inter-glacial periods, you can see that CO2 concentrations rarely get much above 260ppm-& *never* get above 300ppm-in spite of temperatures rising by around a couple of degrees above those at any period in the Holocene. All available Paleo-climate data shows that temperatures in the MWP never reached the heights of previous Inter-Glacial periods. So, if this CO2 is from natural sources only, then why did much warmer periods not produce CO2 concentrations of around 400ppm or more? My understanding is that its because ca. 280ppm is the total amount of CO2 available in the Quaternary Era Atmosphere & Carbon Sinks combined. Therefore the only other source for this CO2 (aside from *massive* volcanism) must be coming from fossil fuels formed when CO2 levels were at levels of 1000ppm or above. My other counter would be "show me the 14-C fingerprint that proves the CO2 from natural sinks". -
johnd at 16:03 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Comparing CO2 to clouds is wrong. Clouds are not a greenhouse gas. Water vapour is however, and it is always present. Whilst much is made of how high CO2 levels may rise to, there seems to be little mention made of how much the water vapour levels will rise and whether there is an ultimate limit. Clouds are also always present providing between 64% and 69% coverage globally. Clouds provide an overall nett cooling effect for the planet. I believe there is a new paper being prepared for publication in the coming months that examines cosmic rays and cloud formation. -
ScaredAmoeba at 15:49 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Karl_from_WylieBias. Increase in Carbon dioxide does not assure Global Warming. There are more variables to the equation.
It is noted that you provided not one shred of evidence for your assertion. You overlooked this:Of course, this is a simplified explanation of global warming, ...
Which rather demolishes the entire point of your post. Perhaps you should learn to read more carefully. Skeptical Science has debunked numerous claims made by a well funded denial industry. Smoke, Mirrors & Hot Air: How ExxonMobil Uses Big Tobacco's Tactics to Manufacture Uncertainty on Climate Science Koch Industries Secretly Funding the Climate Denial Machine Crescendo to Climategate Cacophony Behind the 2006 Wegman Report and Two Decades of Climate Anti-Science - John R. Mashey -
Chris Colose at 15:44 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Karl, it's not very useful to tell people through a quick sound byte on the radio that global temperature change is a function of the net radiative forcing. There's nothing wrong with this approach...CO2 is, and will be, the largest forcing agent driving climate change from the pre-industrial/industrial transition era all the way into the foreseeable future. That other things can offset CO2 is important, especially on relatively short timescales, but no other negative forcing is persistent and strong enough to offset our CO2 which will enhance the greenhouse effect on timescales of centuries to millennia. At least not anything within the bounds of physical plausibility. -
scaddenp at 14:49 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
Well lets see. In terms of energy balance, climate = function(solar, aerosol, albedo, GHG). The complication is indeed feedback. However, if you increase GHG, you need to find a negative feedback that works with increasing GHG to avoid warming. Constraint - this negative feedback has to work in such a way that variations in solar on the earth's surface will also give us the ice ages (or give us an alternative model for ice age cycle). I havent seen anything credible. The much-talked about cloud feedback is response to temperature so if it reduces sensitivity to GHG so much how come it doesnt impede the sensitivity to solar change? -
Doug Bostrom at 14:35 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
For more fully fleshed-out versions of what Karl_from_Wylie speaks of when he mentions other variables, natural variability and the like, there are numerous articles here on Skeptical Science providing information on those topics. The View All Arguments is a fun place to start. Another terrific resource is a book by historian of science Spencer Weart. His history of this topic The Discovery of Global Warming is freely available for reading online as well as being available in print. -
Karl_from_Wylie at 14:21 PM on 30 June 2010What is Global Warming and the Greenhouse Effect?
"..The message for today, however, is that anyone who tells you that carbon dioxide does not cause global warming, either does not understand the basic science, or is being deliberately misleading." Bias. Increase in Carbon dioxide does not assure Global Warming. There are more variables to the equation. Article presents a simplistic argument. Nature has more variablity, and more inputs than simply an increase in Carbon Dioxide.Response: Increase in Carbon dioxide does not assure Global Warming. There are more variables to the equation.
This issue is examined in detail at CO2 is not the only driver of climate. -
ProfMandia at 13:18 PM on 30 June 2010Perth forum on climate change: all the gory details
Barry, at our current 2 ppm CO2 increase per year, we are increasing CO2 at a rate of just under 2,000 times that of the previous 800,000 years where CO2 ranged naturally between 190 ppm and 300 ppm every 100,000 years. Scott A. Mandia, Professor of Physical Sciences Selden, NY Global Warming: Man or Myth? My Global Warming Blog Twitter: AGW_Prof "Global Warming Fact of the Day" Facebook Group -
David Horton at 11:42 AM on 30 June 2010Perth forum on climate change: all the gory details
The MWP lag suggestion falls into the category of those skeptic mechanisms that rely for their validity on the incredible coincidence that they occur exactly at the time when CO2 pumped out by industry begins to really massively increase. That these arguments all rely on us not noticing that is no coincidence. -
Doug Bostrom at 11:41 AM on 30 June 2010Sea level rise is exaggerated
Hi Daniel, glad to see you back, I was afraid I was going to have to argue with myself. I thank you for forcing me to take a closer look at Donnelly and strain my eyesight squinting at his graphs. I see your point about samples 7 & 8, I'm sure Donnelly would have been happier if they'd resolved better but because they're embedded in the middle of the series their effect is not very drastic; interpretation of those is constrained by the surrounding boxes. As to your problems with multiple date ranges for samples, if you read the text carefully you'll see how Donnelly eliminated date ranges by using methods beyond C14: In some cases we can use the Principle of Superposition to determine which range most likely represents the age of the sample. For example sample 9 should be younger than sample 10 (since sample 9 was recovered 3.5 cm above sample 10), so we eliminate the two older ranges (1306–1356 and 1357–1365 A.D., gray on Figure 2); the youngest range from sample 9, 1386–1440 A.D., best represents the age of that sample. Other sample ambiguities were treated with different methods appropriate to the individual cases, with the result that multiple date ranges appear to have been eliminated in all cases if I'm reading Table 1 correctly. With regard to drawing a line through the whole collection, if I get you right and correct me if I'm misunderstanding you, you're suggesting that it's equally reasonable to pick and draw a series of lines perhaps pointing up and perhaps pointing down between any chronologically linear pair of samples. That's not as conservative as doing what Donnelly did. As well, doing such a series of arbitrary choices leaves the issue that the entire series must begin somewhere within the region circumscribed by the sample 4 and 11 confidence boxes, meaning that the overall conclusion of the series of choices made to connect individual samples ends up being nearly the same, confined by the beginning and ending samples. Meanwhile, it appears that the slope described by the direct recent tidal measurements is inevitably going to be steeper than the sum linear product of whatever combination of ups and downs you might choose to impose on the paleo series, and as well covers a disproportionate vertical range compared compared to the paleo series. This suggests to me that attempting to create and insert arbitrary additional information into the series is pointless. So again my take is that you're suggesting a liberal interpretation of the data, Donnelly is picking a conservative approach. And I do think neither of us are equipped with the specific skills we need to cast technical judgment on this article, certainly not to fling the term "utter junk" in describing it. The suite of dating refinements employed by Donnelly I refer to are an example our ignorance, as I mentioned before. -
topquark at 11:27 AM on 30 June 2010Perth forum on climate change: all the gory details
Re the idea that the current rise in CO2 might be due to an 800 year lag from warming during the MWP: I encountered that argument for the first time a few days ago in Ian Wishart's book Air Con. It seemed unlikely; thanks for the counterarguments. -
daniel at 10:49 AM on 30 June 2010Sea level rise is exaggerated
Here's a quote from the above comment from doug # 31 "If I felt free to draw lines wherever I pleased between the samples it might be possible to squeeze in some excursions, but then I'd not only be substituting fiction for reality, I'd almost have to end up with an implausible looking graph, and again I'd have to be creating data to do so. So my conclusion is that Donnelly's more conservative than Daniel." You wouldn't be substituting fiction for reality doug :) The error estimates allow you to draw those lines. The fiction comes from believing that given the uncertainty in the data points we can conclude that short term deviations from the proposed trend are non-existent. Look at the uncertainty in time for samples 7 and 8, it's approximately 150 years. That means the authors are saying that the assigned height (which has it's own level of uncertainty) lies somewhere in the range of 150 years (between about 1500-1650). That is the time span of the current instrumental record. That should give you an idea of the vast difference in certainty between the two sets of data. Can you see that sample 11 has two date ranges assigned to it? Does that sound like a high level of certainty to you doug? We can see also that sample 9, which by the authors own admission should be younger than sample 10, has a date range generally older than sample 10. How much of sample 10's 95% confidence interval can actually be so confidently assigned when sample 9's 95% confidence interval is not even as young as that? It's true statistical methods lead to these confidence intervals but then logic needs to be applied before we write our conclusions section. That portion of the graph, 1300-1500 AD, has a lot of potential for a significant deviation from the proposed trend. As does 1600-1750 AD, if we could more confidently assign samples 7 and 8 toward the younger end of their current 95% confidence intervals then a short term trend of much greater than 1mm/year SLR through sample 5-8 could potentially exist. If such deviations from the trend were visible then the recent sea level rise would not be as alarming as is made out to be. These short term rates of paleo sea level rise do not even have to match the 2.8mm/year observed in recent times it only has to be closer to it than the average 1mm/year in order for the recent rise to be less alarming. The low resolution data really undoes the conclusions of Donnely et. al. but we find that although the Gehrels paper tries to address this issue the uncertainties are still too high to obtain a meaningful result. These attempts to measure paleo sea level rise are certainly commendable for the level of effort put in but the conclusions drawn are unsound. -
Riduna at 10:00 AM on 30 June 2010Perth forum on climate change: all the gory details
All good stuff but in a city with a population of well over 1 million, attendance by 200 does seem a bit disappointing. Perhaps there is already wide acceptance of AGW and knowledge of how to deal with it in the community, though I doubt it. Has there been good press coverage? What follow-up is planned? Maybe a practical demonstration of how individual households can reduce their carbon footprint? -
scaddenp at 09:20 AM on 30 June 2010CO2 is not a pollutant
AWOL - lets ignore the completely hilarious non-physical stuff about venus. The point I was making is that you cant live on venus, there IS an upper bound on temperature and if you chose enough of powerful enough GHG, then we turn earth that way too. The MAIN point I was making is that RATE of change is the cause for concern - too fast for ecological systems to cope with. Current rate of change is too fast, let alone the projected future rate of change. Its the rate that is the problem. Your happy scenario might play out over 1000s of years and as for comments on deltas, I assume you dont live on one. This is fantasy stuff. Ask yourself why all the existing drowned deltas are the happy places you imagine and they drowned with sealevel rates much slower than current and projected. As for CO2 is plant food. Please see other comments in this thread and some reputable science. CO2 does not magically gives the plants extra water or nutrients. -
johnd at 08:50 AM on 30 June 2010Watts it like at a climate skeptic speakers event?
Chris G at 08:00 AM, is not the climate, at the most basic level, self regulating within limits determined by the properties of H2O and in particular the points at which it changes state? -
johnd at 08:44 AM on 30 June 2010Watts it like at a climate skeptic speakers event?
Marcus at 09:41 AM on 23 June, 2010, I have posted at response over at "CO2 is not a pollutant" having had it deleted from here. I have also copied your post over there as part of my response to provide continuity even though your post has been allowed to remain here. -
johnd at 08:38 AM on 30 June 2010CO2 is not a pollutant
This post is a continuation of a discussion at the thread "Watts it like at a climate skeptic speakers event?" in response to post 104, Marcus at 09:41 AM on 23 June, 2010. The Marcus post remains at that thread whilst my reply was selectively deleted. I have copied the Marcus post here to provide some continuity, it follows after my response. My response:- The most obvious point being overlooked is that the limitations listed are not new, nature has RARELY provided ideal conditions, some would swear never. The less than ideal conditions have been there ever since agriculture was first developed, especially, ESPECIALLY, in Australia in the regions similar to where the Horsham FACE trial was conducted which not only simulated higher CO2 levels, but HOTTER and DRIER conditions as well. So far 3 trials have been done over 3 years, 3 below average years, and are ongoing. A couple of points :- (1)Seed yield increased significantly whilst seed protein fell slightly EXACTLY as has always has happened under natural conditions. Nothing new there. (2)Protein yield per hectare INCREASED meaning the process of producing more food from less land can continue. (3)Increased non-grain biomass assists in improving soil carbon content. To increase soil carbon content by 1 tonne per hectare, an extra 4.4 tonnes of dry matter per hectare has to be returned to the soil. (4) Irrespective of CO2 levels, higher outputs require higher inputs of water and nutrients. ALWAYS HAS. However indications are that under higher CO2 levels, water utilisation efficiency is INCREASED. ---------------------------------- Marcus at 09:41 AM on 23 June, 2010 Sorry moderator, but I just can't let John D's latest comments go by without a response. You seriously don't get it-do you John? Nobody here has claimed that-under ideal conditions-CO2 *can't* be a plant food. What they've claimed is that its not that simple because (a) global warming won't provide for ideal conditions & (b) that it is nitrogen, water & trace elements that are more limiting factors on plant growth than CO2 abundance. For all your talk, you've not managed to answer several key questions which are: (a) under ideal conditions, can increased CO2 levels enhance plant biomass for the long-term, given acclimation? (b) even ignoring acclimation, can increased CO2 levels enhance plant biomass given a warmer & drier environment? (c) will increased vegetative biomass, from increased CO2 levels, automatically translate into significantly greater seed yields? (d) does increased quantity of edible biomass automatically translate into increased *quality* of edible biomass. (e) will increased CO2 levels impose any additional costs on farmers? (very important given the slim margins on which most farmers operate). Based on the evidence provided by the *one* FACE trial you've linked to, I'd say the answer is that, (a) though increased CO2 can provide short-term increases in total biomass (under ideal conditions) acclimation might eventually erode those benefits; (b) that though there was a significant increase in total plant biomass, this wasn't translating into significant increases in seed yield for most varieties & (c) that seed quality (in terms of protein content) was decreased, but total nitrogen demand from the plant was increased. As someone who actually deals with farmers on a regular basis, if you were to try & promote that to farmers as a *benefit* from increasing CO2 emissions, they'd probably laugh in your face-rightly pointing out that ideal conditions are already hard to come by, that seed yield & seed quality are all that's ultimately important, & that they would be ill-equipped to afford the significant increase in fertilizer costs that this enriched CO2 environment would demand. ----------------------------------- -
Doug Bostrom at 08:16 AM on 30 June 2010Sea level rise is exaggerated
Upon further scrutiny of my last post, I think it communicates poorly the conservative nature of Donnelly's interpretation of his samples versus Daniel's assertions concerning hidden slewing. Daniel posits There is more than enough slack in this data to periodically reproduce the apparently rapid sea level rise of 2.8mm/year in the NYC tide gauge data of the last ~150 years (cited and compared to by the authors). Donnelly on the other hand sticks to the available data. Looking at Donnelly's figure 2 where he marries together the various data I think shows how Daniel might be right that while short episodes of discontinuous rise and fall may indeed be invisible, a linear interpretation not only avoids speculating signal features where none can be derived from the data but in fact more likely yields a result that is plausible on its face. Supposing for a moment that we are free to make up data however we please, how exactly would discontinuities of the kind Daniel imagines may have happened actually fit within the constraints of connections between the samples while still connecting to the more recent instrumental record? If I felt free to draw lines wherever I pleased between the samples it might be possible to squeeze in some excursions, but then I'd not only be substituting fiction for reality, I'd almost have to end up with an implausible looking graph, and again I'd have to be creating data to do so. So my conclusion is that Donnelly's more conservative than Daniel. Here's the figure from Donnelly by way of illustration:
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VoxRat at 07:22 AM on 30 June 2010Perth forum on climate change: all the gory details
The photo in the post needs a caption. Who's who?Response: Good point, caption added. Thanks for the suggestion. -
kdkd at 06:31 AM on 30 June 2010Astronomical cycles
Ken #110 The main flaw in your argument is that you assume a perfect measurement model through space, time and instrumental precision. As none of these conditions are met, your entire argument is invalid. -
Peter Hogarth at 06:11 AM on 30 June 2010Sea level rise is exaggerated
daniel at 22:03 PM on 26 June, 2010 I did make an assumption and I apologise, I'm not sure where that came from, but it was late! Perhaps "The article claims that skeptics are guilty of interpreting small recent trends from noisy data as significant" figure 1 etc. I assumed this was an oft used reference to the Jason 1 satellite altimeter data showing a decrease in trend a couple of years back (not a decrease in level, it appears we both got the wrong end of the stick), that's what I meant anyway. More relevant to your debate, see Grinsted 2009 which is pertinent to your points on sea level reconstructions. There's a few more I can dig out if of interest and I get time. I'm not sure "Therefore it is invalid to conclude there has been a significant recent increase in sea level rise" is really supportable. Doubt whilst you accumulate more evidence would be ok. -
Peter Hogarth at 05:12 AM on 30 June 2010CO2 is not a pollutant
AWoL at 04:22 AM on 30 June, 2010 "What's good for plants is good for animals which is good for people" Joseph Priestley might have had something to say about this! -
Tom Dayton at 04:50 AM on 30 June 2010CO2 is not a pollutant
AWoL, regarding the benefits of CO2 itself for plants, see the comments before yours on this thread. Click on the links within those comments for supportive details. Regarding your other contentions, see the broader post It’s not bad, which lists positives versus negatives of not just more CO2 for plants to consume, but of all the effects of higher CO2 levels, including warming and ocean acidification. -
Doug Bostrom at 04:50 AM on 30 June 2010CO2 is not a pollutant
Quite a bit of unsupported speculation there, AWoL. Other people with skills specific to the various spheres of knowledge you touch upon draw different conclusions. Anyway, with regard to unchecked formerly insignificant pollutants emerging from burgeoning cultural intensity we have lessons from the past to draw upon. Government (us, acting in concert) ends up owning solutions nobody else can or will provide. For a specific example of effective solutions to pressing need arising from inadvertent effects of commercial activity in combination with exploding demand see the example of cholera and typhoid emerging in London and other developing urban systems. A key feature of this story is that established commercial forces nearly invariably resisted attempts to solve the fundamental causes of these diseases, leaving the public in the form of government eventually forced to insist by agreed-on coercion. -
Baa Humbug at 04:44 AM on 30 June 2010What causes the tropospheric hot spot?
It's 4.45am here so i need to excuse myself. Don't read anything into my silence please. And thanks to all those who replied -
Baa Humbug at 04:26 AM on 30 June 2010What causes the tropospheric hot spot?
The 2 to 2.5 was my understanding and I concede that I can't at this time put my finger on where this figure came from. So I'm happy to take your quoted figure of 1.25 However this 1.25 is GLOBAL MEAN. The hot spot is supposed to be most prominent over the oceans and over the tropics (as shown by chart C 30N to 30S) Unless the colours of my computer screen are off, the legend on these charts show a warming of 2 to 3 times than that of the surface ( 0.4 to 1.2) The charts kindly provided by Peter at #54 show tropospheric warming mainly in the high lattitudes, but very little warming along the equatorial band. like wise with the stratospheric cooling. There is a discrepency there (in relation to the hot spot hpotheses) that I can't explain, maybe someone else can. -
AWoL at 04:22 AM on 30 June 2010CO2 is not a pollutant
Apologies to the Moderator. I posted in the wrong place as a result of not properly familiarising myself with the layout,prior to posting. # AWoL at 07:28 AM on 29 June, 2010 I'm just a vet, though believe it or not, I can remember Boltzman's Constant from our old Physics lectures, so I like to believe that I inhabit the ranks of the scientific semi-literate. My question is, if the Earth has an arbitrary average temperature of circa 15degC and the temperature of space is 270degK ie -270degC, then what's the problem? Anything that stems the ferocious heat loss to the exterior, surely has to be a good thing? Surely the correct thing to do is to pump CO2( or more potent greenhouse gases) into the atmosphere in order to keep the planet as warm as possible? What a nutty idea , I hear you say, but in reply I say....-270degC, out there. Not much chance of too much warming when you're up against that. It's bloody cold out there! # scaddenp at 08:14 AM on 29 June, 2010 Awol - "as warm as possible". Why not even more potent GHGs then and get us to Venus-like temperatures? Well obviously because we want planet to be around the temperatures we evolved to live in. However, this debate isnt really about what would be an optimal temperature but is about how fast we are changing it. Think of your farm animals and about how easily farmers are able to cope with rapid climate change. We have huge urban centers and complex food production systems that have developed in stable climate. Rapid change is not good for them. Ask how farmers on the great deltas are going to cope with coast erosion and salt incursion as sealevel rises as well. Over a 1000 years (ice cycle type change) possible. Over 100 years - hmm. AWoL replies scaddenp has given an answer of sorts,but I have to say I'm not entirely satisfied. The Venus comparison is no good as there is a lot of controversy over the workings of the Venusian atmosphere.Most agree that it is not comparable to Earth, and in fact the greenhouse effect of CO2 plays but a small part in explaining the high surface and atmospheric temperatures on that planet. Regarding the consequences of the overheated planet which you envision. Why all the doom and gloom? In the deltas that you mention, could not the farmland, assumimng that there is any, be replaced with fish-farming and shellfish production? People could live on man-made islands as have been constructed in Dubai.In Japan and Hong kong hasn't there been considerable land reclamation? Then there's the Dutch and their dykes.Isn't nature herself lending a hand in the creation of new land ie the Surtseys and the Icelandic Westmann Islands. Isn't isostatic rebound still underway from the last ice age? Or has that come to a stop? With regard to agricultural production, I can't help feel that you are miles off the beam. Wasn't it Herschel the astronomer, that correlated increased sunspot activity with lower grain prices? Everything starts from plants. What's good for plants is good for animals which is good for people.Plants like the heat,given adequate water, and they positively love CO2. Where you, scaddenp,see doom and disaster, I see formerly barren territories transformed into luxuriant swards and dense woodlands, inhabited by contented happy people. That's the bit I don't get. Why is climate change, ie getting hotter, always accompanied by doom and disaster when if anything it is more likely to be accompanied by happiness and prosperity? Any changes are not going to happen overnight, so there's plenty of time to react.And never before have people been able to move so rapidly, and easily establish new settlements, thanks to the extra power to their elbow of readily combustible,energy-dense hydrocarbons.Markets and the intiative of adaptable people will solve any problems far more effectively than any number of governmental organisations. The Sahara was once green. There was no UN in those days.The people didn't die, but moved, adapted and went forth and multiplied......and very good at multiplication they were ..... a bit too good, for their own good, I sometimes think. -
What causes the tropospheric hot spot?
Humbug, Here is the RSS image from the Wikipedia article Peter was referring to:
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Time range is 1979-2010. From this you can see clearly that your assertion was incorrect, stratospheric cooling + troposheric warming is empirically measured, it doesn't just come from models.
Also note that the tropospheric hotspot is a distinct concept from stratospheric cooling + tropospheric warming. The tropospheric hotspot is a greater warming of the troposphere in lower latitudes relative to higher latitudes. This is a prediction that follows from any warming, not just from CO2. Stratospheric cooling is the cooling of the stratosphere while the troposphere warms across all latitudes. This prediction is unique to warming from GHG's. Figure 1 in this post shows a combination of these two predictions.
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Ned at 03:51 AM on 30 June 2010What causes the tropospheric hot spot?
Baa Humbug, can you explain where you got that "2 to 2.5" factor from? I don't know a lot about that side of things, but my understanding was that the models estimated an amplification factor of about 1.25 globally (1.4 over the oceans and 0.95 over land). But I could easily be misunderstanding either you or the literature (or both)! Also note that the top panel of Peter Hogarth's graphic shows the middle troposphere, not the lower troposphere. -
Baa Humbug at 03:24 AM on 30 June 2010What causes the tropospheric hot spot?
Thanks Peter Short time series? How short? What is it's significance? The label says temperature trend. Trend since when? How does this relate to surface warming? These charts show warming of about 0.2-0.4. Not quite 2 to 2.5 times the surface warming. -
Peter Hogarth at 03:15 AM on 30 June 2010What causes the tropospheric hot spot?
Baa Humbug at 02:26 AM on 30 June, 2010 “So, what tropospheric warming and what stratospheric cooling? So far they only exist in the models”.
This is from the AMSU satellite sensor so is a shorter time series. I have similar images for RSS and UAH which show more warming (since 1979), but I think the RSS one is even on Wikipedia.
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HumanityRules at 02:58 AM on 30 June 2010Return to the Himalayas
I don't know where you live Doug but Western Europe has 'controlled' and reshaped every major river system in the region. And yet the earth continues to turn and the sun continues to rise. Those opposed to dams and the like need to realise we could be denying developing nations the benefits that have come with this successful Western European experiment. -
Peter Hogarth at 02:48 AM on 30 June 2010Astronomical cycles
Ken Lambert at 00:32 AM on 30 June, 2010 Are you looking at the image or the actual data? From JASON 1 data 2002 up to end 2009 I get a trend of 2.61 mm/year, inverse barometer applied, seasonal signals retained. Adding GIA corrections would add another 0.4mm (current estimate) as in the chart you refer to. JASON 2 has obviously not had enough time (2 years) to develop a meaningful trend of its own as yet but the high accuracy and successful calibration means that the data points can be added to the overall picture. I suspect this is what the final points are on the Colorado chart (ie Jason 2) but I will check. Envisat has been going since 2002 as with Jason 1, and TOPEX continues through to end 2005 so there is overlap rather than the step transition you imply. There are also a couple of other satellite altimeters which add to our knowledge. The chart I presented has an unweighted composite of all data, but you can check on several official sites for similar charts. I haven't looked at the data for a couple of months, I'll check and let you know if I find any surprises. -
Steven Sullivan at 02:46 AM on 30 June 2010How many climate scientists are climate skeptics?
omnilogos fudges a bit: "And what have you been reading at RealClimate? How about this: "we note that once the categorization goes beyond a self-declared policy position, one is on very thin ice because the danger of ‘guilt by association’. For instance, one of us (Eric) feels more strongly that some of Prall’s classifications in his dataset cross a line" I say, even the guys at RealClimate could see the "methodological issues" " I saw what you did there. *One* of the two authors of that article at RealClimate (Eric Steig) is on record as having issues with the paper (though from the looks of this article *he co-signed), he's dialed waaaaay back from being 'appalled'). Gavin Schmidt, not so much, apparently. The rest of the 'guys' at RC haven't chimed in. And of course, if you read the *whole* RC article, not just the sentence that looks most condemnatory, you'll get a different picture of what the 'RC guys' think of it, compared to what omnilogos claims. And of course, both 'guys' sign on to the fact that there really is a consensus: "They are misleading because as anyone with any familiarity with the field knows, the basic consensus is almost universally accepted. That is, the planet is warming, that human activities are contributing to the greenhouse gases in the atmosphere (chiefly, but not exclusively CO2), that these changes are playing a big role in the current warming, and thus, further increases in the levels of GHGs in the atmosphere are very likely to cause further warming which could have serious impacts. " All the angry buzzing of skeptic wasps over this paper, just shows how threatening scientific consensus is to them. Their 'successes' are occurring almost entirely in the public relations, not scientific, domains. Historically this isn't tenable; science will out. -
Doug Bostrom at 02:42 AM on 30 June 2010Return to the Himalayas
Thanks for the pointer to the paper, HR. More refinement with cautious conclusions. For me the takeaway on was that future behavior of monsoons is going to be a key determinant of how stable the region remains for cultivation, more so for those areas where solid-state storage counts and diminishes, and we need to understand monsoons better. W/regard to engineered structures they can certainly help but for me to the extent we can avoid stressing both nature and ourselves by avoiding the need to create dams and the like the better. I'm personally a fan of dams but we've sometimes been pretty thoughtless about where they're implemented and of course they cost money. As well, they sit in a nest of complications when transnational rivers are involved. For a truly astonishing example of engineered responses to climate change see this example: Chinese engineers propose world's biggest hydro-electric project in Tibet Comes with strings attached, because nothing's simple in the hands of us humans. China-India history, new dams across upper reaches of Brahmaputra, rationality about net effects downstream may well take a back seat to festering wounded feelings. -
barry1487 at 02:32 AM on 30 June 2010Perth forum on climate change: all the gory details
Simply point out that for it to be true global mean temperature would have to have remained at least the same since the MWP for the entire ocean to have warmed and reached a new, warmer equilibrium. The problem with this fantasy is the Little Ice Age.
Ha! I mentioned that too, in times past, but the rejoinder was that the lag will produce the same curve in CO2 as temps, just 800 years later. So CO2 will go down pretty soon, matching the downturn to LIA 800 years later. If you try to say that sustained warm temps are required, they will hit you with a handful of wiki graphs showing temps going up and down during deglaciation. When you try to point out the time scale of events, you will be informed that the resolution just isn't that good for ice ages. After that, most likely the discussion will descend to the political or personal. -
Baa Humbug at 02:26 AM on 30 June 2010What causes the tropospheric hot spot?
David #48 Thankyou for the reply I don't wish to argue anything, but I do wish to understand better. I'm personally not interested whether the IPCC has worded this well or not. The fact remains that if the surface has warmed, then the troposphere should have warmed by 2 to 2.5 times as much. Between satellites and radisondes this amount of warming should have been detected. It hasn't been. When you say "if the hot spot has not been found, I'd have to argue one of the 3 options you propose", I would contend that I don't have to argue any of that. It's the proponents of the hot spot (the IPCC) who have to argue one of those 3 options. Afterall, it is they who promoted the hot spot, anthropogenic or not. And they felt it was important enough to not only discuss in chp 9 but also in the faq's along with this in the synthesis report... "The observed pattern of tropospheric warming and stratospheric cooling is very likely due to the combined influences of GHG increases and stratospheric ozone depletion". (page 39) So, what tropospheric warming and what stratospheric cooling? So far they only exist in the models. The IPCC is quite clear in the passages that I cited. It is not the affect of warming that's distinguishable, it's the response to the warming. i.e. a troposphere that warms by 2 to 2.5 times that of the surface accompanied by a cooling stratosphere. Also, as much as I appreciate the charts you have posted, the AR4 makes it clear that the sun has had negligable affect on climate in the 2nd half of the 20thC, therefore, if a hot spot was to be detected, (along with a cooling stratosphere) it can only be a response to CO2 forcing, no? -
barry1487 at 02:23 AM on 30 June 2010Perth forum on climate change: all the gory details
My favourite skeptic argument of the evening was a new one to me (and I thought I'd heard them all). One audience member asked Malcolm if CO2 lagged temperature rise by 800 years, wasn't the current CO2 rise just a lagged response to the Medieval Warm Period?
I've come across this one a few times. My reply, FWIW as a layman, was that the lag started at ~800 years, but it was another 4k years before the atmospheric concentration of CO2 increased by 100 ppm. We've had an increase of 100 ppm in 100 years (carbon sinks accommodating excess anthropegenic CO2 up until around the end of the 19th century). This is a rate 40 times faster than ice age carbon cycles - or 20 times faster if we take the start point of modern CO2 rise as the beginning of the industrial revolution. Also, the 100ppm rise accompanied a global temp change of 5 - 6C through deglaciation. The MWP temp rise, at skeptics' highest posit, was less than half that. Therefore, the MWP can only have made a tiny contribution to post-industrial CO2 concentration in the atmosphere, if any. Please, correct any errors in my assumptions or reckoning. The objection is not common and I had only my probably faulty memory of the reams of stuff I've read hither and yon. -
Jim Eager at 02:16 AM on 30 June 2010Perth forum on climate change: all the gory details
John Cook, the "CO2 rise is just a lagged response to the Medieval Warm Period" argument is not at all uncommon, and it is rather easy to counter. Simply point out that for it to be true global mean temperature would have to have remained at least the same since the MWP for the entire ocean to have warmed and reached a new, warmer equilibrium. The problem with this fantasy is the Little Ice Age. This is another example of one "sceptic" argument that is contradicted by another. I've actually successfully stopped a hard-core "sceptic" cold by pointing this contradiction out to him, much to my own surprise. -
JMurphy at 01:55 AM on 30 June 2010Abraham reply to Monckton
AWoL, please provide more information as to your views on Venus - briefly, if you can. Also, with regard to us on this planet, you seem to have forgotten about : Population totals and density, National borders, The slowness of geological time as opposed to the quickness of present climate change, The recent credit crunch, The nonsense of skeptical arguments, and The rise and fall of civilisations. Aside from all that, erm, you have nothing new to add except wishful thinking. See further on this very website.Moderator Response: JMurphy is correct that other posts on this site are appropriate for AWoL's comments and for responses by other people. That conversation is diluting this thread, so further off topic comments will be deleted. Remember that you can see recent comments on all threads at once, by clicking the "Recent Comments" link in the blue horizontal bar at the top of every page on this site. Lots of people watch that page, so you need not worry about people missing your comment even if it is on a different thread than this one. -
David Grocott at 01:45 AM on 30 June 2010What causes the tropospheric hot spot?
Yes Albatross, I've now corrected it, thanks. Damn my frazzled brain. -
David Grocott at 01:44 AM on 30 June 2010What causes the tropospheric hot spot?
There was a documentary on the BBC last night called "Panorama: What's Up With the Weather?" In it Bjorn Lomborg and Prof. John Christy both happily accepted that CO2 has an effect on global temperatures. See here and here. Perhaps Nova's crowd will listen to them? -
Albatross at 01:40 AM on 30 June 2010What causes the tropospheric hot spot?
David and Peter, Thank you both for your very informative posts. David, in your post at #48, shouldn't the lower figure be for 2xCO2, and the top figure for 2% increase in solar forcing? -
Ned at 01:39 AM on 30 June 2010Temp record is unreliable
If anyone is uncertain about what to make of the conflicting claims from BP and me, please do the following: (1) Go here and download the spreadsheet that Zeke Hausfather compiled, showing annual global temperature reconstructions from many different analyses by many different people. The data are described in Zeke's post here. (2) Click on the tab labeled "Land Temp Reconstructions". If you want to see the effects of the GHCN adjustment, select columns A (year), E (v2.mean) and F (v2.mean_adj). (3) To see the effect of the adjustment, subtract column E from column F. To determine the trend in this adjustment over any period of time (like BP's weird choice of 1934-1994) select that range of years and fit a linear model to the differences, as a function of year (and multiply the slope by 100 to convert from degrees C/year to degrees C/century). For 1934-1994 the slope is 0.19 C/century. As stated above, over the past 30 years the adjustments have actually reduced the trend (slope -0.48 C/century). Contrary to what BP claims, it's really important to use some form of spatial weighting (e.g., gridding) when doing this, because the stations are not uniformly distributed. Taking a simple average would only be appropriate if there were no spatial autocorrelation in the adjustments. Given that stations in different countries have been administered differently, this seems like an extremely unlikely assumption. BP's claim that "more complicated" (that is, more correct) methods don't show the temporal evolution of adjustments is likewise inexplicable. All of the reconstructions produce annual temperature estimates. -
John Russell at 01:38 AM on 30 June 2010Perth forum on climate change: all the gory details
When the RTR FM interviewer asked you what you thought was "the most convincing skeptic argument", it was of course because -- being a journalist -- he had got completely the wrong end of the stick about what you represented, John. Did they take a poll at the end to ascertain how many people had been persuaded by what they had heard?Response: No, he got me, he started the segment saying "today we're going to get skeptical about global warming skepticism". I thought, hey that sounds catchy, then remembered that was the slogan at the top of the Skeptical Science website. It was just a clever question, I'm still undecided on what's the best answer (I went with using photos to cast doubt on the surface temperature record as pictures are so persuasive, then pointed out what that's irrelevant from a scientific point of view). -
Tom Dayton at 01:33 AM on 30 June 2010Abraham reply to Monckton
No, AWoL, there is not "a lot of controversy over the workings of the Venusian atmosphere." Perhaps you've been misled by the artificial controversy sparked by Goddard and Motl, and addressed in multiple places such as at Chris Colose's place. -
Rob Honeycutt at 01:31 AM on 30 June 2010What causes the tropospheric hot spot?
fydijkstra... I've not read enough of JoNova's post to comment on whether she rejects the basic theories behind AGW but the crowd who posts on her site most certainly does. I spent about two days posting on her site and was barraged with people telling me, in no uncertain terms, that CO2 has absolutely no affect on global temperature or climate. Arrhenius was wrong. When I posted a video of a simple lab experiment using a cylinder filled with CO2 and an infrared camera, it was brushed off as a trick. JoNova may not agree with that position but she, and a small handful of people who certainly know better, are not making even the slightest attempt to correct their errors. -
David Grocott at 01:17 AM on 30 June 2010What causes the tropospheric hot spot?
Baa Humbug, This is a difficult topic and unfortunately pages 674 and 675 of AR4 Chapter 9 are causing a great deal of confusion - although that's not to say they're wrong. You quote from the FAQs document, page 120 - 121. I repeat:Models and observations also both show warming in the lower part of the atmosphere (the troposphere) and cooling higher up in the stratosphere. This is another ‘fingerprint’ of change that reveals the effect of human influence on the climate. If, for example, an increase in solar output had been responsible for the recent climate warming, both the troposphere and the stratosphere would have warmed.
The quote above says that an increase in solar output, and anthropogenic contributions, should both result in a warming of the troposphere. As your quote testifies, this agrees with observations. It also says that anthropogenic contributions, but not an increase in solar output, should result in a cooling stratosphere. Once again, this prediction agrees with observations. The human 'fingerprint of change' to which the IPCC refers is not a warming troposphere alone (which could be induced by changes in solar output), but a warming troposphere combined with a cooling stratosphere. Your second quote is necessarily taken out of context, but in the process loses some of its intended meaning. The loss of meaning is exaggerated by the fact that it was poorly and ambiguously worded in the first place. The charts accompanying the quote (which are shown in Figure 1 of John's article) are labelled as follows:Figure 9.1. Zonal mean atmospheric temperature change from 1890 to 1999 (°C per century) as simulated by the PCM model from (a) solar forcing, (b) volcanoes, (c) wellmixed greenhouse gases, (d) tropospheric and stratospheric ozone changes, (e) direct sulphate aerosol forcing and (f) the sum of all forcings. Plot is from 1,000 hPa to 10 hPa(shown on left scale) and from 0 km to 30 km (shown on right). See Appendix 9.C for additional information. Based on Santer et al. (2003a).
That is to say that the charts model zonal mean atmospheric temperature change from 1890 to 1999, and assign varying proportions of this change to different forcings. The fact that since 1890 the largest forcing by far has been well-mixed greenhouse gases - or at least that's the 'assumption' the IPCC has based its model on - means (a), and also (f) - the sum of all forcings - show the most prominent hot spot. None of the other forcings have been sufficient in the last 100 years to create a hot spot of similar magnitude. As I pointed out at #2, non-CO2 forcings have been small, so the tropospheric response has been small. Figure 9.1a is not, I repeat not, a demonstration of the possible zonal mean atmospheric temperature changes associated with different forcings. It is merely a modelled image of changes over the last 100 or so years. The wording of the IPCC quote you provided is therefore very poor. It perhaps should have read "The simulated responses to natural forcing [over the last 100 years] have been distinct from those due to the anthropogenic forcings described above". If we run the GISS model equilibrium with 2xCO2 or a 2% increase in solar forcing (forcings in the same order of magnitude) we get the following pattern of zonal atmospheric temperatures: For 2% increase in solar forcing
For 2xCO2
As you can see, the main difference occurs in the cooling stratosphere, but the tropospheric hot spot is clearly evident in both.
You can also see this pattern in picture (a) on the charts you referred to, however, as a result of the lower levels of solar forcing the pattern is not as pronounced.
So to clarify, any warming of a sufficient magnitide should be expected to create a tropospheric hot spot.
If you then wish to propose that the hot spot has not been found, you have to argue for one of the three conclusions I highlight in #46.
By the sounds of it you'd like to argue point 3) - that there is in fact much less warming than our measurements tell us there is. In which case I refer you to 'Are surface temperature records reliable?'
Moderator Response:
I'd like to correct this post slightly, as I think part of it is misleading.
As 'andrew adams' and 'e' have alluded to, the wording of the IPCC quote is not in fact 'poor'. That adjective can be reserved for my interpretational ability.
The following quote is in fact perfectly accurate as it refers to the general pattern of warming troposphere/ cooling stratosphere, as opposed to the existence of a tropospheric hot spot, which is a seperate phenomenon:The simulated responses to natural forcing are distinct from those due to the anthropogenic forcings described above.
The confusion comes because it links to a set of charts which, by necessity, show the tropospheric hotspot in addition to the general pattern of tropospheric warming/ stratospheric cooling.
David -
AWoL at 01:10 AM on 30 June 2010Abraham reply to Monckton
scaddenp has given an answer of sorts,but I have to say I'm not entirely satisfied. The Venus comparison is no good as there is a lot of controversy over the workings of the Venusian atmosphere.Most agree that it is not comparable to Earth, and in fact the greenhouse effect of CO2 plays but a small part in explaining the high surface and atmospheric temperatures on that planet. Regarding the consequences of the overheated planet which you envision. Why all the doom and gloom? In the deltas that you mention, could not the farmland, assumimng that there is any, be replaced with fish-farming and shellfish production? People could live on man-made islands as have been constructed in Dubai.In Japan and Hong kong hasn't there been considerable land reclamation? Then there's the Dutch and their dykes.Isn't nature herself lending a hand in the creation of new land ie the Surtseys and the Icelandic Westmann Islands. Isn't isostatic rebound still underway from the last ice age? Or has that come to a stop? With regard to agricultural production, I can't help feel that you are miles off the beam. Wasn't it Herschel the astronomer, that correlated increased sunspot activity with lower grain prices? Everything starts from plants. What's good for plants is good for animals which is good for people.Plants like the heat,given adequate water, and they positively love CO2. Where you, scaddenp,see doom and disaster, I see formerly barren territories transformed into luxuriant swards and dense woodlands, inhabited by contented happy people. That's the bit I don't get. Why is climate change, ie getting hotter, always accompanied by doom and disaster,when if anything, it is more likely to be accompanied by happiness and prosperity? Any changes are not going to happen overnight, so there's plenty of time to react.And never before have people been able to move so rapidly, and easily establish new settlements, thanks to the extra power to their elbow of readily combustible,energy-dense hydrocarbons.Markets and the intiative of adaptable people will solve any problems far more effectively than any number of governmental organisations. The Sahara was once green. There was no UN in those days.The people didn't die, but moved, adapted and went forth and multiplied......and very good at multiplication they were ..... a bit too good, for their own good, I sometimes think.
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