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Comments 110101 to 110150:

110101. kdkd at 21:30 PM on 15 September 2010
        The contradictory nature of global warming skepticism
        Baz #161 If your argument was reasonable, you would have answered my previous question. However, despite acknowledging it, you have made no attempt to answer. Therefore I declare your position as shallow, incoherent, and not based on the available evidence.
110102. Ann at 21:08 PM on 15 September 2010
        The contradictory nature of global warming skepticism
        "I DO NOT accept that there is sufficient evidence to show that we WILL get warming as a result of our emissions." You seem to claim: as long as there is no absolute certainty, I don’t accept the evidence. Well, tough luck, the certainty is never going to be a 100%, not even after the earth has warmed up 6 degrees or more. It is always possible – although HIGHLY unlikely- that some revolutionary new theory is developed that conjures a whole new climate factor out of its hat to explain the current global warming. Until then we have to make do with the knowledge and understanding we have, assess the risks and act upon it. If there was even a 10% chance that your house will burn down, you would be alarmed and take immediate action (at least get a fire insurance). Now there is a 90% chance that due to CO2 emissions the climate will drastically change, making the earth possibly a hostile environment for life, you demand absolute certainty before taking action ?
110103. JMurphy at 20:57 PM on 15 September 2010
        The contradictory nature of global warming skepticism
        Albatross wrote : "JMurphy, I'm beginning to think "concern troll"." I think you are right. Baz is good proof that it's not just skeptical arguments that are contradictory - the so-called skeptics themselves are even worse. The strange thing is, though, that it is blindingly obvious what Baz is up to but he thinks no-one notices !
110104. JMurphy at 20:51 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        adrian smits wrote : "Hasn't any one here seen the pictures of Soviet and American subs surfacing at the north pole into open water during the 1950s. I have seen some, usually taken at the height of Summer (when open water is to be expected to some degree), but don't know what you are trying to prove. Perhaps you should give some links for some of those pictures - direct links, of course, and not via secondary websites.
110105. nealjking at 20:23 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        55, TTTM: 1) Yes, the amount of thermal radiation power in a frequency range depends on the emissivity; but the overall balance of heat transfer is going to be driven by the direction of the temperature difference. It will always be from warmer to cooler; and if there is no temperature difference, there will be no net transfer. If you have two objects of different emissivities facing each other, they still drive towards an equilibrium with the same temperature, because their absorption at that frequency range is proportional to their respective emissivities: one of Kirchhoff's laws on blackbody radiation. At equilibrium, they don't have to emit the same amount, and they don't have to absorb the same amount; but there is a match between what they emit and what they absorb, individually. So when the two objects are at different temperature, the hotter object will be losing more heat to the colder, on net. And when the temperatures are the same, there will be no net transfer. 2) The full explanation of the way the greenhouse effect works depends on an understanding of how radiation works in the atmosphere, specifically on radiative transfer theory. The best concise explanation I have seen is in a book (which I got in early preview version by softcopy) by Pierrehumbert: http://geosci.uchicago.edu/~rtp1/ClimateBook/ClimateBook.html . It is likely that I will attempt an explanation in another post I agreed to write, on why CO2 can be an effective greenhouse gas even though it represents such a tiny percentage of the atmosphere. But it will be tough: definitely harder to make clear than this feedback model. To try to give some general answer to your specific question: The source of IR radiation in the atmosphere is the ground. Let's consider photons of a particular frequency range, say about 4 micron wavelength. They are emitted from the ground in an upward direction; but because of the greenhouse gases (specifically, in the case of 4-micron IR, CO2), some of them are absorbed. After being absorbed, the CO2 molecule is in an excited state for awhile, and then re-emits a similar IR photon in some random direction. So you can think of it like this: The IR photon headed up, got stopped by a CO2 molecule, bounced into a different direction. It travels awhile, hits another CO2 molecule, bounces into yet a different direction. Basically, each photon is doing a random walk around the atmosphere; but the length of each step in the walk depends on the likelihood of hitting another CO2 molecule. The higher the altitude, the fewer the CO2 molecules, so that means that a photon starting off high up will take a longer step than one starting low down. There is a point where the concentration of CO2 molecules is so low that there is a good chance (more than 50%) that the IR photon will never hit another CO2 molecule: It will be emitted and keep going - it's escaped! That specific escape altitude defines the photosphere for that frequency of photon. A visible example: Ever seen a photograph of the Sun? You get a sense of a visible sphere of substance, with a well-defined surface. But that surface is the photosphere for the frequency of light which was used to make the photograph: If you take the picture with X-rays, you get a completely different picture, with a far smaller radius, because the X-ray photosphere of the Sun is different. This reflects the temperature profile. Anyway, the point is that the IR photons can be considered to escape when they are emitted from the level of the photosphere, whereas when they are emitted from lower altitudes they're still bouncing around. OK, so what is the rate of emission from the photosphere? It depends on the altitude there: the higher up it is, the colder it is, and the lower the emission power. Thus, the higher up the level of the photosphere is, the less emission there will be, the less escaping of the IR photons, and the less the cooling of the atmosphere through that particular frequency band. So when you add more CO2 to the atmosphere, you are increasing the altitude of the 4-micron band IR photosphere, so you are reducing the cooling. Hence, warming of the atmosphere. (Note: I've made a few simplifications: - The photon path is not completely random: I am ignoring some stimulated-emission effects. To do this right, we need to go into radiative transfer theory. Let's not. It doesn't change the overall picture, and it is A LOT of math & physics. - I defined the photosphere as the 50% escape point; a better definition would be when the escape probability is 1 - 1/e = 1 - 1/2.78 = 0.632. It doesn't make much difference. - Probably lots of others; as I said, this is very complex, so to even jump into it, I'm making all sorts of assumptions that would have to be justified in a real exposition.)
110106. Arkadiusz Semczyszak at 20:19 PM on 15 September 2010
        How we know the sun isn't causing global warming
        Given the rapid changes in science - the influence of the Sun on the climate (especially) - should be based on the latest studies. The latest textbook (110 pages!) describing the impact of the sun on climate, is: Solar Influences on Climate, L.J. Gray, J. Beer, M. Geller, J.D. Haigh, M. Lockwood, K. Matthes ,U. Cubasch, D. Fleitmann, G. Harrison, L. Hood, J. Luterbacher, G. A. Meehl, D. Shindell, B. van Geel, W. White (Reviews in Geophysics, 2010). There are, admittedly, such a sentence: “... indicate that solar forcing is playing at most a weak role in current global temperature trends (Lockwood and Fröhlich, 2007).” In his earlier work (Solar change and climate: an update in the light of the current, 2010) Lockwood also writes: “It is important not to make the mistake made by Lord Kelvin and argue that there can be no influence of solar variability on climate: indeed, its study is of scientific interest and may well further our understanding of climate behaviour. However, the popular idea (at least on the Internet and in some parts of the media) that solar changes are some kind of alternative to GHG forcing in explaining the rise in surface temperatures has no credibility with ALMOST ALL climate scientists.”. At the same time defines the problem: “From the GMAST record, we know that we need to explain _TS of +0.8K since pre-industrial times, around a mean value of 287.4 K. This makes the left-hand side of equation (10.1) equal to 4.30 + 0.85=5.15Wm−2 (adopting 0.85Wm−2 for the current value of γ and assuming that Earth was in radiative equilibrium in pre-industrial times). In §2, we discussed how observed GHG changes give a total radiative forcing (contribution to _G) of 2.45Wm−2. Thus feedback loops, through their net contribution to the _A and _G terms, are required to supply a further 2.46Wm−2. In other words, the feedback must essentially double the GHG forcing if they are the cause of the GMAST rise. On the other hand, our best estimate of the first term on the right-hand side of equation (10.1) is 0.23Wm−2 (_ITS =1.3Wm−2). If the analysis of Scafetta (2009) were correct and 65 per cent of the observed warming were due to solar effects, then the first term on the right-hand side of equation (10.1) plus the feedback would need to supply 0.65 × 5.15=3.35Wm−2.” Returning to the "Solar Influences on Climate ', where he co-authored by Lockwood, we find such attempts to solve this problem: „A value of 0.24 Wm-2 solar radiative forcing difference from Maunder Minimum to the present is currently considered to be more appropriate than the 0.12 Wm-2 estimated by IPCC (c.f. the range of 0.16-0.28 Wm-2 ...)” “Periodicities, trends, and grand minima are features of solar activity which, if detectable in climate records, can be used to attribute climate changes to solar forcing (Beer et al. 2000; Beer and van Geel, 2008). However, one must be aware that this may not always work well because there are other forcings as well and the climate is a non-linear system which can react in a variety of ways.” “... other forcings ...” and: “There are additional uncertainties in estimates of solar radiative forcing which also require further consideration.” ... eg: “... there could be effects of magnetic fields deeper in the convection zone, the so-called ‘shadow effects’ and there may small solar radius changes (Lockwood, 2010). The SATIRE modelling has shown that surface emissivity effects explain recent solar cycles in TSI rather well, and these shadow (and solar radius) effects are not significant effects over the past 30 years or so. However, this does not eliminate them as factors on longer timescales.” “Nevertheless, using short-term (3-hourly) ISSCP data, high-pass filtered to remove long term trends, a positive correlation between low cloud and GCR is still evident, indicating a 3% cloud variation (Brown, 2008).” “With the greater spatial and spectral resolution available in the MODIS satellite data, Kristjánsson et al. (2008) found only weak negative correlations between GCR and cloud properties during Forbush events, except for the eastern Atlantic Ocean region in which both the negative correlations between GCR and cloud, and between GCR and cloud thickness were statistically significant.” ... although it is true that: “... no significant effect of cosmic rays on low cloud cover could be found (Calogovic et al. 2010).” ... however: Solar modulation in surface atmospheric electricity, Harrison & Usoskin, 2009.: „Both the lower troposphere atmospheric electricity quantities are significantly increased at cosmic ray maximum (solar minimum), with a proportional change greater than that of the cosmic ray change.”
110107. Eric (skeptic) at 19:28 PM on 15 September 2010
        The contradictory nature of global warming skepticism
        archiesteel (#183), you say "Again, you have failed to make the case that hunting is the main reason behind polar bear population decline." The populations you listed as not threatened by hunting (e.g Baffin Bay) clearly are. The reference I provided refers to studies by Taylor who says in a letter http://www.ff.org/centers/csspp/pdf/200701_taylor.pdf that Baffin Bay is "over-harvested" and the decline is "not due to climate change". Then you say "What about the credibility of those who make claims without backing them up, or worse, who misrepresent the research of honest scientists?" That's exactly what this site did at this thread http://www.skepticalscience.com/polar-bears-global-warming.htm where Dr. Taylor was "rebutted" with a "what the science says" innuendo which implied that Dr Taylor was not a scientist or at least not an knowledgeable of climate change which is false. He clearly describes all aspects of climate change and its impacts in his studies.
110108. TimTheToolMan at 19:14 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        Thermally radiated energy depends on the temperature of the object and its emissitivity. You're confusing thermal radiation with thermal conduction of energy which does depend on temperature differences. What were you saying about the photosphere? That sounds fascinating.
110109. nealjking at 18:41 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        48, 51, TimTheToolMan: Yes, radiated thermal power depends on temperature difference. More power flows from warmer to cooler than the reverse.
110110. nealjking at 18:38 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        52, hadfield: The Stefan-Boltmann T^4 law does not apply to this case, because the Earth is not a blackbody: specifically in the frequency region of interest for greenhouse-effect considerations. There is no one "effective temperature". What matters in a particular frequency region is the altitude of the photosphere for that frequency. For frequencies that are transparent to the atmosphere, the photosphere is at ground level, and so the radiant emission reflects ground-level temperature. For frequencies that are absorbed by greenhouse gases, the photospheres are at various altitudes, depending on the absorption coefficients of those gases for the frequency, and on the distribution of the gases in the atmosphere. Thus the effective temperature at each frequency reflects the temperature at the altitude of the photosphere for that frequency. The way that the enhanced greenhouse effect works is that adding more greenhouse gas raises the altitude of some frequencies' photospheres, thus cooling them (higher altitude implies lower temperature, due to the adiabatic lapse law) and reducing the radiated power from the photosphere. Reduced power radiated => reduced cooling => heating. How does this relate to feedback? - When the ground-level temperature increases, all the temperatures of the different photospheres increase by the same amount (to first-order consideration), because they all shift upward: again, this is due to the adiabatic lapse rate of temperature with altitude. - The heating may introduce changes (probably mostly increases) in the greenhouse gases: methane, CO2, water vapor) which will adjust the photosphere levels again. This is a second-order consideration. - Sea ice will decrease: Most of what I have seen suggests that the dominant effect will be due to reduced albedo: More absorption of radiant energy, particularly in the Arctic. - There will be more clouding: What exactly this will do is a hot topic of discussion.
110111. VeryTallGuy at 17:26 PM on 15 September 2010
        The contradictory nature of global warming skepticism
        Baz, I fear you're trying to prove the article correct. You seem to hold the simultaneous view that 1) the last 10 years of data is a problem for the teory of AGW: "we have had 10 years now of remarkably stable temperatures." "With increasing CO2 we should surely see that mercury rising, shouldn't we Guy?" AND 2) 15-20 years data is required to be significant: "I think we settled on a period of 15-20 years" Can you spot the contradiction ?
110112. peter prewett at 16:51 PM on 15 September 2010
        Does more extreme rainfall mean more flooding? Answer: Not always
        @thingadonta: '3. Flooding in marginal drought/dry regions, such as in most of Australia, actually produce a net benefit. It is only in regions which are already prone to high rainfall that increased flooding generally produces net negatives. However with more dams (eg Brazil, China), this can be largley mitigated.' NO flooding causes erosion, silting up of wet lands, washing away creek and river banks and causing millions of dollars damage. That is why most of Australia has poor soils.
110113. Daniel Bailey at 16:27 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Re: adrian smits (32)

        "Hasn't any one here seen the pictures of Soviet and American subs surfacing at the north pole into open water during the 1950s."

        Open water at the North Pole is one of those urban legends that exist only in myth. This is well documented and well-researched. Here's a picture of the Skate surfaced in an iced-over lead (polyna) at the North Pole on March 17th, 1959. Here's a description of the weather of that day from quotes from the crew:

        "The sun was still just below the horizon and a very heavy overcast made for late twilight darkness (it did not appear until 19 March) the wind ….. was roaring around us at about 30 knots, blowing the snow until one could see no more than a quarter of a mile The swirling snow loomed around the red torches in the 26-below-zero cold….. The wind blew snow into our noses and mouths, and it was difficult to talk or even breathe The wind and bitter cold made it physically difficult to hold and read the prayer book the gale was increasing and the temperature dropping Both sides of the lead were piled with the heaviest and ruggedest hummocks I had yet seen in the Arctic. It was a wild and forbidding scene".

        Taken from Patrick Lockerby's blog The Chatter Box. Quotes from Artful Dodger's comment on Neveen's blog. Nice "open water", eh. Direct, observational testimony to the contrary of the meme. You apparently have the acquired the habit of citing things picked up on...an "unnamed blog" (because it can be inferred quite well)...of repeating things without checking them yourself for accuracy. I don't blame you for being duped; heck, it's happened to all of us at one time or another. But that was in the past. Or at least you now have a choice to make:

        1. Do you want to make a new beginning, free from the misperceptions and myths you've been brought to believe and actually learn what is actually going on in climate science? Or 2. Continue on the path you've been on & wonder why everyone's taking shots at you here?

        No conspiracy here, dude. Just people who want to help. But you have to make that call. Do you want help? Or not? The Yooper
110114. Albatross at 16:09 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Hi Adrian, "Gentlemen I was only responding to the picture posted by albatross" That claim is incorrect. Your first post at 13 above was made before I posted that NASA map. It is now clear that you had made up your mind at that point (i.e., there has been no substantial warming over the Arctic) b/c you have refused to accept the data shown to you here, rather choosing to keep shifting the goal posts. The NASA satellite map is not for screen-level temperature, but the surface temperature or skin temperature. The RSS TLT satellite data show a global long-term warming trend (globally) of +0.163 C/decade over the satellite era. Over the high northern latitude band (60-82.5 N) the rate of warming (for the same period) has been twice that of the global TLT temperatures. You might find these links of interest Part 1 and Part 2
110115. hadfield at 16:07 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        The reason that the various positive feedbacks in the climate system (eq. water vapour, ice and snow) are acting against a very strong negative feedback produced by the Stefan-Boltzman Law for radiative balance of the Earth as a whole emitted radiation = sigma T^4 where T is a suitably defined effective absolute temperature, somewhat lower than the surface temperature, because the greenhouse effect. This isn't usually called a feedback, but whatever you call it, the exponent 4 for temperature means that a small change in temperature produces a large change in emitted radiation. The positive feedbacks would to be really large to overcome this and cause a runaway. At least that's the way I like to look at it.
110116. adelady at 15:42 PM on 15 September 2010
        Does more extreme rainfall mean more flooding? Answer: Not always
        thingadonta. I'm not so sure about Australia's great benefits from drought and flooding. The places where this works are the places where it has always worked. The occasional extensive flooding of north Queensland leading to the occasional filling of Lake Eyre being the classic example. In other regions which have been taken over for crop production, drought leads to water repelling surface soils. Isolated heavy rainfall events can then lead to local flooding and erosion rather than replenishing the surface moisture or the water table. I'm no expert, but I'd not be surprised if similar results eventuated elsewhere. Intermittent heavy rainfall is no substitute for steady seasonal precipitation. This might be merely a feature of Australia's thin and depleted soils. It might also be a consequence of inappropriate past farming practices in other areas as well. I very much doubt that the optimistic it'll-all-balance-out-in-the-end approach is very helpful.
110117. adrian smits at 15:28 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Gentlemen I was only responding to the picture posted by albatross.Look at it. Does it not show approximately 3 tenths of a degree of warming since 1979?I know for a fact that the temperature record for the period 1940 to 1975 was at the very least flat to cooler.Even if it was only slightly cooler that just about eliminates the neglegible warming from 1979 to present.Hasn't any one here seen the pictures of Soviet and American subs surfacing at the north pole into open water during the 1950s.
110118. archiesteel at 14:28 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        @adrian, you make a lot affirmations but provide little sources. By the way, do you know that DMI's official position is that the arctic is warming? That's something the folks at WUWT have conveniently forgot to mention... "Since the 1970s the extent of sea ice has been measured from satellites. From these measurements we know that the sea ice extent today is significantly smaller than 30 years ago. During the past 10 years the melting of sea ice has accelerated, and especially during the ice extent minimum in September large changes are observed. The sea ice in the northern hemisphere have never been thinner and more vulnerable." http://ocean.dmi.dk/arctic/index.uk.php Also, looking at the actual graphs it's clear recent *winter* temperatures in the Arctic are much warmer than they used to be, which is consistent with AGW theory. You've been given quite a few explanations as to why your claims were wrong. You voiced your opinion, however if you are unable to provide actual science to support it it's probably a wise move to stop posting at this point.
110119. Daniel Bailey at 14:27 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Re: adrian smits (29)

        "...and probably no warming at all for the last 70 years..."

        You have a penchant for unsupported claims running contrary what is seen in the world we live in. Or are you referring to a planet other than Earth? If so, there are other threads for claims like those. You also have a penchant for debate, of which type this blog is not. Here claims must be supported by sources or you simply will have no credibility. If you have inputs to offer that can add to the discussions here at Skeptical Science, please make the needed adjustments. Dialogue supported by factual sources are encouraged and desired here. The Yooper
110120. archiesteel at 14:11 PM on 15 September 2010
        Does more extreme rainfall mean more flooding? Answer: Not always
        @thingadonta: "The idea that both droughts and floods will increase with global warming is too simplistic, and ignores the fact that in some or many areas, an increase in one of these partially cancels out an increase in the other." How do you arrive at your conclusion that this will happen in "many areas"? Do you have research to back this up or is this your opinion? "With increased warming, drought and flood-prone regions may merge closer together, which is a net positive effect." So, suffering from two natural disasters instead of one is *better*? You have to realize that droughts and flooding usually don't take place during the same time of the year... I'm sorry, but you are being naively optimistic, here. That's an awfully big risk you're taking with the lives and livelihoods of millions of people.
110121. archiesteel at 14:04 PM on 15 September 2010
        The contradictory nature of global warming skepticism
        @Eric: actually, of the three other examples you give, the only one where the decline *may* be related to over-harvesting is Kane. "The exceptions are SHB and WHB." ...and Baffin, Davis, Southern Beaufort Sea, etc. That's according to the link *you* provided. Again, you have failed to make the case that hunting is the main reason behind polar bear population decline. "The credibility of the CAGW argument as a whole suffers when important facts (the most important facts) are left out." What about the credibility of those who make claims without backing them up, or worse, who misrepresent the research of honest scientists? I think we're pretty much done, here.
110122. John Brookes at 13:52 PM on 15 September 2010
        Positive feedback means runaway warming
        The interesting thing about feedbacks is that to some extent we can get "runaway" feedback. The earth receives a certain power from the sun. For an earth in equilibrium, all that power must be radiated back out to space. The rate of radiation is proportional to T^4, where T is the temperature in degrees Kelvin (about 290 at the moment). For a simple analysis of feedbacks, we model the T^4 dependency by a linear one with matching slope at our current temperature. Over a small temperature range (and compared to 300, 1 or 2 degrees is small), the T^4 curve and the linear model will be almost identical. With the linear model we can now get "runaway" feedback. That is, each iteration of temperature in the spreadsheet analysis above leads to a bigger temperature jump than the one before, so instead of converging on a new value, the temperature just get bigger and bigger. Of course in this situation, the linear model is not accurate. What happens though is that we jump to a different part of the T^4 curve - a place where the slope is great enough so that the local linear model won't produce runaway feedback. To summarise. If feedbacks are small (or negative), you will get a multiplier effect - a small temperature change might get (say) doubled by feedback. If feedbacks are big, you may end up jumping to a different part of the T^4 curve. If one looks at the recent ice-age/interglacial temperature movements, it does look possible that feedbacks are kicking us from one temperature regime to another and then back again. Maybe I should try and post this with graphs and stuff.
110123. TimTheToolMan at 13:26 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        This isn't a tricky concept and the heat doesn't "disappear", its radiated out to space. Compare this to the ocean under ice that cant radiate its heat anywhere. Nobody can answer with any certainty whether all the energy gained during Summer will be radiated but I remind you again that the expectation from scientists is that the arctic will freeze over during winter so its entirely reasonable that all the energy and possibly more than was gained over summer is radiated for a possible net loss of earth's heat. Once you see that, your second question is also answered.
110124. adrian smits at 13:13 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Rob... its not where you are in the solar cycle that has much of an impact on longer term climate its the intensity and how long they last that seems to influence whether we are in a long term cooling or warming trend.Also if the PDO and AMO are in sincronicity of either a cooling or warming faze that can also have a big impact.In any case with temps of 33c in the summer and -44c in the winter .01c warming per decade for the last 30 years and probably no warming at all for the last 70 years aren't we arguing about how many angels can dance on the head of a pin?
110125. Rob Honeycutt at 12:32 PM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian... You might want to check the solar cycle again. I believe we've been in a deep solar minimum. I would expect solar irradiance to start kicking up for another 11 year cycle.
110126. Rob Honeycutt at 12:26 PM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        TimTheToolMan... Sorry, but last I read up on this, energy doesn't just disappear. So, 6 months of winter would not erase summer heating. Also, why is open ocean radiating heat a negative feedback? Can you explain this further?
110127. chris1204 at 12:09 PM on 15 September 2010
        Does more extreme rainfall mean more flooding? Answer: Not always
        Precipitation is one of the interesting twists in AWG - it could mean a positive feedback (water vapour and clouds with heat retention) or a negative feedback (clouds with increased albedo and increased snow cover at higher latitudes). A nicely nuanced post.
110128. Daniel Bailey at 12:06 PM on 15 September 2010
        European reanalysis of temperature confirms record warmth in 2010
        Re: Johngee (26) In order to measure change, you must first start with a baseline. Otherwise, you have no frame of reference and thus cannot measure anything ("Dude, you're lost"). With temperature change this starts with establishing the baseline. In Figure 1, all land surface temperatures for the months of May-July north of 20 degrees were calculated to get an average for the years 1989-2001. The change from this established baseline is called the "anomaly". Anomalies can be positive (evidence of warming) or negative (evidence of cooling). A common convention on temperature trend charts is to express positive anomalies in red and negative ones in blue. Anomalies are used because it is then possible to compare widely diverse and separated areas (not fair to compare absolute summer temperatures in Atlanta, Georgia to those in Nome, Alaska). And to reduce noise in the data, increasing the accuracy. Temperatures are typically taken at about the 2-meter level, for a couple of reasons:

        1. Keeping sensitive instrument packages off the ground keeps them from getting stepped on 2. Ground releases temps more quickly than air; so by removing the gauges off the ground you minimize warming bias 3. Gauges are easier to maintain and service at eye level than when on the ground (just seeing if you're still with me)

        Hmm, what else?

        "Can anybody explain the apparent dramatic shift 10-15 years ago? Or can I not read the graph in this manner?"

        You must be referring to figure 1. Note the baseline is reflected as the 0 horizontal line on the graph. The blue areas below the zero line are from a time period when it was cooler than the baseline period. Red areas above the baseline are from a period when it was warmer than the baseline. Applying a line of best-fit to the totality of the graph (blue and red) shows the overall warming. Where that line crosses the zero line (i.e., breaks the surface) does not imply that temperatures dramatically shifted in any way (yes, it would be a mistake to interpret the graph in that fashion...use all the data). So, both graphs show consistent warming, with no decline at all evident in the overall trend (even in the last 10 years, counter to what "some" may say. The land area reflected in Figure 1 contains the majority of the non-tropic land area of the globe; and its where most people live. Daytime air temps, while setting many record highs, can only warm just so far. The real increase in temperatures shown in Figure 1 come from higher average nighttime temperatures, reducing the temperature variance range between highs and lows, increasing average temps and increasing overall anomalies from baselines. Temperature increases are greatest towards the poles (look up "Polar Amplification" sometime), where the coolest air offers the greatest room for change. Figure 2 is more interesting. By using a 12-month average, seasonal variability is removed. Since it's global (land and ocean combined), one can see that the cherry-picking of "North America is cooling" is exposed as the charade it is. The most interesting thing about Figure 2 is not immediately obvious. About 93% of the warming of the globe has occurred in the oceans. Yes, the land has warmed too, but the oceans (with their huge thermal inertial mass) dominate the global climate. The warming going into the oceans goes two places:

        1. Transported to higher latitudes where the extra heat gets released into the colder air, warming the Arctic (one source of polar amplification) and melting the ice there 2. Through the mixing layer into the deep ocean (temporarily sequestering it...this comes back later to bite our descendants in the a**, but that's a later story)

        Warming is largely driven (in the absence of any change in warming inputs from the sun since 1970) by our greenhouse gases (of which CO2 is the control knob) not being in equilibrium with energy inputs. GHG gases slow the rate of heat release at the top of the atmosphere (primarily the troposphere; this also explains the observed stratospheric cooling). As long as there is a net gain in atmospheric CO2 concentrations, continued warming is inevitable (as reflected in the Mauna Loa CO2 trend data). The warming is predicted by GHG theory, multiple converging lines of evidence (not just temperatures and anomalies) shows it's there and the stratosphere is cooling: as predicted as well. And without the warming from greenhouse gases, there would literally be no liquid water anywhere on the planet, and thus, no life. Perhaps on certain blogs... And, due to the thermal inertia of the oceans, even if CO2 releases by man were immediately reduced to zero and kept there for 30 years, the warming would still continue. And that's just due to the slow feedbacks. There exist longer ones which are still to come. Hope that helps (and doesn't depress the he** out of you like it does me), The Yooper
110129. Eric (skeptic) at 11:51 AM on 15 September 2010
        The contradictory nature of global warming skepticism
        archiesteel (#179), for WHB you are correct that the ice breakup date is more significant than hunting. The venturing of polar bears you seem to want me to talk about is anecdotal and speculative. For all other "very high risk of decline" populations (Baffin, Davis, Kane, etc) hunting is more important than ice breakup. The exceptions are SHB and WHB. In Norwegian Bay the problem is too much ice so breakup would help. The concrete evidence is written in each link in the left column of the status table. Contrary to your assertion that I am wrong about the research not taking hunting into account, I never said anything like that. What I said was that the thread I linked to leaves out the most important current detriment to polar bear sustainability (except along Hudson Bay). Not mentioned, not explained, nothing. In fact some of your protests and explanations should have been part of that thread. The credibility of the CAGW argument as a whole suffers when important facts (the most important facts) are left out.
110130. thingadonta at 11:09 AM on 15 September 2010
        Does more extreme rainfall mean more flooding? Answer: Not always
        Several points: 1. More dams are being built which means less flooding of lowlands. China, Brazil and probably India and hopefully Pakistian have/will make more dams which will reduce flooding. One hopes that various green agendas about non-dam building are weighed up with the human impacts, such as in current areas of Pakistan. 2. The idea that both droughts and floods will increase with global warming is too simplistic, and ignores the fact that in some or many areas, an increase in one of these partially cancels out an increase in the other. One doesn't walk from a desert straight into a wall of jungle. With increased warming, drought and flood-prone regions may merge closer together, which is a net positive effect. Distinctions between rainall zones - eg deserts to savannah to rainfoest may become less abrupt. Some areas of marginal rainfall will become less prone to drought with more rainfall regionally, and some areas with more floods will become less prone to flood with more droughts regionally-that is- some of the effects will cancel out and the net effect from global warming will be positive in these areas. 3. Flooding in marginal drought/dry regions, such as in most of Australia, actually produce a net benefit. It is only in regions which are already prone to high rainfall that increased flooding generally produces net negatives. However with more dams (eg Brazil, China), this can be largley mitigated.
110131. adrian smits at 11:00 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Now that last picture makes a lot more sense than the previous image.About 2 to 3 tenths of a degree warming over 30 years seems very reasonable especially with the sun as active as it has been.Now that the solar cycles appear to be quieting I think we can expect some cooling for the next 30 years.Which is kind of unfortunate because I enjoyed the extra week or 2 of golf in the spring and autumn up here in Canada.
        Response: We explore the idea of whether the cooling sun might cause global cooling in "we're heading into an ice age".
110132. Daniel Bailey at 10:58 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Re: DMI North of 80 degrees Neven offered up a great observation about this yesterday on his blog:

        "When the DMI 80N graph starts shooting up we have a definitive confirmation that the water is freezing up big time. This is counterintuitive (love that word, by the way, just like 'circumnavigation'), but is caused by the water releasing its heat to the air so that it can freeze up. So, air temps shoot up when the waters freeze."

        If the remaining slush that passes for Arctic Ice Cap freezes in place with minimal compaction, Fall/Winter ice advection through the Fram will be significant. Re: adrian smits (18) The extreme Arctic Dipole Anomaly of 2007 caused an enormous amount of ice advection through the Fram Strait into the North Atlantic, where it then melted. And your agenda is showing. Re: adrian smits (23) If you think North America has been cooling for the past decade, you are very mistaken. Erroneous claims like this need a source. Got one? The Yooper
110133. Chris Colose at 10:45 AM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        On the robustness of the Paltridge reanalysis paper, I will will only point to a coming in press paper by Dessler and Davis in JGR which address this issue explicity, although there are many places to find this sort of information. I really can't make sense of the rest of your argumentation, no one else seems to be paying much attention, and it clearly does not derive from the relevant scientific literature so I'm just going to take it as an ill-supported opinion and leave it at that. For those who can't access this in press article, this is the abstract: //"A recent paper [Paltridge et al., 2009] found that specific humidity in the NCEP/NCAR reanalysis declined between 1973 and 2007, particularly in the tropical mid and upper troposphere — the region that plays the key role in the water vapor feedback. If borne out, this result suggests potential problems in the consensus view of a positive water vapor feedback. Here we consider whether this result holds in other reanalyses and what time scale of climate fluctuation is associated with the negative specific humidity trends. The five reanalyses analyzed here (the older NCEP/NCAR and ERA40 reanalyses and the more modern JRA, MERRA, and ECMWF-interim reanalyses) unanimously agree that specific humidity generally increases in response to short-term climate variations (e.g., El Nino). In response to decadal climate fluctuations, the NCEP/NCAR reanalysis is unique in showing decreases in tropical mid and upper tropospheric specific humidity as the climate warms. All of the other reanalysis show that decadal warming is accompanied by a increases in mid and upper tropospheric specific humidity. We conclude from this that it is doubtful that these negative long-term specific humidity trends in the NCEP/NCAR reanalysis are realistic for several reasons. First, the newer reanalyses include improvements specifically designed to increase the fidelity of long-term trends in their parameters, so the positive trends found there are expected to be more reliable than in the older reanalyses. Second, all of the other reanalyses except the NCEP/NCAR assimilate satellite radiances rather than being solely dependent on radiosonde humidity measurements to constrain upper tropospheric humidity. Third, the NCEP/NCAR reanalysis exhibits a large bias in tropical upper tropospheric specific humidity. And finally, we point out that there exists no theoretical support for having a positive short-term water vapor feedback and a negative long-term one. "//
110134. chris1204 at 10:35 AM on 15 September 2010
        What about that skeptic argument that Jupiter is warming?
        Well I'll worry about Jupiter when we have to make our mass migration from the late great planet Earth to a more hospitable part of the solar system ;-)
110135. michael sweet at 10:35 AM on 15 September 2010
        Does more extreme rainfall mean more flooding? Answer: Not always
        Very interesting post. It is too bad that it cannot be extrapolated generally. Do many floods get caused by rapid melt of snow in spring? That might occur more often in an AGW world. My impression is that rapid spring melt has happened in the US midwest, but I have not seen any clear linkage to AGW.
110136. TimTheToolMan at 10:32 AM on 15 September 2010
        Why positive feedback doesn't necessarily lead to runaway warming
        nealjking @43 Err yeah. Case three is that its Winter and there is no sun for 6 months. Scientists dont believe that we'll have an ice free Arctic all year around so its entirely reasonable to expect any heating that happened during the summer months will entirely be lost as the refreeze happens. Additionally there is now the possibility of a net heat loss from the oceans. I see you also believe the radiative heat loss is dependent on a difference of temperature between the atmosphere and the water. You should probably check your knowledge there :-P So I think the negative feedback of open oceans radiating heat is very relevent to an article that quotes it as an example and is considering runaway heating.
110137. Albatross at 10:14 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian, this is more current (RSS MSU data) for the lower troposphere: Trends are for 1979-July 2010. You can get more at their web site here.
110138. Albatross at 10:09 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian, the DMI data are from the ECMWF model, they are not observations. And there are four seasons in the Arctic, funny how WUWT focus on temperature trends in the short summer months. Go here. The image that I posted are in fact observations made by a satellite between 1981 and 2001. The image is from NASA
110139. adrian smits at 10:02 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Albatross what kind of strange art is that satellite picture?If I'm not mistaken North America has been cooling for the past decade.Your picture shows 1.5 degrees of warming.whats this picture from? The late cretaseus lol pardon my spelling
110140. Riduna at 09:59 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Sea ice melting occurs because of warmer sea or air temperatures. Air temperatures north of 80N may be below those needed to cause sea ice to melt but does that mean sea temperature must be similarly below that required to melt sea ice? I don’t think so.
110141. Albatross at 09:54 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian, winds, of course, also play an important role. The climate system is a complex and dynamic system that is undergoing rapid changes. For example, in the Arctic the thinning of the sea ice is making it more susceptible to unusual weather patterns such as the dipole anomaly over the Arctic, and to wave action. These dipole anomaly events over the Arctic have happened many times over the 32 yr or so satellite record, you might want to ask yourself why the ice extent, area and volume did not drop this low prior to 2007. All is not well with the Arctic ice, despite what some "skeptics" might be trying to say.
110142. Rob Honeycutt at 09:52 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian... You would watch Dr Barber's lecture that Dappledwater linked above. It's quite interesting. What you read on WUWT is way off the mark. Why they so tenaciously hold to that idea that the arctic ice is recovering I have no idea. But here is a researcher who has been working on this issue for 25 years. He is someone to listen to. Early in the lecture he says that in the 1980's he was skeptical. In the 1990's he estimated the arctic would have ice free summers by 2100. In the late 90's that became mid century. Now he says between 2016 and 2030. If you're waiting for warmer arctic waters to convince you, hang around a little while. They're coming. The REALLY dramatic part of his lecture is where he's talking about trying to locate the thick multi year ice. They literally had to travel for 3 additional days through "rotten ice" to locate the MY ice. Really great lecture. I recommend it. I'd love to see Anthony Watts to do an arctic trip with Dr Barber.
110143. adrian smits at 09:51 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        The GISS shows extremely hot temperatures in the high arctic when they don't even have any sensors up there at the same time that the DMI is showing below normal temperatures in the summer and they are the ones who are actually measuring the temperature up there.whats up with that?
110144. adrian smits at 09:42 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        From my understanding as the the supposed great melt of 2007 was happening NASA was reminding people that it was being caused by very unusual wind conditions in the arctic that pushing the ice south to warmer water where it could melt
110145. Albatross at 09:33 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian, most of the incoming energy during the short summer seems to be being used to melt ice. Anyhow, do some reading on polar amplification. Also, those DMI are for north 80N, they do not represent Arctic temperatures. That label is highly misleading. I do not know of any reputable climate scientists who says that the Arctic has not warmed significantly in recent decades. Look at this satellite data:
110146. adrian smits at 09:18 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        If there is now more open water near the north pole than there was in the past that should be reflected in the temperature record for the summer time when most melting is happening .Again the DMI shows no warming....still waiting for a reasonable explination.
110147. dorlomin at 09:08 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        adrian smits at 08:31 AM on 15 September, 2010 So tell me why does the DMI from Denmark show almost no summer time warming in the arctic.Whats up with that? Its not like the Danes arent a bunch of greenies. = = = = = = = = = = This would be the graph that shows rapid and very strong warming in autumn and winter?
110148. michael sweet at 09:05 AM on 15 September 2010
        Video update on Arctic sea ice in 2010
        Adrian: Can you provide a reference to your claim that DMI shows no warming? If you are refering to the graph WUWT likes to show with little warming north of 80 degrees, that is easy to explain. It is entirely ice bound that far north. The ice limits the surface temperature in the summer. As long as it is mostly ice covered the temperature will stay the same. AGW causes the ice to melt faster, not the temperature to rise. Increased heat from AGW is shown by the ice getting thinner. The maps this summer, including today's Cryosphere Today , show much open water near the pole. This was not open water in the past. As the ice continues to thin we will see more open water. WUWT picks that graph so they can deceive people who do not understand how phase changes in ice control the temperature. Last winter it was warm at the pole. The winter temperatures are affected by AGW now, the summer temps will go up once the ice melts out.
110149. archiesteel at 08:58 AM on 15 September 2010
        The contradictory nature of global warming skepticism
        @PDA: "What evidence would you find convincing of a human fingerprint on global climate change?" I already tried asking that question (or one quite similar) and didn't get an answer. I think this says a lot about Baz's intentions in posting these contrarian opinions.
110150. archiesteel at 08:55 AM on 15 September 2010
        The contradictory nature of global warming skepticism
        @Baz: "The Earth hasn't continued to warm significantly. I'm happy to accept bumps in temps along the way, but we have had 10 years now of remarkably stable temperatures." Only if you cherry-pick time frames. You have to realize that, if the last 10 years don't show "significant" warming, they also don't show "significant" stability. In fact, it shows *nothing* significantly. So your statement (that we've had remarkably stable temperatures) is just as incorrect as claiming there's been statistically significant warming over the past 10 years, significant cooling over the past 6 years, and dramatic warming since the past 4 years (even though the trend for the last 10 and 4 years has been positive, and the last 6 is negative). In other words, you cannot claim that we are in a cooling or stable period, because the signal-to-noise ratio is too low. Ergo, as long as you continue to make this claim you will be wrong (from a scientific point of view). "With increasing CO2 we should surely see that mercury rising, shouldn't we Guy? What's happened to the heat?" ...but we *are* seeing that mercury rising: Here are the trends for the last 10, 5, 4 and 3 years "Albatross. Quote realclimate again and I'll counter with Lord Monckton!" ...except Lord Monckton has been caught fabricating facts, while RealClimate hasn't. Careful, your bias is beginning to show... "JMurphy. Not worthy of a response, I'm afraid. But if you want to re-write that in a more-polite manner, then I'd be happy to." That's rather convenient, isn't it? We've shown you where you made a mistake (after you admitted yourself you weren't "rational", a strange admission to make in a scientific thread), and yet you insist on repeating the same debunked claims. How should we treat you, exactly?

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