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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 109901 to 109950:

  1. The Pacific Decadal Oscillation and global warming
    Huntjanin there are some Florida-specific articles cited in the comments thread at this article on Skeptical Science. See in particular Climate Change in Coastal Areas in Florida: Sea Level Rise Estimation and Economic Analysis to Year 2080 Back on topic...
  2. The contradictory nature of global warming skepticism
    Paul Daniel Ashe (177) you ask: "What evidence would you find convincing of a human fingerprint on global climate change?" This may surprise you, though it won't if you've been reading my replies... Actually very little evidence. It's not so much of a "human fingerprint" as whether or not (even if we are causing it) that we need to be worried. I'm not convinced that the climate system will roll over at our emissions. All that I require is that global temperatures resume - that's it! As I said above, HadCRUt's last 10 years: 0.40 0.46 0.47 0.44 0.48 0.42 0.40 0.32 0.44 0.49? (2010) ...for me shows that we aren't getting worrying positive feedbacks. However, if those temperatures (that we were getting in the late 1990s) resume then I'll be back on board. As it stands I see no reason to worry. If heat is being absorbed by the oceans then we won't have to wait long. But if the warmth we have witnessed is nothing special, has happened recently before, is checked by the climate system, or is caused by ocean current patterns - then we have nothing to worry about.
  3. Video update on Arctic sea ice in 2010
    Rob @42, the image in question was in all likelihood taken in a frozen lead. If you look in the background (LHS top) you can see pressure ridges. Regardless, why would they try and break through surrounding ice that was say 5 ft or more thick when they could break through this relatively thin ice? I have a hypothesis as to why people post these images-- look how effective the photos from surfacestations.org have been in confusing and sowing the seed of doubt in people's minds, not to mention distracting them from the very real and much larger issue/s.
  4. Video update on Arctic sea ice in 2010
    BP... I think Alden makes a very good case here of how single data points can confuse an issue. I realize he is not talking about the ice 60 years ago but the point he makes at slide 7 really drives home why looking at overall trends are so important.
  5. Video update on Arctic sea ice in 2010
    BP... I'm trying to figure out the point of these North Pole pictures. I know what you're responding to, I've read the whole thread, but do you really think these are conclusive proof of anything? Do you think this means arctic ice is in overall the same condition today that it was 60 years ago? It strikes me as an act of cherry picking to locate photos which represent single data points to try to infer something larger. I had a teacher in high school who said, "Believe nothing you hear and only half of what you see." In that vein, I would be more swayed by data on the state of the ice during those time periods. Similarly, as I mentioned before, Dr Barber's lecture linked above was extremely compelling because of the first hand data he provided.
  6. Video update on Arctic sea ice in 2010
    #38 CBDunkerson at 22:29 PM on 15 September, 2010 The image you posted looks more like 80% concentration. A couple of years ago scientists thought that was possible because the pole was covered with first year ice for the first time in the satellite record. Since then the multi-year ice has all but disappeared Have a look at this image please (click for larger version). It is USS Skate (SSN 578) on 17 March 1959, first through-ice surfacing at the North Pole ever. As you can see the ice is less than a foot thick (in March!). It can't be multi-year ice, can it? Of course it was before the satellite record started, so I suppose it does not count. (They were basically testing "the ability of submarines to operate in and under the Arctic ice in the dead of winter". Test was passed. Considering the strategic importance of the region during the Cold War I wonder how much information concerning Arctic ice conditions is buried in the US, UK & USSR Navy archives)
  7. The Pacific Decadal Oscillation and global warming
    Back in 2008 deniers promised a coming mini ice age due to the negative PDO and low solar activity. Looking at the 2010 global average temperatures, it seems that they were somewhat off target with their predictions. Not hugely surprising, really.
  8. Video update on Arctic sea ice in 2010
    BP @36, First, I concur with what CBDunkerson said. Also, posting that image is misleading. Here is why: I could not find images to compare for 18 May 1987, but here is what your "rotten" ice looked later that year (1987) around the middle of September, compared to the same time this year. And since you brought it up, according to NSIDC, in March 1987 about 40% of the Arctic sea ice was comprised of ice that was at least 4 years old, by March 2010 less than 7% of the sea ice was at least 4 years old. That equates to losing about 2.5 million km^2 of ice four years or older.
  9. The Pacific Decadal Oscillation and global warming
    This is off-topic but I don't know where else to post it. If anyone can tell me what, if anything, Miami plans to do to deal with 1 m. of sea level rise by 2100, please contact me off-list at huntjanin@aol.com.
  10. Video update on Arctic sea ice in 2010
    Adrian: At post 23 you said "If I'm not mistaken North America has been cooling for the past decade." At post 27 you said "Which is kind of unfortunate because I enjoyed the extra week or 2 of golf in the spring and autumn up here in Canada." Your own personal observations contradict your assertions that you got at WUWT. You look stupid when you make these type of claims. You are mistaken in your claims that North America has been cooling. Your observations have been correct. I explained the DMI graph at post 14. WUWT has deceived you. The people at this blog will explain to you what you do not understand. If you only want to argue you should find another place to post.
  11. The Pacific Decadal Oscillation and global warming
    This is a favourite subject of a well-kmown skeptic meteorologist here in Brazil. Not surprisingly, he also claims on occasion that it's the Sun, it's a natural cycle related to deglaciation, and on top of that we're not warming at all. It's just urban heat island effect.
  12. What about that skeptic argument that Jupiter is warming?
    KR, thank you. This makes sense.
  13. Tarcisio José D at 23:51 PM on 15 September 2010
    Does more extreme rainfall mean more flooding? Answer: Not always
    thingadonta (#2) Here in the Amazon (rainforest) we live with the two situations. Floods and drought due to soil sealing to 15 cm deep, which extends up to 50 cm.
  14. Arkadiusz Semczyszak at 23:34 PM on 15 September 2010
    How we know the sun isn't causing global warming
    It should also refresh the knowledge on the D-O: Orbital modulation of AMOC variability T. Friedrich et al., 2009.: “However, without careful considerations of the orbital influences on internally generated millennial-scale AMOC variability, a convincing assessment of the mechanisms for observed D-O variability remains elusive.” About the differences between D-O and BE decides to sea ice cover on the GIN sea - the polar front position - the Sun, however, both choosing - AMOC. Melting of glaciers is secondary. Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period, Capron et al. 2010.: “This shows that for extraordinary long stadial durations the accompanying Antarctic warming amplitude cannot be described by a simple linear relationship between the two as expected from the bipolar seesaw concept. We also show that when ice sheets are extensive, Antarctica does not necessarily warm during the whole GS as the thermal bipolar seesaw model would predict, questioning the Greenland ice core temperature records as a proxy for AMOC changes throughout the glacial period.” “The results display a succession of abrupt events associated with long Greenland Inter Stadial phases (GIS) enabling us to highlight a sub-millennial scale climatic variability depicted by (i) short-lived and abrupt warming events preceding some GIS (precursor-type events) and (ii) abrupt warming events at the end of some GIS (rebound-type events).” Thus, in previous periods of warming in a long time inter LG period, we had BE ... Extreme deepening of the Atlantic overturning circulation during deglaciation, Barker, 2010. It shows that the AMOC is a change from weak to strong, has resulted in: “During the Bølling-Allerød (B–A) warm phase, 14,600 years ago, temperatures rose by 9 degrees Celsius over the course of just a few decades.” Analyzing the same period - Interhemispheric coupling, the West Antarctic Ice Sheet and warm Antarctic interglacials, Holden et al., 2010.: write: “Ice core evidence indicates that even though atmospheric CO2 concentrations did not exceed ~300 ppm at any point during the last 800 000 years, East Antarctica was at least ~3–4 °C warmer than preindustrial (CO2~280 ppm) in each of the last four interglacials. During the previous three interglacials, this anomalous warming was short lived (~3000 years) and apparently occurred before the completion of Northern Hemisphere deglaciation.” “We present two 800 kyr transient simulations using the Intermediate Complexity model GENIE-1 which demonstrate that meltwater forcing generates transient southern warming that is consistent with the timing of WPTs, but is not sufficient (in this single parameterisation) to reproduce the magnitude of observed warmth.”
  15. Arkadiusz Semczyszak at 23:31 PM on 15 September 2010
    How we know the sun isn't causing global warming
    „... the D-O cycle ...” Rahmstorf said, however, that the 1470 +/- 500 years change, corresponds to the Sun - “We conclude that the glacial 1,470-year climate cycles could have been triggered by solar forcing despite the absence of a 1,470-year solar cycle.” Keeling & Whorf, The 1,800-Year Oceanic Tidal Cycle: A Possible Cause of Rapid Climate Change, 2000, (what's interesting is not quoted by Rahmstorf et al. 2003) writes: “We propose that such abrupt millennial changes, seen in ice and sedimentary core records, were produced in part by well characterized, almost periodic variations in the strength of the global oceanic tide-raising forces caused by resonances in the periodic motions of the earth and moon. A well defined 1,800-year tidal cycle is associated with gradually shifting lunar declination from one episode of maximum tidal forcing on the centennial time-scale to the next. An amplitude modulation of this cycle occurs with an average period of about 5,000 years, associated with gradually shifting separation-intervals between perihelion and syzygy at maxima of the 1,800-year cycle. We propose that strong tidal forcing causes cooling at the sea surface by increasing vertical mixing in the oceans. On the millennial time-scale, this tidal hypothesis is supported by findings, from sedimentary records of ice-rafting debris, that ocean waters cooled close to the times predicted for strong tidal forcing.” Solar cycle counting 2300 years and lunar cycle of 1.800 years. Both cycles are shifted against each other for 500 years. On the "lunar tidal" the Sun has a significant impact. Chaos and Intermittency in the Solar Cycle, Spiegel, 2009.: “We have revealed specific patterns in the magnetic activity between successive grand minima which tend to recur approximately every 2300 yr but occasionally alternate with irregular changes. Such intermittent activity behavior indicates low dimensional chaos in the solar dynamo due to the interplay of its dominant modes. The analysis showed that in order to forecast activity level in forthcoming cycles, one should take into account long-term changes in sunspot activity on a ≈2300-yr timescale. “ Obecne Bond Events mogą wynikać z rezonansu stochastycznego D-O (the inertia of the system - despite the lack of direct impact - a cycle of loading), or - more likely - with the cycles interaction - magnetic and gravity, of the Sun and Lunar. Probably "summation" cycles - above solar and lunar (dependent on the Sun) when the overlap in the respective phases (during glaciations occur after a longer interval between the D-O - multiples of 1,470 years) is "guilty" for the emergence of quasi-cycle - 1470 + / -500 years.
  16. Arkadiusz Semczyszak at 23:29 PM on 15 September 2010
    How we know the sun isn't causing global warming
    Let's go back to reading the textbook: “Solar Influences on Climate”: “As in the ozone analysis, the lower stratospheric temperature response is indicative of a large-scale dynamical response, e.g. changes in net equatorial upwelling rates (Shibata and Kodera 2005; Gray et al. 2009).” “... the majority of climate models employed to date ... ... represent primarily the ‘bottom-up’ TSI mechanism and have a very poor, or no, representation of the ‘top-down’ mechanism that requires spectral variations in solar radiative input and ozone feedback effects. Only a few have an adequate representation of the stratosphere and even those do not generate a complete representation of stratospheric effects such as an internally consistent quasi biennial oscillation. Some of the models employed for future IPCC assessments are planned to incorporate these processes, and thus should be better placed to assess the importance of these effects.” “Thus a precise determination of solar RF depends on the response of stratospheric temperatures and ozone to the changes in solar irradiance. These are not well established (see section 3.1) so that published estimates of the ozone amplification of direct TSI forcing show a very wide range (Haigh 2007; Gray et al. 2009) with even THE SIGN of the effect remaining uncertain.” “Modulation of ENSO by solar forcing appears to be consistent with at least some paleo-climate evidence, especially for the Americas where multiple proxies such as fire scars, lake varves (stratified deposits of glacial clay), tree rings, etc. indicate correlations between precipitation and solar irradiance that are similar to ENSO-related precipitation anomalies (Graham et al. 2007). As discussed in section 3.2.2, a mechanism of coupled atmosphere-ocean response to solar forcing in the tropical Pacific has been proposed (e.g. Meehl et al., 2003, 2008). Additionally, the UV/ozone feedback mechanism appears to cause enough heating near the tropical tropopause to significantly affect the tropical hydrologic cycle, with regional impacts on precipitation that are also broadly similar to those related to ENSO changes (Shindell et al., 2006). Thus the two mechanisms may operate together to create the tropical/subtropical response to solar forcing with associated amplifying cloud feedbacks (Meehl et al., 2009).” ... so even though that: “The PMOD TSI data have fallen to unprecedentedly low levels during the current solar minimum, although estimates vary on the magnitude of this decline (Lockwood, 2010).The mean of the PMOD TSI composite for September 2008 is 1365.1 Wm-2, which is lower than that for the previous minimum by more than 0.5 Wm-2. [back to the level of 1924]” ... “Note, however, that if the recent SORCE/SIM measurements of spectrally resolved solar irradiance (discussed in section 2.2.2) are correct then solar radiative forcing at the tropopause would vary out of phase with tsi. In this case, assessments of solar influence on climate, at least over the 11-yr cycle and possibly on the longer term, would need to be ENTIRELY REVISITED(Haigh et al. 2010).” “Recent measurements of SSI by the SORCE/SIM satellite instrument suggest that variations in the UV may be much larger, by a factor of 4-6, than previously assumed (Harder et al. 2009). If correct, this would imply a very different response in both stratospheric ozone and temperature (Haigh et al. 2010 ...).” Although many questions (!), the title “proudly” proclaims: “ ... the sun isn't causing global warming” I would - though for decency - as he Svalgaard - "?" here: (No?) Century-scale Secular Variation in HMF, EUV, or TSI, (2007.)
  17. Tarcisio José D at 23:28 PM on 15 September 2010
    Does more extreme rainfall mean more flooding? Answer: Not always
    Criscanaris (#3) The precipitation, when it is absorbed by the soil represents a negative feedback because the water vapor is the driver of climate. It happens that our soil is sealed by the accumulation of ammonia from the decomposition of organic matter (soil science) which is a natural phenomenon plus the manufacture of fertilizers based on ammonium. See this presentation:
    Greenhouse effect, the bigger the better.
    We must pay attention to the rate of absorption of water by soil (mm / h) because the rains have not only increased speed in millimeters per 48 hours.
  18. How we know the sun isn't causing global warming
    Ken Lambert, my point was only on a change in albedo due to an increase in cloudiness. Just to say that we need to consider all the effects produced by a given change.
  19. How we know the sun isn't causing global warming
    Riccardo #51 and Andreas #52 My unanswered post in **"What caused early 20th century warming"** is revised here and I think a non-trivial calculation Riccardo. All the 'anthropogenic forcings' in Fig 2.4 IPCC AR4 and repeated by Dr Trenberth's famous paper in Figure 4, are relative to a baseline of 'zero' in AD1750. The +0.12W/sq.m for 'natural' Solar forcing is baselined to what? Was it zero in AD1750? If it was not or we don't know; then it should not be added and subtracted from the AG forcings based on 'zero' in AD 1750. Figure 1 from **cited** thread (1713-1996) seems to suggest a baseline TSI at 1365.5W/sq.m, but who is to suggest that the solar forcing was 'zero' in AD1713 given the complex orbital cycles which vary the Earth's exposure to the sun over interglacial time scales. Is 1365.5W/sq.m the 'zero' baseline where the Earth system is neither warming nor cooling in the absence of human induced post-industrial forcings?? The critical point is that the energy accumulation of the Earth system does not necessarily stop when the TSI is flat. This energy is the integral of a constant unbalanced 'forcing' in W/sq.m wrt time represented by the area under the forcing curve which rises linearly with time elapsed. A constant 0.12W/sq.m forcing over one year is 20E20 Joules, which over a century is 2000E20 Joules. 5-6E20 Joules/year covers all the arctic ice melt, land ice melt and land heating (according to Dr Trenberth). So if for example the Earth was warming in AD1713 at a small Solar forcing of say 0.06W/sq.m (half the current IPCC Solar forcing number), and we assume the same shape of the TSI curve since then is offset by an extra 0.06 x 4 /0.7 = 0.34W/sq.m then that would add an extra 10E20 Joules/year to the Earth system for nearly 300 years which is an extra 3000E20 Joules - a big number - most of which must go into OHC. Andreas suggests that the unbalanced forcing was more like 0.24W/sq.m referenced from the Maunder Minimum which would add 40E20 Joules/year for roughly 300 years from AD1715 - which is 12000E20 Joules. Given Dr Trenberth's claimed current warming imbalance from AG and Solar forcings is 145E20 Joules/year, 12000E20 Joules equals 83 years warming at the current rate and much longer at reduced rates averaged over the last 50-100 years. If something like 90% of 12000E20 Joules were sequestered in the oceans over 300 years by the known processes of heat transfer and upper layer circulation, with exhanges released to the atmosphere via complex events like ENSO, La Nina and AMO - I suggest it is entirely feasible for a large portion of observed warming to be accounted for by long term Solar imbalance since the LIA.
  20. Video update on Arctic sea ice in 2010
    adrian smits #32: "Does it not show approximately 3 tenths of a degree of warming since 1979?" I assume you are talking about the Arctic region. In which case your error is thinking that the image shows TOTAL warming. It does not. It shows the trend per decade. That is, 0.3 C average warming each decade since 1979... which translates to about 1 C total warming since 1979. BP, yes there are often spots of open water at the North Pole. What has not yet been seen is a year when the ice at the North Pole melted out completely (or down to the 15% concentration easily determined by satellites). The image you posted looks more like 80% concentration. A couple of years ago scientists thought that was possible because the pole was covered with first year ice for the first time in the satellite record. Since then the multi-year ice has all but disappeared, but the pole still hasn't melted out. Arctic currents tend to concentrate ice in the area and thus it now seems likely that we won't see a truly ice free North Pole until the whole Arctic is nearly ice free... though if PIOMAS volume declines are accurate and continued apace that'd be just a few years away.
  21. Video update on Arctic sea ice in 2010
    Berényi Péter, thanks but the date originally mentioned was the 1950s...
  22. Video update on Arctic sea ice in 2010
    #35 JMurphy at 20:51 PM on 15 September, 2010 Perhaps you should give some links for some of those pictures - direct links, of course, and not via secondary websites. You can check this conceivably authoritative site out:
    This is how it looked like 23 years ago in mid May at a British-American polar jamboree. The ice is obviously rotten. An image gallery at the same site: Submarines Under Ice.
  23. The contradictory nature of global warming skepticism
    With regard to polar bears, has anyone posted a link to Polar Bears International ? The greatest challenge to the conservation of polar bears is ecological change in the Arctic resulting from climatic warming, according to the IUCN Polar Bear Specialist Group (PBSG). [July 6, 2009, Copenhagen]
  24. 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.
  25. 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 ?
  26. 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 !
  27. 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.
  28. 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.)
  29. 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.”
  30. 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.
  31. 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.
  32. 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.
  33. 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.
  34. 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 ?
  35. 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.
  36. 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
  37. 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
  38. 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.
  39. 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.
  40. 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.
  41. 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.
  42. 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
  43. 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.
  44. 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.
  45. 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.
  46. 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.
  47. 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?
  48. 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.
  49. 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?
  50. 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.

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