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Comments 98851 to 98900:

  1. Could global warming be caused by natural cycles?
    Keith, I don't really agree with your plotting there actually. It doesn't show the magnitude of the cycles. You should standardize them and put them on the same axis or something of the sort. You have to remember that 1 unit in one variable could be equal to 3 in another. Plus if you look closely at your temp/AMO graph you will see something very prominent... i.e. spikes in the AMO and temperature in 1878(eyeballing it) 1998 and 2010 which follow synchronously. Standardization can be done in excel with the standardize feature. use x-min/stdev
  2. It's a natural cycle
    From what I hear from people in everyday life and what I see on conservative news outlets and skeptical blogs, "it's a natural cycle should be near the top of the list of skeptic arguments.
  3. keithpickering at 03:23 AM on 12 January 2011
    Could global warming be caused by natural cycles?
    Just to be clear: AO = Arctic Oscillation AMO = Atlantic Decadal Oscillation SOI = Southern Oscillation Index (El Niño) TSI = Total Solar Irradiance
  4. keithpickering at 03:20 AM on 12 January 2011
    Could global warming be caused by natural cycles?
    Nice job, and this has the makings for a new entry in the argument list. Allow me to post a few more graphs from the zombie wars here: Temp vs. AO: AOtemp Temp vs. AMO: AMOtemp Temp vs. SOI: tempSOI Temp vs. TSI (since 1950): TSItemp
  5. Could global warming be caused by natural cycles?
    Kate, excellent job! Thank you for this. Would it be possible to add a Figure? For example, below is Fig.3 from Swanson et al. (2009, PNAS). Solid, bold line = Observed GISS 21-year running mean global mean surface temperature; thin solid = quadratic fit to the observed 20th century global mean temperature; dashed line = that temperature cleaned of the internal signal. I'd like to highlight some key points that you make: "However, internal forces do not cause climate change. Appreciable changes in climate are the result of changes in the energy balance of the Earth, which requires "external" forcings, such as changes in solar output, albedo, and atmospheric greenhouse gases." And "However, the amplitude of the cycles simply can't explain the observed temperature change. Internal variability has always been superimposed on top of global surface temperature trends, but the magnitude....of current warming clearly indicates that anthropogenic greenhouse gases are the dominant factor." I highly recommend people read Swanson et al. (2009), who used an ensemble of 10 models (with coupled ocean-atmosphere dynamics) to study the long-term natural variability over the duration oft the global surface air temperature (GSAT) record. This is what they found: "Variability associated with these latter processes, generally referred to as natural long-term climate variability, arises primarily from changes in oceanic circulation. Here we present a technique that objectively identifies the component of inter-decadal global mean surface temperature attributable to natural long-term climate variability. Removal of that hidden variability from the actual observed global mean surface temperature record delineates the externally forced climate signal, which is monotonic, accelerating warming during the 20th century." And "The monotonic increase of the cleaned global temperature throughout the 20th century suggests increasing greenhouse gas forcing more-or-less consistently dominating sulfate aerosol forcing, although our technique cannot exclude other mechanisms not contained in the current generation of model forcing." So what we most likely have are warming and cooling cycles/oscillations from internal climate modes superimposed on a long-term, monotonically increasing warming from the increasing radiative forcing of GHGs.
  6. Glaciers are growing
    Starnut, can you give a reference for the number of glaciers you state ? While doing that, please read the following study : International glacier monitoring has produced a range of unprecedented data compilations including some 36000 length change observations and roughly 3400 mass balance measurements for approximately 1800 and 230 glaciers, respectively. The observation series are drawn from around the globe; however, there is a strong bias towards the Northern Hemisphere and Europe. A first attempt to compile a world glacier inventory was made in the 1970s based mainly on aerial photographs and maps. It has resulted to date in a detailed inventory of more than 100000 glaciers covering an area of about 240000 km2 and in preliminary estimates, for the remaining ice cover of some 445000 km2 for the second half of the 20th century. This inventory task continues through the present day, based mainly on satellite images. WGMS. 2008. Global Glacier Changes: facts and figures. Zemp, M., Roer, I., Kääb, A., Hoelzle, M., Paul, F. and W. Haeberli (eds.), UNEP, World Glacier Monitoring Service, Zurich, Switzerland
  7. Seawater Equilibria
    60, boba10960, You said:
    In addition, the regrowth of the terrestrial biosphere in response to retreating ice sheets should have lowered the CO2 content of the atmosphere as well.
    I would have expected this to perhaps be the opposite... that during the change into a glacial period, expanding ice sheets would cover a fair amount of vegetation before it has a chance to decay and return to the atmosphere as CO2, and so the subsequent retreat of the ice sheets when moving to an interglacial would expose this carbon and "release" it to the atmosphere (where it would again be used in the constant growth/decay life cycle).
  8. Miriam O'Brien (Sou) at 02:34 AM on 12 January 2011
    Could global warming be caused by natural cycles?
    OT but don't know where else to ask. Is John Cook and family okay given the floods? My best wishes to all in Queensland. Our thoughts are with you.
    Response: [John Cook] Thanks for asking. Although low lying parts of the next suburb are being evacuated, we seem to be okay where we are. Our area is a bit higher than surrounding regions which have flooded. So it's hard to imagine us being flooded. But then it's also hard to imagine an inland tsunami picking up houses with people inside them and carrying them across town which happened earlier this week. So we're keeping a careful eye on things.

    Appreciate your thoughts :-)
  9. thepoodlebites at 02:31 AM on 12 January 2011
    Ice age predicted in the 70s
    muoncounter, Re:PDO; "So you are claiming that correlation requires causality? Did you run that past the denial establishment to see if they reached a consensus on that?" Is this post not inflammatory? Shouldn't all inflammatory comments be pulled? Some comments are more inflammatory than others I suppose.
  10. The Physical Chemistry of Carbon Dioxide Absorption
    Response to #47. Excellent questions. 1.I have not accounted for water vapor overlap. Since the absorptions are basically lines in the spectrum (a quantum mechanical effect -see the specrum from the astrophysics group at Ohio State in GWPPT6) it is only the occasional overlap that will have an effect and that to reduce the absorption by CO2 slightly. My guess is that this would result in less than a 10% reduction in the absorption and a far lesser effecct in the change in absorption with increasing CO2 ppm. Since my earth-year temperature increase result fits very well with what is actually observed (see #25 above) I am quite certain that overlap is not serious problem and what GWPPT6 shows is the basic thrust of what is occurring. 2.The increase that I am calculating comes directly from the increase in the broad-band diffuse transmissivity as a result of the increase in the ppm of CO2. The latter is measured by the Keeling curve. The former results directly from the physics of GWPPT6 generalizing Beer's Law from s linear absorption of intensity to a broad-band, diffuse abosrption of flux. I input nothing that is not calculated or observed. 3.Clarification: The absorption is a process in which carbon dioxide is excited from some rotational level in the ground vibrational state to some rotational level in the first excited vibrational state. The short explanation of the fact that half is returmed to the earth is: absorbed radiation is then reemitted through any of a number of processes and this emission is in all directions, i.e. half up and half down. Thus half the reemitted absorbed radiation returns to the earth as GHG flux. A slightly longer explanation of the reemission follows. Once this excitation has occurred the molecule either relaxes to the ground state or, more frequently, gives up the energy to the translational motion of another molecule (e.g. nitrogen) through collision. In the more probable collisional dectivation case this energy then becomes part of the thermal bath in which the molcules reside, in other words the atmosphere is locally heated above its steady state temperature. This excess bath energy is then lost through any of a myriad of collisional processes, say with the ubiquitous water molecules. This excitation is then lost through emission. In either case - direct emission or collisional deactivation follwed by remission from some other infrared active molecule the remmission is isottropic, i.e. nondirectional, and thus occurs with equal probability up or down.
  11. Seawater Equilibria
    Starting to drift off-topic, but this has some bearing on the current focus of the discussion: Gas escape features off New Zealand: Evidence of massive release of methane from hydrates GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L21309, 5 PP., 2010 doi:10.1029/2010GL045184 "Evidence that massive quantities of methane gas have been released from the sea floor during past ice ages has been reported. The discovery supports the hypothesis that huge releases of ocean methane contributed to the rapid warmings of the Earth that have ended past ice ages." As reported in Reporting Climate Science .Com. Free PDF here. Adds a bit of credence to the clathrate-gun hypothesis. Must've been a bumpy ride. The Yooper
  12. Seawater Equilibria
    59, Sphaerica You are correct. If there was a temporary change in physical processes at the end of the last ice age that caused the ocean to release CO2 to the atmosphere, and if that physical forcing came to an end, then one would expect the ocean to reabsorb some of the CO2 that had been released. In addition, the regrowth of the terrestrial biosphere in response to retreating ice sheets should have lowered the CO2 content of the atmosphere as well. The ice core records show that CO2 levels did fall slightly between roughly 10,000 and 8,000 years ago before they began slowly rising again. These back and forth trends illustrate the complexity of the multiple processes that affect atmospheric CO2. These processes are still subjects for ongoing research, but two things are clear: 1) The physical forcing that helps release CO2 from the deep ocean has not returned to the conditions that existed during the last ice age, and 2) The alkalinity of seawater (related to the negative ion balance referred to by Dr. Franzen) has changed since the end of the last ice age as well, in a way that keeps atmospheric CO2 high when other processes are tending to bring it down. We know that ocean alkalinity has changed because the dissolution of microscopic calcium carbonate shells that settle onto the deep ocean floor has been increasing steadily over the past several thousand years. That is, water in the deep ocean has become more acidic, and corrosive to calcium carbonate, reflecting the change in alkalinity. This change in seawater chemistry was recognized more than two decades ago, but the cause is still a matter of debate and ongoing research. I favor the hypothesis that the growth of coral reefs, and the burial of calcium carbonate on continental shelves, following the final rise of sea level has been a major factor lowering the alkalinity of the oceans (formation of calcium carbonate shells by organisms removes alkalinity from seawater), but not everyone agrees with this hypothesis. Whatever the cause, lowering the alkalinity of ocean water drives the chemical equilibria described by Dr. Franzen in the direction of converting carbonate ion and bicarbonate ion into dissolved aqueous CO2, which may then escape to the atmosphere. Undoubtedly, this partially offsets any tendency for the ocean to reabsorb CO2.
  13. Glaciers are growing
    Starnut: Yawn. You're going to trust Crichton but not climate science. Lovely. Don't you think it's odd that someone would write a novel trying to scare people about a project designed to scare people? Where did you get that "over 100,000 glaciers" number, btw? And you don't think that monitoring, say, 10 glaciers in 10 different areas of the world will give us useful data? Or you think that these particular glaciers in the WGMS have been carefully selected by scientists who are in on the hoax? Also, what's a "short-term climate model"? Climate is 30 years, according to climatologists. Finally, speaking of zombies, the science of climate is, by most measures, about 150 years old. The basic radiative physics of CO2 have been established for about that long as well. It's established science. The remaining questions we have are mainly about ocean heating and and cloud effects.
  14. thepoodlebites at 01:50 AM on 12 January 2011
    Ice age predicted in the 70s
    I've tried to post replies but my posts are being pulled. What's the point of continuing the discussion when only one side is being represented? The posts concening my college experiences is true. Why do you question my veracity and censor my replies?
    Moderator Response: [Daniel Bailey] I see only one deleted comment. That comment was deleted as it contained an inflammatory comment about another poster here on Skeptical Science. Keep the dialogue on the science and on the subject matter of the post (being off-topic is a prime reason comments get pulled) and all will be well.
  15. Could global warming be caused by natural cycles?
    Well done, Kate.
  16. Glaciers are growing
    I checked the WGMS and their data is from 100 monitored glaciers. Since there are over 100,000 glaciers world wide this can lead to an entierely new discussion on how or why these were chosen. Trying to figure out the science of climate is still in its infancy and so many things are based on simulations that are based on limited data and potentially flawed assumptions that what impact an additional 100 - 200 ppm of CO2 is doing to the world is truly just a guess for now. When short term climate models(3-5 year) are consistently correct then we can start looking at longer term modeling systems. I don't doubt we need to be better shepards of our planet, but the only way to not impact the planet is to not be on the planet and that is not going to happen (at least any time soon regardles of any zombie movies you may watch). An interesting fiction novel to read is by Michael Chrichton - STATE OF FEAR. He makes many interesting points on the science and politics of Global Warming and Climate Change. While it is fiction, he does add many true facts to the story line.
  17. Seawater Equilibria
    56, boba10960, One thing nags at me. Ultimately, the ocean-atmosphere interface is a "rate of reaction" situation with a balance (which can then be altered by temperature, partial pressure, and other factors, such as acidity and the biological pump to which you refer). So if the ocean temperature change was insufficient to alter CO2 enough to account for the rise in CO2, but some other event injected CO2 into the atmosphere, would that not have put things out of balance and caused the ocean to begin to absorb CO2 to try to restore the balance? Shouldn't CO2 levels have fallen after such an event, or the ocean subsequently warmed enough to balance things (which you are saying clearly didn't happen)? Are we now in an environment where CO2 levels should be naturally falling (slowly reabsorbed by the ocean) even prior to the next orbital shifts towards a glacial period? Something in this doesn't make sense to me.
  18. Seawater Equilibria
    56, boba10960, Thank you. I've only skimmed it so far, but it looks like a fascinating paper, and an important set of details in understanding past events.
  19. It's not us
    #16: "the total Earth weather system(s) has only studied intensively for 40 years compared" Wow. Aside from being factually incorrect (weather and indeed climate science is more than 40 years old): We've only gone into space since the '60s, not even a mere 50 years. So by your illogic, we cannot know anything about what happened before we went into space? However, moon rocks are much older than even '30+ million years' (try 3.5 Byears). We study those moon rocks, as we study signals in the universe that are almost as old as the universe itself! Please, for your own self-respect if nothing else, stop making statements things like that.
  20. Miriam O'Brien (Sou) at 00:05 AM on 12 January 2011
    Could global warming be caused by natural cycles?
    This 'it's a natural cycle' argument is one of my pet annoyances. Thanks for the post - it's clear and concise and should be obvious to all, but obviously some still have some trouble in understanding the basics. Now if someone said the rising temperature trend and other changes (eg ocean acidification etc) are 'a natural response' to all the CO2 waste we're dumping into the atmosphere, that would sit very well with me. @ skywatcher #9 - I suspected the Tisdale article was just another variation of McLean's 'I'll just remove the temperature increase to show there is no temperature increase' trick! I wasn't prepared to wade through the tortuous post in detail, but it looked that way when I skimmed it. Thanks for the confirmation.
  21. Could global warming be caused by natural cycles?
    Philip64 at 19:58 PM on 11 January, 2011 "Climate changes 'naturally'; so it's nothing to worry about." Forests burn naturaly, yet we still worry about human caused forest fires.
  22. Seawater Equilibria
    - Alexandre @ 23 "Gish gallop. I did not know this expression. Very descriptive." "A key technique that denialists use in debates, dubbed by Eugenie Scott the “Gish gallop”, named after a master of the style, anti-evolutionist Duane Gish. The Gish gallop raises a barrage of obscure and marginal facts and fabrications that appear at first glance to cast doubt on the entire edifice under attack, but which on closer examination do no such thing." - Real Climate As in Mr Pilmer does the "Gish Gallop"... http://scienceblogs.com/deltoid/2009/04/plimer_does_the_gish_gallop.php
  23. Could global warming be caused by natural cycles?
    @ScienceofDoom at 21:28 PM on 11 January, 2011: We know sea level is rising. While some of this comes from groundwater sources being discharged and some from glacial\ ice sheet melt, much\ most of it is from thermal expansion. This indicates to me the ocean is accumulating energy. If the oceans were losing energy to the atmosphere they would not be undergoing thermal expansion. We cannot answer all the questions yet, but we can put boundries on the uncertainties. Any hypothised mechanism must be within these boundries. If a natural cycle is part of the solution, where is the energy entering the atmosphere coming from? "That's why this article seems like an over-simplification of the problem." As it is only the intermediate answer I suspect the simplification is deliberate, though I would leave that answer ultimately to the author.
  24. Seawater Equilibria
    Martin #16, Sphaerica #39 and keithpickering #54 Although Dr. Franzen is mainly referring to shorter time scales, the principles he describes apply to the end of the last ice age as well. The average ocean temperature (mainly deep ocean) warmed by about 3 degrees C with the end of the ice age. The exact warming is still debated, but it is not nearly large enough to account for the entire rise in CO2 (see above posts). At least three factors contributed to lower CO2 during the last ice age: 1) A colder ocean absorbed more CO2, 2) The biological pump was more efficient than today, transferring more carbon from the atmosphere to the deep ocean, and 3) The ocean's alkalinity (the negative charge that Dr. Franzen refers to) was greater than today. Furthermore, the efficiency of the biological pump depends on both the rate of biological processes that transfer carbon from the atmosphere to the deep ocean, and on the rate of physical processes that mix CO2 from the deep ocean back up to the surface where it can be vented to the atmosphere. These factors are interrelated in complex ways, and it is the complexity of these interactions that has made it so difficult for scientists to unravel the exact suite of processes responsible for glacial-interglacial changes in atmospheric CO2. The sequence of events at the end of the last ice age was summarized by G. H. Denton, et al., The Last Glacial Termination, Science 328, 1652 (2010): 1) Around 21,000 years ago changes in Earth's orbit (seasonality of solar insolation) started to melt the northern hemisphere ice sheets. 2) Around 18,000 years ago the amount of freshwater entering the North Atlantic Ocean due to melting ice became so large that it severely perturbed deepwater formation and global meridional temperature gradients. Note the timing here: The first signs of warming in Antarctic ice cores occurred at 18,000 years ago, long after ice started melting in the northern hemisphere, and coincident with the severe perturbation in the North Atlantic. There is general consensus among paleoclimatologists on these first two points. What happened next is the subject of substantial disagreement. One view is that a change in deep ocean mixing, around 18,000 years ago, caused by all of the meltwater flowing into the North Atlantic, vented CO2 from the deep ocean and also helped to warm Antarctica (D. M. Sigman, et al., The polar ocean and glacial cycles in atmospheric CO2 concentration, Nature 2010, 47 (2010)). The alternative view is that the change in global temperature gradients, around 18,000 years ago, triggered by all of the meltwater flowing into the North Atlantic, perturbed atmospheric wind patterns in a way that both warmed Antarctica and released CO2 from the deep ocean, a process that takes place mainly around Antarctica (R. F. Anderson et al., Wind-driven upwelling in the Southern Ocean and the deglacial rise in atmospheric CO2. Science 323, 1443, (2009)). Which ever view proves to be correct, the end of the ice age was triggered by a change in Earth's orbit that started melting northern hemisphere ice sheets. Some thousands of years later, the meltwater entering the North Atlantic Ocean perturbed ocean and atmosphere physics in a way that caused CO2 to be released from the deep sea - mainly by an increase in physical mixing that reduced the efficiency of the biological pump. Although the warming that lowered the solubility of CO2 in the ocean cannot be neglected, it had less impact on atmospheric CO2 than was caused by the change in ocean mixing.
  25. Eric (skeptic) at 23:00 PM on 11 January 2011
    Could global warming be caused by natural cycles?
    My explanation of variations in warming is that variable natural factors amplify or delay warming. The warming from increased CO2 is steady but there are two primary natural factors involved: variable storage of heat in the ocean (correlates with ENSO pretty well) and variable amplification of warming (correlates with AO pretty well). The Erl Happ article at WUWT postulates AO levelling off and going negative. Whether it does remains to be seen, but a more negative AO will lead to less amplification and perhaps cooling if it continues.
  26. It's not us
    @cloa513: "You can't average temperature readings" Sure you can.
  27. Could global warming be caused by natural cycles?
    To those who offer the Singer/Avery "Unstoppable Global Warming: Every 1500 Years" arguments, you might ask whether, every 1500 years, the world's population discovers and exploits vast reserves of petroleum and whether, every 1500 years, that population reaches six billion.
  28. Could global warming be caused by natural cycles?
    A combination of what things, HumanityRules? I've yet to see any of the contrarians come up with a decent explanation of what-other than CO2-might be causing the last 60 years of warming (the period during which CO2 emissions rose at the fastest rate). Basic Physics tells us that CO2 molecules help to trap Infrared Radiation, & its this radiation that causes an overall warming of the planet. That's basic physics, HR, no matter how much you try & skirt around it. Also, if PDO & Incident Solar Radiation have both been trending downwards for the last 30 years, then why is that period of warming more rapid than the period of 1950-1980?
  29. Seawater Equilibria
    Tom Curtis #46 and as quoted by muoncounter #50 Two quick comments: 1) The CO2 sensitivity values I have seen are substantially smaller than that attributed to Bacastrow; more like 7 or 8 ppm increase in atmospheric CO2 per degree of ocean warming than 12 ppm. 2) More important, the correct sensitivity is not to SST (sea surface temperature, which encompasses only the upper few tens of meters of ocean depth), but rather to the change in average average temperature of the entire ocean (the average depth of the ocean is 3800 m). Whether the correct sensitivity is 7 ppm/degree or 12 ppm/degree, it is necessary to warm the entire ocean to gain this effect. Most of the deep ocean, e.g., below 1000 m, has not warmed significantly since the beginning of the industrial period. Consequently, since most of the volume of the ocean has not warmed historically, and the surface ocean has warmed on average less than 1 degree C, warming of the ocean cannot have contributed significantly to the recent rise in atmospheric CO2 (approx. 100 ppm). (Just a different way of agreeing with the original post of Dr. Franzen.)
  30. Could global warming be caused by natural cycles?
    It's well worth understanding what Bob Tisdale did in the post you link to macwithoutfries. He took a long time and a lot of figures to identify two small regions on the globe (one north and one south) on either side of the ENSO region, that most neatly encapsulate the progressive warming trend of his two larger regions. Once you subtract the progressive warming trend in both... surprise surprise the warming trend mostly disappears! The 'trick' he uses to 'hide the incline' is to pretend that the two smaller regions are oscillating in relation to some part of ENSO when in fact they are progressively warming with superimposed oscillations. He does not tell his reader why these two small regions show the warming trend. No real surprise that the overall anthropogenic warming with superimposed ENSO/La Nina-like oscillations happens to look a lot like the warming of the tropics and mid-latitudes, and so when you subtract one from another you end up with no trend. It is simply a cleverer way of doing the same thing McLean et al were guilty of last year. What we learn from Bob Tisdale: 1: The tropical oceans show a strong ENSO signature. 2: Subtropical/midlatitude oceans are dominantly progressively warming, with overlain pulses of heating/cooling influenced by heat originating from ENSO. Ah wait.. we knew that already. Do we learn what is causing the progressive warming (and of course the Arctic amplification)? Of course not! Do we learn how this fits in with other fingerprints of warming? Of course not...
  31. Could global warming be caused by natural cycles?
    I was quite struck reading Trenberth's 2009 paper, "An imperative for climate change planning: tracking Earth’s global energy". For example: "It is not a sufficient explanation to say that a cool year is due to natural variability. Similarly, common arguments of skeptics that the late 20th century warming is a recovery from the Little Ice Age or has other natural origins are inadequate as they do not provide the physical mechanisms involved. There must be a physical explanation, whether natural or anthropogenic." I recommend people read the whole paper because he points out that currently we can't actually total up the elements of the global heat budget to say why a given year is cooler or hotter. That's why this article seems like an over-simplification of the problem. As a relevant digression, I've read a lot of papers on the ice ages. There are lots of theories to do with Milankovitch cycles. But many Milankovitch theories cancel out many other Milankovitch theories because they are contradictory. Perhaps one is correct. To say we know and understand what causes temperature variations seems like something that needs demonstrating. I invite the writer to list the ocean heat changes for each year over the last 10 years and then match up the changes in albedo, OLR, ocean temperature with ocean heat content along with an explanation that links them together. Perhaps it is clear - I would really look forward to seeing the article. I did write an article some time ago about Trenberth's paper but from a different direction - Is climate more than weather? Is weather just noise?
  32. Could global warming be caused by natural cycles?
    Excellent piece. The 'natural cycles' argument is the one that is usually inferred, if not directly evoked, every time skeptics mention the Vikings, the Medieval Warm Period etc. Climate changes 'naturally'; so it's nothing to worry about. Makes you want to pull your hair out ...!
  33. Could global warming be caused by natural cycles?
    macwithoutfries The timing is great. Dismissing it as ramblings may play well with the gallery but I'm not sure it works well with the mindful "avarage person".
  34. Could global warming be caused by natural cycles?
    Kate, "What if global warming is just a natural cycle?" To turn this question around I think the "average person" also struggle with the idea that it's just CO2. What are you talking about here? The last 150, 50 or 30 years? There is always the option that it isn't just anything, rather the combination of many things. Afterall the IPCC wording goes "that most of the warming observed over the last 50 years is attributable to human activities." The argument seems to be more nuanced than is it just natural or is it just anthropogenic but to what extent each is contributing to the present trend.
  35. It's not us
    cloa513, could you provide more details of the difficulties due to physics, relating to average temperature readings. Also, what makes you state that the earth has existed for "30+ million years" ? Why not write '4.5+ billion years' - the reality ? Do you think it is nearer to 30 million years old ?
  36. macwithoutfries at 19:14 PM on 11 January 2011
    Could global warming be caused by natural cycles?
    Perfect timing - see the same-day denier misinformation from here! (ideally now those ramblings should be debunked in a slightly more specific way).
  37. Could global warming be caused by natural cycles?
    "it's just a natural cycle" that happens to coincide precisely in timing and rate with the massive outpouring of CO2 over the last 150 years, and especially the last 30. The odds of the two things coinciding are astronomical (so to speak).
  38. Could global warming be caused by natural cycles?
    Great Job Kate!
  39. It's not us
    You can't average temperature readings (impossible due to physics) so can't really prove temperatures are increasing. We simply do not know enough to make extreme statements that changes are the result of humans- the total Earth weather system(s) has only studied intensively for 40 years compared to the Earth existing for 30+ million years so only 4 "fingerprints" are real evidence. The rest are changes.
    Moderator Response: [Daniel Bailey] You have me at a loss for what to say (and that never happens). All I can say is that you are not even wrong. I recommend that you start here, then go see the big picture, then top it off with a proper demonstration on how to compare temperature records.
  40. keithpickering at 17:23 PM on 11 January 2011
    Seawater Equilibria
    Martin #16 Orbital forcing kicks in first, by changing the relative lengths of the seasons. (E.g., in a warming phase summer is the longest season, but in a cooling phase winter is the longest season). This results in ice-albedo feedback from the greater (or lesser) snow amount over the course of the year. Albedo is a huge forcing agent. Oceans warm, and CO2 feedback kicks in.
  41. Understanding the CO2 lag in past climate change
    Apiratelooksat50, The fact that your cite, Roy Clark, thinks the current gaseous composition of the atmosphere has held steady for the last billion years should tell you all you need to know about his competence (which is nil). The quality of your arguments suggest you aren't really thinking about the information you're assimilating, but simply repeating it uncritically. Nice Jimmy Buffet reference though.
  42. Understanding the CO2 lag in past climate change
    @apiratelooksat50: "It supports the orbital changes theory as an initiator of change" Yeah, except we have a pretty good idea that orbital changes aren't responsible for the current warming.
  43. Understanding the CO2 lag in past climate change
    @gallopingcamel: "Enough of the straw man approach." Yes, please stop using strawman arguments. "It may surprise you when I assert that CO2 "always" correlates with climate as it affects the energy balance through the well understood process of capturing long wavelength radiation." You may assert it, but in fact you'd be wrong if by "correlating with climate" you mean exactly correlating with temperature. CO2's effect on temperatures is not direct. Sure, the energy imbalance may closely follow the amount of CO2, but the effect of the energy imbalance are anything but linear. "Where we diverge is in the magnitude of the effect in relation to other things that influence climate, such as water vapor, clouds, aerosols, cosmic rays etc." We do diverge on that. The problem is that you have no evidence to support your position. "What should be red flags to those of you who are so sure that CO2 is the magic bullet of climate change is the inability of the modelers to explain past climate change and their lack of predictive powers." That's not a logical argument. Why would uncertainty in models change the basic physical properties of CO2? Also, their "lack of predictive powers" is highly subjective. In fact, models have worked pretty well so far, and there is no lack of explanation for past climate change. Again, it's quite simple: CO2 used to be a feedback, now it's a forcing. You have yet to even come close to challenging this simple fact. "As "apiratelooksat50" and others including myself have pointed out many times, the uncertainties are great." Not so great that we cannot have a pretty good idea that CO2 sensitivity is between 2.5 and 4C. "We are trying to measure changes of a few tenths of a degree in measurements that oscillate over very wide ranges from night to day and summer to winter." Appeal to complexity "What we know about climate change is vastly exceeded by what we don't know. " Again, appeal to complexity. Just because you don't understand the science doesn't mean it isn't true. "Those who express certainty that CO2 is driving modern climate come across as zealots rather than scientists." Well, the evidence supports it, so it is very likely to be true. Of course, certainty is for fanatics, but that doesn't mean we can't evaluate the chances of something being true or not. To argue otherwise is simply not logical. When a lot of evidence points one way, and virtually no evidence points the other way, then chances are the one supported by evidence is true. Again, that may not be a very romantic view (I suspect most contrarians get a kick out of being the underdog), but it's the truth. "You have it backwards. It is up to the proponents of AGW to make better case for the hypothesis." Nice try. As others have pointed out, the case of AGW has been made. It is up to you to disprove. So far, you've been doing an extremely poor job at it. Perhaps it's time to reevaluate your position? "Like the above esteemed scientists" That's sarcasm, right? Singer and Lindzen are far from being esteemed scientists. They are scientists-for-hire who've been shown to be wrong time and time again. "Trenberth's "rebuttal" of Lindzen & Choi 2010 was a fine piece of nit picking but failed to change the main conclusions of the paper." Actually, Trenberth's rebuttal left Lindzen & Choi in tatters. But keep rooting for the "underdogs," I'm sure they'll be vindicated in the third act, right?
  44. Not So Cool Predictions
    Re: Norman (69) Your source uses data from 1979-2002 from the CDC. Albatross' source uses NOAA data from 1997-2006. I've broken down the data (183 deaths due to hypothermia, average 18.3 per year) for you here: Why the disconnect? Good question. NOAA's data tracks from 1988 while the CDC goes back to at least 1979. Probably a wider definition of hypothermia deaths being used by the CDC (multiple ICD-9 codes). An example of apples-n-oranges in action. Good comeback. Much better. The Yooper
  45. Not So Cool Predictions
    Also ...
    Last winter the continent of South America had a record cold winter
    Cite? Parts of SA had unusually cold weather, but I've seen no *credible* source suggesting that the entire winter over the entire continent set a record. You can claim it. You claim to be a scientist. Therefore you can cite it ...
  46. Not So Cool Predictions
    I mean, the graph is actually *labelled* "weather-related" (not *climate related*) deaths.
  47. Not So Cool Predictions
    How about this one then, this one has graphs and comes straight from the CDC. You please tell me how from the graph in figure 1 (shows generally over 600 deaths a year caused by hypothermia) you can go down to just 18 deaths a year?
    Because roughly 600 people die per year due to hypothermia, and extra special cold weather only adds about 18 deaths to that average. Climate vs. weather, the basic principle denialists can never, never grasp.
  48. Not So Cool Predictions
    Chemist1:
    The East coast is currently expreriencing record breaking cold conditions, (and snowfall in some places exceeding expectations of climate scientists and many meteorologists)
    Yet another person who doesn't understand that deep cold leads to little snowfall ... And of course he's leaving out the fact that many parts of the northern hemisphere are experiencing intense warmth, because, well, umm ... Why, chemist1? Is there any reason you fail to mention the anomalous warmth up north, where sea ice extent is once again *receeding* rather then increasing, in winter? Because it's effing warm in parts of the arctic?
  49. Not So Cool Predictions
    "others try and look at paleoclimate extending 400,000 or more years ago." These would be looking at *changes* in climate, and would never argue that you need to look at 400,000 year intervals to detect such *changes*. Chemist1 would define climate as being the average conditions in the area of earth over the last 12 billion years, in which case the billions of years before earth was fully formed would dominate the climate record.
  50. Seawater Equilibria
    48, Dan Bailey, No, it was much older than that. It was focused, I think, on a published paper. I can't remember any keywords that will help me find it. Dang.

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