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Comments 126051 to 126100:

  1. How do we know CO2 is causing warming?
    I don't believe any of these studies are meanigful any sense to come to any conclusions on AGW. Otherwise serious scientists would have made those conclusions already based on these theoretical results. Its more or less a theoretical excercise in exploring current limitations in regards to piecing together how the climate system works. The data discussed is over the region with the highest OLR anamolies, not to mention during opposing seasons for the regions with ~4% humidty and 10F differences. Change in CO2 bands in clear sky mostly indicates change in the stratospheric temperatures. This says nothing about the earths energy balance and its system, and certainly not anything about the final number of that energy balance in regards to CO2. Cheers.
  2. What do the hacked CRU emails tell us?
    @Ricardo--So, we are left with a highly personal opinion (based on ?) of "useless", but in this case I agree with you: The dropped data was indeed "useless" if one's objective is to create a hockey stick graph and "hide the decline" evident in the dropped data. In any event, how could Jones have known the data was "useless" if he couldn't explain WHY the tree rings no longer served as a useful proxy for temperature. Perhaps they never did? Perhaps tree ring width correlates more closely with some other variable related to but independent from temperature such as...I don't know...rainfall/humidity?
  3. Can you make a hockey stick without tree rings?
    Nice post. John, where do you find the time? You are prolific! Here is another good source for what may have caused the warming in the early part of the 20th century: http://tamino.wordpress.com/2008/10/19/volcanic-lull/
    Response: Where do I find the time? The key is realising that sleep is a luxury item.
  4. Heide de Klein at 01:05 AM on 5 December 2009
    The hockey stick divergence problem
    Your statement that the instrumental evidence must always be preferable doesn't hold water. The land-based record has been fraught with problems in the last few decades. Either you question it, or you bury your head in the sand declaring CO2, warmth and light stunts tree growth. Now, perhaps you can point me to other independent proxies that don't exhibit the decline. I know for sure that speleothems and the Tijlander series (used upside-down) do!
  5. Heide de Klein at 00:52 AM on 5 December 2009
    Can you make a hockey stick without tree rings?
    The speleothem record exhibits the divergence problem. Is that why it was truncated?
  6. Heide de Klein at 22:47 PM on 4 December 2009
    The hockey stick divergence problem
    It seems to me that you either believe the trees or the instruments. Either some unknown agent is affecting the trees, causing them to stunt their growth - perhaps it is a heady mixture of more warmth, CO2, and sunlight. Or, the quality of the instrumental record has become compromised in some way, for some reason, by someone.
    Response: Direct instrumental evidence is always preferable over proxy methods of determining temperature changes. The fact that tree-ring proxies have also diverged from other independent proxies is a strong indication that it's the tree-ring sensitivity to temperature that has changed. This is also borne out by the fact that tree-ring divergence isn't universal but is concentrated in high latitude northern sites.
  7. The physical realities of global warming
    Berry, you're definitely right and it is exactly what i said should be avoided in that comment. I said "almost flat" because i was going to compare with the developed nations numbers, of the order of 10 or more tons.
  8. The physical realities of global warming
    24 Riccardo: In the last decades global per capita emissions has been almost flat globally.(...) According to a recent article in Nature Geoscience (17th Nov) "Trends in the sources and sinks of carbon dioxide" (Corinne le Quéré, et al.), the per capita emissions has actually risen the last decade: "The growth in emissions since 2000 was also accompanied by an increase in the world per-capita emissions from 1.1 metric tons of carbon in 2000 (Fig. 1d) to an all-time high of 1.3 metric tons of carbon in 2008" (...).
  9. Can you make a hockey stick without tree rings?
    Leto, CRU controversy or not, we all (and the scientists in first place) always try to have more evidence. The more the evidences the more we trust the findings. But even if one thinks that there's not enough evidence, one is not scientifically allowed to ignore (or worst throw away) what as already been done.
  10. Can you make a hockey stick without tree rings?
    Leto, what you are asking is strange. Scientists tried hard to collect as many different proxies as possible to avoid problems any single proxy type may have. Different proxy types also tend to be geografically located in different environments, so using more proxy types guarantee a better coverage. If you for some reason do not trust tree rings, i'd suggest to look at reconstructions where just tree rings have been dropped while keeping all the other. If you look, for example, at the data of the Arctic from the paper linked by John in comment #5, they used 4 tree rings data sets out of 23 total. One might anticipate that their influence will be modest. I've seen somewhere the comparison of reconstructions with and without tre rings, but i can't remember where; i can't help you more.
  11. Was there a Medieval Warm Period?
    In Mann's graphs, why are there cells with a grey X and others without it? What does the grey X mean? (I don't have access to the full document, so I cannot look it up). Thanks.
  12. How do we know CO2 is causing warming?
    guinganbresil, not true that that if CO2 increases OLR must be dropping, as the step change example shows. It's a matter of when and how it all occurs. Working out realistic details is not at all easy. Crudely speking, CO2 concentration is quadratic with time, the associated forcing is logarithmic with CO2 concentration, temperature variation is linear with forcing and has it's own time response, thermal emission goes with the fourth power of temperature. But physics helps us if you immagine a quasi-equilibrium situation (small deviation from equilibrium), which is not far from the reality of the earth system. The increasing CO2 concentration produces warming. Thermal emission must be increasing, more rapidly so the more the system is out of equilibrium; consider also that it is generally stronger than the forcing due to it's 4th power dependence on T. In the assumption of small deviation from equilibrium, you will reach a balance between the two opposite tendencies so that OLR would be roughly constant in time a little below equilibrium. It is then this departure from equilibrium that goes with the rate of CO2 increase. Here you can also appreciate why it's so hard to observe it experimentally, it's intrinsically small. Now, if you observe the OLR increasing with time it means the CO2 has increased (some times in the past) so rapidly that the earth system is still keeping up trying to reach the new equilibrium. You will see a decrease only if CO2 increases very rapidly; after a while the system will reach again a quasi-equilibrium or it will all end up in what climatologists call a runaway warming. Venus is always quoted as an example of the latter.
  13. Can you make a hockey stick without tree rings?
    Hi there, It is somewhat disappointing that the examples you provide generally do not go back through the MWP (those that do seem to involve tree-rings, which I do not trust, or involve composites, which I do not trust). Could you point me to single-modality, non-tree-ring proxies that examine this period, and that do not suffer from a modern divergence problem? Preferably, they should be regional, to assess claims that the MWP was confined to Europe or the northern land mass. The ideal proxy would be one that matched historical accounts of the MWP. I am not making any point here - I am genuinely curious, and just starting to look at the evidence in view of recent CRU controversies. Regards, Leto.
  14. How do we know CO2 is causing warming?
    Riccardo, I think I am beginning to understand. The step response graphic in Murphy gives the impression that OLR should be going up - I don't think that is true in reality. The step response of a system is very useful in understanding how the system responds to changes but it does not represent the reaction to a real signal (unless of course it is a step function!) If you imagine the vertical increase in CO2 as actually having an upward slope (which it does in reality), then the vertical drop in OLR will also have a slope - going down. We are really in a condition where CO2 is still rising so the the OLR should be dropping - not rising. This is VERY important. I will see if I can find a reference, but I have seen plenty of step response problems (charging capacitors etc.) when I studed EE to know that a system with this step response will have a decreasing OLR if CO2 is still increasing. The return to equilibrium (an increasing OLR) occurs when the CO2 stops increasing. --- I am of course ignoring saturation and other non-linear effects. I am just trying to sort out whether it is supposed to be going up or down!
  15. How do we know CO2 is causing warming?
    Riccardo, I think I am beginning to understand. The step response graphic in Murphy gives the impression that OLR should be going up - I don't think that is true in reality. The step response of a system is very useful in understanding how the system responds to changes but it does not represent the reaction to a real signal (unless of course it is a step function!) If you imagine the vertical increase in CO2 as actually having an upward slope (which it does in reality), then the vertical drop in OLR will also have a slope - going down. We are really in a condition where CO2 is still rising so the the OLR should be dropping - not rising. This is VERY important. I will see if I can find a reference, but I have seen plenty of step response problems (charging capacitors etc.) when I studed EE to know that a system with this step response will have a decreasing OLR if CO2 is still increasing. The return to equilibrium (an increasing OLR) occurs when the CO2 stops increasing. --- I am of course ignoring saturation and other non-linear effects. I am just trying to sort out whether it is supposed to be going up or down!
  16. There is no consensus
    angeloftheknight, you might want to also read cce's The Global Warming Debate site, because it gives a broad overview. That background would help you better select which topics on this most excellent Skeptical Science site to focus on.
  17. Can you make a hockey stick without tree rings?
    It seems to me that if we are trying to decipher which proxies are actually good proxies for temperature this thread doesn't really help very much. While the borehole and glacier reconstructions for the last 100 or so years(when we supposedly have good temperature measurements) are more or less consistent with one another, the actual temperature measurements (at least as referenced in Mann above) are much higher ~0.5C increase as opposed to closer to 1C for the temp reconstructions(the two of which don't agree with one another too closely incidentally). Unless you think that the temp reconstructions are badly biased, you are then forced to conclude that the proxies are(they can't both be right). If the proxies are biased, then reconstructions based on them can't be relied on. Cheers, :)
  18. Water vapor is the most powerful greenhouse gas
    Mizimi, unfortunately who wrote that page failed to notice that using the very same ESR utility it can be easily found that the upper troposphere has indeed warmed. An obvious question then arises as to how can specific humidity drop while temperature rises. It looks more like a convection issue. P.S. The first graph shown in you link has been demonstrated to be wrong quite a while ago. But you know, things keep hanging around forever over the internet ...
  19. angeloftheknight at 10:37 AM on 4 December 2009
    There is no consensus
    Long ago, in post #150, hrnsoftware asked about the ozone layer. No one replied, so far I could tell, so I offer this site: www.themonitor.com/opinion/ozone-5103-depletion-protocol.html This might provide an answer to his/her question regarding recovery of the ozone hole and what effect the Montreal protocols had, or did not have, on it. I just stumbled on this site today, and I think it's marvelous. I'm not a scientist but I consider myself a logical thinker and I like a good argument. In the interest of transparency I acknowledge I'm a "denier" (some of us prefer "realist" per Frank Beckmann, WJR-Detroit). I like hearing opposing views. I'll check in as often as possible, but If I'm not careful, I could become addicted to the pheromones my brain produces by reading this site! Thx
  20. Can you make a hockey stick without tree rings?
    nofreewind, the problem with "historical anecdotes" is that they are just that...anecdotes. An anecdote almost by definition relates to a personal or localised observation, and it's usually qualitative...and "common sense" can often lead one smartly to the incorrect conclusion! A case in point is glacier recession. There's little doubt that Alpine glacier maximum was in the mid 18th century as you indicate. The earth (at least the Northern latitudes, and especially Europe, where most anecdotal, and more scientific observational evidence, comes from) was coolish in the so-called Little Ice Age. This was a prolonged period of low solar activity and highish volcanic activity. Glaciers advanced. Some of the recovery from the LIA was natural recovery from natural negative forcing (sun returned to "normal", volcanic activity lessened). Quite a bit of it was anthropogenic resulting from a rather significant rise in atmospheric CO2 from ~280 ppm in the late 18th century to 300 ppm by 1900 and 320 ppm by 1960. It's easy to determine (knowing what we know about the quantitiative relationship between atmospheric CO2 change and earth temperature change) that this will have made a large, and likely dominant contribution to the warming from the early 19th century to the mid 20th century. And after that it's a question of degree and quantitation that can only be addressed by a non-anecdotal analysis. You mention the Alps, so we could look at those beautiful mountains. A detailed study of Alpine glaciers was published by the World Glacier Monitoring Service in Zurich a couple of years ago. This shows that the rate of Alpine glacier retreat has followed the temperature trend with rather slow glacier retreat as the N hemisphere warmed v. slowly following the LIA, and then faster as the anthropogenic contribution to warming kicked in. The latest (post 1970's) bout of warming has seen Alpine glacier recession retreat rather remarkably. I know this from first hand since I try to spend a holiday each year in the Alps or the Pyrenees. The changes can be rather remarkable, even in the anecdotal sense of a personal observation... Haeberli W et al. (2007) Integrated monitoring of mountain glaciers as key indicators of global climate change: the European Alps Annals of Glaciology 46,150-160 Abstract: The internationally recommended multi-level strategy for monitoring mountain glaciers is illustrated using the example of the European Alps, where especially dense information has been available through historical times. This strategy combines in situ measurements (mass balance, length change) with remote sensing (inventories) and numerical modelling. It helps to bridge the gap between detailed local process-oriented studies and global coverage. Since the 1980s, mass balances have become increasingly negative, with values close to -1 m w.e. a(-1) during the first 5 years of the 21 st century. The hot, dry summer of 2003 alone caused a record mean loss of 2.45 m w.e., roughly 50% above the previous record loss in 1998, more than three times the average between 1980 and 2000 and an order of magnitude more than characteristic long-term averages since the end of the Little Ice Age and other extended periods of glacier shrinkage during the past 2000 years. It can be estimated that glaciers in the European Alps lost about half their total volume (roughly 0.5% a(-1)) between 1850 and around 1975, another 25% (or 11% a(-1)) of the remaining amount between 1975 and 2000, and an additional 10-15% (or 2-3% a(-1)) in the first 5 years of this century.
  21. Can you make a hockey stick without tree rings?
    nofreewind, if you click on the link to Oerlemans 2005 associated with Fig. 3 above, you'll see that the number of glaciers for which quantitative data are available is extremely limited prior to the late 1800s. The earlier data are completely dominated by Alpine glacier records. Despite this Alpine dominance, Oerlemans' Fig. 3A does not show more than a modest decline in reconstructed temperature prior to about 1850. So I would conclude from this that the information you cite from Fagan's book is largely anecdotal, and the data as shown by Oerlemans are not consistent with it. *Global* warming as determined from globally distributed glacial records appears to begin around 1900, with the usual pause around the 50s. This is yet another proxy record that suggests some past climate variability that is overwhelmed by changes in the last 40 years. Climate appears to be sensitive to even modest forcing (as the proxy records show), and there is no denying that CO2 results in a significant net radiative perturbation. Certainly this is a cause for concern.
  22. What do the hacked CRU emails tell us?
    sgking, the facts speak for themselves, indeed; they just dropped the (know for years) useless data to make the graph. Period. Simple enough, unless one is trying to see the evil in any case and can always come up with specious accusation of some sort. P.S. The first sentence on McIntyre was just a joke, i apologize if i didn't make it clear enough.
  23. Can you make a hockey stick without tree rings?
    John, of course the planet is warming? According to Fagan's book the Little Ice Age, the glaciers in the Alps reached their maximum in 1750. They have excellent historical accounts of how the ice buried various towns. Since that time, most glaciers around the world have been receeding, for >200yrs. Yet even in the CRU emails the scientists admit they only account for mans hand since the 1970's, their own data shows no temp rise from mid 40's on. (I know we can find the reason it was mans hand causing the cooling - which in reality was just a pause) We have glaciers melting for 250 yrs, yet AGW caused them to melt the last 35 yrs? As a rational person I say if they receded for 200 yrs w/o AGW how can we possibly even mention AGW as a cause of glacier melting, and sorry, I get very skeptical of anything you would say, if you blame glacier melting on AGW. (although soot contamination as a real factor makes good sense to me for both glaciers and the artic) Is this the kind of "direct observation" you are talking about? Same thing goes for African droughts, etc etc etc. In fact, every nook and cranny I look into, I usually find the same natural variability and historical anecdotes to prove my "common sense". http://www.appinsys.com/GlobalWarming/GW_4CE_Glaciers.htm Of course other people might look at things differently when they START with the premise that man is at fault and then work backwords, as the IPCC clearly state in their founding mandate. Proud to Be A Skeptic, but I'm no Denier.
  24. What do the hacked CRU emails tell us?
    @Riccardo--Do you dispute McIntyre's summary of the steps involved in "the trick"? And do you claim that Jones disclosed his methodology in the IPCC report? If so, then please be specific and set me straight. If not, then it shouldn't matter to you you whether I cited McIntyre's summary or someone else's. The facts speak for themselves. Res ipsa loquitur.
  25. Water vapor is the most powerful greenhouse gas
    "The specific humidity has been increasing over the last few decades near the Earth’s surface (as shown by the 1000 mb data), while it has been decreasing in the upper troposphere (as shown by the 300mb data). The increase in specific humidity at the Earth’s surface (1000 mb) is related to surface temperatures. For all except the far southern hemisphere bands, the effect of the 1997/98 El Nino can be seen in the specific humidity graphs. The decreasing specific humidity in the upper troposphere (300 mb) indicates that the warming at the Earth’s surface does not match the CO2 based warming theory. This is especially so in the northern hemisphere, which has experienced most of the warming in recent decades.....This is a major area of contention in the climate science area, since without the water vapor feedback the CO2 based theory loses its significance." http://www.appinsys.com/GlobalWarming/WaterVapor.htm
  26. The hockey stick divergence problem
    This is the first webpage I've come accross that actually seems to understand the divergence problem. Cheers to post #14 for plainly stating the three possible outcomes. I have a question regarding the Cook paper (I would read it myself if I had more money or were a computer hacker). The phrase thrown about is "before the 1960s, the groups tracked each other reasonably well back to the Medieval Warm Period." Does this mean back to the *end* of the MWP or back into the middle or beginning of it? The reason I ask is some of the tree ring proxies might respond non-linearly to temperature as a simple natural matter of fact. If the agreement between tree rings and other proxies is only between the end of the MWP and the beginning of this most recent warm period, then there is a real possibility that the proxy is only valid under a certain (low) temperature range and beyond a cuttoff growth rate becomes a proxy for precipitation and not temperature. If the response to the high temperatures of the MWP was linear as expected, while the response to current high temperatures is not, then there's good reason to think some recent phenomena is causing the divergence problem.
  27. Can you make a hockey stick without tree rings?
    So what happened in 1900 to trigger the steep rises in T ( 0.6C in 45 years)that the graphs depict? "Using modelling techniques, the Finnish team was able to extend data on solar activity back to 850 AD. The researchers found that there has been a sharp increase in the number of sunspots since the beginning of the 20th century. They calculated that the average number was about 30 per year between 850 and 1900, and then increased to 60 between 1900 and 1944, and is now at its highest ever value of 76." http://physicsworld.com/cws/article/news/18692 commenting on: #I G Usoskin et al. 2003 Phys. Rev. Lett. 91 211101 # Since the peak in sunspots circa 2000 there has been a steep and lasting decline in solar activity and an observable decline/flatline in T trends.
    Response: Be wary that you don't fall into the "it's the sun" trap (you wouldn't be alone if you do). The same study that found "the sun has been more active in the last 60 years than anytime in the past 1150 years " (Usoskin 2005) also found the correlation between solar activity and temperature ended in the mid 1970s. At that point, temperatures rose while solar activity showed no long term trend (in fact, independent methods indicate a slight cooling trend). Their conclusion:
    "during these last 30 years the solar total irradiance, solar UV irradiance and cosmic ray flux has not shown any significant secular trend, so that at least this most recent warming episode must have another source."
  28. What do the hacked CRU emails tell us?
    Steve McIntyre ... ipse dixit. (Sorry for the two out of maybe three latin words i know) :) Seriously, now thanks to McIntyre we know that there's nothing wrong in "hiding" the data when they are obviously not representative of the temperature. This is a small step back and good news indeed. We are left with a highly personal opinion (based on?) of "not evident" and "not adequately disclosed". Just a little effort away from "there's nothing relevant to us in that email".
  29. Measuring Earth's energy imbalance
    sgking, that email has absolutely nothing to do with models, it's about data on energy balance. Then the first three points you made have nothing to do with it. (No comment on the fourth point). One thing I do not understand of you comment. What you mean by "science isn't settled"? That we do not have numbers for all the quantities we like with a precision to the tenth decimal digit? Or, instead, that the basic physical processes involved are understood and we are able to quantitatively describe the real world with a good aproximation? There's a sea of difference between the two, the former being true just for a small set of the physical constants we know. We'd have to throw away maybe 99% of the known physics ...
  30. Can you make a hockey stick without tree rings?
    I'm wondering where this article fits into this: http://news.mongabay.com/2009/1019-hance_sediment_core.html Sediment Cores from a lake in the arctic show unprecedented 20th century warming and indicated that cooling should have continued... Can a hockey stick also be made out of this? Also, is this not independent evidence for rapid 20th centuring warming in the norther hemisphere that has nothing to do with tree rings? AL
    Response: In preparing this post, I nearly did include one paper Kaufman 2009 which combined proxies of tree-rings, ice cores and lake sediment. I only decided not to include it because the study did include tree-rings and only covered the Arctic region. I'm not sure if this is the same study as the one you mention but they do seem to come out around the same time.


    Figure 4: The long-term cooling trend in the Arctic was reversed during recent decades. The blue line shows the estimated Arctic average summer temperature over the last 2000 years, based on proxy records from lake sediments, ice cores, and tree rings. The shaded area represents variability among the 23 sites use for the reconstruction. The green line shows the long-term cooling trend. The red line shows the recent warming based on instrumental temperatures (Kaufman 2009).
  31. How do we know CO2 is causing warming?
    guinganbresil, referring to fig 1 of Murphy et al. 2009, if you have a step increase in greenhouse gas you'll initially have a step decrease of OLR. Then temperature will start rise and OLR will progressively increase toward the original value to restore balance. Remember that thermal emission typically has a much stronger temperature dependence than the other factors and tends to dominate the OLR.
  32. Can you make a hockey stick without tree rings?
    You may also want to consider wine harvest dates as was once published by a French group who went through their church books dating back to 1300. Presently the wine harvest dates occur later in the autumn compared to medieval times, and it is all about temperature of course.
  33. Can you make a hockey stick without tree rings?
    Good post. I was hoping you could clarify this point though: "Of course, these examples only go back as far as 500 years - this doesn't even cover the Medieval Warm Period. When you combine all the various proxies, including ice cores, coral, lake sediments, glaciers, boreholes & stalagmites, it's possible to reconstruct Northern Hemisphere temperatures without tree-ring proxies going back 1,300 years" I'm assuming that the 1,300 figure comes from ice cores, coral, and lake sediment, which aren't depicted as separate graphs in the post. Is that accurate? Do you have separate graphs of those proxies?
    Response: Plotting separate graphs from each proxy was my initial intention for this post. I scratched around for global reconstructions from other proxies, found it difficult to find (I probably could've kept looking but I only have so many hours in the day). My impression is that some of the other proxies are sparse enough to make global averages from that individual proxy problematic. It's when all the proxies are combined that a more global spatial pattern is possible.
  34. What do the hacked CRU emails tell us?
    Let's be clear as to exactly what the "trick" was. Steve McIntyre lays out the various steps as follows: Jones deleted the post-1960 values of the Briffa reconstruction, replaced them with instrumental values, smoothed the spliced series (see posts by both Jean S and myself proving this) and ended up with a reconstruction that looked like an accurate reconstruction of late 20th century temperatures. He didn’t merely show a temperature series alongside a proxy reconstruction, which is what the NAS panel did. The NAS panel had a different approach to the “problem” of the Briffa reconstruction. They simply didn’t show it. Many of these steps were not evident and were not adequately disclosed. Thus, the "trick" was much more than simply "plotting recent instrumental data along with the reconstructed data" as John Cook states above.
  35. Measuring Earth's energy imbalance
    For all of the above, there are still deep uncertainties in the models, which climate scientists are willing to admit privately if not publicly. For instance: From: Kevin Trenberth To: Michael Mann Subject: Re: BBC U-turn on climate Date: Mon, 12 Oct 2009 08:57:37 -0600 Cc: Stephen H Schneider , Myles Allen , peter stott , "Philip D. Jones" , Benjamin Santer , Tom Wigley , Thomas R Karl , Gavin Schmidt , James Hansen , Michael Oppenheimer Hi all Well I have my own article on where the heck is global warming? We are asking that here in Boulder where we have broken records the past two days for the coldest days on record. We had 4 inches of snow. The high the last 2 days was below 30F and the normal is 69F, and it smashed the previous records for these days by 10F. The low was about 18F and also a record low, well below the previous record low. This is January weather (see the Rockies baseball playoff game was canceled on saturday and then played last night in below freezing weather). Trenberth, K. E., 2009: An imperative for climate change planning: tracking Earth's global energy. Current Opinion in Environmental Sustainability, 1, 19-27, doi:10.1016/j.cosust.2009.06.001. [1][PDF] (A PDF of the published version can be obtained from the author.) The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't. The CERES data published in the August BAMS 09 supplement on 2008 shows there should be even more warming: but the data are surely wrong. Our observing system is inadequate. *** Kevin Respectfully, if our leading scientists "can't account for lack of warming", then the science isn't "settled" on this matter. To be clear, I (and most other fair-minded skeptics) concede that the earth has warmed, but we are much less certain that the "consensus" as to: 1) How much it has warmed; 2) How much of that warming is man-made; 3) How sensitive the climate is to additional CO2 forcing; 4) How many liberties we should all be prepared to sacrifice to counter the threat. On these points, there are great uncertainties and the science most certainly isn't settled. This is especially true with regard to the issue of climate sensitivity. And regrettably, I find little on this website that seeks to resolve these uncertainties. Instead, the site seems to be primarily designed to attack the straw man argument that "skeptics" deny warming altogether.
  36. How do we know CO2 is causing warming?
    Riccardo, I agree and disagree. An overall TAO energy balance would mean that incoming solar would be equal to outgoing long wave plus outgoing short wave. An increase in OLR should be a combination of an increase due to a high temperature (obviously) modified by any changes in cloud or other OLR factors. If Golovko is correct (this is only one paper!), the increase in long wave anomaly is greater than the decrease in short wave anomaly (see figure 3): http://www.isprs.org/publications/related/ISRSE/html/papers/332.pdf Assuming that the incoming solar is constant, this would imply that the Earth is losing more heat over time. I agree that the Earth has been warming over the period Golovko analyzed, but this does not preclude it from moving back toward a TOA radiative balance. Based on the article above "How do we know CO2 is causing warming?" I would have expected increasing CO2 concentration to cause an overall (integrated over the whole spectrum) decrease in OLR, which results in radiative inbalance at TOA the thus warming. Am I misinterpreting the mechanism of how CO2 affects the radiative balance?
  37. Can you make a hockey stick without tree rings?
    John, How can this type of reasoning be broadly disseminated out to the general public, as a counter to the viral spreading of "climategate". In general those who read this blog need no convincing but the information serves to deepen our conviction, thanks for all you do. There is a desperate need to reach out beyond the bounds of this site and others that support the science, beyond a preaching to the choir, as public understanding and support for mitigation declines.
    Response: The best way to get the science out there, as Auriam says, is to actively discuss climate science on other websites, blogs, forums, etc. I provide a webpage that generates quick links to all the various pages on Skeptical Science so you can point people to where they can find out more info.

    I do recommend if you do post links to Skeptical Science that you take the time to read the page you're linking to and describe the page you're linking to in your own words. One of my pet peeves is comments that merely post a link without any explanation - a lazy way to discuss climate science. You show more respect for the people you're discussing with and provide more useful, enlightening discussion if you can at least give a brief description of the science you're linking to.
  38. Can you make a hockey stick without tree rings?
    What can I say? Well done!
  39. Empirical evidence that humans are causing global warming
    Regarding CO2 saturation in our atmosphere (post#1), isn't it also true that over-saturation would cause MORE heat to be trapped at lower and lower altitudes in our atmosphere, where the effect actually matters (since surfaces are where H2O is evaporated, ocean temps are affected, and much of what constitutes 'weather' is determined)? I mean, who cares if the stratosphere is hot or not?
  40. Climategate CRU emails suggest conspiracy
    As i see it, there are two parts in this story. One is the behaviour of the few scientists involved in the stolen emails, the other is the broad impact on climate science. Starting from the latter, which i think is the topic of this post, i can see no impact whatsoever. Luckly, science is not a matter of a few guys or a few experiments. So even if some fake science could have made it's way through the selection of the scientific community, it does not affect climate science as a whole. And even admitting (i do not) scientific misconduct by those CRU scientists, are we allowed to doubt of hundreds of other? Not for sure, each of us is responsible of its own actions and there is nothing in the emails pointing to a much broader involvement of the whole community. Here is the link to the first part of the problem. What did they actually do? I mean, actions, not words. At the very least, from the emails we can't deduce anything and there are no facts elsewhere confirming any action. There is some not appropiate wording, but nothing regarding arbitrary data manipulation. While I can understand that they might be "condemned" for their personal attitudes i strongly disagree to involve the science. Finally, a political consideration. Before a couple of decades ago, global warming was not a political issue. But then, when the "risk" of concrete actions became too high, it switched to a political issue. The explicit interest was to confuse the two planes, politics and science. This is not new, indeed, we've seen this happen before (mainly in the USA i admit). Who is responsible? Not scientists for sure, they kept doing their work while were being involved in the arena. Some of them even started to be advocate, which is definitely a right for anyone. Should we conclude that AGW is now politics and not science? Not at all. The solution of the problem is politics, indeed; its assessment is science.
  41. The hockey stick divergence problem
    HumanityRules, as you correctly say, we all need a full explanation of the divergence problem and this is exactly what scientists are researching actively. In the meanwhile we are forced to stick to possibility #2 "devaluing" (i'd say put on hold) part of the data, which is all but the most desirable solution. I hope there's no #3, throw away all the data. This would really be giving data no value at all.
  42. Climategate CRU emails suggest conspiracy
    As stated above: "However, the crucial question is whether these emails reveal that climate data has been falsified." It's your website, but, for what it's worth, I disagree with your line of reasoning here. I think the crucial question is: was this scientist attempting to mislead? And if so, what was his motivation? Also, could this same motivation broadly exist in the climate science community. If we are intellectually honest, we have to address this question. I think reasonable people could agree that the climate issue has been so politicized over the last decade that it is often extremely difficult to discern the truth. I appreciate the efforts of this site to attempt to coherently dispute the disputers. I do, however think that the recently publicized e-mails by a "ranking" member of the non-skeptic climate community are harmful to the cause of discerning the truth, at least for those people who have not drawn a final conclusion about the evidence, which apparently concludes that anthropogenic CO2 + feedbacks = catastrophy, and that climate sensitivity is a solved problem.
  43. The hockey stick divergence problem
    The "hide the decline" storm in a teacup is very pertinent to this discussion. The 'divergence problem' is essentially a question on how much value you put on the data. The divergence means that the correlation between the temp record and tree ring data is lowered. The data data becomes a less valuble tool. There are several ways to get around this. 1)Fully explain the divergence and do the appropriate compensation to the data. This would maintain the high correlation and high value to the data. 2)Remove the divergent period, another way to put this is "hide the decline". Many would see this as intrinsically devaluing the data. I would struggle with doing this to my own data. With a failure to fully explain 1) then it appears there is a move toward 2) John the value of data is an important aspect of science I hope you don't think this is off topic!!
  44. There's no empirical evidence
    Sorry if I seem dense. Allow me to make an analogy to evolutionary theory. It is observed that species change over time (evolution). Natural selection is a theory that explains how that happens. The fact of evolution doesn’t prove natural selection. Natural selection explains evolution. If evolution did not happen (species did not change over time) then natural selection would be in trouble, but that doesn’t mean that a scientist can say, “Look at how these species have changed. Natural selection is therefore proven!” Evolution is consistent with natural selection, but evolution doesn’t prove that the natural selection hypothesis is correct. Instead, we accept that evolution happens (based on considerable evidence) and compare different explanations for what causes it (natural selection vs. Lamarckism, for example). Natural selection makes many correct predictions, while Lamarckism makes many incorrect predictions. Therefore, natural selection is accepted as true (as true as anything in science). In the same manner, once we accept global warming, it does nothing to support AGW vs. any other explanation for increased global temperatures. What testable predictions does AGW make? What testable predictions do alternative theories (such as increased solar activity) make? How do those predictions hold up when compared with facts? That’s really the case that needs to be made here, I think.
    Response: I had hoped that I had made a clear case above not only for global warming, but more importantly, that humans are causing global warming. If humans are causing global warming, we expect to see an enhanced greenhouse effect. More specifically, we expect to see the enhanced greenhouse effect at the wavelengths that CO2 absorb energy. This has been observed both by satellite measurements observing less infrared radiation escaping to space and surface measurements observing more infrared radiation returning back to the Earth's surface.
  45. Was there a Medieval Warm Period?
    @TruthSeeker: If you are really seeking the truth, how come you over and over again present judgments and 'facts' that are clearly contradicted by lots of information many consider as facts? "Firing their editorial staff"? Could you please check out better? It _is_ a big problem in science when flawed papers get through, and journals with too bad quality control _should_ be questioned. It is not about whether someone is factually correct, it is the quality of data, data processing, reporting and discussion. Soon/Baliunas may well be right, but that does not make the paper more worthy of publishing. One particularly important point, is to discuss alternative hypotheses, conflicting results and possible interpretation issues. In this regard, I think a lot of work should be improved. This is one of the reasons why the 'skeptics' often experience problems with the peer review process: They very often fail to discuss evidence contradicting their own views, and it does not help them that the mainstream guys also do a lot of the same. When you represent consensus, you normally don't have to discuss everything yourself, because so much of the stuff under discussion has already been handled by others. And the weight of consensus is mainly the weight of the evidence, not the weight of the 'authorities'. If we have 7 studies indicating no MWP in an area, and 2 indicating it, all studies equally reliable, the best estimate would probably be that there wasn't any, but we can't say for sure. It is always a mistake to neglect conflicting evidence, but it is a greater mistake to neglect 7 studies than to neglect 2. Such things must be kept in mind, otherwise it's too easy to become a conspiration theorist instead of a truth seeker. Remember, too, that shortcomings don't necessarily render a work worthless, nor do errors by themselves 'prove' fraud.
  46. The physical realities of global warming
    TrueSeeker, adding to what chris just said, it's not even true that there has been no warming in the last 10 years. The decade 1999-2008 (annual GISS data) gives a trend of 0.19+-0.09 °C/decade. Would you call this "no increase"? But I know, you (or someone else), will come out with a different and accurately choosen range to show that there has been no warming ... In any case, eyeballing is not enough in science because the eyes can be easily fooled. So please, stick to science; it might not be the "Truth" (it surely isn't) but it definitely is the best that we can do.
  47. 1934 - hottest year on record
    This post needs updating. USHCN v2 makes a slight adjustment upward in U.S. mean temperature over the last decade, which puts 2006 and 1998 above 1934. Almost nil implication as far as global warming goes, just like the previous adjustment, although one wonders what the spin from the global warming denial crowd will be this time...something like "NASA fabricates data to support hoax! Erases fact that 1934 was the warmest year on record!" "Nov. 14, 2009: USHCN_V2 is now used rather than the older version 1. The only visible effect is a slight increase of the US trend after year 2000 due to the fact that NOAA extended the TOBS and other adjustment to those years. " http://data.giss.nasa.gov/gistemp/graphs/ Revised U.S. data: http://data.giss.nasa.gov/gistemp/graphs/Fig.D.txt
  48. Was there a Medieval Warm Period?
    Here's the EOS article that helped further convince the Climate Research editors that publishing Soon/Baliunas was a failure of the peer review process of that journal. http://www.geo.umass.edu/faculty/bradley/mann2003a.pdf It was also a clear attempt from Soon/Baliunas to game the peer review system by sending political junk to an editor they knew wouldn't give it critical evaluation. All of this context is lost when viewing only stolen personal emails on the topic. Mann and colleagues should be applauded for standing up for science.
  49. The physical realities of global warming
    That's an odd interpretation TS. It looks like the maximum temperature is 2005. Obviously we aren't so ill-informed that we don't understand that 1998 was lifted around 0.2 oC above the long term trend by the strongest El Nino of the last century! Come December, every year of the "noughties" will be warmer than every year of the 90's bar the well understood anomalous 1998. So yes the earth's surface temperature hasn't warmed since 2005. That's probably not surprising given that the solar output has decreased a tad during the last 20 years and the glaringly obvious fact that we're smack at the bottom of the solar cycle. We expect all the greenhouse warming of the last 5 years to be (temporarily) opposed by the solar cyle, since we all know rather well that the solar cycle has an effect on the surface temperature near 0.1 oC max-min (and min to max!). That's pretty straightforward, wouldn't you say?
  50. Was there a Medieval Warm Period?
    Today's Nature has an insightful editorial on the CRU nonsense (apols for posting this on the wrong thread): http://www.nature.com/nature/journal/v462/n7273/full/462545a.html (not sure if this is freely accessible)...

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