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Comments 124651 to 124700:

124651. SNRatio at 09:02 AM on 6 February 2010
        The role of stratospheric water vapor in global warming
        @ doug_bostrom, 51 I really appreciate that you raise those questions, and I think you give important elements of possible answers. I'll try to expand a little, very speculatively, as I'm a merry amateur in this field. First, the ENSO events aren't just simple breathing in and out of ocean heat. Surely, lots of the heat released during an ElNino was stored during LaNina conditions, but LaNina will often be associated with "impaired" radiation balance, cloud conditions effectively increasing albedo etc. Therefore, the energy uptake can be much smaller than average during strong LaNinas - you can get an indication of this if you look at sea level rise during the last years - it has continued at constant or somewhat falling surface temperatures, but more slowly. Indicating continous ocean heat uptake, but at a reduced rate. On the other hand, in ElNinos, it seems that radiation imbalance may actually increase, in spite of hotter conditions. That may lead to a temperature increase beyond what is "supported" by the normal conditions, and temperatures fall after the episode. Not because of negative radiative balance, heat still accumulates these days, but - I think we may formulate it this way - because of _less positive feedback_. In addition to ENSO events, Mojib Latif has pointed to a ca 60 yr cycle in the NH, and the rapid temperature increase 1980-2000 may in part come from this, maybe 0.05-0.1 degC/decade. And we have the solar cycles accounting for maybe 0.1 degC. Putting all this together, I think we may have a reasonably good explanation of the events of the last 10-15 years. Maybe more deterministically inclined people dislike the variability in feedbacks - but this I think is a fact of life in climate. I interpret the changes in stratospheric water vapor content discussed here as an important example of such variable feedbacks. It has been observed once, and I can't understand why it should not happen, over and over again. And with increased energy content of the troposphere, we might expect more of it, as it seems mainly to be an effect of that, to a lesser extent of CH4 degradation.
124652. Riccardo at 05:39 AM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        oracle2world, could you please quote where in the report it is written?
124653. oracle2world at 05:26 AM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Stop apologizing for the IPCC - the latest is the claim that 55% of the Netherlands was below sea level. The Dutch government says 26%. Now this is not a hard figure to check. Any wonder why folks suspect the rest of the report is equally sloppy?
124654. miguelveraleon at 04:40 AM on 6 February 2010
        CO2 lags temperature
        Hi John, I really appreciate your effort to explain the science of climate change. Your posts have helped me to solve a lot of doubts I had about the subject. I have a question regarding this graph. When the CO2 forcing is added to the Milankovitch cycles forcing after the triggering of deglaciation, shouldn't there be a noticeable increase in the rate of warming? Or is it too small to be noticed?
124655. Doug Bostrom at 04:26 AM on 6 February 2010
        The role of stratospheric water vapor in global warming
        Ber�nyi P�ter at 20:43 PM on 5 February, 2010 "The Solomon event is likely just a major "avalanche" among many others, happening all the time on all scales." To make a case for that you need to show it with details. Simply saying "look, this test is only used in this field, therefore I'm suspicious of its validity" is not a case, it's sheer speculation. I know from other things you've written here that you can do better.
124656. Doug Bostrom at 04:23 AM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie A at 18:47 PM on 5 February, 2010 "A 2008 article published in Geophysical Research Letters states that "�The surface area of glaciers across the TP is projected to decrease from 500,000 km2 measured in 1995 to 100,000 km2 in 2030 [Cruz et al., 2007],� It's right there in peer reviewed literature --- most of the glaciers in the Tibetan Plateau will be gone by 2030! Perhaps you'd better read the article and discover where are the errors, then mention them here specifically? For instance, one might find that ice will retreat with a steep initial slope over time, with a flattening of the slope as time passes, meaning that the ice will never actually disappear as you imply but the authors apparently do not. It's impossible to tell from the little you write, you'll need to provide much more detail before anybody will find your suspicions credible.
124657. CBDunkerson at 02:08 AM on 6 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie and Berényi, I don't think anyone is suggesting that the process of peer review magically transforms humans into infallible beings. To be human is to err. Scientific peer review can help to reduce the frequency and severity of errors, but not to eliminate them. That said, there actually has been quite a bit of research on Himalayan glaciers which the IPCC will be able to draw on for AR5. Not enough to make definitive projections, but estimates have been made based on a few different methodologies. They won't be saying 'all gone by 2035' again, but don't be surprised if it is along the lines of '66% gone by 2050'.
124658. Riccardo at 01:47 AM on 6 February 2010
        Increasing CO2 has little to no effect
        1) different satellites and/or instrumets are always calibrated against one another in a better way than just the reading on a single day. 2) the first graph is a difference between spectra taken in two different points in time; the second graph is just a point in time. The difference depenss on how much the relative contrbution changed over time. IR from the sun is indeed absorbed by CO2. When you calculate an energy balance in a layer of the atmosphere you take both the incoming and outgoing energy into account. The tiny amount of energy (one and something W/m2) taken up by increasing CO2 will not make the earth look like Venus but it's enough to increase the temperature by a couple of degrees, maybe three by the end of the century. That's unfortunately enough to produce a significant change in the biosphere. There is no saturation effect to help us. The lifetime of the CO2 excited state is short enough for the CO2 molecules to be ready to absorb more of the incoming photons.
124659. psilax at 01:29 AM on 6 February 2010
        It's microsite influences
        Questions: 1) The belgian media jumped on a result similar to what is posted on http://surfacestations.org/ of summer 2009 (no source reference in Belgian media) in which it seems that a lot of american surface stations have a deviations of more than 1°C and that for some "accurate" surface stations the temperature has been decline the last 100 years. Is this already incorporated in the graphs above? (No post date of the graphs). 2) Why do your graphs only go back to 1980 while other stations have data going back more than 100 years on the graphs of surfacestations.org?
124660. Riccardo at 01:28 AM on 6 February 2010
        On the reliability of the U.S. Surface Temperature Record
        Alexandre, the difference is what they measure. Satellites measure the whole lower troposphere while surface stations just a few (usually two) meters above the surface.
124661. ConcernedCitizen at 00:52 AM on 6 February 2010
        Increasing CO2 has little to no effect
        Some quesitons. 1) Graph one is derrived from the difference between two satelites launched 26 years apart. How are their sensors callibrated so that they would give the same readings on the same day? 2)Graph 2. Why is there no downward radiation for CFCs, HNO3 NO2 etc, as there is for CO2, when the first graph shows that their energy is being 'trapped' in the atmosphere? Additionally. from the picture showing solar light penetrating the atmosphere but terrestrial IR being trapped, what happens to the solar IR? The sun produces aproximately 400000 times as much IR at the frequency absorbed by CO2 as the earth. The atmosphere must therefore absorbs and re-radiate half of this back into space. Also given the far larger solar IR radiation the CO2 will be saturated. Additional IR from the earth is a tiny amount in comparison. Answers appreciated.
124662. Alexandre at 23:14 PM on 5 February 2010
        On the reliability of the U.S. Surface Temperature Record
        A bit OT, yes, but still on temperature records: Sattelite time series, like the UHA, show a much stronger El Nino peak in 1998 (which makes for a favorite source for guys like Watts). Where does the difference come from?
124663. Berényi Péter at 20:43 PM on 5 February 2010
        The role of stratospheric water vapor in global warming
        doug_bostrom at 18:09 PM on 5 February, 2010: "Was there some specific issue with that treatment that bothers you?" Yes, definitely. Just google for "sandpile avalanche dynamics". Highly nonlinear, self-organized sytems (like climate/weather) often show this kind of intermittent behavior. The sloppy phrase used by mainstream climate science to identify phenomena like this is "natural variability". Now. Take a simple sandpile model, generate pile weight time series, apply SNHT and you are left with an ever growing sandpile. The Solomon event is likely just a major "avalanche" among many others, happening all the time on all scales.
124664. Berényi Péter at 20:19 PM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Charlie, we have already done with this issue. The "Cruz et al., 2007" reference in the Kehrwald et al. paper is to IPCC AR4, WG II Report, chapter 10. Figure 10.4, letter "s" omitted. http://www.skepticalscience.com/IPCC-2035-prediction-Himalayan-glaciers.html#7875 Basic circular reinforcement technique of new age science at work.
124665. Charlie A at 18:47 PM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Peer reviewed literature is not the holy grail many assume. For example, in the 5th assessment report, IPCC can use peer reviewed literature to make essentially the same claims about glacier melting that were made in AR4. A 2008 article published in Geophysical Research Letters states that "“The surface area of glaciers across the TP is projected to decrease from 500,000 km2 measured in 1995 to 100,000 km2 in 2030 [Cruz et al., 2007],” It's right there in peer reviewed literature --- most of the glaciers in the Tibetan Plateau will be gone by 2030! Ref: “Mass loss on Himalayan glacier endangers water resources”, Kehrwald, etal Geophysical Research Letters Vol 35. doi:10.1029/2008GL035556 http://bprc.osu.edu/Icecore/Kehrwald%20et%20al%202008.pdf This article has very many other "interesting" statements. All in a peer reviewed journal. All available for the IPCC to cite in the next assessment report.
124666. Doug Bostrom at 18:09 PM on 5 February 2010
        The role of stratospheric water vapor in global warming
        Berényi Péter at 09:38 AM on 5 February, 2010 "I know what SNHT is supposed to be, even if I've never heard of a Standard Cylinder Compression Test. However, if there is such a thing, it makes sense to test any kind of cylinder the same way which should endure high pressure, not just those in combustion engines, e.g. hydraulic cylinders come to mind." Hah! The second I hit "submit" I knew I'd been insufficiently specific. The point I was trying so foolishly to make is that certain tests are going to be confined in utility to narrow ranges and types of inquiry and that by itself should not and does not mean they are invalid. The specific test I was referring to was one where an IC engine crank and camshaft are rotated such that valves are closed and the cylinder under test is at top of travel. All cylinders in that state should yield reasonably similar pressure readings and should hold that pressure for similar periods of time, all those readings should be within a specification range. This test is an excellent diagnostic for IC engine cylinder wear, would be inapplicable to most other machinery but is nonetheless very valuable as well as uncontroversial. The test you were referring to is used to process not only temperature but also other meteorological readings such as precipitation gathered from multiple sites. It's going to be of no utility in many other fields. It also does not appear to be controversial. I'm not an expert, obviously. Was there some specific issue with that treatment that bothers you?
124667. Doug Bostrom at 17:54 PM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        thingadonta at 13:51 PM on 5 February, 2010 Your examples of previous instances of natural variability are poor analogies to the situation we are now creating. From various historic examples it appears uncontroversial that we have the ability to exert significant power over various ecological systems, as exhibited by extinctions of various species we've accomplished. The scope of our ability to modify planetary systems also appears rather uncontroversially to have been steadily increasing, as demonstrated by CFC emissions and our subsequent successful initiation of reversal of CFC impacts on the upper atmosphere, or for that matter acidic emissions from industrial sources. These events and the story they tell of our growing capability to harm ourselves beg a couple of questions. Should we continue doing so even after we've developed the skills to perform in a more competent way? Are we in control of ourselves sufficiently to choose the changes we impose? The answers will not come from nature, the responses must come from us.
124668. Pat T at 17:39 PM on 5 February 2010
        It's cooling
        If your kid grows an inch and a half each year between fifth grade and eighth grade and then doesn't grow any more through high school, is he still growing? No. And if someone says "but but but his average height during high school is taller than his average height during middle school!" does that change your mind? It's not still warming. It's still warm. Perhaps it shouldn't be - the known natural forcings over the last decade should perhaps have caused cooling but haven't yet. Is 1998 "cherry picking one year?" No. It's one year of natural variability - but 11, going on 12, years of CO2 emissions. And 1998 is warmer than - or if you use GISS, within 0.01 deg C as warm as, each year since then. If 11 becomes 15 or 20, that's the skeptics' point - - if the climate is as CO2-sensitive as is thought, then no single year of natural variability should offset two decades of cumulative CO2 buildup. 11 hasn't become 15 or 20, so I don't think that "it's still warm though it's neither warming nor cooling" disproves your thesis. So one has to ask, why continue to belabor the point? I understand that "it's still warm even though perhaps it shouldn't be" is complex and you might lose people at the lowest common denominator, but when you oversimplify to the point that you've reduced the thesis to a statement that isn't really accurate, you lose some critical thinkers - as with the "anthropogenic cause of tree ring divergence," this practice probably fuels more skepticism than it quells.
        Response: I understand the use of metaphors but eventually metaphors get so tortured, the usefulness fades. In the case of the 'growing kid' metaphor, an appropriate comparison would be if you had a child that would grow 2 inches in one year, shrink 1 inch the next year, grow 1.5 inches the year after that, shrink .5 inches the next year. His height is shooting up and down but gradually in the long term rising. But really, that's just a weird metaphor!
        
        Don't be beguiled by the year 1998. Be aware that the HadCRUT record which finds 1998 as the hottest year on record doesn't include the whole globe - it excludes regions where the warming trend is greatest. A fully global temperature record finds 2005 as the hottest year on record, 2009 as the 2nd hottest year on record and a statistically significant warming trend throughout this period.
124669. Pat T at 17:20 PM on 5 February 2010
        The hockey stick divergence problem
        1) The spaghetti graph a) has its own issues discussed in climateaudit, b) isn't a hockey stick but rather shows a MWP within half a degree C of late 20th century temps and that lasted a few centuries and didn't result in runaway warming, and c) doesn't include Loehle, which shows a more pronounced MWP. 2) None of the direct evidence for the MWP has been addressed (except for realclimate's thesis that, because after 900 years of breeding grapes for cold-hardiness and advances to growing techniques, they now again have vineyards in England, somehow that means that it must be as warm now as it was when they had vineyards 900 years ago). We're talking about acknowledged history from nearly every corner of the world. If someone were to tell you that based on examination of the Delaware River or the soil underneath it or some other indirect physical proxy, Washington and his men couldn't have crossed it with their horses and gear that night, would you accept this without an explanation as to how it is that the next morning they were on the other side? 3) Right - tree rings are reliable within the temperature range experienced between 1880 and 1960. Above those temperatures they're not reliable - the most obvious explanation is that once you get above the temperatures experienced in 1960, the correlation between tree ring width and temperature falls off. There are other possibilities but there's one clear, obvious explanation that you really have to want to reject in order to reject it. The mental gymnastics engaged in to defend the notion of an anthropogenic explanation for the tree ring divergence is a prime example of what I'm talking about. You fall back on logical contortions to defend aspects of your thesis that could be discarded without jeopardizing your main point. This tendency turns critical thinkers into skeptics. If you just said yep, the MWP was warmer or comparably warm for 200 years but the CO2 we're emitting won't go away and so eventually we're going to have a problem, especially if whatever caused the MWP happens again, I'd be inclined to believe you. There are a lot of skeptics who are skeptics primarily because of this and other needless exaggerations (such as "it's still getting warmer" rather than "it's still warm and it shouldn't be given that natural forcings are have been on the cool side for 3-4 years"). I think the overzealous AGW proponents do their cause more harm than good.
124670. mazibuko at 15:16 PM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Thingadonta: "What the WWF fund and other green groups fail to appreciate is that if the forest size reduces/expands quite naturally, why is there so much concern from human activities?" The concern is that human activities alter forest cover far more rapidly than the changes experienced during glacials/inter-glacials. Species adaptation is much easier when a habitat change occurs gradually. A species, particularly an endemic with a narrow range, will struggle to adapt if a large portion (or all) of its habitat is clear-felled within the course of a few months or years.
124671. Tom Dayton at 14:59 PM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        thingadonta, "a high natural species turnover" contradicts "species adapt to this."
124672. thingadonta at 13:51 PM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        The Amazon rainforest was severely reduced in size during any of the geologically recent ice ages. This is well-known in the peer reviwed literature. Since these drastic reductions occur naturally, there is no reason to be overly concerned with the forest shrinking/expanding in the first place, (which isn't even mentioned above). The supposed 'lungs of the earth'(a ridiculous term, seeing as northern termperate forests dwarf the size, and effect, on C02 of the Amazon forests) have expanded and receeded markedly during recent glacials/interglacials, meaning all this nonsense about species-area vulneribility with regards to the Amazon is rubbish. There is obviously a high natural species turnover within the Amazon durng glacials/interglacials. Sepcies adapt to this. I the Amazon reduces in size with warming, (which is opposite to what it shoudl do, since it reduces in size with cooling in glacials) its nobig deal. What the WWF fund and other green groups fail to appreciate is that if the forest size reduces/expands quite naturally, why is there so much concern from human activities? It's is a fair question, depsite all the rhetoric.
124673. Riccardo at 09:59 AM on 5 February 2010
        What do the hacked CRU emails tell us?
        To whom it may concern, Penn State inquiry finds no evidence for allegations against Michael Mann. Here the full report of the inquiry panel
124674. Berényi Péter at 09:38 AM on 5 February 2010
        The role of stratospheric water vapor in global warming
        doug_bostrom at 07:35 AM on 5 February, 2010 'Lots of "no" here' I know what SNHT is supposed to be, even if I've never heard of a Standard Cylinder Compression Test. However, if there is such a thing, it makes sense to test any kind of cylinder the same way which should endure high pressure, not just those in combustion engines, e.g. hydraulic cylinders come to mind. If SNHT is a valid statistical procedure, it should make sense to apply it to time series analysis in general, not just climate data. The definition itself is rather formal, never mentioning climate. It is a plain a mathematical procedure. Could you kindly explain why one should not apply it to mortality data? Of course it would be rather easy to get rid of plagues this way, but that's exactly the point.
124675. Marcus at 09:35 AM on 5 February 2010
        The role of stratospheric water vapor in global warming
        RSVP, I was merely saying that a fall in industrial output is *not* the reason for the slower rate of climate change over the last decade, because I've seen no evidence that industrial output *has* fallen. The drop in SWV & TSI are far more likely explanations for the slower rate of warming. Trust me, I am *not* one of those people that goes around saying "we shouldn't do anything about pollution because is just going to fill the gap". Indeed, I really *hate* these people as the cop-outs they are. In truth, China & India are already doing significantly more to reduce their pollution levels-per capita-than what most Western Nations are (with the possible exception of Northern Europe). Hope that clears things up!
124676. Doug Bostrom at 07:35 AM on 5 February 2010
        The role of stratospheric water vapor in global warming
        Ber�nyi P�ter at 07:16 AM on 5 February, 2010 "could you show me a single serious application of the so called "Standard Normal Homogeneity Test" No. Now, let me ask you a question: Can you show me an example of a cylinder compression test used outside of internal combustion engine maintenance? No? Why not? Because it's a technique used for a specific, narrow range of inquiry. Does that mean it has no value? No, again. Lots of "no" here. Learn more about the "Standard Normal Homogeneity Test" here: http://scholar.google.com/scholar?start=60&q=%22Standard+Normal+Homogeneity+Test%22&hl=en&as_sdt=100000000000000
124677. RobM at 07:22 AM on 5 February 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark, Jones never said that the UHI didn't exist, he said it hadn't changed in London over the time period in question. Which makes sense, considering how long the city has been developed.
124678. Berényi Péter at 07:16 AM on 5 February 2010
        The role of stratospheric water vapor in global warming
        guys, could you show me a single serious application of the so called "Standard Normal Homogeneity Test" (SNHT) outside climate science? Anyone?
124679. jpark at 06:39 AM on 5 February 2010
        On the reliability of the U.S. Surface Temperature Record
        HI ys I saw that - if one has to 'correct' for it then presumably Jones was not right in saying it did not exist - which I think is the main point Pielke is making. I will see his son debate with Bob Ward this Friday in London - I hope it is enlightening.
124680. Riccardo at 06:24 AM on 5 February 2010
        Sea level rise is exaggerated
        Arno Arrak, we all know that Al Gore didn't quote any time span for the 20 feet rise. We all also know for sure that the sea level will not stabilze by the end of this century. Comparing Al Gores number with a one century rise is (intentionally?) misleading.
124681. Riccardo at 06:16 AM on 5 February 2010
        On the reliability of the U.S. Surface Temperature Record
        jpark, ironically, the question asked by Pielke Sr. and you has an answer in the very same post. When he quotes Willby paper to assess the UHI effect in London, the very same comparison can be used to check for a difference in the trends. I don't know if Jones at al. used these two stations, but for sure this is the way UHI effect on a trend is checked and corrected for, if any.
124682. Pat T at 04:54 AM on 5 February 2010
        The hockey stick divergence problem
        This just seems like a pattern - when the evidence doesn't support the theory as you've written it, you change the evidence instead of the theory, when it would take only a minor adjustment to the theory to maintain its viability. It's very stubborn, it's unnecessary, and ultimately it detracts from your credibility. Tree ring width is affected by many factors besides temperature. Tree growth is obviously affected by many factors besides temperature - predators, sunlight, water, etc.... You can throw up these other remote possibilities but the obvious explanation is that the linear relationship between tree ring width and temperature breaks down above certain temperatures, which means that the absence of wider tree rings during a given period doesn't mean it wasn't warmer then. Why go to all the effort to string together an alternative thesis just so you won't have to budge on the "hockey stick" when you don't need the hockey stick? Sometimes you're wrong. It's better for your credibility to admit it and move on. It's clever, it's lawyer-like, to come up with "well the divergence must be anthropogenic too" but it's transparent. Don't risk losing credibility over a sub-issue that isn't necessary to make your larger point - - don't lose the forest for the trees!
        Response: I think a few clarifying points are in order as many misconceptions re the hockey stick still prevail:

        1. The hockey stick is not dependent on tree-rings. There are a number of proxies independent of tree-rings that give the same result.
        2. The hockey stick is not the smoking gun proof of human caused global warming. It shows past temperature change, not what's caused it. Sure, it's suggestive and visually persuasive but from a scientific point of view, it does not constitute proof.
        3. The reason tree-rings are considered reliable before 1960 is because there is close correlation between tree-ring proxies and the instrumental record for the periods where the two overlap (Briffa 1998).
        4. Personally, I have no emotional investment in the hockey stick. If it turned out it was erroneous and past climate change was greater than currently thought, this would mean climate is more sensitive than we currently think. This means the climate response to the extra heat trapped by CO2 will be even greater.
        5. Lastly, the peer review science doesn't say the divergence MUST be anthropogenic. It says the "decline in tree growth may have an anthropogenic cause". As the cause is yet to be definitely defined, it's speculation at this point. Similar to the hockey stick, it's not hard proof but it's suggestive. 

        This is not a case of "hockey stick" versus "not a hockey stick". This is a case of considering all the various proxies together and determining what is the most accurate temperature reconstruction.
124683. Svatli at 04:28 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        I'm always surprised when the "argument", "that it's all a lie" comes in to the discussion. But to adress the problem at hand. My view of these matters is that the world is warming up, as the science is making clearer to us by various studies. In the future (even now) there will be climate changes as a result of this warming. Of course there are some uncertanties about how these changes will be in the future, expecially if we are talking about some specific areas (like the Amazonas). But also these changes in climate will have some consequence in the future and science is trying to adress those questions as well as possible, with scientific studys. Of course there will be some mistakes made, but overall I don't think the mistake is the big issue (and of course we'll have to learn from them). With all this noise beeing produced by some "critics" it's going to take more time then it should, but if that's the process we have to go through, well then thats what we'll do. It's amazing how some arguments do evolve and how the small issues are sometimes made to look like as they are the whole picture. The big picture in my mind is that the climate is changing because of human emission of CO2, there will be consequences of these changes, but how severe is up to us, because we are starting to get the pieces together to make the big picture even better.
124684. Pat T at 04:18 AM on 5 February 2010
        The hockey stick divergence problem
        Man-made divergence? That definitely falls into the "oh come on" category. The divergence problem is "unprecedented" and therefore must be anthropogenic? That's quite a reach. The most logical explanation would seem to be that the relationship between tree ring width and temperature changes above a certain temperature level - the level experienced in the 1960s. That means that tree rings are a useful proxy for temperatures up to that level. It also means that tree rings are not useful beyond that level - i.e., it means that when it's warmer than it was in the 1960s, it's not going to show up in tree rings, thus the fact that tree rings don't show higher-than-1960s-temperatures during past periods doesn't mean it wasn't warmer during those periods. And when you take the tree rings out of the equation, voila, the pre-hockey-stick climate history re-emerges. Does the inability to rewrite the climate history preclude man's involvement in the climate changes that have occurred over the last century? No. But the effort to rewrite the climate history adversely affects the credibility of those arguing that man has been deeply involved in those recent climate shifts. So why go through the effort? Tree lines were higher in mountain ranges around the world, including the Sierra Nevadas and Alps. The droughts were so severe in North America that they were a factor in forcing the Anasazi to abandon their elaborate cliffside dwellings. American Indian legend holds that the buffalo migrated far to the north to richer grassland. The Vikings sailed the North Atlantic in wooden boats on ice-free waters (that would during the 14th century become choked with icebergs - i.e., from sea ice breaking off much like today) and maintained a colony on Greenland - and the settlers' diets were for 200 years 80% land-based. They maintained vineyards in England (and the fact that after 900 years of breeding new varieties of grape and improving technology for cold-hardiness British wine production has reemerged is really not a counterpoint). Olive trees in Cologne. Glacial retreat in the Alps is revealing archaeological finds from the MWP - items left behind by traders using mountain passes only now resurfacing. Lake Naivasha in Kenya dried up for 200 years. Further evidence has been found in Mongolia, Japan, the Arctic and Antarctic. And don't forget the countless contemporaneous observations. These have not been explained away as having occurred for reasons other than warmer temperatures, and they cannot be dismissed as "merely anecdotal evidence." These examples all occurred during the 1000 AD - 1200 AD timeframe. That there were a few cold years in between is about as relevant to the "geosynchronous" nature of the MWP as the fact that the United States had its third coldest October on record last year is relevant to geosynchronous warming now. Even if some combination of boreholes and other indirect evidence indicates an MWP slightly cooler than late 20th century temperatures, we still have an MWP plateau that lasted for a few centuries within a few tenths of a degree of the peak modern warmth to date. Rather than try to downplay this or write it out of the climate history altogether, why not simply accept it and try to make the case that the 20th century warming is different because its suspected cause is something that won't reverse itself, which means that it will continue? Why not also point out that since what caused the MWP isn't fully understood, there's every reason to expect that it could reoccur - and that the combined effect of increased CO2 plus whatever naturally caused the MWP would be severe? You might be less able to make a case that we're only a few years away from a "point of no return" but nobody believes that and it's a risky argument anyway - when those few years pass but the point of no return doesn't, it will simply fuel more skepticism. There are a lot of skeptics who would be more open minded about AGW if it weren't for some of the overstatements and misstatements made by the more zealous of AGW supporters, including the efforts to rewrite the climate history. The Hockey Stick has done the AGW proponents more harm than good - when you mess with the established history, you create skeptics of your theories as to the present and future.
124685. Berényi Péter at 04:14 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Arno Arrak at 02:50 AM on 5 February, 2010: "That the Brazilian forest is sensitive to drought is not a world-changing revelation. [...] idiotic policies that have no effect on climate but [...]" My understanding is that there is not much trend in rainfall over the Amazon basin during the last 60-80 years. If anything, it is increasing slightly. And draught is draught, it just happens every now and then. It is not even true, that biomass decreased there in 2005 tremendously. In most parts of the basin phosynthesis even inreased due to more light from cloudless skies. That is, water availability was not a limiting factor. Deforestration and wildfires is clearly a problem and it is a man-made one. Not through global warming though, but irresponsible land use practices by large corporations whose business is government subsidized biofuel production (soy bean diesel & sugar cane methanol). It is not that Amazon should be left alone. In fact it could support a large population, just some ancient practices are to be picked up again. About 10% of the basin is covered by terra preta, an up to 2 m deep, tremendously fertile black anthropogenic soil, made by a large population between 450 & 1500 AD. Five hundred yers ago most of the people were exterminated by plagues brought in by conquistadors. The rest were hunted by slavers, escaped to forest. Most of the so called primitive tribes there are in fact offsprings of refugees, deprived remnants of a higher civilisation. Considerable part of the basin is not native forest, but an abandoned garden. Terra preta, even after five hundred years with no further care, turned out to be self regenerating. It keeps growing into the barren clay below. The long forgotten technology to create terra preta do indio is already rediscovered, it could also be reimplemented.
124686. Arno Arrak at 04:09 AM on 5 February 2010
        Sea level rise is exaggerated
        Can I point out that your statement about rising sea level is false? B. F. Chao, Y. H. Yu, and Y. S. Li (Science, 320:212-214) have shown that sea level rise for the last eighty years has been linear, with a slope of 2.46 millimeters per year. Theirs is the sea level that has been corrected for the effect of water held in storage by all dams built since the year 1900. Something that has been linear this long is not likely to change anytime soon. Which means that you can be a futurist and predict that sea level will rise a little under ten inches in a century, not twenty feet that Al Gore is still peddling in his movie.
        Response: Arno, thanks for bringing our attention to that paper which actually shows that the situation is worse than I described. The paper is Impact of Artificial Reservoir Water Impoundment on Global Sea Level (Chao 2008). It reconstructs how much water has been impounded in water reservoirs since 1900. The amount of water stored skyrocketed after 1950. If this hadn't occured, sea level would've been even greater. Consequently, they calculate what global sea level should be after accounting for reservoir impoundment water. They then compare their results to actual observed sea level:
        
        
        
        What they find is the increase in the rate of sea level rise is actually greater when you factor in water impoundment. This increases the significance of retreating ice sheets. A sobering result, considering the accelerating ice loss from Antarctica and Greenland.
124687. danielbacon at 03:37 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        You could also add Hutyra et.al. 2005 “Climatic variability and vegetation vulnerability in Amazonia” to your list too. http://eebweb.arizona.edu/faculty/saleska/docs/Hutyra05_Var.Vuln_GRL.pdf
124688. jpark at 03:04 AM on 5 February 2010
        On the reliability of the U.S. Surface Temperature Record
        Leo I think he used Reno because the National Weather Service includes the UHI factor in one of it’s training course using Reno, NV. So says Watts anyway. But this is quite a shock from Pielke blog (link below) where Phil Jones (et Al) is quoted as saying "London however does not contribute to warming trends over the 20th century because the influences of the cities on surface temperatures have not changed over this time." Pielke says: 'However, how would they possibly know that? The assumption that any temperature increase in the last couple of decades in London is not attributable to an increased urban heat island effect, at least in part, needs be documented, for example, by satellite surface temperature measurements for the more recent decades when they are available.' http://pielkeclimatesci.wordpress.com/2010/02/04/the-urban-heat-island-issue-the-released-cru-e-mails-illustrate-an-inconsistency/
124689. Miriam O'Brien (Sou) at 02:36 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        It's my understanding that the IPCC reports themselves are reviewed. Each of the 2007 reports lists a very large number of reviewers. I also thought I saw written on realclimate.org that for at least some of the WG docs the guidelines do not stipulate that all references must only come from peer reviewed journals. I don't have a problem with that provided the IPCC review process works well. The current kerfuffle is likely to result in one of two things: either relevant material will be omitted because, while known, it has not been published in a peer reviewed journal; or material such as potential impacts will be included that are not referenced at all but simply checked by IPCC reviewers for accuracy and relevance, based on their personal knowledge. Neither of these is satisfactory to my mind. I hope that any review of drafting and review processes does not result in important information and likely impacts under specific scenarios being omitted from future reports.
124690. HumanityRules at 01:36 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        And this for a historical view of rainfall in the amazon basin. http://www.scielo.br/pdf/aa/v35n2/v35n2a13.pdf
124691. HumanityRules at 01:05 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Isn't this a bit of a tautology. Surely by its nature a rainforest ecology is going to be affected by reduction in rain. Just like a saltwater marsh would be affected if its no longer inundated by seawater or a lake system is affected by in flow from rivers. The question is what is the relevance to climate change, what's causing the drying? The 1999 paper specifically links the drought to the 1998 El Nino. There are papers which show that fire has played an important part in amazonian rainforest for over 6000 years. Holocene fires in the northern Amazon basin. Saldarriaga, JG | West, DC Quaternary Research [QUATERN. RES.]. Vol. 26, no. 3, pp. 358-366. 1986. The paper puts forward the hypothesis that there have been "unstable environmental conditions" for >6000years in the Upper Rio Nagro region as evidenced by dated charcoal in the soil. Also http://jisao.washington.edu/data/brazil/ Do you see a trend or fluctuation? Peer-review or WWF is a red herring. The question is relevance.
124692. chris at 00:43 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        chriscanaris, this is a pertinent paper (see below). It addresses the latitude-dependence of expected changes in precipitation in a warming world, and compares this with the observational evidence. The observations and predictins are that the central latitudes experience increased drought in a warming world, whereas the higher latitudes will experience increased precipitation. The region from the equator to ~30 oN is the particularly vulnerable region that is expected to dry fastest, and this has already been observed during the observational period (1925-1999). X. Zhang et al. (2007) Detection of human influence on twentieth-century precipitation trends Nature 448, 461-465 http://www.nature.com/nature/journal/v448/n7152/abs/nature06025.html
124693. CBDunkerson at 00:05 AM on 5 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        chriscanaris, it is fairly obvious that higher temperatures will lead to increased evaporation of surface water and greater quantities of atmospheric water vapor (since the amount of water air can hold increases with temperature). From there it also seems clear that increased atmospheric water vapor will lead to increased precipitation - though not necessarily in direct proportion. However, it needs to be understood that these are localized phenomenon. Increased evaporation drying out scrub-lands is helping the Sahara desert to grow... because that extra evaporation is not offset by equally increased rainfall in northern Africa. The same is true of glacier loss all over the world... higher temperatures are leading to increased melt rate. That extra flowing water does mean increased precipitation, but it is spread out around the world rather than all falling back onto the glacier to replace the mass lost to melting. So your question of whether global warming will lead to a 'wet world' or a 'dry world' isn't really on point... the hydrologic cycle will certainly continue to intensify, but that will result in some areas becoming drier and others wetter... rather than increased evaporation and melt being perfectly offset by increased precipitation in each region.
124694. chris1204 at 22:28 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Thank you, Alexandre - a fascinating paper. It's an amazingly complex system with many unknowns. Deforestation seems to be a major culprit and perhaps an amplifier of AGW impacts.
124695. Alexandre at 21:46 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Oh, sorry for the poor citation: Marengo 2006 On the Hydrological Cycle of the Amazon Basin: A historical review and current State-of-the-art
124696. Alexandre at 21:45 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Since we're talking about the Amazon, here's a Brazilian paper (in English) on water vapour recycling in our rainforest. Climate change is projected to shift rainfall from Amazonia to the La Plata river basin, inducing a permanent El Niño-like behaviour. http://www.rbmet.org.br/port/revista/revista_dl.php?id_artigo=202&id_arquivo=352
124697. chris1204 at 21:33 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Nevertheless, I really would love to know whether we're likely to be looking at a warm wet world or a warm dry world as it makes a world of difference - pardon the pun. I note the Phillips paper states, ‘Tropical droughts may intensify and become more frequent this century as a result of anthropogenic climate change...’ However, I wonder if this automatically follows if stratospheric water vapour increases. I certainly do have some understanding of probability - a very salient part of my professional field (psychiatry) but I am no climatalogist. However, I hope I can still ask a halfway sensible question. So might increased stratospheric water vapour lead to increased precipitation or does only tropospheric water vapour count? I ought to add that I spent my childhood years 5 degrees north of the equator in West Africa – very warm and very wet! Moreover, Freddy Norton might see dry stressed eucalypts outside assuming he’s living in southeastern Australia (as I do now) – he would encounter a very different environment if he travelled north to the Cape York Peninsula where lush tropical rainforest abounds. As an aside, I note the Phillips paper also says with appropriate caution: ‘We find that relative drought is indeed strongly implicated as the driver of the network-wide shift in forest behavior (Fig. 2) but that the absolute intensity of the 2005 dry period was only weakly related to biomass dynamics... Those forests experiencing the most elevated moisture stress relative to their long-term mean tended to lose the most biomass relative to their pre-2005 trend (Fig. 2). These losses were driven by occasionally large mortality increases and by widespread but small declines in growth. Our method may fail to capture growth impacts well because intervals were longer than the period of potential moisture constraint, thereby masking its effects (drought can kill trees but can only temporarily stop growth).’ Incidentally, Phillips also states: ‘However, our findings do not translate simply into instantaneous flux estimates because carbon fluxes from necromass will lag the actual tree death events.’ This raises the further question of whether ‘necromass’ truly just ‘deadwood’ or is it in fact an intensely complex ecosystem made up of microscopic biomass with its own carbon dynamics and carbon sink properties? Given the exceptional nature of the 2005 drought, I wonder if we don’t run the risk of making long term forecasts based on a single event akin to popular assertions that the severity of the recent northern hemispheric winter ‘disproves’ AGW. It would be more pertinent to ask what is happening to the rainforest five years down the track. Quite a few questions, I know. Any ideas from anyone out there?
124698. Arkadiusz Semczyszak at 21:17 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Already professor S. Stanley in the "old" textbook: "Earth System History", 1999; for example, African gorillas, and another; reported by high climatic stability of the tropics ... It’s for this, also, in the process of evolution of the coral is not created to adapt to large changes in temperature. This tropical thermostat - it is obvious for climate students... but not for the IPCC ...?
124699. Doug Bostrom at 18:32 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        chriscanaris at 18:24 PM on 4 February, 2010 "I am wary of attributing all environmental problems to AGW" More really a matter of probabilities than definite assignment, and that's where error bars really help. Unfortunately error bars or the equivalent are the very first thing generally stripped away in communications styled for the general public, a shame because they're not at all hard to understand. I think journalists give too little credit to the average reader's ability to keep up. If you're sucked in by the headline and lede, you're probably going to stick around for the whole story as long as it is not egregiously dense.
124700. chris1204 at 18:24 PM on 4 February 2010
        What the IPCC and peer-reviewed science say about Amazonian forests
        Which raises the question of whether the Amazonian drought can be blamed on AGW. The last post on this site dealt with the connection between AGW and stratospheric water vapour. The question is – does increased water vapour lead to increased precipitation? If so, then the Amazonian drought may have its origins in more complex mechanisms. I am wary of attributing all environmental problems to AGW – this detracts from sober assessments of the issues and provides ammunition for those who might have an axe to grind.

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