Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings

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

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
New? Register here
Forgot your password?

Latest Posts

Archives

Recent Comments

Prev  2513  2514  2515  2516  2517  2518  2519  2520  2521  2522  2523  2524  2525  2526  2527  2528  Next

Comments 126001 to 126050:

  1. Measuring Earth's energy imbalance
    Tom, I hate to be in a position of defending an analogy, but it does get to the root of my point. The OLR spectrum covers more than just the CO2 band. The total OLR (integrated over the spectrum) is the term that will affect the radiative balance - not just the CO2 band. If CO2 is the causative factor in radiative imbalance, it will need to dominate the overall OLR behavior. If the CO2 is not dominating the behavior of the total OLR then it could/would be an aggravating factor to other causative factors. This is CRITICAL to evaluating the applicability of predictions made by climate models. The figure 1C (Harries 2001) shown in "How do we know CO2 is causing warming?" is only showing the effect of trace gases. It gives the false impression that total OLR is going down. If you look at Harries figure 1B, it shows an increase in the range 750-1000 cm^-1 that clearly exceeds the decrease in the CO2 band. That is the "Non-CO2 hole" in the bucket. Harries explains the increase in this range as due to the effects of ice crystals not completely removed from the data set due to the differences in FOV between the IRIS and IMG detectors. This does not explain how the same effect is seen by Griggs 2004 and Chen 2007 with the addition of AIRS and TES data with different FOV's. Chen asserts that the behavior in the window region is not due to cloud contamination. Satellite measurements of total OLR also indicate an upward trend. To boil it down - looking at only the decrease in the CO2 15 um band and concluding that the overall energy balance of the Earth is controlled by that decrease neglects the effect of the non-CO2 regions of the OLR spectrum. The argument that the decrease in CO2 warms the Earth which causes the other regions of the spectrum to increase even more does not conserve energy. To go back to the dreaded analogies it is like saying that you wrap a space heater in insulation and the heater inside heats up (I agree) and the room outside of the insulation also heats up (I disagree.) I would agree with CO2 being the causative factor if the increase in the window region was less than the decrease in the CO2 band - that would make sense both with increased blackbody from a warmer Earth and still conserve energy. If more IR is being trapped by GHG's then the total OLR must decrease - this should be basic stuff - I am missing something? Look at Venus, OLR is ~150 W/m^2 compared to Earth's ~235 W/m^2... Riccardo mentioned an observed increase in OLR due to the recovery from a past transient and referenced Murphy (seen in response to #1 above). I am not aware of any historical records (Vostok etc.) indicating that we should be recovering from a large transient. The step response in Murphy shows an increase in OLR but ONLY AFTER the increase in CO2 stops. The OLR should be decreasing while CO2 increases if the CO2 is the causative factor.
  2. Can you make a hockey stick without tree rings?
    @leto, 42 My very personal opinion: Gather trustwothy anectdotal data, and proceed from there in whatever manner you have statistical justification for. If there were one proxy series of the type you are asking for, we would have known by now, I think. I can give you a couple of examples from Norway. In Halvdan Svartes saga, it is told that he drowned (about 880 CE) in Røykensvik in late winter when the ice broke under horse and sledge because of cattle being watered out on the ice and their droppings making the ice rotten. That means it can not have been much warmer than now, but not much colder either. In Eigils saga (ca 950 CE), Eigil Skallagrimson is ordered by king Håkon to take a trip to Vermland (now Sweden) to collect taxes. It seems to be about this time of year, and the saga tells us that the winter roads are cleared ('breyttir vegar'). Well, I can tell you, they are not frozen, so there is no way you can use those tracks right now, I happen to live along them. That piece of information indicates temperatures around or slightly below the 2000-2009 mean. This is all in line with the present consensus in Norway, that medieval temperatures were 0.5-1 oC higher than the 1961-1990 mean, which means about what we experience now. No amount of proxy reconstructions is going to change the historical record, and I guess quite a lot of good information is still to be gathered from careful analysis of anecdotal evidence. And the 'precision' you get from proxy reconstructions is most often illusionary. Just compare the different reconstructions.
  3. Can you make a hockey stick without tree rings?
    DeNihilist, Thanks for the response. I will look at the material in more detail, but I have already heard a lot from the anti-AGW (skeptical) camp. I am familar with the whole Yamal saga, which is part of the reason I do not trust tree rings. I am somewhat surprised I have not had any reply from the pro-AGW camp pointing me to one unambiguous non-tree proxy that fits the 'global hockey stick with local European MWP' pattern. This is, after all, supposed to be the scientific consensus, or so I'd been told. Is there such a proxy? I would have thought, from the title of this thread, that such proxies did exist. Reconstructions based on combined data don't carry the same evidential weight for me, I'm afraid. I'm not saying data can't be combined but there is always room for human subjectivity and confirmation bias to creep into the combination process. I repeat, I am not not trolling to make a point here. I would just like to know if there is any firm ground to stand on before launching into my own analysis of the more complex statistical methods. Leto.
  4. An overview of glacier trends
    An excellent read, Thanks for the suggestion.However, not much information of the sort i am seeking.
  5. An overview of glacier trends
    well, perhaps, I have other use for this data than the current climate change issue, wich i do.Thats why i was hoping someone could help me.I am specifically looking for North American continiental deglacition rates from the point in time of its southern most advance to the present day.estimated original mass,percentage of the original mass that exist today.wether it be tables, graphs etc. Im not sure that such estimates even exist.However, you have knowledge i dont wich points that its far far greater than it was in time frames of geologic scale. perhaps you could provide those geologic time frames you work with ? I have to start somewhere
    Response: I don't know of tables or downloadable data but one paper How sensitive is the world's climate? (Hansen 1993) examines the period when the Earth fell into the last major ice age, calculating the change in Earth's albedo due to growing ice sheets. Should be worth a read - a good introduction to the concept of climate sensitivity also.
  6. An overview of glacier trends
    bigdaddy, the point is that the changes we are experiencing now are far, far faster than those in more geologic time frames. That's the point, and that's the problem.
  7. Can you make a hockey stick without tree rings?
    how about isotopes from tree rings? http://www.arctic.ucalgary.ca/main/documents/media_release_pdfs/Analysis%20of%20isotopes%20in%20tree%20rings%20can%20reveal%20past%20climate%20events.pdf
    Response: This seems to be a developing technology (or to be more precise, an existing technology that has become more affordable) so hopefully this will provide a lot more proxy information in upcoming years.
  8. Was there a Medieval Warm Period?
    Anyone know if there has ever been a search through the monastic enclaves of europe/middle east, etc. for any kind of climate/temperature data from before instrument period?
  9. Philippe Chantreau at 18:24 PM on 6 December 2009
    Can you make a hockey stick without tree rings?
    Blair, watch that program again and read some books. You are extremely confused. Levels of CO2 "hundreds" of time higher than preindustrial would be at or above 56000ppm; care to point when exactly was that happening? And look at that word again from a good source. It's Neanderthal.
  10. An overview of glacier trends
    Additionally, if any could resolve Mr.Lindzens concerns about climate modeling,as expressed in this article. http://online.wsj.com/article/SB10001424052748703939404574567423917025400.html?mod=googlenews_wsj
  11. An overview of glacier trends
    Pardon me gentlmen,Its my initial observation that your discussion is based on relatively short spans of time. Could any point me in the direction to obtain graphs of N.A.contitnental ice sheet deglaciation rates in more geologic time frames?
  12. Can you make a hockey stick without tree rings?
    As far as I can see, from my perspective, the issue is not the rise in temperature, rather, what is its cause. Now, I haven't gone through all of the postings above, but it appears that little, if anything, is said about the CO2 levels. There was a program on PBS regarding mankind and our evolution. To summarize, our precursor was nethanderals. The great ice age gradually forced the nethanderals further south as a consequence of impact of great droughts. Further, statements (not in this program) have been made to effect, the CO2 levels during this period were 100s of times greater than the CO2 level today. (One wonders what brand of SUVs the nethanderals were driving?) Yet, there was an ice age. Anyhow, the survivors ended up on eastern mid-Africa. Out of the survivors, came us, the homosapiens (shades of Darwin). Indeed, our genes have nethanderal traces. The next item that is relevant to this issue of warming is the reaction time of influences. Just because you give your car gas, it doesn't mean that in 1 second you will be going 60 mph. Likewise, how long does it take for a car going 60 mph to stop. Let alone the other issue of relaxation time. i.e., once the influence is removed, how long does it take to go back to the previous level. To continue, I think that the next few winters are going to be interesting regarding the CO2 hypothesis. So far, this winter is starting up as a cold one, even though there have been forecasts of a warmer NE. To summarize, I think that that the CO2 people still have to make their argument. Certainly, their postings and data manipulations have not given a lot of people the feeling that their science is objective.
    Response: "the issue is not the rise in temperature, rather, what is its cause. Now, I haven't gone through all of the postings above, but it appears that little, if anything, is said about the CO2 levels"

    This is because proxy records tell us what temperature has been in the past, not what's causing the temperature changes. But as you say, attribution is indeed the central issue of global warming - I would go so far as to say the hockey stick controversy serves as a distraction from the more crucial observations that rising CO2 levels are causing an enhanced greenhouse effect which is the main contributor to global warming.

    The issue of relaxation time is also an important point that is rarely discussed. In an earlier post, we examined the whole concept of climate time lag and "warming in the pipeline".

    There is also a detailed examination of the argument that CO2 has been higher in the past.
  13. Al Gore got it wrong
    why are errors by al gore acceptable just because he isnt a scientist? he is reading a script isnt he? hopefully, scientists wrote the 'script'. but, if 'scientists' did write the script, then why is it filled with so many glaring lies. sorry, i cant call them errors or untruths. the included 'information' was clearly deliberate for causing alarm. so, then, back to my original question. why are errors acceptable in the global warming but so aggressively belittled and attacked when skeptics raise a legitimate question? i am very curious about the bias attitude of error forgiving/overlooking nature of global warming vs strike down global warming skeptics. heck, i would rather be a ufo believer. at least i will just get laughed at instead of being vehemently attacked!
  14. Can you make a hockey stick without tree rings?
    DeNihilist, here is a short page with links regarding Loehle. There is a lot of material here on Skeptical Science, too, if my fuzzy memory serves.
  15. Can you make a hockey stick without tree rings?
    Well, i found some time today to look over those papers, now realize that i am not a scientist but do have a capacity to understand technicalities. Chris, the Moberg paper in my opinion is top drawer, the only critique I have, is I wish that they would not lay the instrumental on top of the original data. My eyes are not as good as they use to be. Tom, the second paper you put up was to me what science should be, a constructive argument about anothers' work. thank-you. Since you don't seem to have much respect for "my friend" JoNova, how this paper then, by Loehle... http://www.ncasi.org/publications/Detail.aspx?id=3025 any hidden agendas here that I should know about? Thanx
  16. Models are unreliable
    The above article attempts to debunk the "skeptic argument." However, the attempted debunking rests upon the abnormal semantics which the article attaches to the word "prediction." As normally defined, a "prediction" is a logical proposition about the outcome of a specified statistical event that is made at a specified interval in time in advance of the occurrence of the event's outcome. As it is an example of a proposition, a prediction is true or false. I understand that the climatologist James Hansen once predicted that the highway outside his office in Manhattan would be underwater 20 years later. Hansen had made a prediction. In the event, Hansen's prediction proved false, invalidating Hansen's hypothesis. All of the article's examples of "predictions" are computed temperatures. They provide the basis for comparison of computed to measured temperatures. However, by itself such a comparison neither validates nor invalidates the associated model for the events are unspecified. With the events unspecified, the model lacks the property of "falsifiability" that is possessed by every model that is "scientific" in nature. To render one of the IPCC's models falsifiable, the builders of this method would have to specify the statistical event that is associated with each prediction. According to authorities that include the IPCC itself, this task has not yet been accomplished. In its most recent report, the IPCC states that its models do not make "predictions" but rather that they make "projections." While predictions support the validation of a model, the IPCC's "projections" support only "evaluation." The distinction is an important one, for to control any sort of system, one must have the capacity for predicting the outcomes from movement of the control system's actuators. Whether the IPCC's models have the capacity for doing so remains unknown pending the definition of the events and conduct of a validation exercise. Thus, whether regulation of carbon dioxide emissions would have the desired effect of controlling global temperatures is also unknown. Associated with confusion over the differing meanings of "prediction" and "projection" in the language of climatology is a mistake repeatedly made by people who are interested in climatology but unfamiliar with the methodology of science. This mistake is to confuse a model built by scientists with a scientific model. A scientific model makes predictions. A model that makes no predictions is not a scientific model even when built by scientists.
  17. Can you make a hockey stick without tree rings?
    i find that most of the cynic blogs are a complete waste of my time , the inhabitants therein seek only to spread denial they are not interested in fact, the best way to help is to answer their letters to the editor garbage in your local paper.remember though to make your reply interesting and use lay terms . the use of logic rather than ad infinitum scientific opinion also can be very usefull. simple and to the point ,,,
  18. Measuring Earth's energy imbalance
    guinganbresil, the bucket analogy is only that--an analogy. It's not nearly a perfect one. I'm not going to try to improve it, because that will yield diminishing returns. But consider what I wrote in #24. The real atmosphere behaves on a continuum, but with a delay. Insulation causes energy accumulation which increases temperature which increases outgoing radiation. That takes a little while, but not very long. Blackbody radiation laws that fit really well to nearly all condensed matter. Of course, a portion of that outgoing radiation gets absorbed and re-emitted, which raises the temperature, and so on.
  19. Measuring Earth's energy imbalance
    Riccardo, Look at #23-#29 (Tom and canbanjo)... I didn't see them before. I like the analogy, but the bucket should have two holes - one representing the CO2 band at 15um and the other the other represents the much larger non-CO2 OLR. As the CO2 "hole" is made smaller, the rate of water exiting the bucket is reduced (i.e. OLR goes down) and the water level starts going up. The increased pressure causes more water to exit the non-CO2 "hole". There is less water exiting the CO2 "hole" (has to be, since when the CO2 "hole" is completely closed, no water will be exiting! You don't get more water exiting a smaller hole.) The total water exiting the two holes will only start going up again when you STOP shrinking the CO2 "hole" - then it will go up until it equals the input and you are back in equilibrium. Moral of the story: OLR should be going down with increasing greenhouse effect.
  20. How do we know CO2 is causing warming?
    Riccardo, I think the confusion is in the definition of the system - if you consider the boundary at TOA, the OLR must go down to cause the radiative imbalance as described by the greenhouse effect. To say that the CO2 absorbs long wave from the surface and re-emits it back down causing a temperature increase and subsequent temperature rise that causes total OLR to increase does not conserve energy. Look at a block of CO2 at TOA - that reasoning would have it emitting more IR downward AND more IR upward! Unless it is creating energy (which it is not) or converting short wave (which it is not) or is being warmed by some other source (of which I am unaware...) this scenerio is non-physical. I fully agree with your point on increasing OLR due to a drastic imbalance in the past that we are still moving back toward equilibrium. As I understand historical CO2 concentrations, they have been much lower than present for 100K's of years, so this rapid CO2 event you mentioned did not happen in the recent past. Please take a much closer look at the behavior of a system with the step function response (as described by Murphy) driven by a ramp instead of a step. You can get a feel for it by looking at a series of small steps (like a staircase) and add up the step responses. The OLR should go down while the CO2 is going up. The OLR will go up only after the CO2 increase has stopped (or the rate has gone down significantly.) All of the complications and nonlinearities you mentioned should be buried in the step response and as long as you are in a quasi-equilibrium condition, the general behavior should hold. This is pretty basic stuff in electrical engineering (charging capacitors etc.) Concerning Venus - I found a great paper describing the atmosphere - very interesting! I thought it resembled a baked potato wrapped in aluminum foil. In fact, Venus looks cooler at TOA than Earth! This is completely consistant with the decrease in OLR with increasing CO2 I mentioned earlier. Also, a large portion of the high surface temperatures on Venus are due to the high atmospheric pressure via adiabatic lapse rate. http://yly-mac.gps.caltech.edu/Z444/Flash4/Venus_greenhouse/RT_in_Venus_Atmosphere_AGU_GM01301CH08.pdf
  21. What do the hacked CRU emails tell us?
    Also, I'd like to add that when proposing a theory, the onus is on those that aim to prove the theory correct, not on the skeptics. The skeptics provide very useful information in keeping all the scientific avenues open for exploration, and gradually theories that contradict the hypothesis may be brought down with carefully investigated evidence and with the utmost consideration... absence of politics.
  22. Can you make a hockey stick without tree rings?
    Just for the record, there are plenty of ways ocean heat redistribution can potentially impact how much heat is kept and/or brought into the system. For instance, changes in the SOI can cause changes in precipitation, increases in precipitation cause cooling and increased precipitation means (see Wentz et al. 2007 How Much More Rain will GLobal Warming for a discussion of the precipitation, temperature and WV effects of El Ninos. Cheers, :)
  23. Can you make a hockey stick without tree rings?
    #31 sgking sgking: As you seem to accept Jo Nova as an authority on this, maybe you would care to get an explanation from her why she uses the 1997 Huang/Pollack paper in the post, with no mention of their later work? If she has found errors in those later papers, it would be very interesting to know. I would also like to know your own reflection on this. Since you are referring to that blog post here, you must have made some assessments.
  24. Can you make a hockey stick without tree rings?
    Thanks, chris!
  25. Can you make a hockey stick without tree rings?
    sgking, unfortunately the person who created the stuff you linked to is misrepresenting the science. Their misrepresention of the Moberg’s paleotemperature reconstruction is described above (see my post: chris 07:25 AM on 5 December, 2009) Their misrepresentation of the 1997 Huang/Pollock/Shen (HSP1997) borehole data is a truly dismal piece of cherrypicking; the misrepresenter has declined to point out that Huang/Pollock/Shen (HPS) have already pointed out that their 1997 data is completely unsuitable for comparing the temperatures of the MWP with current temperatures[**]. They have recently concluded that their borehole reconstruction indicates that the MWP was around 0.5 K cooler than current temperatures.[*] So the borehole data is entirely consistent with all the other scientific data and analysis. [*]S. P. Huang and H. N. Pollack P.-Y. Shen (2008) A late Quaternary climate reconstruction based on borehole heat flux data, borehole temperature data, and the instrumental record Geophys. Res. Lett. 35, L13703, doi:10.1029/2008GL034187 Abstract: We present a suite of new 20,000 year reconstructions that integrate three types of geothermal information: a global database of terrestrial heat flux measurements, another database of temperature versus depth observations, and the 20th century instrumental record of temperature, all referenced to the 1961–1990 mean of the instrumental record. These reconstructions show the warming from the last glacial maximum, the occurrence of a mid-Holocene warm episode, a Medieval Warm Period (MWP), a Little Ice Age (LIA), and the rapid warming of the 20th century. The reconstructions show the temperatures of the mid-Holocene warm episode some 1–2 K above the reference level, the maximum of the MWP at or slightly below the reference level, the minimum of the LIA about 1 K below the reference level, and end-of-20th century temperatures about 0.5 K above the reference level. ------------------------------------------------- [**]HSP describe carefully in their 2008 paper why their 1997 paper (HSP 1997; used by the misrepresenter that you linked to) can’t be used to compare MWP with current temperatures. The data in HSP 1997 contains no data for the 20th century, because of concern in the large number of boreholes analyzed that the top 100 metres of depth might be contaminated by non-climatic influences. The end of the record in HSP1997 defines the estimated temperature around the turn of the end 19th century. The data in John Cook’s Figure 1 (Huang 2000) is from a set of boreholes that have passed a quality control for eliminating non-climatic contributions, and this approaches is extend much further in HSP2008 cited just above.
  26. What do the hacked CRU emails tell us?
    So Jones has resigned. UEA is conducting an enquiry into data 'misuse' The head of the world climate forum is also launching an enquiry. For an overview of the situation go here.... http://mensnewsdaily.com/sexandmetro/2009/12/01/top-global-warming-scientist-resigns-over-allegations-he-overstated-the-case-for-man-made-climate-change/
  27. Can you make a hockey stick without tree rings?
    Here are some graphs that seem to suggest something different than those above: http://wattsupwiththat.com/2009/12/04/jo-nova-finds-the-medieval-warm-period/
  28. Can you make a hockey stick without tree rings?
    John 27 response does last glacial maximum = LIA ?? If you set out to find the LIA in the borehole, stalagmite and glacial data presented above you really couldn't find it. If that data can't identify this 'period of dramatic climate change' why should we trust it to identify any period of dramatic climate change. I don't see how we can defend this data as a climate proxy and believe in the LIA. We have to throw away one or the other.
  29. Was there a Medieval Warm Period?
    I am even more perplexed now. Fig 3 and Fig 4 span 10 years of data. Fig 1 and Fig 2 span 300 years of data How can you compare 300 years of data to 10 years of data (what's more the hottest). I hope you realise that some of your detractors are accusing your side of cherry picking the data. Please don't do it on the site intended for the general public.
  30. Was there a Medieval Warm Period?
    I am a bit perplexed when i look at Fig1 and Fig2 for MWP and LIA. Why do we have this remarkable anomaly over GreenLand?
  31. Can you make a hockey stick without tree rings?
    WeatherRusty - the simplest method of getting the word out is just to post, post, post - on your blog, on Facebook, and especially on the comments sections of news sites which run the misleading stories. Link them here so they can read the info for themselves. Sure, you run the risk of more uninformed commentary, but maybe some minds will be changed.
  32. The growing divide between climate scientists and public opinion
    The challenge for objective people is to remain skeptical while not becoming drawn into the blind faith that is becoming increasingly a feature of the deniers (people who claim to be skeptics). It is important to question things but, not in the process of doing so, to deny evidence or indicators that do not reinforce a particular theory. Sadly, a significant number of people are latching on to points of view that are more driven by inverse intellectual snobbery than a considered point of view that is soundly based. My biggest concern is that points of view that reinforce our deep seated human desire to do nothing are quite appealing.
  33. Water vapor is the most powerful greenhouse gas
    Just a thought, are any of you familiar with global dimming. The article states that there has been an increase in WV in the atmosphere which has been recorded since 1988. If this is true then in essence there should be greater cloud cover which acts as both a negative feedback mechanism and a positive feedback. I cant remember where but i read that the suns rays have a greater impact on the evaporation of water than a rise in temperature alone. Something about the excitement of water molecules. So the increase in cloud cover and aerosols act as both a positive and negative feedback mechanism not exactly canceling each other out though. Apparently global dimming is half as strong as global warming. I'm sure that if i have made an error some where in my logic you will correct me.
  34. Can you make a hockey stick without tree rings?
    Just back from work Tom, will review the papers in the next couple of days, as Christmas is coming up rather quickly, and being a typical guy, haven't started the "shop" yet. Phillipe, point taken. Bad use of grammer. Should have been a bit more precise. One of the papers that Tom pointed to, if my quick look was somewhat close to right, seems to show a new way to analyze the data. This is what I meant, science grows with every new discussion. Sometimes the new ways are right, sometimes wrong, but from this we gain valuable knowledge. Will try to slow down my thoughts in the future to be more clear. LOL Chris, my friend Jo! Not quite, but I would bet that you would have a great discussion with someone that seems that passionate! I visit about 12 different blogs during the week, and try to keep them even - yes/no/maybe-so. The main thing is to have a bit of time to let your critical thinking sift through the "junk" from all sides. I found it interesting that Prof. Mann has "allowed" the MWP to at least be shown in his latest paper. His explanation is intriquing to say the least. But again, I have not had time to go as deep as my depth of understanding will allow me. This silly thing called life keeps getting in the way! Thank-you for the link to Moberg and your explanation. I can see a BIG pot of coffee is going to be consumed in the near future.
  35. Can you make a hockey stick without tree rings?
    What you show doesn't cover the MWP but does extend over the LIA. Do we believe in the LIA? My understanding is there is evidence ice/glaciers reached their maxima around 1700's (may be some variation based on location) and that things have been warming since and glaciers retreating. Lets look at the different methods 1) Boreholes show on evidence of LIA. 2) The stalagtite graph shows a temperature peak in 1700's. 3) The glacier record shows no 1700's temp minima (glacier maxima) followed by slow climb to 1900's. This is very strange as one method used to confirm the LIA (glacier treat) now seems to be refutting it's existence. Do we have to abandon the LIA idea to accept this data?
    Response: Mann's graph does go back 2000 years well past the MWP but I included just part of that graph in the interest of keeping the presentation as simple and clear as possible - extending the graph doesn't change the end result (that the last few decades are the hottest in the last 1000/2000 years). Anyhoo, here is the complete graph:



    Re "abandon the LIA", there seems to be a common notion kicking around that climate scientists are trying to talk down past climate change. This is decidedly not the case. On the contrary, as Dana Royer puts it: "the geologic record contains a treasure trove of 'alternative Earths' that allow scientists to study how the various components of the Earth system respond to a range of climatic forcings." For this reason, periods of dramatic climate change like coming out of the Last Glacial Maximum are of strong interest to climate scientists. These periods indicate that the climate is sensitive to radiative forcing which in turn tells us that the climate is sensitive to the current very strong radiative forcing from CO2.
  36. The hockey stick divergence problem
    Chris #18 Some issues with the instrumaent data 1) there has been a bit of a divergence between the HADCRUT and GISS data, the two main global records, over the past decade. THis has lead to the arguement about whether the last decade has shown cooling. 2) What is presented is not what has been noted down from the thermometer. The data goes through manipulation to account for changes in instrument, position, local changes, urbanisation etc. This process can be contraversial. As an example you can read about how this process upset some sceptical scientists in New Zealand if you wish. http://nzclimatescience.net/index.php?option=com_content&task=view&id=550&Itemid=32 I'm sure I could list more. As an aside. If people like little gizmo's to play with online then NOAA have graphs on there front page where you can play with a slider. Hours of fun. www.climate.gov
    Response: The divergence (word du jour) between HADCRUT and GISS is largely due to the fact that HADCRUT doesn't include the Arctic when calculating the global temperature. As the Arctic is warming faster than other areas due to polar amplification, this means the HADCRUT time series underestimates recent warming trends.
  37. The hockey stick divergence problem
    In what sense has "the land-based record has been fraught with problems in the last few decades", Heidi? The temperature record is consistent with the broad rsnge of real world warming consequences (sea level rise, sea ice retreat, polar and mountain glacier recession, biologicsl cosequences etc.). I haven't read any analysis that indicates that there is a problem with "the land based record". What did you have in mind?
  38. Can you make a hockey stick without tree rings?
    DeNihilist, your friend “Jo” on that odd web site is being rather naughty! It’s easy to download Moberg et al’s data, e.g. from the NOAA paleodata repository here: http://www.ncdc.noaa.gov/paleo/globalwarming/moberg.html If one plots the data (try it yourself), you’ll see that your friend “Jo” has done some odd things to it. S/he has applied some unspecified smoothing that has accentuated/broadened some of the spikes in the earlier part of the record and attenuated the spike in the mid 20th century, and shifted all the data upwards by a few tenths of a degree for some reason. In fact the spikes are simply noise. The major spike around 990 AD lasts only for about 7 years, up and down, and is obviously noise. Likewise with the spikes around 1020 and 1110 AD, although the reconstruction is consistent with a real N. hemisphere MWP that slowly reached a temperature around 0.2 – 0.3 oC warmer than the preceding and following period, but quite a bit cooler than now. Moberg’s reconstruction puts the MWP temperature at around the same temperature as the mid 20th century global temperature. Remember that Moberg et al is a Northern hemisphere reconstruction. One needs to be careful in comparing a smoothed record with a real, unsmoothed instrumental record. However we know that the earth surface really has warmed by around 0.5 oC since the middle of the 20th century and by around 0.7 oC in the N. hemisphere (if one thinks it’s appropriate to compare like with like).
  39. Can you make a hockey stick without tree rings?
    The problem with that scenario Mizimi, is that the mechanisms that you speak of (ocean heat redistribution due to cyclical shiftsd in ocean dynamics) simply can't add significant heat to the earth system. Tsonis et al have recently pointed that out [*] So Tsonis et al have converted the qualitative suggestions of their 2007 paper into a quantitative analysis of the contribution of these effects to 20th century warming [*]. They conclude that these effects made a significant contribution to early 20th century warming, and a small contibution to warming since 1960 (perhaps 0.1-0.15 oC) with zero contribution to warming since around 1985. The nett contribution to 20th century warming from the effects you are describing is (according to Tsonis et al) close to zero (perhaps 0.05 oC). So the scientists whose earlier work you are rather over-embellishing to support a notion, simply don't agree with you. Their earlier qualitative analysis idicates that cyclic ocean regime changes can have temporary small effects on surface temperature. A quantitative analysis establishes that the nett effects of these are small, and that their contribution to the marked warming since the early 80's is close to zero. [*] K. L. Swanson, G. Sugihara and A. A. Tsonis (2009) Long-term natural variability and 20th century climate change Proc. Natl. Acad. Sci. 106, 16120-16123 (see Figures 2 and 3 and text).
  40. Can you make a hockey stick without tree rings?
    JoNova makes many, many false claims. Her Skeptic's Handbook is filled with claims that have been debunked countless times. 1) Joanne Nova did not do her research or did so without due diligence. or 2) Joanne Nova is intentionally misleading the general public.
  41. Philippe Chantreau at 06:46 AM on 5 December 2009
    Can you make a hockey stick without tree rings?
    DeNihilist says "And that Tom , is what science is about! Point - counterpoint." No. That's what rethoric, politics or court room arguments are about.
  42. Can you make a hockey stick without tree rings?
    DeNihilist: Those two pages I pointed you to are appropriate not just to the JoNova page, but also to the co2science page you pointed to.
  43. Water vapor is the most powerful greenhouse gas
    Riccardo - thanks for the PS pointer. I recently read a paper ( which I seem to have lost) showing that there has indeed been an unexpected increase in convective turnover in the tropics...must try and relocate it. Just as a side issue... the amount of WV is not just T dependant - you have to have a source. No source in the Sahara so it's dry even tho' T is high. Lots of water in the tropics so it's humid. Also, in general terms, the atmosphere could hold a lot more WV -if the contact surface area between air/water was increased - without an increase in T. Air conditioning spray humidifiers do just that.
  44. Can you make a hockey stick without tree rings?
    #6...no I don't think it is just the sun, although solar fluctuations have an effect. I think it is the resultant of a lot of chaotic behaviour from a variety of events ( El Nino/a. PDO,NAO, TSI etc) which when synchronised cause a pronounced shift in climate. "The above observational and modeling results suggest the following intrinsic mechanism of the climate system leading to major climate shifts. First, the major climate modes tend to synchronize at some coupling strength. When this synchronous state is followed by an increase in the coupling strength, the network’s synchronous state is destroyed and after that climate emerges in a new state. The whole event marks a significant shift in climate. It is interesting to speculate on the climate shift after the 1970s event. The standard explanation for the post- 1970s warming is that the radiative effect of greenhouse gases overcame shortwave reflection effects due to aerosols [Mann and Emanuel, 2006]. However, comparison of the 2035 event in the 21st century simulation and the 1910s event in the observations with this event, suggests an alternative hypothesis, namely that the climate shifted after the 1970s event to a different state of a warmer climate, which may be superimposed on an anthropogenic warming trend. from: "A new dynamical mechanism for major climate shifts" GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L13705, doi:10.1029/2007GL030288, 2007 (Tsonis et al 2007) which describes the results of treating climate as a chaotic networked sytem using observed data for such events and modelling the results. The model indicates a synchronisation roughly every 10yrs...1910..20..30..40..50.. but shift in climate state occurs only if the result is an increase in coupling strength - which happened in 1910, 1940 and 1970 - and in each case the result was an increase in temperature.
  45. Can you make a hockey stick without tree rings?
    And that Tom , is what science is about! Point - counterpoint. Brilliant reply. I will delve deeper into those two pages later, Thanx! PS - just to let you know, I find the volume on MOST of these blogs a bit to loud. Like panning for gold, you have to dump about 99.7% of the raw material to filter out the gold. Though both sides do have some funny ad hommien attacks, in my experience, the truth is found in the quieter moments.
  46. Can you make a hockey stick without tree rings?
    DeNihilist: "Excellent post" by JoNova? Really? Have you seen this or this?
  47. Can you make a hockey stick without tree rings?
    Leto, try here - http://joannenova.com.au/2009/12/fraudulent-hockey-sticks-and-hidden-data/ an excellent graphic representation of the MWP. Warning, Jo is a strong sceptic, so though the graphic is of immense value, her writing style is quite brunt
  48. Can you make a hockey stick without tree rings?
    Whoops - :)~ http://www.co2science.org/data/mwp/regions/nhemis.php
  49. Can you make a hockey stick without tree rings?
    John, you might want to check out JoNova's site for an excellent post on the MWP. She got her info from this site, all peer reviewed. Peace
  50. Was there a Medieval Warm Period?
    This is more or less n topic, thanks mostly to TruthSeeker going off topic. TS, please read the detailed expose made by deepclimate.org. They have shown that it was Chris de Freitas (and others) who were in fact manipulating and subverting the peer-review process, not the other way round! The papers in question are all pseudo-science and should have never made it through peer review. The same culprits now often publish at Energy and Environment with other "sceptics" because contrarians have allegedly infiltrated that peer review and editorial process. PeterPan, in figures such as those shown above, the hatching is typically used to indicate statistical significance. Maybe John Cook could change the captions to specify exactly what the hatching means?

Prev  2513  2514  2515  2516  2517  2518  2519  2520  2521  2522  2523  2524  2525  2526  2527  2528  Next


The Consensus Project Website

THE ESCALATOR

(free to republish)


© Copyright 2024 John Cook
Home | Translations | About Us | Privacy | Contact Us