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  2497  2498  2499  2500  2501  2502  2503  2504  2505  2506  2507  2508  2509  2510  2511  2512  Next

Comments 125201 to 125250:

  1. Models are unreliable
    We have no idea how reliable climate models are: IPCC AR4 8.6.4 How to Assess Our Relative Confidence in Feedbacks Simulated by Different Models? [quote]A number of diagnostic tests have been proposed since the TAR (see Section 8.6.3), but few of them have been applied to a majority of the models currently in use. Moreover, it is not yet clear which tests are critical for constraining future projections. Consequently, a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed.[/quote] Any person on earth knows that clouds can warm and cool. IPCC knows that too. Cloud feedbacks are not well modelled. IPCC AR4 8.6.3.2 Clouds [quote]In many climate models, details in the representation of clouds can substantially affect the model estimates of cloud feedback and climate sensitivity (e.g., Senior and Mitchell, 1993; Le Treut et al., 1994; Yao and Del Genio, 2002; Zhang, 2004; Stainforth et al., 2005; Yokohata et al., 2005). Moreover, the spread of climate sensitivity estimates among current models arises primarily from inter-model differences in cloud feedbacks (Colman, 2003a; Soden and Held, 2006; Webb et al., 2006; Section 8.6.2, Figure 8.14). Therefore, cloud feedbacks remain the largest source of uncertainty in climate sensitivity estimates.[/quote]
  2. The chaos of confusing the concepts
    Ned, One can roughly say there are two classes of chaotic system, deterministic and non-deterministic. The behavior of the latter is the same as a random system. However a deterministic chaotic system isn’t the same as a random system. All deterministic system can in principle be predicted. Therefore saying weather or climate is chaotic is not the very same thing as actually claming it can not be predicted to some degree of certainty, they claim is only that it may be hard to predict, how hard is another matter thou. Climate is affected by regular cyclic phenomena and random event, these can be seen as ramps and step pulses to the system. Any system, linear, chaotic or random will respond to such pulses and such response can in principle be measured or filtered out from a time series of measurements. In a linear system this filtering is trivial, but for a chaotic system the process is non-trivial, a detected pulse may very well be a false positive in such system, this is very hard to say with out knowing anything about the history of the system itself. A linear system response to a pulse is easy to predict, but for a chaotic system one can not in general do this, except within small time scales. Chosen time scale short enough even the behavior of a random system can be predicted, but the error will soon grow to large to get any meaning full prediction out from it. The difference in predicting a linear system vs. a nonlinear lies in the rate of error growth. Linear system has a much smaller growth rate, and therefore we can make the prediction over longer times series with high confidence, while this is not the case with non-linear system. That errors in prediction grows by time is an inherent property of any simulations. The task in making a good prediction is to try make a system in which the growth of error is as small as possible. When you say you can predict that the weather in the next 6 month will be 20 to 30 C degree, then you are NOT basing this on the system itself but on a pulse respond to a ramp signal you know exist. However, still there is very tiny and small possibility your prediction may turn out wrong, but it is so unlikely to happened that you are not regarding it, which you probably do perfectly right in. But never less, it less to weather being non-chaotic and more to weather being affected by a ramp signal that you are able to do such prediction.
  3. On the reliability of the U.S. Surface Temperature Record
    I don't think the UHI can be regarded as a myth. I can't comment on the US and haven't yet read the Memme/Menne paper. Perhaps the UHI is neglible in the US as Peterson found. But a 2009 IJC paper: Detection of urban warming in recent temperature trends in Japan, by Fumiaki Fujibe, showed a 0.1'C/decade UHI effect for the larger cities. This was based on 1979-2006 from 561 stations recording hourly data and compared with local population density data. You can see more about this paper at http://scienceofdoom.com/2010/01/17/urban-heat-island-in-japan/ There is also the Ren paper from 2008 in Journal of Climate which also found a significant UHI in China.
  4. On the reliability of the U.S. Surface Temperature Record
    It's one thing to endlessly kvetch and complain, another to actually exert some effort. Watts and crew did some work, hats off to them, misguided though they were. I hope these results will encourage doubters to purchase historical weather records for those locations where they are complaining about interpolation. As NewYorkJ remarks, many doubters will play the "hoax" wildcard yet again in order to explain this latest disaster for their strange cause. However, each time the doubt community must draw that card from their hand the remaining slice of the behavioral bell curve containing them loses area.
  5. Skeptical Science now an iPhone app
    re #18 Not quite sure what your difficulty is HumanityRules: 1880-current global temperature rise is around 0.85-09 oC (NASA Giss or Hadcrut3v). atmospheric CO2 rise from 290 ppm (mid-late 19th century) to 386 ppm (current), should give 1.24 oC at equilibrium within the mid-range of climate sensitivity (3 oC of warming per doubling of [CO2]). So we've had 0.85-0.9 oC of expected temperature response of ~ 1.25 oC. It's obvious (I would have thought) that the temperature response to enhanced radiative forcing is the equilibrium response. There shouldn't be a lag in the onset of the response of course, but the earth will take quite a while for the slow elements of the response, especially the accumulation of heat into the oceans, to come to equlibrium with the enhanced forcing. So the only "sleight of hand" would be to pretend that the earth should somehow miraculously come instantaneously to the new forced surface temperature. Even the most blatant efforts[*] to pursue that canard didn't go as far as to insinuate an instant temperature response to enhanced forcing. Perhaps you're having a general difficulty with the fact that the earth's temperature response to forcing, while not that complex, isn't amenable to simplistic interpretations. As several of us have pointed out on another thread, you do need to consider all of the forcings and their contributions (including anthropogenic aerosols, which have significantly countered anthropogenic greenhouse gas-induced warming). The question of the temporal response to enhanced forcing is difficult (there are obviously multiple time constants in the earth's response - atmosphere responds quite quickly, the surface and especially the oceans much more slowly), and that's the reason that determination of climate sensitivity is difficult based on analysis of (say) the 20th century response to enhanced greenhouse forcing... [*] e.g. (see Schwartz 2007) http://www.skepticalscience.com/climate-sensitivity.htm and his retraction and revision of the notion of a fast earth temperature response to external forcing
  6. On the reliability of the U.S. Surface Temperature Record
    Typo in 3 places: "Memme 2010" should be "Menne 2010". So the Watts project shows there is, if anything, an overall cool bias in the raw data, which is a moot point considering the adjustments remove most of this bias. "Adjustments applied to USHCN Version 2 data largely account for the impact of instrument and siting changes, although a small overall residual negative (“cool”) bias appears to remain in the adjusted maximum temperature series." One criticism of the Menne result is that they are relying on the data the Watts army of volunteers puts together with regards to the rating classification. How reliable is that data? Do they have the expertise and objectivity needed to effectively assign a rating to each station? The Watts project has served it's purpose, which is to spread doubt about the data among the laypersons. Peer-reviewed academic studies will just be dismissed as being part of the hoax. How can they be believed, when "photos" prove otherwise?
    Response: Thanks for the alert, I've fixed the typo. Re the issue of relying on the surfacestations.org classifications, the NOAA also have their own independent ratings. The dotted lines in the figures above represent the good/bad trends according to their own classifications while the solid lines are according to the surfacestations.org classifications.
  7. The IPCC's 2035 prediction about Himalayan glaciers
    Jesús Rosino @4: Thanks for the link to Karger et al.. It is by far the best objective and quantitative discussion of the status and outlook of the Himalayan glacier that I have come across. I highly recommend it. After reading their "report", it is clear that there is still much reason for concern.
  8. The chaos of confusing the concepts
    Nice article.. It's worth restating that treatment of chaos requires a careful consideration of exactly what one means by the term in any particular instance. The notion that climate might be chaotic in the same sense that weather is, not really suportable. The example of ice age cycles just referred to is a good one. During the last several hundreds of thousands of years the earth underwent glacial-interglacial-glacial transitions which had profound effects on climate regimes - there was nothing chaotic about the broad properties of these transitions and the climate state transitions that these induced. The transitions were paced by earth orbital cycles, and in each glacial/interglacial the earth transitions were driven towards new equilibrium states having characteristic, (and rather reproducible through several cycles over hundreds of thousands of years) global temperatures, atmospheric CO2 concentrations, ice sheet coverage, sea levels etc. And in the general state, climates and their responses to variations in forcings are non-chaotic. Of course there may be stochastic elements to forces that vary these states. For example the "transient" temperature rises and falls in the N. hemiphere in glacial periods during Dansgaard-Oeschger and Heinrich events seem to be due to periodic ice discharge fom the Arctic ice sheets, and temporary slowing or stopping of the thermohaline circulation. These may be contingent/stochastic events (i.e. essentially non-predictable), but local climates likely responded in a well-defined manner according to the resulting changes in local ocean/air heat transport; atmospheric moisture contents etc. The idea that climate is something like the long term accumulation of weather is a silly concept that is presumably raised so as to give the impression that climate is hopelessly non-predictable given that one can't predict weather. As Ned has said, this isn't true. The relationship between weather and climate is, of course, more sensibly defined the other way round; i.e. weather is the day to day variation in seasonal atmospheric parameters (temperature, wind, precipitation) within a given climate regime...
  9. On the reliability of the U.S. Surface Temperature Record
    http://ams.confex.com/ams/15AppClimate/techprogram/paper_91613.htm "The National Weather Service MMTS (Maximum-Minimum Temperature System) -- 20 years after Nolan J. Doesken, Colorado State Univ., Ft. Collins, CO During the mid 1980s, the National Weather Service began deploying electronic temperature measurement devices as a part of their Cooperative Network. The introduction of this new measurement system known as the MMTS (Maximum-Minimum Temperature System) represented the single largest change in how temperatures were measured and reported since the Cooperative Network was established in the 1800s. Early comparisons of MMTS readings with temperature measurements from the traditional liquid-in-glass thermometers mounted in Cotton Region shelters showed small but significant differences. During the first decade, several studies were conducted and published results showed that maximum temperatures from the MMTS were typically cooler and minimum temperatures warmer compared to traditional readings. This was a very important finding affecting climate data continuity and the monitoring of local, regional and national temperature trends. It has now been 20 years since the initial deployment of the MMTS. The Colorado Climate Center at Colorado State University has continued side by side daily measurements with both the MMTS and the traditional liquid-in-glass thermometers. This paper presents a 20-year comparison of temperatures measured 4 meters apart. Results show that little has changed in the relationship between MMTS and liquid-in-glass. Despite a yellowing of the MMTS radiation shield over time, the MMTS continues to read cooler during the daylight hours at all times of year. Minimum temperatures show little difference but with a small seasonal cycle in temperature differences. The largest differences continue, as they were first observed in 1985, to occur with low sun angles, clear skies, light winds and fresh snowcover. In addition to quantitative comparisons, some general comments on the impact of MMTS and other electronic temperature measurements on long-term temperature measurements and observed trends will also be offered." So it is consistent with the findings in 2005
  10. Jacob Bock Axelsen at 03:44 AM on 23 January 2010
    The chaos of confusing the concepts
    @Berényi Péter I just browsed through your reference, and I have some rather informal comments. The paper bases its statements solely on power spectral analysis of timeseries data. This gives you resonance frequencies (non-chaos) and characteristic timescales (indicative of chaos). No strange attractors, no direct correlations or actual physical processes. For instance, the paper claims that turbulence is present on millenium scale in less than an order of magnitude in a bounded frequency region. Even for power spectra I would say this is weak evidence. Turbulence in heat transfer over millenia cannot exist within the solar system, which the paper also states. The requirements for turbulent Navier-Stokes dynamics in advection is simply destroyed by viscocity and dissipation. That is also why climate models work well based on average radiation assumptions on the structure of the atmospheric energy budget. The paper claims that the source could be the turbulent galactic electron density field modulating cosmic ray fluxes. However, research indicates that this mechanism is too weak to cause major climate change: http://www.agu.org/pubs/crossref/2009/2009GL037946.shtml http://www.skepticalscience.com/cosmic-rays-and-global-warming.htm The final claim is that CO2 power spectra give indications of chaos during the last 500 million years. Keeping the regularity of ice age cycles in mind, I would personally need more proof to accept more than quasi-linear responses. I hope this was useful.
  11. The IPCC's 2035 prediction about Himalayan glaciers
    As earlier posters have implied, other science based sites (e.g. Deltoid, RealClimate) have also put up articles that add to the background and current status of Himalayan glaciers. Of interest is the 2009 article by Xu et al Black soot and the survival of Tibetan glaciers (open access)."We find evidence that black soot aerosols deposited on Tibetan glaciers have been a significant contributing factor to observed rapid glacier retreat."
  12. On the reliability of the U.S. Surface Temperature Record
    My guess is that it wasn't deniers that instigated the rating process of weather stations but good old climatologist way back. What was the initial justification for this? And Marcus again it wasn't deniers who invented the Urban Heat Island idea. I just put this into Google Scholar search with many limitations and got over 400,000 hits (900,000 without the limitations). As far as I'm aware denier websites don't show in scholar searches.
  13. The chaos of confusing the concepts
    Excellent post, concise and very readable. Thanks!
  14. On the reliability of the U.S. Surface Temperature Record
    Watts writes that "the GISS data isn’t much to be trusted," but he doesn't say why.
  15. On the reliability of the U.S. Surface Temperature Record
    A clear and unambiguous analysis. However, I think it is optimistic to think the outcome of this survey will be presented by Watts or other skeptic bloggers in the way it has been here. If they mention it at all, it will be in a way that shows (if not proves!) somehow or other that the results they were hoping for have indeed been found. Several studies published in SCIENCE a few years ago pretty much demolished the notion of the urban heat island, but since when have such things ever troubled the denialist/skeptic/contrarian campaign? Admittedly, since the field research was organised by their own sympathisers in this occasion, it will be harder to conclude that corrupted scientists and the socialist/liberal/big government conspiracy has rigged the data. But never underestimate the inventiveness of the paranoid mind.
  16. On the reliability of the U.S. Surface Temperature Record
    Oh dear, poor deniers. Another of their imaginary supportive planks falls away beneath them...
  17. IPCC is alarmist
    While I understand the two first pictures, I dont get the last one (figure 4) to make sense. The observed trend starts to diverge from the IPCC models mean at latest in the end of the 1970's - so what were those models based on, pre-1980 data?
  18. Skeptical Science now an iPhone app
    But the fall and rise after volcanos is concomitant with the fall and rise in radiative forcing even though the delta T spike is smaller. A lag would suggest at the very least a slower recovery in delta T. Another example is the period 1910-1940. A relatively modest increase in radiative forcing (compared with present times) yet no apparent lag. In fact the rise of ~0.5oC in delta T occurs alongside the smooth rise (no volcano's) in radiative forcing. 1910-1940 RF increase ~0.5, delta T 0.5oC 1980-2003 RF increase ~2, delta T 0.6-0.7oC The numbers don't seem to add up.
  19. On the reliability of the U.S. Surface Temperature Record
    Oh dear, Watts will not be a happy camper. I wonder how long until we see this as a headline on WUWT? I'm not holding my breath. Point is, after reading about a dozen different articles on the issue, I've known all along that the so-called Urban Heat Island effect was nothing more than an Urban Legend!
  20. The IPCC's 2035 prediction about Himalayan glaciers
    Charlie A, it's a typo, the starting year is 1947 not 1847.
  21. The chaos of confusing the concepts
    Berényi Péter writes: "This is not so. Weather/climate is chaotic on all time scales." Hmmmm. Are you suggesting we can't make long-term predictions of trends in temperature, precipitation, etc.? Because where I am now (New England, USA) it's currently -16 C. I am highly confident that six months from now, the outside temperature will be in the +20 to +30 C range here. I can make that prediction confidently because although the day-to-day weather is chaotic and unpredictable, there is a physical process ("the seasons") superimposed on that short-term variability. Likewise, with climate change, we know that increasing CO2, CH4, N2O, CFCs, etc. in the atmosphere will superimpose a warming trend on the global climate. We can't predict the details of the weather on a specific date in 2050 (any more than we can predict them for a given day in New England this summer), but we can predict that on average the climate will be warmer.
  22. The chaos of confusing the concepts
    I'm not sure if it applies, but I thought of one analogy reflecting the phenomenon that climate on its scale is more predictable than weather. Consider the position at time 0 of a specific N2 molecule in a closed room filled with air, vs the temperature at time 0 in the same room. After one hour, it would be much easier to predict the temperature in the room than it would be to predict the position of the molecule. I assume that from a physics point of view one could argue that the two phenomena described is essentially the same, but on different scales, which you may also say about weather and climate. However my academic background is far from both physics and meterology so I'm not sure that my analogy is a particularily good one.
  23. Berényi Péter at 20:48 PM on 22 January 2010
    The chaos of confusing the concepts
    This is not so. Weather/climate is chaotic on all time scales. Chaotic climate response to long-term solar forcing variability A. Bershadskii 2009 EPL 88 60004 (5pp) doi: 10.1209/0295-5075/88/60004 http://www.iop.org/EJ/abstract/0295-5075/88/6/60004 A slightly earlier (6 Jul 2009 19:10:25 GMT) version of the same paper can be found at arXiv.org http://arxiv.org/abs/0903.2795
  24. The IPCC's 2035 prediction about Himalayan glaciers
    Perhaps someone can explain something else in Section 10.6.2: The Himalayan glaciers of the IPCC Fourth Assessment Report: How is the second line of table 10.9 calculated? http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch10s10-6-2.html Pindari Glacier; 2840 meters of retreat from 1845 to 1966; average retreat 135.2 meters/year. I calculate an average 23.5 meters per year, which more closely matches some other reports of 27 meters/year from 1847 to 1906, slowing to 20 meters per year from 1906 to 1958; with a further slowing to about 10 meters per year since 1966. My e-mails to IPCC go unanswered. Perhaps other readers of this blog can explain the 135.2 meter/year average retreat number for Pindari Glacier.
  25. The chaos of confusing the concepts
    Amazing post!! I remember reading about this in the book "Chaos" by James Gleick years ago and playing around myself with the bundled software doing fractals and strange attractors. You can download the shareware version of it here and source code too. http://www.cs.sjsu.edu/~rucker/chaos.htm From memory...I also remember reading that Lorentz discovered it by accident (like all great science) when he was in a rush or there was a power cut and he had to start his weather model with less decimal points in it and was very surprised by the print out the next day.
  26. Skeptical Science now an iPhone app
    A slight of hand appears to occur in the Hansen paper. Total net forcing 1880-2003 = 1.85Wm-1 delta T 1880-2003 = 0.6oC but 1Wm-1 should give delta T of 0.6oC so where is the delta T from the remain 0.85wm-1 of net radiative forcing? Oh yeah it's "in the pipeline". Three words can dismiss the fact that close to half the delta T is so far unaccounted for. I guess there is a suggestion of a lag here but no attempt to justify it. In fact when you look at the cooling caused by volcano's and the subsequent recovery after aerosols are removed there appears to be no lag in delta T to radiative forcing.
    Response: Actually, volcanic eruptions are a good example of climate lag and how "warming in the pipeline" works. Note the comparison between radiative forcing and global temperature over the 20th Century:



    The big downward spikes in net forcing are due to volcanic eruptions. Why doesn't temperature fall the same amount? Because of the great thermal inertia of the oceans. What happens is a volcano erupts, throwing up sulfate aerosols into the atmosphere. This immediately creates an energy imbalance - suddenly less sunlight is getting in. So the planet starts to cool.

    Note - the atmosphere responds relatively quickly. But it takes time for the oceans to cool - this is what you would call "cooling in the pipeline". However, and fortunately for us, the aerosols wash out of the atmosphere within a few years and the energy imbalance bounces back to what it was before. But if for some reason, the aerosols stayed in the atmosphere, what we would observe is the planet cooling over a few decades until the climate reached equilbrium.
  27. The chaos of confusing the concepts
    Excellent post! Thanks!
  28. Jacob Bock Axelsen at 11:22 AM on 22 January 2010
    The chaos of confusing the concepts
    @Riccardo Thanks for your positive comment. The picture is just artwork - or an example, as you put it. The weather attractor would be huge on this scale, so I scaled it down to match the fluctuations instead. I hope you still like it.
  29. Could CFCs be causing global warming?
    I currently am not able to access my institution's library, so I can't go through the paywall to read Lu's paper. I'm curious though to know exactly what technique he employed that permitted him to establish that "correlation between global temperature and CFCs is evidence that CFCs have been the dominant driver of climate over the past century". When I look at the first graph, I see a 20th century warming trend that commences before the increase in EESC, and I see a period of (aerosol attributed) cooling kicking in at the time that EESC does begin to rise. This would seem to indicate that for a decade or so either side of the point where EESC begins to increase, there is no relationship with temperature at all. Any 'correlation' seems to occur after 1960, or even later, and given the vast number of human-produced substances that would demonstrate a similar trend, I would suggest that the correlation is a completely spurious one. At first blush, and given the poor relationship implied by the graph, it's certainly no evidence of a (partial, at best) correlation indicating causation. If this truly is Lu's claim, it should have been weeded out during review.
  30. The IPCC's 2035 prediction about Himalayan glaciers
    I am a touch puzzled by the confident assertion that warming may equal increased precipiation which may equal in some cases increased glacier growth. I seem to recall that precipitation may cause at least local warming as water vapor when it turns to liquid water or ice releases latent thermal energy. I'm happy to be subject to correction on this score. Anyway, I will check out the suggested online sources with interest.
  31. The chaos of confusing the concepts
    That's a good question, Riccardo. At first, I thought it was just an illustrative example, but a growth in the Lorenz attractor might represent larger chaotic variation in weather (i.e. more weather extremes). Obviously, whether this occurs or not is an important question when discussing the effects of long-term shifts in climate averages.
  32. The chaos of confusing the concepts
    Excellent. Clear, concise and easy enough for averyone to understand. One question, the growth of the Lorenz attractor in the last picture is an observed feature or is just an example?
  33. The chaos of confusing the concepts
    Dr. Spencer Weart's "The Discovery of Global Warming" has a truly excellent chapter devoted to the foundations and evolution of climate modeling, particularly general circulation models: http://www.aip.org/history/climate/GCM.htm Note to doubters, skeptics, etc: Even if you're not prepared to join the mainstream, Weart's book covers this topic warts and all. If you're looking for weaknesses, you need to read it. Don't take on faith what you can pull from a primary source.
  34. The IPCC's 2035 prediction about Himalayan glaciers
    WeatherRusty at 01:53 AM on 22 January, 2010 Alexandre, You may be interested in this online "textbook" which provides a very good synoptic overview of climate science. It covers most areas of interest in a factual, unbiased way. Also be sure to view Weart's book, also online: http://www.aip.org/history
  35. The IPCC's 2035 prediction about Himalayan glaciers
    Yesterday, the IPCC released an apology and reaffirmed that the conclusions reported in the Synthesis Report are robust:
    Climate change is expected to exacerbate current stresses on water resources from population growth and economic and land-use change, including urbanisation. On a regional scale, mountain snow pack, glaciers and small ice caps play a crucial role in freshwater availability. Widespread mass losses from glaciers and reductions in snow cover over recent decades are projected to accelerate throughout the 21st century, reducing water availability, hydropower potential, and changing seasonality of flows in regions supplied by meltwater from major mountain ranges (e.g. Hindu-Kush, Himalaya, Andes), where more than one-sixth of the world population currently lives. This conclusion is robust, appropriate, and entirely consistent with the underlying science and the broader IPCC assessment.
    *I find the apology a bit indulgent anyway, and I hope that they add a corrigendum to the text soon.
  36. Berényi Péter at 06:02 AM on 22 January 2010
    The IPCC's 2035 prediction about Himalayan glaciers
    IPCC still has it on its website with no footnote, comment or whatever. IPCC Fourth Assessment Report: Climate Change 2007 Climate Change 2007: Working Group II: Impacts, Adaption and Vulnerability 10.6.2 The Himalayan glaciers http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch10s10-6-2.html
  37. Skeptical Science now an iPhone app
    Are they so different, HR? The Hansen et al analysis (see pdf in my post #15; it's the same data that John uses in his response in post #8) gives a solar contribution that is around 8% of the greenhouse forcing. Damon's 1999 analysis yields 15% (contribution of solar cycle length to total warming) through the 20th century (up to 1997). These values are not that different, and a number of analyses using up to date estimation of the change of solar irradiance, puts the solar contribution around 10%...these all seem to be reasonably self-consistent. One has to be careful with Damon's analysis. He wasn't particularly determining the solar contribution to warming. He was really addressing an analysis of Friis-Christensen and Lassen which purported to show that apparent correlations between solar cycle length and climate indicated that the solar contribution was 100%. Damon was pointing out that the F-C/L analysis wasn't done correctly and if it were, the solar cycle contribution would be 15% through 1997. However there isn't much evidence I think that the solar cycle length is a very good proxy for solar output, and there isn't a good theoretical basis for this relationship; far better to use a well-characterized analysis of solar irradiance, either by direct measurement, or by analysis of the solar cycle/sunspot measure for periods before direct monitoring of irradiance.
  38. The IPCC's 2035 prediction about Himalayan glaciers
    #11 danielbacon, I'm not 100% sure, but it seems to have been Prof Graham Cogley (Trent University, Ontario), who has also sent a letter (with Kargel, Kaser and Van derVeen) to Science. The first public comment seems to be the one by Madhav L. Khandekar (introduced as "research scientist from Environment Canada and is an expert reviewer for the IPCC 2007 Climate Change Documents") in a guest post on Roger Pielke Sr.'s blog on December 1st. But he credits the relevant statement to Graham Cogley.
  39. The hockey stick divergence problem
    He, Michael Mann says there is no divergence problem: http://www.realclimate.org/index.php/archives/2007/05/the-weirdest-millennium/#comment-34017
  40. The hockey stick divergence problem
    @lord_sidcup: No, quite the opposite. McIntyre was aware of the divergence problem. Actually he has a commented on ipcc 2007: "Show the Briffa et al reconstruction through to its end; don’t stop in 1960. Then comment and deal with the “divergence problem” if you need to. Don’t cover up the divergence by truncating this graphic. This was done in IPCC TAR; this was misleading. (Reviewer’s comment ID #: 309-18)" It was rejected: "Rejected – though note ‘divergence’ issue will be discussed, still considered inappropriate to show recent section of Briffa et al. series." Can anyone explain me, why it is 'still considered inappropriate ' to show a graphic in a honest way?
  41. Skeptical Science now an iPhone app
    Just to add more to your list Chris. From the diagram posted by John in response to post #8, GISS seem to give solar almost 0 net change in radiative forcing over the whole of the century. Suggesting solar has had almost no net effect on global warming for the whole of the 20th century. John's Damon 1999 paper suggest 25% in 1980 and 15% in 1997. These are surely mutually exclusive.
  42. The IPCC's 2035 prediction about Himalayan glaciers
    Alexandre, You may be interested in this online "textbook" which provides a very good synoptic overview of climate science. It covers most areas of interest in a factual, unbiased way. SEE: http://stratus.astr.ucl.ac.be/textbook/index.html
  43. The IPCC's 2035 prediction about Himalayan glaciers
    "The mistakes were found not by skeptics like Michaels, but by a few of the scientists themselves, including one who is an IPCC co-author." http://news.yahoo.com/s/ap/20100121/ap_on_sc/sci_un_climate_change... So any one know who found it and when?
  44. 2009 - 2nd hottest year on record while sun is coolest in a century
    John I've been working on showing current TSI data. I have added a widget to my blog to show NASA's SORCE TSI data. University of Colorado - Bolder posts the data about 1 week after readings. Here's a link to my most recent TSI image, using SORCE daily readings
    Response: Thanks Kelly, that's a great resource. It's interesting to see the upturn of TSI in recent months as the next solar cycle begins - the PMOD TSI data stops halfway through 2009 so its good to have more recent data.
  45. Skeptical Science now an iPhone app
    re #12,13 Yes, the solar scientists that analyze solar output in detail have determined that solar contributions to 20th century warming are rather small overall. Several recent analyses indicate a solar contribution to total 20th century warming of the order of 10%, with none of this in the period of late 20th century and contemporary warming [*]. So solar contributions made a small contribution to early-mid 20th century warming. A significant proportion of the warming in the period to the mid 20th century warming was likely the recovery from very high volcanic activity in the late 19th, early 20th century [*;** ; ***]. There was obviously a contribution from anthropogenic greenhouse gases [*; **; ***; ****], and perhaps a small contribution from ocean circulation effects [****]. Obviously the attribution of 20th century warming requires an assessment and incorporation of all of these contributions as is done in the papers below marked [*] and [***]. [*] C. M. Ammann et al. (2007) Solar influence on climate during the past millennium: Results from transient simulations with the NCAR Climate System Model Proc. Natl. Acad. Sci. USA 104, 3713-3718 http://www.pnas.org/content/104/10/3713.abstract Lean, J. L., and D. H. Rind (2008), How natural and anthropogenic influences alter global and regional surface temperatures: 1889 to 2006 Geophys. Res. Lett., 35, L18701 http://www.atmosp.physics.utoronto.ca/~jclub/journalclub_files/LeanGRL2008.pdf R.E. Benestad and G. A. Schmidt (2009) Solar trends and global warming J. Geophys. Res. 114, D14101 http://europa.agu.org:8005/?view=article&uri=/journals/jd/jd0914/2008JD011639/2008JD011639.xml&t=2009,Benestad [**] Mann M.E. (2007) Climate over the past two millennia Annu. Rev. Earth Planet. Sci. 35, 111-136 http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.earth.35.031306.140042 [***] Hansen, J. et al. (2005) Earth’s Energy Imbalance: Confirmation and Implications Science 308, 1431-1435 http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf [****] Swanson K.L. et. al. (2009) Long-term natural variability and 20th century climate change Proc. Natl. Acad. Sci. USA 106, 16120-16123 http://www.pnas.org/content/106/38/16120.abstract?sid=a5bc499d-5e20-48cc-97ae-8e54afbebb8e
  46. Skeptical Science now an iPhone app
    "Response: When the sun is showing a long term warming trend, the solar cycle tends to get faster. Conversely, when the sun is cooling, the solar cycle slows. This is why the solar cycle 24 is taking so long to get started at the moment - because the sun is cooling at the moment. Why this is so, I leave as an exercise for the reader :-)" Isn't wrong to describe the sun as cooling or warming? We are surely dealing with surface immittance and not total energy content by unit.
  47. Berényi Péter at 00:43 AM on 22 January 2010
    Skeptical Science now an iPhone app
    Riccardo, working on a problem for decades is not the same as getting the easy (and most important) part of the job done ASAP. I am not even talking about a full scale reanalysis as it is undersood in "climate science" circles (the one involving extensive statistical data kneading), but straightforward correction for known and deterministic instrumental biases. I am not implying it would be a low budget operation. But it is easy indeed as a scientific endeavor. One does not have to bother with hypothetic climate/atmospheric models and the like, just simple instruments and raw data. Proper collection of metadata, reconstruction of devices and testing their response to varying pressure, temperature, moisture and radiation histories costs money, but does not require much ingenuity. Just plain old honest work. I am surprised beyond imagination that this issue is not pushed much more forcefully. In fact it seems no one has got grant money to do it. Of course there is a danger the results could turn out "supporting lower climate sensitivity than the standard IPCC range". Come to think of it, could be rather difficult to get a grant for this purpose with opinionated referees around. Considering it is THE experimentum crucis for the present climate modelling paradigm, everyone involved should welcome such an opportunity, not suppress it. Just imagine Albert Einstein trying to prevent Sir Arthur Stanley Eddington to get to Príncipe in time to capture full eclipse by "saying people are working on eclipses for millenia, so why the rush". No one doubts the lower troposphere is getting wetter nor older instruments tending to have a longer relaxation time at low temperatures. But I would not bet on correcting for relaxation time bias could charm away the decreasing specific humidity trend measured by radiosondes up there, for this trend is also observable at the 700 hPa level, where all instruments behave reasonably well, even the ancient ones. Also, the ongoing loss of high altitude glacier mass is more consistent with decreasing relative humidity at that level than with a constant one.
  48. Skeptical Science now an iPhone app
    Yet the radiative forcing graph in your response to post #8 would suggest that GISS think solar has remained almost unchanged in it effect for the whole of the century. All the quote from the paapers you mention, including Lassen 1999, suggest solar can only be ruled out for the most recent warming period.
  49. The IPCC's 2035 prediction about Himalayan glaciers
    Thanks for the great post, John. The paragraph with the moral of this story summarizes well my own view, too. I'd like to place a suggestion. It's off-topic, but I don't know where else I should send it. I know a few good websites (like this one) dedicated to debunk "skeptical" claims. I've been questioning this approach, though. I think it is much more compelling and instructive to explain the existing science behind AGW then to respond to denialist (mostly) nonsense. People can learn, then, how robust the mainstream consensus is and THEN compare it with the feeble contrarian reasoning. I find it much more constructive. Would it be feasible/interesting to add a section like this here? Could anyone point me a website with this approach?
  50. Skeptical Science now an iPhone app
    Given the good correlation upto 1975 do we conclude that solar was the dominant factor controlling change in global temp for the first 3/4 of the century?

Prev  2497  2498  2499  2500  2501  2502  2503  2504  2505  2506  2507  2508  2509  2510  2511  2512  Next


The Consensus Project Website

THE ESCALATOR

(free to republish)


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