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Comments 111101 to 111150:

  1. Arkadiusz Semczyszak at 23:12 PM on 2 September 2010
    Urban Heat Islands: serious problem or holiday destination for skeptics?
    I complete only Berényi Péter It is worth to make such a comparison for Africa. He soon joins the population - in particular cities - escape from poverty (shockingly fast - as fast as forests are cut or burn), leading to significant changes in the Earth's albedo and evaporation, the local "dry" glacier - eg Kilimanjaro (Between a logging and fire, Kilimanjaro has lost a third of its forest Since 1929. ) create strong NBL ... - because all this is also UHI ... particularly UI- warm effects. Of course most clearly in Africa.
  2. Sea level rise: the broader picture
    HumanityRules at 02:23 AM on 1 September, 2010 The overall satellite trend offers true global coverage, but it is a relatively short record, though Wenzel 2010b has made an an interesting attempt to bridge the gap between Topex and GEOSAT altimeter data (1986 to 1989). The recently re-processed (corrected) altimeter datasets from Ssalto/Duacs which now includes GDR-C reprocessing for Jason 1 are now available. The overall 17 year trend, which must include GIA corrections if we are to compare with the corrected tidal values, is around 3.3 +/-0.4mm/yr. Peter B and Ken, for the record (once again), Topex/Poseidon runs to Autumn 2005, Jason 1 runs from beginning 2002 to present, Jason 2 runs from half way through 2008. Thus there is overlap which allows correction for (some quite large) offset biases. The real absolute raw offsets make any talk of “offsets” in the accessible data more than a little academic. The trends for Topex/Poseidon, Jason1, and Jason 2 (including GIA) are 3.5mm/yr, 3.0mm/yr, and 3.1mm/yr respectively. Peter Bs figures showing a split between Poseidon and Jason1 data, (and hence the trends and offset) are incorrect. In addition the uncertainties in these separate trends will certainly be greater than the 0.4mm/yr error bars for the overall series. Any suggested decrease in overall trend is therefore not significant from this data. Nevertheless, why might the interannual trends vary over short periods? As Dappledwater has mentioned, ENSO. From Nerem 2010 showing de-trended Global MSL compared to MEI (Multivariate ENSO Index). The correlation of MSL interannual variations with ENSO is significant at the 95% level over the altimeter period. This kind of variation is also observed in the tide gauge records, whose interannual variations follow global and local regional climate patterns. This is why we must take the overall satellite record and use all of the data, rather than chop the record into arbitrary mini-trends. This is why we should if possible look over longer periods than the 17 year satellite record to determine MSL acceleration (which is significant over the tidal record we have). Ken Lambert at 23:33 PM on 30 August, 2010 The GDR-C altimeter re-processing is also relevant because (from Nerem 2010) the “GDR-B bias error in Jason1 was large enough to cause GMSL from GDR-B data to be nearly 1 mm/year too high for the period from July 2003 until June 2007, which partially explains the misclosure of the sea level budget between Jason-1, GRACE, and Argo (Willis et al. 2008; Leuliette and Miller 2009)”. To some extent this answers your point (which quoted values from Sea level budget from Trenberth based on this same 2003 to 2007 data). If this is changed to something like the 1993 to 2007 value for thermal expansion (table 1 Cazanave 2010) the sea level budget appears to close, but I’m sure there will be a paper or two on this pretty soon.
  3. It's the sun
    "more to the point, without citing other people stats or research, what do you think is the cause behind climate fluctuations and why?" If you discount stats and research (ie, science), you're pretty much left with anecdotal data. Why, in this day and age, anyone would think that anecdotal data has any real standing in science amazes me. Looking for science information in the media also seems suspect to me. I'm not a climatologist, but I am a scientist, and the number of times that the media has gotten things wrong in areas I do know about are depressing.
  4. Urban Heat Islands: serious problem or holiday destination for skeptics?
    Let's be completely clear about what's happening here. BP proposed a model whereby there is a UHI-sourced bias in global temperature records. He claimed that this bias was large enough to explain much of the observed warming trend, but this claim was based on the unrealistic assumption of uniform population growth everywhere. I used his own model with actual spatially-distributed population growth data, and found that his model actually estimates a global mean UHI bias of around 3% of the observed warming trend. This took a fair amount of work on my part. Rather than acknowledging that inconvenient fact, BP is moving the goalposts around. I'm disappointed, frankly. This is not conducive to productive discussion.
  5. It's the sun
    my personal unaided view is chopping down the amazon, solar activity and increased agruculture have alot to answer for!
  6. It's the sun
    more to the point, without citing other people stats or research, what do you think is the cause behind climate fluctuations and why?
  7. Urban Heat Islands: serious problem or holiday destination for skeptics?
    Dappledwater, since BP prefers not to provide it, here's a good figure showing global sea surface temperatures. This is from Kelly O'Day: Source code and data are available via the link. Note the unsurprising similarity to the other surface temperature records.
  8. It's the sun
    ps. that was just a small cross section of some of the media reports etc, im not quoting any of them specifically
  9. It's the sun
    http://news.bbc.co.uk/1/hi/8299079.stm http://www.canadafreepress.com/2004/deweese121404.htm http://www.telegraph.co.uk/earth/environment/climatechange/7369339/New-evidence-for-man-made-global-warming.html http://uk.answers.yahoo.com/question/index?qid=20091123115037AAItLGF they are not scientific sources although they do cite them selves as such, however given the massive number of variables at play in the overal arena of 'warming' or 'cooling' whos to say they are any more accurate than anyone elses opinions? im sure next week will be another startling media discovery or discreditation to do with climate anomolies... from where Im sitting with the information presented to me via these forums, the internet as a whole not to mention having lived in many locations around the globe and witnessed first hand from real people discussing the way in which their environments have changed, eg lack of snow on peaks, reservoir depletion and also the opposite too, snow storms, floods etc all of which where loclalised events but none the less at each place I have been to every one seemed to agree that one way or another something is changing percevably with the climate. anyhow, I could fire up a supercomputer and feed lots of stats in and see what the results tell me, but even so, if I miss so much as one variable or miscalculate or use inaccurate results im going to be back at square one with 'im not sure'... however theres a good chance its this...
  10. Sea level rise: the broader picture
    HR#65 Dappledwater #67 Nice summary of the 2003-2007 SLR scene HR. Notice that the only paper which has the steric rise anywhere near the mass rise is Leuliette and Miller (2009) with a 0.8+/-0.8mm for steric and 0.8+/-0.5 for mass. I wonder at the value of a measurement which has error bars equal to the value. If I expressed my height as 1.8m +/-1.8m, you would not know if I were a giant or a midget. If the mass far exceeds the steric, the energy budget shortfall gets rapidly worse. And Dappledwater (DW in short in future): pray tell us if the decent sized La Nina's are sending heat out to space or redistributing heat around in the Earth system (atmosphere, land, ice, oceans)?
  11. Arkadiusz Semczyszak at 22:17 PM on 2 September 2010
    How we know an ice age isn't just around the corner
    “The change from glacial to interglacial occurs over thousands of years.” present interglacial in exactly,(!) three years (a major change; the whole - seven years), probably even the Sahara became the Sahara (with green, thriving savannah to desert - as today) in less than 100 years (movie: Man on Earth). I can present hundreds of works that the former changes were equally dramatic - not just warming. “H” events occurred during the life of one man - the main changes sometimes within one of the winter. Richard Seager (The Gulf Stream, European climate and Abrupt Change, 2009) says: “These abrupt changes - the Dansgaard-Oeschger events of the last ice age and the Younger Dryas cold reversal of the last deglaciation - are well recorded in the Greenland ice core and Europe and involved changes in winter temperature of as much as thirty degrees C!” Changes have always been violent - even those much smaller than the “H” events, because: „In its place we need serious assessments of how changes in ocean circulation will impact climate change and a new look at the problem of abrupt climate change that gives the tropical climate system and the atmosphere their due as the primary drivers of regional climates around the world.” (Seager, 2009.) Again, the tropics ... I think that the AMOC - “two-pole swing” - it's just delayed in time - delayed warming in the SH to NH - as the globally is warmer - is less. And after a period of warming to the 2030s, waiting for us again but slightly weaker LIA ...
  12. Climate change: Water vapor makes for a wet argument
    TOP #7, the fact that the IR absorption bands of water vapor largely overlap those of CO2 and methane does NOT prevent those gases from causing warming in those IR bands. That argument was first made by Angstrom in 1900 (who also thought water vapor overlapped entirely because instruments of the time lacked sufficient resolution). However, it has since been proven false; Water vapor is generally not found in the high atmosphere (see the discussion about jet contrails above for an exception). However, carbon dioxide and methane ARE. Which means that IR photons which manage to get through the 'water vapor layer' then get absorbed and re-emitted by CO2 and methane higher up. Without the CO2 and methane they'd all have escaped to space immediately once past the water vapor... with these other GHGs they get bounced around in the atmosphere more and this delay in radiating to space means more warming. So no, rising temperatures do NOT lead to decreased IR absorption by CO2. The 'band overlap' argument is simply false... though a reasonable mistake a hundred years ago.
  13. Urban Heat Islands: serious problem or holiday destination for skeptics?
    BP, got a plot of the global sea surface temperatures?.
  14. The surprising result when you compare bad weather stations to good stations
    Omnologos @ 54 - "Why? Because the evidence of the warming trend is for the time being only (as a matter of course) in the well-sited stations" And the "bad/naughty" stations too. Omnologos -"This can't be taken as evidence of a warming trend. It's an hypothesis, however well rooted, not a conclusion. And the alternative, however badly in need of extraordinary evidence, still can't be taken as "disproven" See I was right, Reductio ad absurdum "A common species of reductio ad absurdum is proof by contradiction (also called indirect proof) where a proposition is proven true by proving that it is impossible for it to be false."
  15. The empirical evidence that humans are causing global warming
    I recently attended a seminar where the presenter stated that overwhelming proof exists for industrial humans contributing to the increase of atmospheric CO2. One proof was based upon atmospheric ratios of C12, C13 and C14. Recall that all living systems incorporate C14 into their tissues, and that C14 has a half-life of 5,730 years, and that fossil fuels are so old that they contain virtually zero C14. This means that burning massive amounts of fossil fuels will result in much lower C14 in the atmosphere than the amount placed there by current/recent living processes (which also includes other stuff like burning wood, slash and burn farming practices, etc.) Apparently economic records exist for all fossil fuels sold since 1960 (on a country-by-country basis). These records can be used to compare fossil burning against the carbon isotope ratio for the same time period. Scientists can see the resultant dilution of C14.
  16. It's the sun
    sun tzu, stick to the science and the peer-reviewed literature, rather than opinion on blogs. There is plenty of information on this site : Start Here There is also plenty of information (and many sources) here : IPCC Summary for Policymakers Why aren't you more forthcoming as to the sources of your information ? Provide a few examples of where contrary information is being given that you believe is as believable as any of the information you find on this site.
  17. Arkadiusz Semczyszak at 21:02 PM on 2 September 2010
    Climate change: Water vapor makes for a wet argument
    FF - RF should be, very sorry ...
  18. Arkadiusz Semczyszak at 20:54 PM on 2 September 2010
    Climate change: Water vapor makes for a wet argument
    Water vapor - albedo - temperature ... Present here we see that it changes inversely as the temperature. Clouds - questioned the measurements on ISCCP high clouds, but low clouds affect the albedo (high thin clouds increase the FF - is a positive feedback to CO2) - are changing just like albedos. Overall, the circa to 2000 yr . decreasing cloud cover - now slightly increases - the opposite as the temperature. Professor Ole Humulum writes: “Within the still short period of satellite cloud cover observations, the total global cloud cover reached a maximum of about 69 percent in 1987 and a minimum of about 64 percent in 2000 (see diagram above), a decrease of about 5 percent. This decrease roughly corresponds to a radiative net change of about 0.9 W/m2 [!!!] within a period of only 13 years, which may be compared with the total net change from 1750 to 2006 of 1.6 W/m2 of all climatic drivers as estimated in the IPCC 2007 report, including release of greenhouse gasses from the burning of fossil fuels. These observations leave little doubt that cloud cover variations may have a profound effect on global climate and meteorology on almost any time scale considered.” Where is the most water vapor - trapped energy ? In the tropics - which coincides with decreasing cloud cover in the tropics. Of course, I do not say that it is responsible for the cosmic radiation - according to me is of little importance, but I add the most important: the three explosions, "sulfur" volcanoes that destroyed the ozone and limited the tropical algae - cloud condensation nuclei, decrease of water vapor in the stratosphere and ... ... summed up this (depending on - now in superposition - solar cycles) factors together ...
  19. It's the sun
    suntzu, you could start with WIKIPEDIA, which will give you all the available sources of temperature readings, where you will see how all of them agree on an upward trend : Instrumental temperature record Why not look further from there, or from another thread on this site : Are surface temperature records reliable? There are three versions to look at in the above, depending on how much detail you are looking for. You still haven't said where you got your information concerning the "mild period of cooling over the last couple of years". Can you reveal all, to me or Jim...
  20. Sea level rise: the broader picture
    HR @ 66 - Oh I see, just confusing the way I phrased it. The whole paste is from Leuliette & Miller. However, I see you've also mixed up @ 65. Willis & Chang don't appear to have the same numbers at all, assuming your paste is correct. As far as the sea level budget, nope doesn't seem to be resolved quite yet, but clearly there was a slow down in sea level rise from 2003 - 2007, driven largely by ENSO. If you have a look at Cazenave 2010 Contemporary Sea Level Rise figure 2 (the satellite altimetry record 1993 to 2008) the dip in sea level rise around 2007/2008 is very evident & coincides with a couple of decent sized La Nina's. For the satellite era Cazenave finds: "Accounting for the small correction of −0.3 mm year−1 due to global deformation of ocean basins in response to GIA (Peltier 2009), we thus get a rate of global mean sea level rise of 3.4 ± 0.4 mm year−1 over 1993–2008."
  21. It's the sun
    just for the record I am not denying or admitting that I consider global warming or regional warming/cooling (altering the global statistics) to be occuring, The question is how much of it is man made? how much of it is a natural cycle, and if either is the case is one accelerating the other? and does nature have a counter balance? however for every argument I have read there are an equal number of counter arguments which usually end up in slanging matches with lots of opposing data being thrown around. It occurs to me that there are far too many motives both commercially, governmental, or in terms of attention seeking scare mongering in order to secure funding and the whole subject of research into climate change is completely polluted with its own hot air. Basically from what I have read between it all is CO2 and other gasses are being released at a greater rate than at any other time in recorded history and the averages of global temperature over a given period show a relatively rapid increase in warming. The bit that gets me is that every time I try to find out atmospheric concentrations of CO2 or global average temperatures (its a starting point, some places seem get colder others hotter seasonally) im confronted by a whole array of wildly differing information! the overal summary as a layman is 'we jsut dont know the answer to why the place is getting warmer but its highly likely to be related to the increase in certain atmospheric gasses as a result of mans activity, however not every one agrees on this!' I might be wrong or right and I am not a scientist, but from someone trying to casually research the subject I find that I am continually going around in circles with out any clear answers!
  22. Berényi Péter at 20:41 PM on 2 September 2010
    Urban Heat Islands: serious problem or holiday destination for skeptics?
    #8 Ned at 04:13 AM on 1 September, 2010 Are [...] sea-surface temperature trends also affected by UHI? It seems improbable given the lack of pavement in the middle of the Pacific Of course they are not. Therefore where it is measured properly, in spite of the large excursions there is no trend whatsoever in ocean temperatures during the last three decades (probably due to the noticeable lack of pavement there).
  23. It's the sun
    Actually, got another question, Jim asked where did I get my data from which lead me to ask, where does everyone else get their data from? is there an unbiased neutral source of climate data available with reference to Earths average temperature? Ive had a good look around the internet (must be accurate!) and theres alot of conflicting information out there all cited by 'credible' sources!
  24. It's the sun
    thanks Jim, its more looking for answers to some personal observations (theres so much conflicting information on temperature statistics and other environmental information its difficult to choose which ones are genuine and statistically stable or otherwise!)and I do not profess to be an expert at all.. I'll have a read of those threads Thanks again
  25. It's the sun
    sun tzu wrote : "...we have been undergoing a mild period of cooling over the last couple of years..." Have we ? Having seen this year so far break most global temperature records, it would be interesting to see how you came up with that particular statement. Where did you get it from ? Or is it something you worked out yourself ? If so, what information did you use ? Here are some other threads on this site, to do with other matters you have included in your post : Mars is not warming globally Land use CO2 coming from the ocean CO2 is the main driver of climate change It's the sun Climategate 'conspiracy'
  26. The surprising result when you compare bad weather stations to good stations
    @KR - I am making no extraordinary claim at all. All I am saying is that we should make explicit a logical assumption behind all of this reasoning about trends observed in "well sited" and "poorly sited" US stations. The logical _assumption_ is that the similarity in trends means there is an actual warming pattern that is independent from the quality of the siting. This can't be taken as _evidence_ of a warming trend. It's an hypothesis, however well rooted, not a conclusion. And the alternative, however badly in need of extraordinary evidence, still can't be taken as "disproven". Why? Because the _evidence_ of the warming trend is for the time being only (as a matter of course) in the well-sited stations, until somebody proves exactly why warming trends are independent from the quality of the siting. In fact, Menne et al's results are counterintuitive (="surprising", according to Meador). This doesn't mean they are wrong. It means (Menne's suggestion) there is something there to investigate, rather than be dismissed out of hand as "precision vs accuracy" or whatever else we can think of in a blog's comments section. I believe in this respect that I am the one perfectly in line with Menne's and Jim Meador's reasoning. This is a great opportunity to further our scientific knowledge in the topic and should be welcomed rather than swept under the carpet just in case "deniers" would make any use of it. No paleontologist would hide a "surprising" finding out of fear creationists might take it as evidence there is something wrong with evolution theory. Why should it be any different in climate stuff, I really do not understand. BTW I am not making any claim about any other surface temperature record. This blog entry is about the "suprising results" as per Menne et al 2010. Let's stick to those please. And let's not forget that even if the US stations would show falling temperatures, that wouldn't necessarily disprove warming either.
  27. Carbon dioxide equivalents
    Daniel Bailey #14 In reference to trees not helping global warming... you point to links in statement... "See here and here for a nice discussion." I went there and read these. I think I understood the reasons explained as to why trees in northern latitudes may not help global warming, but this argument does not appear to make a distinction between conifers and deciduous trees. At least, I did not see this. I know near to nothing on this subject, but can only imagine that the mass of all those leaves that pile up in autumn come from CO2 taken directly out of the air. And as far as how deciduous trees affect albedo, after loosing their "canopy", they would therefore tend to shade snow less in the winter than conifers that do not shed as much. So it would seem that the planting of deciduous trees is good for the environment. The leaves are good for soil mulch, and many of these types of trees even provide food. All of which seems like a win win to me.
  28. It's the sun
    Another thought in a devils advocate kind of way is perhaps there are just too many people? is there a correlation between warming and population both in the more technologically advanced/dependent societies and some of the less industrialised nations? could sewerage/carbon cycling of crops be a major factor? eg. biomass stores co2 and would traditionally store it, however its now being consumed with some of the co2/methane being released prematurely? could crops also affect the heat absorbing properties of the earths surface?..anyhow.. the questions are endless lol..
  29. It's the sun
    Thanks for the reply, actually the above question stemmed from reading a book by Sir Patrick Moore called 'Astronomy' where he briefly covered solar activity and the effects on the thermosphere (I am currently starting to study Astronomy and astrophysics as a past time and found it to be a great starting point!). The reason I considered the atmospheric effect is we have been undergoing a mild period of cooling over the last couple of years whilst the upper atmospheric altitude is apparently reduced. It occured to me that another effect of this is, if the atmosphere has a smaller diameter then is it logical that the planets solar foot print is also smaller meaning more solar energy just keeps on going through space rather than getting absorbed by atmospheric gasses?.. Another area I dont think I have seen mentioned on here is the question of why are the planet Mars Ice caps also receeding? is this in some way linked to our own warming or is it simply a matter of Mars orbit in realtion to the sun? has anyone been able to reference Martian Polar recession with our own warming cycles in relation to its proximity to the sun?... Im not 100% in favour of 'The sun did it' as there are many many other areas that affect global climate, Deforestation of the rain forests, Methane, CO2 Emissions, Atmospheric particulates, Atomic Testing infact a whole load of variables.. however, it does occur to me that perhaps CO2 is more an effect than a cause? eg CO2 release due to polar ice decay, Deforestation etc... I would hate to describe myself as a 'tree hugger' but from what I can tell perhaps everyone in both camps might be right here increased carbon gasses and solar activity may both have a role to play in global warming, amongst many many other variables!... another thought as well is the icecaps are receeding then doesnt that put alot more cold water at the bottom of the oceans too? and im guessing that might in someway cause for carbon release? Anyhow, looks like i have a few years worth of reading, experimenting and computer modelling to go lol... All I can say is Im half between 'Tax on Co2' being a government attempt to charge more for less resources (charge more for fuel and electricity whilst not having to invest in infrastructure for the ever growing global population,peak oil etc, after all Climategate has done the scientific community no favours at all either way) and a very serious genuine problem that needs to be addressed urgently yet is being cashed in on by unscupulous politicians and glory seeking scare mongerers!..anyhow, thanks for the excellent reply and will get thinking, researching and trying to test some ideas out!
  30. How we know an ice age isn't just around the corner
    It would also appear that the so-called skeptics' belief that last Winter in some parts of the Northern Hemisphere (AKA 'the world' in so-called skeptical speak) was a sign of things to come (i.e. the coming Ice Age), was a little premature : Northern Hemisphere winter snow anomalies: ENSO, NAO and the winter of 2009/10 Winter 2009/10 had anomalously large snowfall in the central parts of the United States and in northwestern Europe. Connections between seasonal snow anomalies and the large scale atmospheric circulation are explored. An El Niño state is associated with positive snowfall anomalies in the southern and central United States and along the eastern seaboard and negative anomalies to the north. A negative NAO causes positive snow anomalies across eastern North America and in northern Europe. It is argued that increased snowfall in the southern U.S. is contributed to by a southward displaced storm track but further north, in the eastern U.S. and northern Europe, positive snow anomalies arise from the cold temperature anomalies of a negative NAO. These relations are used with observed values of NINO3 and the NAO to conclude that the negative NAO and El Niño event were responsible for the northern hemisphere snow anomalies of winter 2009/10.
  31. Climate change: Water vapor makes for a wet argument
    TOP - the point about water vapour is that it is a feedback not a forcing. You dont have a physical process that increase or decrease water vapour content independent of temperature. ANY forcing that increases or decrease surface temperature will be amplified by the feedback of water vapour. With solar and aerosols stable or decreasing, its GHG that is the dominant post-1975 forcing. This isnt hand-waving - its backed by solid measurement of the extra radiation heating the surface matching the theoretical calculation of GHG effect resulting from the observed increases.
  32. How we know an ice age isn't just around the corner
    GC - give me some science to support the "temperatures will drift lower over next decade or so". What will be your position if they dont? And also, the 100 year rate of change is still near order of magnitude higher than rate of change from Milankovich cycle.
  33. Climate change: Water vapor makes for a wet argument
    Yes I did miss the emoticon. I read some of your other posts, in other threads, & realized that (a) denialist you are not & (b) you usually provide some excellent analysis. Consider my comment retracted :)!
  34. Sea level rise: the broader picture
    59.Dappledwater You seem to have mixed up the sources of your quotes but I get your point about regional variation. Figure 7 from Merrifield does suggest that the lack of good data in the southern and tropical oceans prior to 1950 comprises all comparisons of early and late 20th century SLR. It looks like the experts like to compare apples and oranges as well.
  35. Sea level rise: the broader picture
    I've found 4 papers looking at closing the sea-level budget around 2003-2007. The latest is from this year. Basin patterns of global sea level changes for 2004–2007 You-Soon Chang, Anthony J. Rosati, Gabriel A. Vecchi Journal of Marine Systems 80 (2010) 115–124 Chang, like the others, calculate the steric and mass components using ARGO and GRACE and compare it to the total change calculated from altimetry. They handily summarize the 4 published attempts to close the sea-level budget in a table. Chang et al (2010) STERIC −0.11±0.22 MASS 0.70±0.34 TOT 2.67±0.52 Willis et al. (2008) STERIC −0.5±0.5 MASS 0.8±0.8 TOT 3.6±0.8 Leuliette and Miller (2009) STERIC 0.8±0.8 MASS 0.8±0.5 TOT 2.4±1.1(2.7±1.5) Cazenave et al. (2009) STERIC 0.37±0.1 MASS 1.9±0.1 TOT 2.5±0.4 Chang and Willis fail to close the budget and interestingly fail with pretty much the same numbers. Leuliette and Cazenave manage to close the budget but by very different means. Leuliette through an equal contribution from steric and mass. Cazenave primarily (80%) through mass. If we look at all the available estimates there appears to be no real concensus on this issue.
  36. Water vapor is the most powerful greenhouse gas
    daisym, I believe that some types of clouds are understood to have a net cooling effect, and some a net warming effect. The difficulty, I believe, is in figuring out the relative contributions of those types of clouds in any given scenario. Realclimate has a post addressing clouds' role in albedo changes. It has another post on the role of aerosols in triggering cloud formation. And it has another post on the purported role of galactic cosmic rays in triggering clouds.
  37. How we know an ice age isn't just around the corner
    ScaredAmoeba (#12), Your comments make sense although I believe you are judging "Denialists" too harshly. Ned (#13), It may sound odd but I do care about what will be happen long after my demise. I plant trees and work to reduce river pollution in the hope that my children (and yours) will benefit. GFW (#16), You seem to buy David Archer's idea that rising CO2 concentrations will have a more powerful effect than Milankovitch cycles. I hope you are right. How do you explain the glacial periods that occurred when CO2 concentrations were ten times higher than today? scaddenp (#17). I agree that the rate of change is important. However, you cannot assume that the rapid warming that occurred from the 1975 to 1998 will be the norm. Global temperatures have drifted lower over the last decade and are likely to fall for at least another 10 years.
    Response: "How do you explain the glacial periods that occurred when CO2 concentrations were ten times higher than today?"

    The sun was cooler back when CO2 was higher.

    "Global temperatures have drifted lower over the last decade"

    Global temperatures have not drifted lower over the last decade - the planet is still accumulating heat and the hottest 12 months on record are June 2009 to May 2010.

    NASA GISS global temperature - hottest 12 months on record June 2009 to May 2010
  38. Climate change: Water vapor makes for a wet argument
    Re: Marcus Denialist? Moi??? Been accused of many things in my life (never convicted) but never a denialist. Dude, you must've missed the smiley emoticon...see Poe's Law. The Yooper
  39. How we know an ice age isn't just around the corner
    Bern No, these rapid changes where counter hemispherical(as you say, as good as can be ascertained from the paleo reconstructions) And im not just talking about the younger dryas event.. the rise out of glaciation was punctuated with rapid shifts, several degrees a decade. This whole "most rapid warming" is referring to extremely recent geological record... the last 1-2kybp. The early Holocene was not a stable climate.
  40. Climate change: Water vapor makes for a wet argument
    One of the Easy Teasy Lemon Squeezy sources says: It is currently not clear how much of the correlation between air traffic and cirrus cloudiness is actually due to a causal relationship. Hence the determination of the radiative forcing of contrail cirrus is fraught with large uncertainties; studies to resolve the differences and to constrain the error margins are certainly needed. All studies suggest that air traffic actually induces additional cirrus clouds, which seems plausible. However it is extremely difficult to demonstrate and prove such a correlation because the variation of cirrus cloudiness due to natural influences is much larger than the possible aviation effect. Hence, to look for the latter is like looking for a signal hidden in strong noise. This particular article is primarily concerned with parameters for models. Another one attributes a 1.2C increase in Tmax and a .3C increase in Tmin in areas with high contrail concentrations. This study used the paucity of civilian air traffic during 9/11 - 9/14/2001 to obtain temperature sensitivity to contrails. One of the factors that had to be corrected for was that the CONUS was essentially cloud free during that period.
  41. Climate change: Water vapor makes for a wet argument
    No Joe Blog, the estimates I gave are based on the reports of J. T. Kiehl & Kevin E. Trenberth in "Earth’s Annual Global Mean Energy Budget"-from the "Bulletin of the American Meteorological Society 78 (2): 197–208." The point remains the same though, which is that on a ppmv basis CO2 is a significantly more powerful GHG than Water vapor, by at least 3:1. @ Daniel Bailey #6. Seriously, this kind of childish post might be acceptable for your fellow Denialists, but it really does nothing at all to advance anyone's understanding when you put up posts that are devoid of any intelligent analysis (like the fact that Ice & Snow don't *cause* Ice Ages, but are a symptom of Ice Ages caused by significantly reduced insolation.)
  42. Climate change: Water vapor makes for a wet argument
    This is a straw argument. Both water vapor and CO2 absorb IR radiation. Water vapor is a broad spectrum absorber with a large gap in absorption at IR wavelengths that effect the temperature regulation of the planet's atmosphere. CO2 is a notch absorber that overlaps and somewhat extends into the lower end (higher wavelength end) of the gap in water vapor's absorption. As the temperature of the atmosphere increases so the wavelength of the IR carrying heat by radiation shortens and moves away from the wavelength that CO2 absorbs and into the center of the gap in the water vapor absorption band allowing more IR energy to escape. The higher the temperature of the atmosphere, the less the effect of CO2. Of course it will be pretty toasty when that day comes. Anybody that has looked at the absorption of CO2 and methane overlaid on that of H2O would know this. Secondly H2O has another nice property. When it absorbs IR it causes the air in which it exists to rise with it. When the lapse rate causes the water vapor to condense the heat is released to continue traveling up while the air below is cooled. CO2 doesn't have this nice phase change under normal atmospheric conditions. But it goes along for the ride anyway. Water vapor is the most powerful greenhouse gas. That statement doesn't imply anything about the importance of CO2. CO2 is also a greenhouse gas. Speaking about CO2 out of the context of it's relation to the water vapor can be and is misleading.
  43. How we know an ice age isn't just around the corner
    Joe Blog - as I understand it that high-rate temperature change was strictly a localised phenomenon - one of the candidates for cause is the release of meltwater from behind the ice sheet over North America, interrupting the flow of warm water to Europe. While this would have caused a dramatic drop in temperatures in Europe, it probably would have led to even *warmer* temperatures further south - after all, if that equatorial heat isn't ending up at northern Europe, it's gotta go somewhere! I imagine a good global reconstruction for that time period would show this effect quite well, while also showing that the global average temperature continued to change at a relatively slow rate.
  44. Climate change: Water vapor makes for a wet argument
    Yes, Virginia, water vapor IS a GHG, regardless of altitude. Except for the white lumpy kind that collects & causes ice ages. :) The Yooper
  45. Climate change: Water vapor makes for a wet argument
    Marcus, i believe the figures you are using are derived by subtracting the persistent gases effect in isolation from the total 33k effect... but then water vapor should still be around the 65% mark... but in reality is more inline with about 80% i believe on "average". But if you stripped all the water vapor out of the atmosphere the temp doesn't drop by 26.4k, but more by around the 65%-70% mark (21.45k-23.1k) There is a good thread on it at real climate. And yes mattj, i too have been learning about the non linear response o water vapor over at science o doom. A not so simple Q with water vapor... even taken in isolation(ignoring possible albedo effects)
  46. Climate change: Water vapor makes for a wet argument
    Re: MattJ
    Vapour trails or contrails, by affecting the Earth's radiation balance, act as a radiative forcing. Studies have found that vapour trails or contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). Therefore, the overall net effect of contrails is positive, i.e. a warming. However, the effect varies daily and annually, and overall the magnitude of the forcing is not well known: globally (for 1992 air traffic conditions), values range from 3.5 mW/m² to 17 mW/m². Other studies have determined that night flights are mostly responsible for the warming effect: while accounting for only 25% of daily air traffic, they contribute 60 to 80% of contrail radiative forcing. Similarly, winter flights account for only 22% of annual air traffic, but contribute half of the annual mean radiative forcing.
    Easy Teasy Lemon Squeezy Source Higher humidity at lower elevations means that the water vapor in the exhaust is released below the saturation point of the air, thus no condensation/crystalization of the vapor & no contrail. The Yooper
  47. Water vapor is the most powerful greenhouse gas
    #94: Interesting! Now imagine that a decrease in water vapor in the atmosphere would cause fewer clouds to form. As a result, the Sun can warm the surface more than when clouds got in the way, which puts more water vapor back into the atmosphere to form clouds. Imagine a planet with no cloud cover. What would the surface temp be? If the answer is "hot", then clouds could rightly be said to have a cooling effect. If not, then the opposite would be the case. Which is it? Clouds have often been said to be where the biggest disagreement remains. Is the net effect of clouds to a positive or a negative feedback? I'm not aware that this has been settled.
  48. Climate change: Water vapor makes for a wet argument
    Here's the thing, though. Water vapor accounts for just over 50% of the total Greenhouse effect-on average (it obviously varies according to temporal & geographic factors). Wheras CO2 accounts for just under 20% on-average. Yet water vapor accounts for between 1% to 3% of the atmosphere, whilst CO2 accounts for less than 0.1% of the atmosphere. This suggests that, on a ppmv basis, CO2 is clearly a more potent greenhouse gas than water vapor.
  49. Climate change: Water vapor makes for a wet argument
    One consideration neglected by skeptic and non-skeptic alike is: water vapor is a GHG at some altitudes, but not all. Or so I learned years ago. The example given was that water vapor emissions from high altitude airliners was a problem, but water vapor at lower altitudes is not. Or has this result been overturned since then?
  50. Climate change: Water vapor makes for a wet argument
    So where is all this heat?
    Moderator Response: Go to the home page. At the top right, click on the big image that says "Global Warming Is Still Happening." In the resulting page, click the "Intermediate" tab.

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