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Comments 83301 to 83350:
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dana1981 at 03:49 AM on 10 June 2011IEA CO2 Emissions Update 2010 - Bad News
Mark - I did cover it in the caption to the figure, but your'e right it would be good to include in the figure itself for when it's re-used. We'll look into that. -
trunkmonkey at 03:47 AM on 10 June 2011Can we trust climate models?
I checked out climateprediction.net and was pleased to find an actual table of the parameters and their values for one of the Hadley models. It was a daunting list, and after looking at scaddenp's GISS documentation it is clear what an enormous undertaking separating the parameters from the physics would be. Riccardo mentions difficulties approaching things the right way and this brings to mind the model handling of the THC. The cartoons at the top of this thread show schematically how the approach is rooted in the notion of Meridional Overturning Circulation. There is a large literature on MOC and I was disappointed to see at climateprediction.net references that people are stilled mired in this notion in 2010. IMO the entire notion of MOC reflects a Euro-American bias toward the Atlantic, sort of like we study Greece and Rome and ignore the Han Dynasty.
To really understand how the THC works requires a continuous ocean view like the one above (if it works)by Alexandro Van de Sande.
That the Atlantic bottom water is being actively pumped out is supported by satellite measurements that it is about a meter lower. The Antarctic beltway sure looks like a centrifugal pump to me...
The models are at their best when the fluid dynamic equasions spontaneously produce observed behavior. I don't think we can even evaluate the behavior if we are stuck on the notion of MOC.
Moderator Response: [Dikran Marsupial] "would be" is the wrong tense. As I said, sensitivity analyses have allready been done, including by climateprediction.net and you can even download their results if you want to analyse them for yourself. -
Yvan Dutil at 03:42 AM on 10 June 2011Geologists and climate change denial
Without going deep into sociological interpretation, scientist most sensible to climate change are those: used to playing with model or seeing the impact of climate change first hand. The first criterion affects older and lab rats scientist. The second criterion impacts those working on very long and very short time scale (Geologist and meteorologist). This match my own observations. Off course, political orientation play also. -
Alexandre at 03:42 AM on 10 June 2011Geologists and climate change denial
garethman at 02:56 AM on 10 June, 2011 by what route do they get to commenting on the validity of Climate change Science ? They don't. I've engaged in some unfruitful debates with geographers here, and the basic pattern is what you see with denialists elsewhere: copy/pasting arguments they don't really understand, and if you respond to them, they just move on to some other denialist meme. The USA in an imperialist way could be using the problems of climate change to conveniently prop up it’s own economy. Geopolitics is a complicated game, and a major player like the US can play rough. The problem, of course, is when people get lost in these yummy conspiracy plots and forget to look at the evidence. The US could be the worse nasty exploiter of the world, but IR would still be obstructed by CO2. -
Mark-US at 03:29 AM on 10 June 2011IEA CO2 Emissions Update 2010 - Bad News
PS sorry Dana, I just saw the back and forth at comment 44. So the graph was energy combustion only.... ok that's clear. However, I still think a revision is in order for the reason that casual viewers might go away with the impression that OVERALL emissions (including everything) are still within IPCC ranges (which don't include lots of things such as permafrost carbon). If the lines on the figure are energy-combustion lines only, the lay newcomer should be told there is more to the story. I'm not enough of an expert to suggest a specific tweak. Thanks for your work Mark (USA) -
MA Rodger at 03:25 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Not a good link @#13. It's URL is:- https://1449103768648545175-a-1802744773732722657-s-sites.googlegroups.com/site/marclimategraphs/collection/G14.jpg -
Geologists and climate change denial
MajorKoko@33, In addition to the link DSL has provided here is a quick summary of terms: positive feedback - Climate responds to increase the magnitude of the original forcing. Does not mean that the warming/cooling continues without limit. Example: 1 degree of original forcing results in 3 degrees of net change after feedbacks. negative feedback - Climate responds to decrease the magnitude of the original forcing. Example: 1 degree of original forcing results in .5 degrees of net change after feedbacks. The Broecker quote uses "self-stabilizing" as a synonym for negative feedback. The climate will still stabilize in the sense that feedbacks will be finite, even though they are positive. The geological record serves as evidence for a positive feedback because the magnitude of temperature swings seen is too great to be explained without taking positive feedbacks into account. -
Mark-US at 03:18 AM on 10 June 2011IEA CO2 Emissions Update 2010 - Bad News
Thanks for the graphic in Figure #1, though I'm having some trouble with the label "Observed CO2 Emissions". Two things. #1 A casual reader might think the picture shows EVERYTHING. For example emissions from increasing wild fires. There's no reason to think emissions from wildfires went down during the recession. Unless I'm just confused (very possible) a revision might be in order. #2 Also, I'd be interested to know if this really is an apples-to-apples comparison. How did IEA generate their data? From the scant bit I read, it sounds like they looked at international energy consumption and projected. If so, their data doesn't show emissions from a number of other sources. But IPCC's scenarios, so I believe, imagine at least some emissions sources beyond energy consumption. Go easy on me, I'm a newbie, and its a lot of material to compare. So the question is... do the lines show the same thing? Or are their some emissions sources in IPCC's lines that are not in the IEA curve in Figure 1? If so, and we added some amount to the IEA curve in accord with the IPCC's scenario definitions, wouldn't that push the IEA curve higher than A1FI? Thanks for comments Mark, USA -
MA Rodger at 03:16 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
I'm perplexed why Arctic Sea Ice should have but two futures – either a tipping point & rapid disappearance of summer ice or a gradual decline into this state over 20 years. The former “seems to be unfounded” according to this post. Certainly the dramatic melt of 2007 proved not to be a tipping point being not followed by more drama in 2008. Yet the dramatic output of the PIOMAS model (see link @ #4) suggests ice free summers at least before 2020. My own humble efforts at extracting this PIOMAS data are graphed here & are just as dramatic. If this is anything near reality, an ice free summer Arctic surely has to be years away, not decades. -
DSL at 03:16 AM on 10 June 2011Geologists and climate change denial
Garethman, I have to take exception at your use of "alarmist." You imply that "alarmist" and "denialist" are binary opposites. That's clearly not true. You also fail to define "alarmist." Can you point out any poster on this site who you would consider to be an "alarmist"? And could you point out any climate scientist who you consider to be an "alarmist"? You might want to reply an a more appropriate thread. -
dhogaza at 03:14 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
garethman: "It’s interesting to note from the NSIDC that the area of ice dropped considerably between 1997 and 2007, since when the melt has levelled off with the ice remaining at a significantly reduced level. The last 4 years has seen this low level stabilisation which cannot be seen as a recovery, but how long would it be before this is seen as the norm?" It's almost as though garethman isn't aware that the three years following 2007 are *all* lower in minimum extent than any other year in the satellite record, and that two of the three were well below the long-term trend, and the third right on the trend, isn't it?
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Eric the Red at 03:10 AM on 10 June 2011A detailed look at climate sensitivity
Tom, Sorry for the delay. Yours was a better analysis than mine, but it looked like John was confusing the equation by substituting oC for W/m2. Hence, he was arriving at a higher figure for climate sensitivity. -
DSL at 03:08 AM on 10 June 2011Geologists and climate change denial
MajorKoko, you might want to read all three levels this article and post any responses/questions there. -
KR at 03:06 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Badgersouth - Using the "Search" box with "Christy Crock #" will locate all of them. -
JMurphy at 03:03 AM on 10 June 2011Websites for Watching the Arctic Sea Ice Melt
With regard to the UAH graph shown by villabolo, I remember one or two people posting on here back in April, saying that the anomaly showing for March 'proved' that temperatures hadn't risen since the readings began, or whatever cherry-picked date was relevant at the time; or that all the warming had now been 'wiped out'. Where are they now and what do they think at the moment ? I'm genuinely interested, if only to discover more about their thought-processes. -
garethman at 03:02 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
It’s interesting to note from the NSIDC that the area of ice dropped considerably between 1997 and 2007, since when the melt has levelled off with the ice remaining at a significantly reduced level. The last 4 years has seen this low level stabilisation which cannot be seen as a recovery, but how long would it be before this is seen as the norm? I strongly suspect the ice will once more resume it’s overall melt, but it would be great to see some opinions on why this low level stabilisation has occurred. -
garethman at 02:56 AM on 10 June 2011Geologists and climate change denial
Alexandre In Brazil the denialist bunker is Geography, which apparently is more of a social science here than elsewhere. They love the conspiracy theory of an imperialist evil USA plotting to control developing countries through emission targets. Garethman You never know, both ideas are not incompatible. The USA in an imperialist way could be using the problems of climate change to conveniently prop up it’s own economy. By the way, if Geography is seen as a Social Science, by what route do they get to commenting on the validity of Climate change Science ? -
JMurphy at 02:55 AM on 10 June 2011There's no room for a climate of denial
Eric the Red, I can't understand why you didn't link to the paper which actually created the graph rather than a version of it shown by CO2SCIENCE ? It can't have been difficult to find. -
garethman at 02:51 AM on 10 June 2011Geologists and climate change denial
Steve Brown It would be interesting to know if there was a correlation between the age of Geologists and potential denialist traits. If you were at University earlier than 1980, then you are unlikely to have had much exposure to the explosion of knowledge in Earth Sciences from the various ocean and ice-core drilling programs that began in the mid 70’s. Garethman I would bet that you were right on this Steve, from observation there is certainly correlation on the alarmists side, i.e. the younger an activist is, the more catastrophic the predictions. (Note, based on observations only!) -
JMurphy at 02:51 AM on 10 June 2011There's no room for a climate of denial
apiratelooksat50, what evidence do you have that shows (to your satisfaction) what is actually changing the climate now ? Does this evidence provide figures that everyone else can look at ? Can you also provide the evidence for the potential benefits ? -
MajorKoko at 02:44 AM on 10 June 2011Geologists and climate change denial
You quote the following... "The paleoclimate record shouts out to us that, far from being self-stabilising, the Earth's climate system is an ornery beast which overreacts to even small nudges." So I have a question... If the climate is not self-stabilising, why did the over-reactions that the paleoclimate record is "shouting to us" about *not* lead to runaway global cooling or warming, such that we are now in either a deep-freeze, or baked-dry situation? I don't understand how you can say that the Earth exhibits strong positive feedback (i.e. far from self-stabilising) during climate changes? The fact that we are here at all (and not enjoying a never-ending ice-age, or global meltdown) quite clearly shows that, historically at least, there must be some, as yet unidentified, braking effect (negative feedback) within the system? Otherwise we would already have found ourselves at either extreme I mention above would we not? Please explain... -
Eric the Red at 02:37 AM on 10 June 2011There's no room for a climate of denial
JMurphy, The site of the graphic does not concern me, since the only change was the added yellow bar, which does not change the data on the graph (I was unaware of the site, just looking for a link to the graph). The previous graphic references was the temperature plot in #27. Also, several different dates have been listed for the Medieval Warm Period, so I will not get bogged down with specific differences. The "bump" is uncertain, hence it is not filled in like the remainder of the graph. The decline from the 7th century to the 8th looks similar to what has happened in the past century. There is no "bump" currently, so if the "bump" was real, then it is not happening now. If it was not real, then it is happening now. I have no reason to dispute the paper's conclusions, as it is supported by the data. I cannot say if the same thing is occurring now. The intent was to show data comparing recent temperatures to those of past times. -
John Hartz at 02:19 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Clive and Dirk Cussler do not pull any punches about climate change's impact on the Arctic in their Dirk Pitt nove, "Arctic Drift" If the Climate Denial Spin Machine can tout novels, so can we. BTW: I really enjoed reading "Arctic Drift" Much of the novel is based on the ill-fated Frankin expedition. The fate of the crews of the HMS Erebus and the HMS Terror is retold in gruesome detail. -
Albatross at 02:13 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Rob @5, Did you source those Arctic ice volume data from here? Also, for more context, we have this from Polyak et al. (2010): "Historical records indicate that Arctic sea-ice extent has been declining since the late 19th century. Although this decline was accompanied by multidecadal oscillations,the accelerated ice loss during the last several decades lead to conditions not documented in at least the last few thousand years. Taking together the magnitude, wide geographic distribution,and abruptness of this ice loss, it appears to be anomalous in comparison with climatic and hydrographic variability observed on sub millennial timescales and longer-term insolation changes." And if I may take the liberty of directing those in denial about the rapid loss of ice to the video featured here. -
John Hartz at 02:05 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Recommend adding a "links" tab to other relevant SkS postings on this topic. -
Eric the Red at 02:03 AM on 10 June 2011Christy Crock #6: Climate Sensitivity
Sphaerica, I would agree that there are four inputs (and I would agree than any thing else is a result of those inputs), with any time of galactic input being an anomaly. In the past, volcanoes have had short-term effects, except for the few super volcanoes. That leaves three primary inputs. The location of the continents has been shown to affect input, but change on such a long time scale to be only relevant to paleoclimatology. Surface albedo may play a much greater role. Orbital factors cause changes on a much shorter time scale; thousands up to a hundred thousand years. That leaves the sun. Total solar irradiance has been shown to vary only slightly, and is unliekly to be a large climate influence. Sunspots are much more variable, as is the solar magnetic field, and the results are inconclusive. I would argue that CO2 is only an input with regards to cloud formation and blocking incoming solar radiation. Most of the effects concern restricting output. Also, CO2 is affected by temperature; ocean dissolution and plant respiration. The physics is not going to change. While your four inputs may have changed significantly in the past, the sensitivity to CO2 has probably been fairly constant, except during the early Earth, when atmospheric concentrations approached 1%. -
John Hartz at 02:02 AM on 10 June 2011Christy Crock #6: Climate Sensitivity
Is this the first article in the Christy Crock series to be posted? If so, why is it #6? -
Alexandre at 02:00 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
skywatcher at 00:32 AM on 10 June, 2011 You're right. So 190 GT of methane carbon would actually mean 4750 GT of the equivalent in CO2 (25x). Or 558 years worth of human emissions, considering a 100 year CH4 time span. Is this right? Feel free to correct me if anyone sees a mistake in my calculations. I remember David Archer claiming that no model showed a self-sustained warming from permafros emissions alone. So my figures here seem too high to be true... -
Rob Honeycutt at 01:59 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Jay... What is being projected by pretty much everyone is ice free summers in the coming 10-15 years. And that has all kinds of implications from habitat loss issues for a wide range of Arctic species, loss of summer ice albedo, warming Arctic ocean, methane release... it's extremely concerning and it's happening right now. -
JMurphy at 01:57 AM on 10 June 2011There's no room for a climate of denial
Eric the Red wrote : "This graphic by Hanspeter Holzhauser shows changes in the Great Aletsch Glacier in recent times which mimics the previous graphic (reverse axis of course). http://www.co2science.org/data/mwp/images/l2_greataletsch.gif" What "previous graphic" are you referring to, and why do you rely on graphics from a dodgy site like CO2SCIENCE(sic) ? Doesn't it bother you that they have added a yellow bar alluding to what they want you to see as the MWP, when the original graphic (from the paper) shows a later Medieval Climate Optimum (MCO) ? And what about that bump during that warmer time-period ("from around AD 800 to the onset of the LIA around AD 1300") that "was interrupted by two weak advances in the ninth (not certain because based only on radiocarbon dating) and the twelfth centuries AD (around AD 1100)" ? Is that happening now ? And what about the conlusion that "the residual 14C records supports the hypothesis that variations in solar activity were a major forcing factor of climatic oscillations in west-central Europe during the late Holocene" ? Is that occurring now ? -
Rob Honeycutt at 01:54 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Jay... To put that into a more current context... try this. -
Albatross at 01:32 AM on 10 June 2011There's no room for a climate of denial
The "skeptics" here continue to create and then argue a strawman concerning the Holocene climate or concerning climate pasts. I find it ironic that they are willing to grasp onto the meme that "Climate has changed before and been warmer before" while completely missing the point and completely missing about where we are heading. That is just another form of denial folks. To add to Daniel's informative figure @27:
[Source]
Also, I find it odd that some "skeptics" are of the belief that paleo data are of little use, but then use (or abuse) those same data to (incorrectly) reinforce their preconceived ideas and misguided ideas.
Finally, a lot has changed since the peak warmth of the Holocence, the planet is now home to 7 billion people, and by the time we have doubled or tripled CO2 there could be more than 10 billion people on the planet.
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CBDunkerson at 01:09 AM on 10 June 2011CO2 is not increasing
The global recession did cause a dip in CO2 emissions for a couple of years, but emissions started rising again in 2010 and the emissions dip was much too small to have any impact atmospheric concentrations... which have continued increasing at about 2ppm per year through the recession. -
Albatross at 01:07 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
Thanks to Alexandre and Skywatcher for ruining my morning tea...jeez. Excellent points though. -
Albatross at 01:03 AM on 10 June 2011Geologists and climate change denial
Be careful about painting all geologists with the same brush. The Canadian Geophysical Union is also convinced by the evidence that humans are causing global warming. Then again, I concur with this statement: "So climate scepticism seems strongest among geologists closely linked to the mining and fossil fuel industries". Think the coal lobby in Australia and the USA, two mention but two examples. Also think ClimateAudit. -
DSL at 00:45 AM on 10 June 2011CO2 is not increasing
John, you might update the article with the recent news about CO2 increasing despite the recession. I recall NETDR claiming that recessions cause dips in CO2. While that's possible (and may still be possible with this double dip or super-dip), so far it hasn't been evident. -
DSL at 00:37 AM on 10 June 2011Conspiracy theories
An addition to the conspiracy theory discussion. The article points out that conspiracy theories inevitably fail to take into account the numbers of people who have to be willing participants in the conspiracy. Also discussed is the social reality of human knowledge production. Form the article (neuroscientist Neil Levy speaking): "It is a perennial temptation to think that one can do better than the distributed network of experts . . . Though the distribution of cognitive labour is something that goes quite far back in human evolution, it is far more pervasive than we are evolved to deal with. We expect to have some grasp on how things work." and more from Levy: "In complex societies we are all in relations of epistemic dependence: we simply cannot hope to cut ourselves off from the distributed systems of knowledge production (media, government, economists, academia) and come to a better understanding of the world." "I think that for many conspiracy theories, the explanation of why they are accepted is very similar to the explanation of why people reject climate change and evolution: a mistaken and hubristic belief that a lone blogger (or a small network of bloggers) can do better at explaining events than thousands of well-qualified experts." "Today we can't have more than the shakiest grasp (if that) in many areas, no matter who we are: the knowledge is too specialised and detailed for us to acquire. Given we have this expectation (which generates what has been called the illusion of explanatory depth), we find it difficult to take things on trust." -
Eric (skeptic) at 00:35 AM on 10 June 2011Are you a genuine skeptic or a climate denier?
scaddenp, legal remedy requires actual harm. My understanding is the lowest point in NZ is near your airport (-2m) and not full of seawater so that offers the possibility that the airport could have a wall around it. Your overall point that "stopping CO2 is much more direct" is valid, but that doesn't automatically deprecate mitigation measures, they should all be examined thoroughly. -
skywatcher at 00:32 AM on 10 June 2011Impacts of a melting cryosphere – ice loss around the world
#1: Is it not also even worse as the 190GT of carbon released from the permafrost will contain a significant proportion of methane, which is of course a more effective greenhouse gas than CO2 in our current atmospheric composition? -
Eric the Red at 00:31 AM on 10 June 2011There's no room for a climate of denial
Yes Norman, Most research suggests that temperatures were warmer during the Holocene Climate Optimum (hence the name). During this period Arctic sea ice and mountain glaciers were in rapid decline. Some may have reached a minimum during this time, others during the Roman Warm period, some during the Medieval Warm period, and still others today (all warm periods on the graph). This graphic by Hanspeter Holzhauser shows changes in the Great Aletsch Glacier in recent times which mimics the previous graphic (reverse axis of course). http://www.co2science.org/data/mwp/images/l2_greataletsch.gif Some of the past changes in climate may be tied to temperature changes, other may not. The drying of the Sahara, which lead to the rise of the Egypian Empire, occurred during the cooling after the Holocene Optimum. The Mayans may have succumbed to a recurring drought combined with other factors. Other civilizations may have suffered similar fates (Anasazi). On a microcosm, the climate is not very stable. However, in the broader spectrum, the climate has been relatively stable for almost 10,000 years. -
Tor B at 00:03 AM on 10 June 2011Geologists and climate change denial
Geologists (and others) should watch Richard Alley’s 2009 American Geophysical Union (AGU) lecture on CO2 and climate change over geologic time. As a student of hard rock geology (BS & MS) in the 70s and early 80s, I learned virtually nothing about paleoclimatology, even as paleoecology was the only part of paleontology that interested me. My relevant climate science education really started a couple of years ago when I intentionally read about how and why CO2 is a greenhouse gas, really basic physical chemistry, I’m embarrassed to admit. I wanted to understand why “some people” were saying “AGW”. A significant event in Phanerozoic time that may have caused climate to change as rapidly as it is now changing is when the Siberian traps poured out at the end of the Permian. Try Stephen E. Grasby, et. al.’s hypothesis on Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction or an article based on it titled Massive volcanic eruptions + coal fires = the Great Dying. -
Eric the Red at 23:52 PM on 9 June 2011Geologists and climate change denial
The discussion about geography is only scratching the edges. Yes, geography is much more of a social science than a hard science, but it does tnclude the effects of human activities on the environment. The effects are less to do with the chemical or physical effects of CO2 emissions, than with the changing structure of the land and populace. Much of the climate focus concerns deforestation and urbanization. Hence, these factors are given considerably more weight by geographers than by atmospheric physicists. This compares with geologists giving greater weight to paleoclimatology, meteorologists giving greater weight to natural responses, or oceanographers giving greater weight to the PDO, etc. Those working directly in a particular field see the effects in the field more clearly than others, but also tend to over-extend their importance. -
Alexandre at 23:11 PM on 9 June 2011Geologists and climate change denial
skywatcher at 22:50 PM on 9 June, 2011 Yeah, I heard that Geography here is taught more as a social science. I think that allows for more distance from the physics involved. Anyway, you're right about the specialism that does not automatically define your position. -
Alexandre at 23:07 PM on 9 June 2011Impacts of a melting cryosphere – ice loss around the world
About this paragraph: Researchers from the National Snow and Ice Data Center (NSIDC) estimate that if permafrost melt continues, around 190 gigatonnes of carbon could be released into the atmosphere by 2200, further warming the planet. To put this figure in context, in the year 2010 manmade greenhouse gas emissions were at around 30 gigatonnes. Actually, it's worse. 2010 emissions of CO2 were 30.6 GT. To compare this to the NSIDC data, we have to convert it to carbon and get 8.5 GT. Those 190 GT mean some 22 years worth of human emissions, then. -
Robert Murphy at 22:51 PM on 9 June 2011Geologists and climate change denial
Lloyd Flack makes a good point; a certain amount of the skepticism from some geologists and archaeologists has to do with their narrow focus on how paleoclimate changed, but not why it changed. Geologists especially view the Earth through its almost 5 billion history and sometimes have a difficult time resolving their vision from the "big picture" to shorter time spans. I do agree that having an economic conflict of interest is also a very strong incentive to want to deny AGW, but it isn't the only one. -
skywatcher at 22:50 PM on 9 June 2011Geologists and climate change denial
#26: Odd one, that, and a pity to hear it. In the UK, departments specialising in geography have provided a lot of the supporting hard observational science, from glaciology, geomorphology, remote sensing and interferometry through to various kinds of climate change modelling and estimations of the impact of various emissions scenarios. But it goes to show that your specialism does not automatically define your position, just as there are a good number of meteorologists and petroleum geologists (I know quite a few) who clearly understand the science. -
Bob Lacatena at 22:48 PM on 9 June 2011Christy Crock #6: Climate Sensitivity
On climate sensitivity in general, I would point out that there are only four factors (well, five, if you introduce humans, and even then... but I'm getting ahead of myself)... Sorry. I would point out that there are only four factors which affect climate, and are themselves unaffected by climate: 1) The sun 2) The locations of the continents 3) The orbital factors of the earth (inclination, precession, obliquity, etc.) 4) Volcanic activity [The last, volcanic activity, obviously is only a continuous forcing if the earth enters a sort of "new volcanic activity regime" such as a sudden explosion or quieting of the Circle of Fire.] For these factors, if the climate changes, it does not alter their inputs, while for all other inputs, although sometimes on massive time scales, a change in climate in turn changes their inputs. CO2 in the atmosphere, ice albedo, clouds, water vapor, lapse rate, everything will changes (over large time scales, in some cases) if temperature changes. One comment mentioned a different sensitivity, for instance, if the Greenland and Arctic ice sheets were already melted. I don't think, in properly complete climate time scales, that this matters. If climate changes, those ice sheets would reform, albedo would drop, and that would be a positive feedback (unless their absence was a result of land mass configuration, which is the point I'm trying to make). I believe (and by believe I mean that my logic and thought process is obviously limited, without doing extensive studies and verifications to confirm that my logic is accurate) that while climate sensitivity may vary based on alterations in long term, non-climate affected inputs (sun, land disposition, orbit, volcanoes), within any set regime it will be pretty constant, and I actually do not see much reason for much variation in sensitivity even with changes to those four parameters. Obviously there would be some, but I see no reason to believe that the degree would be too great (except, perhaps, in the case of landmasses, which by adopting a configuration which prevents the formation of ice caps also prevents a major feedback, ice albedo, and by removing one feedback from the equation could alter sensitivity by a notable degree). But everything else depends on physics which is in turn affected by temperature; lapse rate, water vapor, cloud formation (maybe also affected by land masses), CO2 balance, etc. Now to the new, fifth forcing: humanity. At first, I thought of that as a true forcing because it does not also respond as a feedback. We burn CO2 regardless of whether the temperature goes up or down. We don't decide to burn more CO2 because the planet warms, or stop burning it when the planet cools. Then I thought about it on geologic time scales, and realized that maybe that's not true. I'm not sure that modern civilization would ever have formed during a glacial, so maybe our ability to poor CO2 into the atmosphere is a one-time positive feedback response to a warming planet. And we can't keep doing it forever. The increase in temperature will either kill us, or force us to wise up and ease off the gas, so the speak. In which case rising temperatures will cause us to stop (not a negative feedback, but instead a stop-forcing response). So we're back to the original 4: sun, land configuration, orbit, and volcanic activity, as the only true forcings that affect climate and might also vary sensitivity.... but I still don't see it varying by much, because except for ice albedo and land mass configurations, the physics is not going to change. -
Alexandre at 22:35 PM on 9 June 2011Geologists and climate change denial
In Brazil the denialist bunker is Geography, which apparently is more of a social science here than elsewhere. They love the conspiracy theory of an imperialist evil USA plotting to control developing countries through emission targets. -
Bob Lacatena at 22:27 PM on 9 June 2011Christy Crock #6: Climate Sensitivity
34, Eric the Red,I disagree that the sensitivity has never been less than 2.5 or been as high as 5.
Evidence and citations, please. -
Chemware at 22:24 PM on 9 June 2011Geologists and climate change denial
@ 11 Arkadiusz: Then the Committee of Geological Sciences of the Polish Academy of Sciences is in complete disagreement with its mother body, the Polish Academy of Sciences, who have endorsed the conclusions of the IPCC.
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