Confident predictions of catastrophe are unwarranted.
A commentary by Richard S. Lindzen in the WSJ
Is there a reason to be alarmed by the prospect of global warming? Consider that the measurement used, the globally averaged temperature anomaly (GATA), is always changing. Sometimes it goes up, sometimes down, and occasionally—such as for the last dozen years or so—it does little that can be discerned.
Claims that climate change is accelerating are bizarre. There is general support for the assertion that GATA has increased about 1.5 degrees Fahrenheit since the middle of the 19th century. The quality of the data is poor, though, and because the changes are small, it is easy to nudge such data a few tenths of a degree in any direction. Several of the emails from the University of East Anglia’s Climate Research Unit (CRU) that have caused such a public ruckus dealt with how to do this so as to maximize apparent changes.
The general support for warming is based not so much on the quality of the data, but rather on the fact that there was a little ice age from about the 15th to the 19th century. Thus it is not surprising that temperatures should increase as we emerged from this episode. At the same time that we were emerging from the little ice age, the industrial era began, and this was accompanied by increasing emissions of greenhouse gases such as CO2, methane and nitrous oxide. CO2 is the most prominent of these, and it is again generally accepted that it has increased by about 30%.
The defining characteristic of a greenhouse gas is that it is relatively transparent to visible light from the sun but can absorb portions of thermal radiation. In general, the earth balances the incoming solar radiation by emitting thermal radiation, and the presence of greenhouse substances inhibits cooling by thermal radiation and leads to some warming.
That said, the main greenhouse substances in the earth’s atmosphere are water vapor and high clouds. Let’s refer to these as major greenhouse substances to distinguish them from the anthropogenic minor substances. Even a doubling of CO2 would only upset the original balance between incoming and outgoing radiation by about 2%. This is essentially what is called “climate forcing.”
The full article may be found here.
I knew nothing about Richard Lindzen before viewing a debate at ‘IQ2 US’ –
After watching that, I wouldn’t even trust him to tell me the right time. It was an utterly dishonest performance. He just trotted out a whole bunch of the usual tired old lies and myths that we read from amateurs on the net.
Great article, tangible, logical, but will anybody listen or will it just come down (or back) to:
“After several hours, Joe finally gave up on logic and reason, and simply told the cabinet that he could talk to plants and that they wanted water.”
– Idiocracy, Mike Judge, 2006
Icarus,
I watched Prof Lindzen. What in particular would make you write that you “wouldn’t even trust him to tell me the right time”? And what did he say that was “utterly dishonest”? And what are the “lies” and “myths” that Prof Lindzen copies from “amateurs” on the net?
You admit that you knew nothing about Richard Lindzen before you watched YouTube. You need to get up to speed here. Dr Lindzen is MIT’s top climatologist. He chairs its Atmospheric Sciences department. MIT is in the top tier of the world’s engineering schools, and it would certainly protect its reputation by at least demoting Prof Lindzen if he was, as you mendaciously label him, “utterly dishonest.”
Finally, why should anyone listen to your baseless opinion, rather than listening to an individual who knows what he’s talking about regarding the Earth’s climate?
Icarus,
“After watching that, I wouldn’t even trust him to tell me the right time. It was an utterly dishonest performance. He just trotted out a whole bunch of the usual tired old lies and myths that we read from amateurs on the net”
You mean tired old lies like:
The sea level is going to rise by 20 metres
The number of climate refugees will number 500 million
The arctic will be ice free by 2009
Hurricanes will become more frequent and intense
Polar bears will become extinct
Droughts and floods will ravage the world
I used to read your posts thoughtfully. I usually disagreed, but I thought they were sincere opinions. But suddenly your prejudice has come into plain view. You’re mind is completely closed and to me you’ve just lost all credibility.
yonason (02:57:41) :
“Lindzen has claimed that the risks of smoking, including passive smoking, are overstated.”
My mother died of lung cancer after a lifetime of smoking and denial so I have emotional as well as logical reasons to believe in a link between smoking and death. Sucking particulate organic matter into your lungs cannot be good for you. I can’t see how anyone can argue with that.
I also can definitely believe in a link between ill health effects and being trapped in closed areas for extended intervals with someone who smokes, for the same reason. However, I do have significant doubts that irregular contact with trace amounts of tobacco smoke can have any significant long term effect, and I think the zealots have exaggerated the risks beyond rationality.
Regardless, Lindzen’s stance on tobacco have no bearing on his climate science. It is either right, or it is wrong, on its own merits. If we are going to disqualify his voice on the basis of unrelated matters, then we need to do an investigation into the vices of all the climate scientists from both sides and disqualify any who eat junk food, fail to exercise regularly, are overweight, insert objects smaller than their fingers in their ears, run with scissors, drive aggressively, listen to loud music… or smoke.
Icarus (09:49:06) :
“After watching that, I wouldn’t even trust him to tell me the right time. It was an utterly dishonest performance. He just trotted out a whole bunch of the usual tired old lies and myths that we read from amateurs on the net.”
I did not see that he asserted anything that would be controversial even among IPCC climate scientists, though he couched it in such a way that they might take offense. He was just getting to the controversial bit when they called time on him.
Could you be specific as to which statement or statements you took exception?
Hmmm. A few budding poetasters are adding to ‘The Ballad of Hadley CRU’, but we need more.
And as lead author in this project, I must regretfully inform some contributors that their data does not conform to my preconceived expectations of what a ‘Clementine’ form ballad should actually look and sound like.
So I’m going to cherry-pick your verses, to hide the decline in Clementinate standards which by my unassailable judgement, has clearly taken place.
Icarus (09:49:06) :
“…was an utterly dishonest performance. He just trotted out a whole bunch of the usual tired old lies and myths that we read from amateurs on the net…”
Icarus, I’m very disappointed to see your baseless attack on a respected scientist like Richard Lindzen. I thought you were here to find out the truth about how climate operates, but now I see you’re just another AGW believer, pushing a tired and outmoded hypothesis which has long been falsified. You should read the CRU Climategate documents if you want to find some climate scientist who deserve some abuse.
I won’t be replying to any of your further posts – I’ve got better things to do.
I was unnecessarily rude in my first contribution – my apologies to everyone.
I’ll try to explain (calmly and rationally) what I took exception to in Lindzen’s presentation:
1: “We’re not even arguing about whether greenhouse gas emissions are contributing at some level to warming. They most certainly should, though I would suggest it would be very little”.
It’s widely accepted that climate sensitivity is around 0.75ºC/W/m², meaning that even with *current* anthropogenic forcings of 1.6W/m² we should expect 1.2ºC of global warming at equilibrium (perhaps 100 to 200 years hence). My understanding is that this will be a substantial warming, not “very little”, and that the world hasn’t previously been as warm as this for around 100,000 years. And remember, this is only with the forcing we see today (or more accurately, at the time IPCC AR4 was published). I think everyone agrees that there is no realistic prospect of halting the rise in anthropogenic forcings at today’s values, so the real warming is bound to be larger still, whatever we do. I think therefore it’s misleading to claim that the warming from anthropogenic greenhouse gases will be “very little”. Climate sensitivity would have to be *much* lower for the warming to amount to “very little”, and the observed natural variability of the Earth’s climate (from solar forcings and volcanoes and such) rules this out.
2: “Even our opponents do not claim that global warming is a crisis at present”.
I think this is misleading too – to me it implies that there is no urgency, and that even if his opponents are right about global warming, we can deal with it later. In reality, his opponents are practically shouting from the rooftops that we need to make serious changes right now, because if we wait until the effects of global warming are more dramatic, not only will there be much more suffering as a result, but also it will be much harder and much more expensive to deal with it then.
3: “Much of the current alarm, I would suggest, is based on ignorance of what is normal for weather and climate”.
I’m quite sure that climate scientists aren’t ‘ignorant’ in this regard, and it is those scientists who (almost unanimously) are raising the alarm. The people who are in the best position to understand past and present climate are the ones who are most concerned about AGW.
4: “Extreme weather events happen all the time – there is really no evidence of systematic increases”.
IPCC AR4 states:
Some extreme weather events have changed in frequency and/or intensity over the last 50 years:
It is very likely that cold days, cold nights and frosts have become
less frequent over most land areas, while hot days and hot nights have become more frequent. {WGI 3.8, SPM}
It is likely that heat waves have become more frequent over most land areas. {WGI 3.8, SPM}
It is likely that the frequency of heavy precipitation events (or proportion of total rainfall from heavy falls) has increased over most areas. {WGI 3.8, 3.9, SPM}
It is likely that the incidence of extreme high sea level3 has increased at a broad range of sites worldwide since 1975. {WGI 5.5, SPM} (and more)
To say that there is “no evidence” is once again misleading.
5: “… variability should decrease in a warmer world”.
I don’t know how you would weigh up a sum total of ‘variability’ of *all* kinds of weather but certainly *some* weather events have been projected to become more extreme, such as heavier precipitation events (due to a warmer atmosphere holding more moisture), and as noted above such phenomena are likely to be occurring already. Again, misleading.
6: “… in recent centuries the rate [of sea level rise] has been relatively uniform… and amounts to a couple of millimetres per year, and this is a residual of much larger positive and negative changes… due to tectonics, and the risk of sea level change from these changes is much larger than it is from warming”.
Again, completely disregards the evidence that sea level rise is accelerating and is not due to ‘tectonics’ but to warming –
Increases in sea level are consistent with warming (Figure 1.1). Global average sea level rose at an average rate of 1.8 [1.3 to 2.3]mm per year over 1961 to 2003 and at an average rate of about 3.1 [2.4 to 3.8]mm per year from 1993 to 2003. Whether this faster rate for 1993 to 2003 reflects decadal variation or an increase in the longerterm trend is unclear. Since 1993 thermal expansion of the oceans has contributed about 57% of the sum of the estimated individual contributions to the sea level rise, with decreases in glaciers and ice caps contributing about 28% and losses from the polar ice sheets contributing the remainder. From 1993 to 2003 the sum of these climate contributions is consistent within uncertainties with the total sea level rise that is directly observed. {WGI 4.6, 4.8, 5.5, SPM, Table SPM.1}
(IPCC AR4, SPM)
7: “The impact of warming on agriculture is not easy to ascertain, but for example India has warmed in the second half of the 20th Century and agricultural output has increased greatly”.
This is surely a red herring – agricultural output has increased because of crop breeding programmes, improved farming methods, foreign aid etc.
8: “The impact on temperature per unit carbon dioxide goes down, not up, with increasing CO2”.
What he means is that the T/CO2 relationship is logarithmic, which is certainly true, but since CO2 is rising exponentially it means temperatures are rising in a linear way, not slowing down – hence not much comfort there. Again, technically true but misleading.
9: “… in terms of greenhouse forcing we’re already three-quarters of the way to [doubling CO2] and we’ve only seen 0.6C [of warming]”
Highly misleading as it completely ignores the difference between transient climate response and equilibrium climate sensitivity – i.e. he fails to mention that a lot of the warming that will inevitably arise from greenhouse gas levels *today* hasn’t even occurred yet – the warming ‘in the pipeline’ or the additional warming commitment.
I could go on but I’ve run out of steam. It seems to me that nearly everything Richard said was patently untrue or deliberately misleading. How can that be appropriate behaviour for someone of his stature?
Icarus writes:
“The people who are in the best position to understand past and present
climatevampire infestations are the ones who are most concerned aboutAGWvampires.”[Fixed. Belief doesn’t make AGW real. Only the Scientific Method is convincing. And that doesn’t apply to the IPCC’s CO2=CAGW conjecture.]
Regarding the IPCC’s false claim that extreme weather events are increasing: click1, click2, click3.
Next, sea level is following its long term trend line. Nothing unusual is happening: click.
In fact, the sea level trend has been flat for several years: click. And the sea level may be a function of sunspot activity: click.
Icarus continues: “…agricultural output has increased because of crop breeding programmes, improved farming methods, foreign aid etc.”
Actually, it’s primarily due to the added CO2: click.
It’s hard to debate someone who totally believes that a harmless and beneficial trace gas is going to get him. And saying that what Prof Lindzen [one of the world’s esteemed climatologists] stated is “patently untrue or deliberately misleading” means that any facts contrary to Icarus’ position are automatically assumed to be dishonest. Dismissing out of hand one of the world’s principle authorities on the climate in favor of the Icarus world view comes pretty close to solipsism.
Smokey (15:58:26):
Belief doesn’t make AGW real. Only the Scientific Method is convincing. And that doesn’t apply to the IPCC’s CO2=CAGW conjecture.
But there is plenty of evidence for it, isn’t there? So it’s not really just conjecture.
Regarding the IPCC’s false claim that extreme weather events are increasing: click1, click2, click3.
Can you prove it’s false? Published scientific papers support it. Doesn’t that count for anything?
Next, sea level is following its long term trend line. Nothing unusual is happening: click.
Everything I’ve seen says the opposite – i.e. that actually the rate of sea level rise is increasing and has roughly doubled since the 19th Century:
http://www.cmar.csiro.au/sealevel/sl_hist_few_hundred.html
Icarus continues: “…agricultural output has increased because of crop breeding programmes, improved farming methods, foreign aid etc.”
Actually, it’s primarily due to the added CO2: click.
Certainly CO2 will be a factor, you’re right, but if your CO2-enhanced plants then die because glacier run-off has vanished as a result of AGW, it won’t do you much good.
It’s hard to debate someone who totally believes that a harmless and beneficial trace gas is going to get him. And saying that what Prof Lindzen [one of the world’s esteemed climatologists] stated is “patently untrue or deliberately misleading” means that any facts contrary to Icarus’ position are automatically assumed to be dishonest. Dismissing out of hand one of the world’s principle authorities on the climate in favor of the Icarus world view comes pretty close to solipsism.
It’s not my ‘world view’, it’s the evidence from the vast majority of climate scientists worldwide, and I haven’t just “assumed” anything – I’ve provided the evidence to support it.
“Craig Moore (19:48:07) :
A bit OT. However, does anyone have thoughts on the following paper that claims to demonstrate the falsification of CO2’s greenhouse effect? http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.1161v4.pdf
”
I don’t know if they got it right or are merely a coupla mathematicians applying math and assuming it’s physics. It’s close in a lot of ways but I can’t say that it’s right or that I agree with it. The reference made to physics forums discussion – at least what little I read up front may have some valid arguments but in general appeared to have less understanding of the physics and of the paper than does gerlich.
And, it always boils down to some notion of understanding that radiative equilibrium does have a higher temperature caused by the primary heat source when something increases the insulation. However, that doesn’t mean that the rebalancing always works out only for radiative nor does it mean that the only effect of adding a ghg is to increase the effective insulation. Also, the complexities of a ghg in the atmosphere and the effects of temperature and pressure are more than a simple relation and both absorption and emission are affected by variations. Ultimately, the co2 ghg is a bit player and the cloud cover fraction variable, that which is least understood, is a major player. Personally, I think whatever answer exists is in some variation of Lindzen’s iris effect concept, probably in conjunction with Svensmark’s cosmic ray cloud interactions.
Icarus (17:07:39) :
Honestly, I see nothing in your laundry list which is not open to debate. Some are acknowledged as such by your sources themselves (It is likely, it is very likely, etc…).
Several items are, at best, conjectural, and others have been called into question by the “Climategate” revelations.
I don’t know why you think these items will make an impression on most people reading this site. I am sure I speak for many when I say, I reject your characterization of any of them as “tired old lies and myths”. Such pushy assertions do not make any impression on people who demand evidence, and who are confident in their own ability to analyze data and draw conclusions for themselves.
[snip. now now ~ ctm]
Icarus,
“It’s widely accepted that climate sensitivity is around 0.75ºC/W/m², meaning that even with *current* anthropogenic forcings of 1.6W/m² we should expect 1.2ºC of global warming at equilibrium. ”
It was widely accepted for over a thousand years that the Sun circled the Earth. What’s your evidence? Considering that the warmer’s claim of 1.6 W/m^2 corresponds to 0.7 degrees of warming since the beginning of the industrial revolution, where do you get .75w/m^2???? If you look at those numbers, you get less that 0.5 deg per w/m^2 power increase. However, Climategate suggests that maybe it really is NOT 0.7 deg C rise. Also, various sources have accounted for around 1/2 of that in the form of other forcings, leaving more like 0.3 or 0.4 C rise (assuming there really has been 0.7 C total) attributable to ghgs. If you look at simple radiative concepts – without benefit of convection or the h2o cycle, you get less than that value. If you look at total forcing of the atmosphere and the difference between current T and a blackbody orbiting at 1 AU, you get something like 130W/m^2 for 33C rise or around 0.25 C per W/m^2.
If you try to get more sophisticated with these screwed up models of nothing and try to attribute h2o added forcing due to the temperature rise caused by co2, assuming relative humidity being constant – the source of gcm’s massive multi degree T rise due to h2o vapor (while ignoring corresponding increases in cloud cover), you are then faced with the serious problem that radiative transfer depends on a log function of actual molecular density which limits the consequences such that even an assumption of a 5 deg. C rise due to co2+h2o results in only enough additional h2o to do a fraction of a W/m^2 increase, leaving the vast majority of that 5 deg C rise to black magic and extremist rhetoric and not the laws of radiative physics.
“Icarus
I think therefore it’s misleading to claim that the warming from anthropogenic greenhouse gases will be “very little”. Climate sensitivity would have to be *much* lower for the warming to amount to “very little”, and the observed natural variability of the Earth’s climate (from solar forcings and volcanoes and such) rules this out.
”
I don’t care what you think. Your thoughts don’t jive with the data – what there is of it. Climate sensitivity is low and warming amounts to very little. If you create video games that fail to account for all parameters you get garbage. Since, for instance, albedo is around 0.31 and it’s only been measured very poorly for 2 or 3 decades and is known to vary with cloud cover in a dramatic fashion, most sensitivity measurements are as screwed up as the worst of these temperature and treemometer series after malicious meddling by so-called climate scientists.
”
I’m quite sure that climate scientists aren’t ‘ignorant’ in this regard, and it is those scientists who (almost unanimously) are raising the alarm. The people who are in the best position to understand past and present climate are the ones who are most concerned about AGW.
”
most ‘climate’ scientists are in a position to profit handsomely from alarmism via grants, books, and the like. Since they fail to understand the climate variations shown by geology, I’d dispute that they are as competent as geologists in that realm and geologists tend to disagree substantially with claims. Their failure to eliminate the maunder minimum and MWP by improper use of statistics and proxies further indicates they are not necessarily capable or honest.
Climatology is a multidiscipline area and very few people succeed in mastering one, much less several disciplines. It’s like the old joke about what physical chemists talk about (which is physics when they’re around chemists, chemistry when they’re around physicists and their family when they are around other physical chemists). The vast majority of these climatologists do not have the physics background and understanding beyond the superficial. While they might not totally foul up the 2nd law of thermo, they do not have much if any understanding beyond that.
As for the unanomous, parth of Climategate is the efforts by some of the principles to subvert efforts of others with opposing views – just like attacks on Lindzen and others. One I remember is the conspiring to damage a peer reviewed journal because it published something they didn’t like.
“To say that there is “no evidence” is once again misleading.
”
What evidence? – some apparently corrupt political entity claims it is likely that…. Or the last 50 years has brought some weather extremes ???? Guess what, lots of things have cycles and lots of things vary randomly – meaning sometimes it’s more and some times it’s less. Right now, the atlantic hurricanes have been quite low for two or three years now and a few years ago they were quite a bit higher than now. Turns out, they go by cycles which have existed for as long as they can measured. Also, it turns out that better technology means more are detected as compared to what happens with sparsely populated areas where one might exist without being spotted.
As for oceans sucking up energy – forget it – it ain’t there. That’s because warm water rises and IR doesn’t penetrate and evaporation absorbs energy. What’s more, if it were there, the heat flow from below could not supply enough power to compete with the radiative transfer and convection going on. That’s why there appears to be a skin effect with a lower temperature in the top few microns. There isn’t enough energy being transferred to maintain a higher temperature. It’s a foolish argument to presume that there is going to be any significant effect that we haven’t seen yet because all there can be is a tiny fraction of what we already see. It doesn’t matter how big the reservoir is. What matters is how fast the heat flow can occur. Low heat flow means low effect. A big reservoir means little effect for a long time – again assuming the measured data is wrong and that there is a magical mysterious buildup caused by no physical phenomenon but rather by alarmist pseudoscientific rhetoric and histrionics.
outa time now so I can’t continue dissecting your arguments tonight but suffice to say they’re as bogus the earlier ones. You can take it to the bank that Lindzen may be right or wrong but there is nothing you are capable of comprehending that even comes close to being able to show that he is right or wrong. Not so with your ipcc source or anything tainted by the Climategate scandal. BTW, at one time Lindzen was a part of the ipcc effort – before it started to show its true colors (as I recall).
cba you are one intelligent person! The best of what you write is it seems your own thinking process. So often I just read cut and paste from RealClimate.
Worst thing AGW supporters do is call any questioning of their belief system “deniers”.
Icarus,
“It’s widely accepted that climate sensitivity is around 0.75ºC/W/m²
I’m sorry Icarus, this most certainly is not widely accepted. Maybe among the AGW alarmist tribe, but there is no, I repeat no underlying scientifc rationale for those figures. The ONLY widely accepted figure is for a forcing of 3.7 watts/meter squared for a doubling of CO2. The temperature sensitivity is a hotly disputed area. I suspect that the figure you have quoted came out of a model somewhere.
The whole thesis underlying Lindzens arguments are that the models do not understand feedbacks correctly. If you think the models are correct then please make that point clear. At least then we will all know how you come to justify those figures.
Thanks, Craig, for link to Gerlich Paper. Shows where the co2 theory
is at odds with the Physics. People need to read this.
Beth Cooper (04:10:16) :
“Thanks, Craig, for link to Gerlich Paper. Shows where the co2 theory
is at odds with the Physics. People need to read this”
For God’s sake, people, the CO2 theory is NOT against the laws of physics. Please, please apply your skepticism to BOTH sides of the debate, not just the one you believe in.
Why do colleges and universities still have “Climate Science” departments if the “science is settled” ? Asking young men and women to spend their valuable treasure to be schooled in a branch of science that is “settled” is tantamount to fraud.
For that matter, why do they keep funding CRU ? .. or NASA GISS ?
Vincent (01:29:49):
Icarus,
“It’s widely accepted that climate sensitivity is around 0.75ºC/W/m²
I’m sorry Icarus, this most certainly is not widely accepted. Maybe among the AGW alarmist tribe, but there is no, I repeat no underlying scientifc rationale for those figures. The ONLY widely accepted figure is for a forcing of 3.7 watts/meter squared for a doubling of CO2. The temperature sensitivity is a hotly disputed area. I suspect that the figure you have quoted came out of a model somewhere.
No, it’s from palaeoclimate and from direct observations (e.g. response to volcanic forcings in the 20th Century).
I could quote lots of references pinning down climate sensitivity to about 3ºC but instead I’ll ask you two questions if I may:
1: Do you know of any published studies that come out with a *much* lower value?;
2: Even if it was (say) 1ºC (which seems unlikely as we’ve already seen ~0.6ºC of warming at 385ppm CO2) then isn’t that still cause for concern?
Thanks…
Icarus:
“I could quote lots of references pinning down climate sensitivity to about 3ºC but instead I’ll ask you two questions if I may:
“1: Do you know of any published studies that come out with a *much* lower value?”
Your ‘references’ are in reality simply disguised grant applications. The scarier the sensitivity number, the more likely a grant will be awarded. If climate sensitivity was anywhere close to 3°, the planet would be warming fast instead of cooling.
Regarding ‘published studies’, the author of this very article, Dr Richard Lindzen, puts sensitivity *much* lower. Search is your friend. Look it up.
Answer to your question #2: No.
Icarus,
“No, it’s from palaeoclimate and from direct observations (e.g. response to volcanic forcings in the 20th Century).
I could quote lots of references pinning down climate sensitivity to about 3ºC. . .”
First let me deal with your point above. I would be surprised if palaeoclimatic studies can yield a CO2 sensitivity of 0.7C/W/m2. In the first place the relationship between CO2 and temperatures have been stochastic on geological time scales. For example, the late ordovician glaciation occured during a period when CO2 levels were 16 times higher than now.
One thing we know about paleoclimate is how little we actually do know. It is a travesty that we can’t account for glaciations and warm periods over geological time scales. I would therefore be very suspicious of any studies that purport to show such precise measures as these.
“. . . but instead I’ll ask you two questions if I may
1: Do you know of any published studies that come out with a *much* lower value?;”
As Smokey mentioned, the Lindzen & Choi paper suggest 0.5C. Spencer leans more towards 1C. The IPCC position is 1.2C for 2 x Co2 without feedbacks. The larger values are obtained only because climate models are programmed to assume positive feedbacks due to water vapour while at the same time ignoring the effect on cloud formation, because it is “poorly understood”.
“2: Even if it was (say) 1ºC (which seems unlikely as we’ve already seen ~0.6ºC of warming at 385ppm CO2) then isn’t that still cause for concern?”
It would not be of concern because it is wholly trivial. I would suggest that most individuals could not even detect the difference of 1C of air on their skin. A slightly warmer, higher CO2 world would be a greener one in which life thrives. That has been true in the past, but I very much doubt we would get close to the temperatures of the mesozoic.
You note that we have seen 0.6C from an increase of 100ppm. But because temperature is logarithmically related to concentration, the next 100ppm would lead to less than another 0.6C and the next 100ppm to an even smaller addition. Probably 0.6 + 0.4 + 0.3 = 1.3C. Nothing to worry about.
Clearly argued and simply put. Well done, despite the weak metaphor.
No need to associate warming with CO2 or man.
The emperor has no clothes and more and more people are beginning to notice it.
Vincent (12:14:35):
First let me deal with your point above. I would be surprised if palaeoclimatic studies can yield a CO2 sensitivity of 0.7C/W/m2. In the first place the relationship between CO2 and temperatures have been stochastic on geological time scales. For example, the late ordovician glaciation occured during a period when CO2 levels were 16 times higher than now.
The Ordovician was mostly a warm world. 450 million years ago the Earth was a different place – the continents were in different places (largely in the southern hemisphere) and the sun was about 2% cooler, so you wouldn’t expect any particular level of CO2 to result in the same climate as it would today. In particular, in the late Ordovician most of the dry land on the planet was centred on the South Pole where massive glaciers formed, causing shallow seas to drain and sea levels to drop.
If you want to characterise the effect that forcings are likely to have on the Earth *today*, you need to look at conditions that were not so dramatically dissimilar to what we have today. Figures from the Last Glacial Maximum indicate around 5ºC of temperature change from around 7W/m² of forcing – i.e. around 0.75ºC/W/m². This paper discusses several different ways of estimating current climate sensitivity and concludes that the most likely value is around 3ºC, supporting previous calculations:
http://www.jamstec.go.jp/frcgc/research/d5/jdannan/GRL_sensitivity.pdf
As Smokey mentioned, the Lindzen & Choi paper suggest 0.5C
I think we can rule that out as we already have around 0.6ºC of warming just from 100ppm increase in CO2, as Richard himself acknowledges.
Spencer leans more towards 1C. The IPCC position is 1.2C for 2 x Co2 without feedbacks. The larger values are obtained only because climate models are programmed to assume positive feedbacks due to water vapour while at the same time ignoring the effect on cloud formation, because it is “poorly understood”.
Can you show any evidence for that? As I understand it the values aren’t obtained from models at all – they’re put *into* models after being estimated from palaeoclimate and observations.
“2: Even if it was (say) 1ºC (which seems unlikely as we’ve already seen ~0.6ºC of warming at 385ppm CO2) then isn’t that still cause for concern?”
It would not be of concern because it is wholly trivial. I would suggest that most individuals could not even detect the difference of 1C of air on their skin. A slightly warmer, higher CO2 world would be a greener one in which life thrives. That has been true in the past, but I very much doubt we would get close to the temperatures of the mesozoic.
1ºC doesn’t seem like much to us but it still puts the climate outside of the natural range of the 12,000 years since the last glaciation, doesn’t it? You’d be seeing climate outside the range of anything experienced by modern human civilisation. I don’t see how you can really call that “wholly trivial”.
You note that we have seen 0.6C from an increase of 100ppm. But because temperature is logarithmically related to concentration, the next 100ppm would lead to less than another 0.6C and the next 100ppm to an even smaller addition. Probably 0.6 + 0.4 + 0.3 = 1.3C. Nothing to worry about.
Remember that because heat accumulates quite slowly, the current 0.6ºC is only slightly more than half of the warming we would expect to see even from today’s forcings – the additional warming commitment would take that to 1.2ºC. Add another 175ppm to that (to double pre-industrial CO2) and it’s clearly going to take you to a lot more than 1.3ºC (my maths isn’t up to working out how much more). 3ºC doesn’t seem unreasonable.