The problem of the second derivative
According to the World Meteorological Organization, The year 2009 is likely to rank in the top 10 warmest on record since the beginning of instrumental climate records in 1850, according to data sources compiled by the World Meteorological Organization (WMO).
Sounds pretty serious. In fact, it might be.
However, parsing this portion of the press release indicates that what it doesn't say is just as telling as what it does. Clearly, since 2009 ranks in the warmest 10 years, warming is continuing.
Maybe, maybe not. Firing up the WaybackMachine© to the days of yore when I was proficient in Calculus, it is worth thinking about derivatives. When we hear of changes in the Earth's average temperature over time, that is the first derivative: ∆T/∆t, the rate of change in a given quantity at a given point. At the moment, with moment defined as the time span between roughly 1950 and 2000, the value of the first derivative is roughly -- and working from memory here -- 0.2C/decade.
Taking things one step further, the second derivative describes how much the rate of change is changing. Think of a car accelerating from a stop to its top speed. At each tick of the clock, the car has an acceleration rate. However, over time that rate changes: it is very high at the start, and reaches zero at its top speed. The second derivative is negative, strongly at first, before reaching zero at the same instant the car is no longer accelerating.
So what does this have to do with global warming? Global warming can have come to a stop, and still have the warmest years in the record. If average temperatures are no longer increasing, the annual rate of change is zero, and the rate of change of the rate of change is also zero, just like a car that is no longer accelerating.
Taking one step further out on the intellectual limb, this appears to present an insoluble problem for AGW. So long as CO2 concentrations are increasing, there are only three reasons the second derivative can be near zero:
Taken as a whole, which average global temperature does, the rate of change can decrease to zero only if the Earth's energy balance reaches zero.
Near as I can tell, there is no explanation that is not fatal to AGW. So far as I have read, this has gone completely unmentioned.
That must mean I am wrong. But I can't figure out how.
Sounds pretty serious. In fact, it might be.
However, parsing this portion of the press release indicates that what it doesn't say is just as telling as what it does. Clearly, since 2009 ranks in the warmest 10 years, warming is continuing.
Maybe, maybe not. Firing up the WaybackMachine© to the days of yore when I was proficient in Calculus, it is worth thinking about derivatives. When we hear of changes in the Earth's average temperature over time, that is the first derivative: ∆T/∆t, the rate of change in a given quantity at a given point. At the moment, with moment defined as the time span between roughly 1950 and 2000, the value of the first derivative is roughly -- and working from memory here -- 0.2C/decade.
Taking things one step further, the second derivative describes how much the rate of change is changing. Think of a car accelerating from a stop to its top speed. At each tick of the clock, the car has an acceleration rate. However, over time that rate changes: it is very high at the start, and reaches zero at its top speed. The second derivative is negative, strongly at first, before reaching zero at the same instant the car is no longer accelerating.
So what does this have to do with global warming? Global warming can have come to a stop, and still have the warmest years in the record. If average temperatures are no longer increasing, the annual rate of change is zero, and the rate of change of the rate of change is also zero, just like a car that is no longer accelerating.
Taking one step further out on the intellectual limb, this appears to present an insoluble problem for AGW. So long as CO2 concentrations are increasing, there are only three reasons the second derivative can be near zero:
- The rate of change is unchanged, but this is excluded because none of the previous ten years are the warmest.
- Feedback is much less positive than AGW adherents believe.
- The earth is getting less energy from the sun than it did before 2000.
Taken as a whole, which average global temperature does, the rate of change can decrease to zero only if the Earth's energy balance reaches zero.
Near as I can tell, there is no explanation that is not fatal to AGW. So far as I have read, this has gone completely unmentioned.
That must mean I am wrong. But I can't figure out how.
posted by Hey Skipper at 3:29 PM
72 Comments:
The smoothed 2nd derivative is negative at this point, indicating a concave down curve.
This isn't necessarily fatal to AGW. This could just be noise (i.e., natural climate variability) added to an AGW signal.
On the other hand, it certainly calls into question, the robustness of the GCMs which didn't predict this.
But the main problem is that it lets the natural variability cat out of the bag. If the natural variability can cause temperatures to stabilize and/or even go down for a while, who's to say how much of the past increases in temperature can be attributed to natural variability?
(i.e., natural climate variability) added to an AGW signal..
That is precisely what doesn't wash with me.
Utimately, AGW theory treats the earth as a radiating body, and the equilibrium temperature -- i.e., the average displacement from some defined zero point (it doesn't matter what that point is) -- of the earth increases as CO2 concentration increases.
Consequently (keeping in mind the caveat that I am wrong, I just haven't figured out how yet), natural climate variability simply doesn't apply. Colder in someplace this year is balanced by warmer in someplacelse. Summed over the whole, which is what average global temp does by definition, Earth's temperature must continually increase with increased CO2 concentration, ceteris parebus.
Those last two words are where the trouble lies. So far as I can tell (repeat caveat), the only places where ceteris is not parebus are holes below the AGW water line.
BTW -- I'm glad to hear that I didn't commit gross crimes against calculus.
'who's to say how much of the past increases in temperature can be attributed to natural variability?'
I am going to say that, for the 11th c., all of it. And so long as the 11th c. was warmer than the 20th c., the I am going to ask Mr. Ockham to rule that there's nothing to explain about warming.
Hey Skipper,
I'm probably just tired, but I can't seem to decipher your response to me. Please try again if you get a chance - why doesn't that wash with you?
Harry Eager wrote: "..so long as the 11th c. was warmer than the 20th c."
Personally, I have no faith in the reconstructions going that far back. While historical studies seem to indicate a warmer period in Europe and Greenland, nobody has any clue what was happening in the southern hemisphere or much of the rest of the world, so the warming may or may not have been global.
Oh come on. No one is saying that AGW is the only thing affecting global temperature. All sorts of other things affect it - distance from the Sun, average cloud cover, El Nino events, experimental error reading instruments, etc. The claim is that AGW will create a trend of increasing warmth - but there will be ups and downs within that trend.
So your three options are not mutually exclusive. The underlying rate of change may remain but other affects may cause temporary fluctuations from that trend.
This seems so mind-blowingly obvious I think I must have missed something.
Bret:
It may well be that my response was undecipherable, no matter how much rest you might have.
I don't see how climate variability can answer for the second derivative of average global temperature going to zero. First, it is an answer that answers nothing; what element of global climate (is there even such a thing?) changed in order to offset continuing increases in atmospheric CO2? What's more, if there is an answer to that question, it seriously calls into question catastrophic AGW's insistence upon positive feedback.
Second, (SFAIK) AGW theory and modeling never predicted, indeed, would have completely contradicted, the possibility that the Earth's radiative budget would balance over a decade despite increasing CO2. While I wasn't thinking of it when I wrote this post, I think a few of the CRU emails say precisely the same thing.
Mark:
If you had asked for the consensus opinion of climate scientists in 1998 about global temperature trends for the next ten years, what would the answer have been?
As for what affects global temperature, each of your listed options, while valid, don't change things.
Precession of the Earth's orbit matters, but not over a ten year period. Average cloud cover certainly would, since clouds are reflective the radiation would go right back to space regardless of CO2. However, what would globally increase cloud cover (presuming such a thing actually happened)? Well, CO2 mediated increase in temperature is supposed to increase water vapor, which is supposed to add positive feedback. Unless it leads to increased cloud cover ( at which climate models are notoriously bad).
Experimental error is presumably a common mode problem; that is, it existed just as much before 2000 as after.
El Nino events have to somehow increase the earth's LW radiation (or increase SW reflection) in order to make a difference. Do they?
Of course, there is the sun's part of the energy balance. It is on the verge of setting a record for the fewest number of sunspots in a year. Unfortunately, I remember climate scientists denigrating the notion that the sun was a significant contributor to warming in the nineties…
The first of my three options is excluded by the evidence. The second two are not mutually exclusive. However, AGW didn't account for either.
I must note that headline writers at the NYT don't have a clue: No Slowdown of Global Warming, Agency Says.
The decade is the warmest on record, and global warming has not just slowed down, it has stopped.
Skipper, you are forgetting that the left uses semantics not to inform, but to obfuscate, ergo the statement in the NYT headline, No Slowdown of Global Warming, is absolutely correct.
You said it yourself, GW hasn't slowed down. The fact that it's stopped isn't information the NYT deems necessary for their readers to know.
Hey Skipper,
Please plot y = x + 5 * sin(x/4) for the range 0 < x < 100. Consider x to be years from the present and the result (y) to be, say, hundredths of a Kelvin degree above current temperature.
The linear term (x) could represent the AGW signal. The other term (5 * sin(x/4)) could represent natural variability including solar activity PDO, AMDO, ENSO, etc.
This simple function shows ten year periods of cooling alternating with twenty year periods of stronger warming, much like we've seen over the past 150 years.
Is this function accurate? Of course not. The point is that the temperature drivers could be something like that - an AGW signal combined with some oscillations and/or noise which result in up and down periods but overall trending up.
'Personally, I have no faith in the reconstructions going that far back. While historical studies seem to indicate a warmer period in Europe and Greenland, nobody has any clue what was happening in the southern hemisphere or much of the rest of the world, so the warming may or may not have been global.'
Bingo!
I have no faith in the reconstructions even going back to 1998 (when, as I never tire or reminding people, no direct observations were being made).
Still, we know for a certainty that the 11th c. in Europe was warmer than the 20th c. in Europe. I can also cite evidence that the 6th c. in Europe was warmer than the 20th c. in Europe. (It's at RtO today, in fact.)
It's like Oakland. There's no there there. Mr. Ockham says that if you don't have evidence that things are warmer, you don't have to explain why it's warmer.
The linear term (x) could represent the AGW signal. The other term (5 * sin(x/4)) could represent natural variability including solar activity PDO, AMDO, ENSO, etc.
Do the PDO, AMDO, and ENSO change the earth's radiative balance, or merely shift temperature and rainfall around the planet? (Honest question, actually. I have assumed that things like the PDO change the weather where I live, but have no effect on the global average temperature.)
If they actually change the radiative balance, then climatologists should have seen this coming. They didn't.
Do the PDO, AMDO, and ENSO change the earth's radiative balance, or merely shift temperature and rainfall around the planet? (Honest question, actually. I have assumed that things like the PDO change the weather where I live, but have no effect on the global average temperature.)
If they actually change the radiative balance, then climatologists should have seen this coming. They didn't.
I am sure they do affect global surface temperature - although I am not sure why. The high temperatures of 1998 are routinely explained in terms of an El Nino and all climatologists that I have read (sceptical and warmers) accept this explanation.
I don't think it is the radiative balance. Is it not possible that they cause a temperature change in surface temperature by exchanging heat with the ocean and the atmosphere?
To insist the climatologists should be able to predict short (< 5 year) fluctuations round a longer term trend is a big ask and their failure to do so does not invalidate their longer term predictions.
Hey Skipper wrote: "Do the PDO, AMDO, and ENSO change the earth's radiative balance..."
Yes. Stored hot water in the pacific warm pool is distributed across the Pacific which warms the average surface temperature across the globe and changes the radiative balance.
The above is specifically an example of ENSO.
There is an easier response to this announcement, which is that it is completely unconvincing. It is based on the CRU historical temperature reconstruction, which CRU can't reconstruct and which is based on raw data they no longer have.
Notice how the press release goes out of its way to suggest (falsely) that its conclusion is based on simple instrument readings (that is, that they've been reading thermometers around the world since 1850, and those readings show increasing temperatures).
Of course, not being convinced that 2009 is one of the 10 warmest years on record is not the same as concluding that it is not.
David
As it says in the press release:
he WMO global temperature analysis is thus based on three complementary datasets. One is the combined dataset maintained by both the Hadley Centre of the UK Met Office and the Climatic Research Unit, University of East Anglia, United Kingdom. Another dataset is maintained by the National Oceanic and Atmospheric Administration (NOAA) under the United States Department of Commerce, and the third one is from the Goddard Institute of Space Studies (GISS) operated by the National Aeronautics and Space Administration (NASA).
The CRU is only one of three datasets. As it happens the three more or less match.
It is true that there are direct temperature readings since about 1850 (as opposed to using proxies such as tree rings before then). Of course they have to be processed in some intelligent way to come up with a usable trend - at a minimum there has to be some basis for averaging the figures. Is this what you are objecting to?
Mark:
The three data sets are not independent. That's what WMO means when it says that the three repositories "develop and maintain homogeneous global climate datasets based on peer-reviewed methodologies."
You're just wrong about the instrument record. Only a very few stations, clustered geographically, have uninterrupted records from 1850, and careful parsing of the press release shows that WMO is aware of that. Presumably, for example, we don't have satellite data since 1850. What we have is satellite data over the last few decades that has been "homogenized" through a process that cannot be reproduced.
Mark;
David's comment plus you write
"Of course they have to be processed in some intelligent way to come up with a usable trend"
Of course, we have no idea if the raw data was processed in "some intelligent way". It is precisely that processing that has been concealed at great effort. It is the refusal to provide that information that makes what the CRU and effectively all of the "climate research" non-scientific. As the CRUtape Letters are perused it is becoming clear precisely why they didn't want to reveal their methods, because "intelligent" is not an adjective an objective observer would apply.
Mark, Bret:
Thank you both for your time -- it helped me to clear a couple intellectual log jams.
I don't think it is the radiative balance. Is it not possible that they cause a temperature change in surface temperature by exchanging heat with the ocean and the atmosphere?
After some reading up on things, it seems that the PDO shifts warm water from where air temperatures do not get measured -- mid-North Pacific -- to where it does get measured -- the eastern Pacific. I didn't have time to look at the others, but the PDO is sufficient illustration for me.
My logjam was due to thinking of the value for earth's average temperature was obtained from space observation, hence thinking in terms of radiative balance, but it isn't.
To insist the climatologists should be able to predict short (< 5 year) fluctuations round a longer term trend is a big ask and their failure to do so does not invalidate their longer term predictions.
Agreed.
David:
Notice how the press release goes out of its way to suggest (falsely) that its conclusion is based on simple instrument readings (that is, that they've been reading thermometers around the world since 1850, and those readings show increasing temperatures).
Somewhere I stumbled upon a graphic showing the locations of reliable temperature readings in 1850. There weren't many, and most of the earth had none.
1900 was scarcely better, and ocean temperatures were not reliably measured until the 1970s.
Mark:
Of course they have to be processed in some intelligent way to come up with a usable trend - at a minimum there has to be some basis for averaging the figures. Is this what you are objecting to?
In principle, no. At least sometimes in practice, yes.
Unfortunately, the methods used to establish continuous temperature records from discontinuous measurements are opaque. On top of that, land use changes and citing problems seem to invariably bias temperature readings upwards.
On a whim, I have looked for places that have not had those issues. Granted, my search hasn't been anything like exhaustive, but over time the results are far less alarming than the global average temperature would indicate. (I'm too pressed for time to provide links, but using a google search string along the lines of "[location] temperature 1930 1940 1950 1960 1970 1980 1990 2000" produces reasonable results.)
Mauna Loa's warmest year was 1998. In my previous post, I cited a central Alaskan network that shows essentially no warming over 80 years. Greenland (see page 9) appears similar. (Yes, I am aware a skeptic wrote the piece, but the data seems unimpeachable.)
To be clear, I am persuaded that increasing CO2 causes an increase in average temperature. I am far less persuaded climate is particularly sensitive to those changes. And I wouldn't be the least bit surprised if the intelligent way to merge discontinuous temperature series wasn't at least a little affected by confirmation bias.
Like David, I agree the announcement is completely unconvincing. Indeed, its very premise is dead wrong. And, per David, the problems with the CRU historical temperature reconstruction taints the entire enterprise. There is no way of telling whether there are common mode problems between the three data sets.
Interestingly, should anyone actually be able to unscrew the CRU mess and produce results substantially different, then faith in NOAA and GISS data must suffer.
I am persuaded that increasing CO2 causes an increase in average temperature.
Why? I agree that there is a theoretical case to be made that this is true, all other things equal. But as far as I know, there is no empirical evidence that, in nature, this is how things work. To the extent we have evidence, it's that rising CO2 follows temperature increases.
Congratulations to Hey Skipper for taking an opposing argument seriously and even modifying his views based on that argument. In my experience this is almost unknown in internet debate on climate.
David:
The three data sets are not independent.
What do you mean? They are all based on the same raw data - but that is hardly the point. If you are suggesting that they actually process the data in the same way or use each other's results then I must ask you for a reference. NASA is remarkably explicit about how it creates the record and makes the software publicly available. http://data.giss.nasa.gov/gistemp/ There is no mention of CRU.
You're just wrong about the instrument record. Only a very few stations, clustered geographically, have uninterrupted records
I wrote:
It is true that there are direct temperature readings since about 1850
Your statement is compatible with this and it is not "plain wrong". Actually there have been direct temperature readings since 1659 (Central England Temp record). Clearly the number of records has steadily increased since then and someone decided that in 1850 there were enough to justify combining them to estimate global temperature. I suggest that this decision is best left to experts in the field. The fact that they are not continuous is a problem but one that is met and overcome all the time as stations go out of use or move. That is another reason why it is necessary to process the data.
Susan's husband:
Of course, we have no idea if the raw data was processed in "some intelligent way". It is precisely that processing that has been concealed at great effort. It is the refusal to provide that information that makes what the CRU and effectively all of the "climate research" non-scientific.
As I said above NASA is explicit about how it processes the data and provides the software. I believe CRU does so as well but has been criticised for not providing sufficient documentation. (I will check this when I have more time).
David asks: "Why?"
Because it's extraordinarily unlikely that adding a greenhouse gas to the atmosphere will cool the globe. It may cause negligible warming because of other negative feedbacks, but it almost certainly will cause at least a tiny bit of warming.
The fact that temperature changes preceded CO2 changes during the ice ages does not exclude the possibility of a small positive feedback loop between temperature and CO2 levels. I've looked at that data and have determined that virtually nothing can be said about the link between CO2 and temperature other than CO2 can at most be responsible for a minority of the temperature fluctuation during the ice ages.
Mark Frank wrote: "In my experience this [modifying view] is almost unknown in internet debate on climate."
I was once a supporter of the concept of doing something about AGW but over the last few years, based on extensive reading, have concluded that it's very foolish to waste money trying to do something about it. My explanation is here.
I think people are modifying their views at a pretty rapid rate as shown by various surveys.
'That is another reason why it is necessary to process the data.'
And, unlike CRU, GISS does reveal something (but not everything) about how it adjusts the observations.
One thing it does is adjust one temperature according to other stations within 600 miles. Because, as we all know, knowing what the temperature is in St. Louis allows you to know the temperature in Chicago to within a tenth of a degree.
Among the questions about this method are: what is the effect of adjusting within a 600-mile circle for, say, Des Moines; vs. adjusting for a 600-mile circle for, say, San Diego?
Ah, my mistake - I confused Hansen with NASA, the former being the one who fought to valiantly to keep his methods secret despite using public funds. Two points, though --
1) Does the openness of NASA cover for the hiding by Hansen and CRU, given the greater prominence and reliance on the latter?
2) Not everyone thinks GISS successfully overcomes the spotty data. I think this skeptic lays out quite a convincing case.
This one isn't bad either.
The data is, in my opinion, at best, somewhat suspect. The two links provided by Susan's Husband provide some of the reasons.
I pretty much only trust the satellite data at this point, knowing that it has some issues as well. It's available since 1979 (for the lower troposphere) and shows a warming trend of about 1 C per century.
That's it.
The 3 not-so-independent series are CRU (Hadcrut, Phil Jones), GISS (NASA and Hansen) and NOAA.
I am not aware that any of them is completely open about what stations it uses, why it doesn't use other stations and what it does to the data it does use.
Merely being transparent is not the end goal. Some of the adjustments that GISS makes look squirrelly to me.
The sixth-grader is using adjusted data, I believe.
That doesn't detract from what he found, necessarily. But he might not have found UHI. He might have found adjustments that mimic UHI.
A visit to surfacestations.org, if you haven't already, is interesting. Among the problems with the stations themselves that amused me was that in big snow areas, the sensors are place around 14 feet up, instead of the standard eyeball height, with a corresponding imputed deviation from the norm, although as far as I can see, that is one adjustment that is not adjusted for.
It's a dog's breakfast all around.
David:
Why? I agree that there is a theoretical case to be made that [CO2 causes an increase in average temperature] is true, all other things equal.
Because I am sufficiently satisfied with the theoretical case, and am willing to take it as read. Besides, the crux of the matter is not CO2 itself, but knock-on effects. Those I do not buy.
Mark:
As I said above NASA is explicit about how it processes the data and provides the software.
This from the same agency that trashed a Mars lander because it couldn't figure out English - Metric conversions. Or nearly trashed a certain space telescope because it couldn't be bothered to check a certain mirror's focus.
[/snark off]
The link that Susan's Husband provided was truly illuminating. I had no idea how, well, invented, the global average temperature numbers are. That, in and of itself, does not invalidate AGW -- after all, all those numbers could be wrong, but understating, instead of overstating, CO2 effects.
However, remembering the magnitude of AGW predictions over the years (smaller, longer term), my bet is not with understating.
++++
Time for ignorance on parade. Given the increase in CO2 over the last 150 years, does that translate into an increase in average sea level pressure?
Skipper;
Here is some very interesting temperature data. It nicely illustrates one of the valid skeptic positions about warming and its consequences.
As a general proposition, to be accepted a causal explanation requires at least two and if possible three components: compelling theory; wide-spread, longitudinal empirical evidence from multiple sources that does not contradict the theory; and, if possible, multiple experiments from multiple experimenters. (Technically, lab experiments are the only legitimate basis for causal statements, but some issues do not lend themselves to experiments.)
I would argue that AGW has none of these, but it certainly doesn't have either widespread, longitudinal, multi-sourced, non-contradictory empirical data or experimental support.
Mark: The data is not independent because (a) it comes from the same source and (b) the three sources admit that they use the same peer reviewed, established methods. Moreover, we actually don't know that GISS doesn't just use the CRU homogenized data (and we have some reason to think that it does). "Independence" doesn't mean that the numbers are run through the same calculation by different people.
I read both WMO and your comments as trying to suggest that what the climate scientists are doing is simply reading thermometers, a suggestion that minimizes error. In fact, they are blending different sources and different types of measurements that they are manipulating in ways that can easily be swayed by their bias ("Hey, this doesn't look like CRUs result, we'd better keep trying").
What you are saying, in effect, is that we have no choice but to destroy our current standard of living based on our faith that certain scientists are both right and honest in doing calculations that they do not disclose.
I like to stop the discussions at 'no evidence.'
Too many skeptics, it looks like to me, are reasoning backward: The cure is worse than the disease, so I'm disease free.
Further, that's how the believers look at the non-believers, which lessens the (already small) chance of persuasion.
Even if GW is all-natural, nothing to do with burning coal, if it's as bad as their models predict, we still have to go live in caves.
Harry Eager wrote: "Even if GW is all-natural nothing to do with burning coal, if it's as bad as their models predict, we still have to go live in caves."
Why?
Even the worst projected outcomes aren't all that bad, not to mention that every issuance of the IPCC has less catastrophic projections, a trend I see no reason not to expect to continue.
Moreover, there are various geo-engineering solutions which could ameliorate the problem. Best of all those solutions make the source of GW irrelevant. The opposition to such things by the warmenists is yet another indication of how preventing damage from GW is not their actual goal.
sarc on/
If we have to abandon modern ways because it is warmer, then we have to abandon modern ways because it is warmer.
Count me a skeptic about geo-engineering, too.
If the primary driver of climate flux is variation in the Earth's orbital path (which we are at least sure exists), then there may not be any way to titrate the temperature.
David wrote: "I would argue that AGW has none of these [theory, empirical evidence, multiple experiments]..."
I think that may depend on how you define AGW. That CO2 is a greenhouse gas certainly has theory, evidence, and multiple experiments. That burning fossil fuels adds CO2 to the atmosphere has theory, evidence, and multiple experiments. That man is digging up and burning fossil fuels is directly observable. That CO2 concentration is increasing is also directly observable.
That, all else being equal, AGW would be happening therefore satisfies your requirements for a causal relationship. The only question is how equal is all else.
Sure it has theory, which can be summed into a sentence: carbon dioxide levels dominate climate to the exclusion of every other physical process.
Harry,
That would be an alarmist theory for which there is no solid evidence. The more moderate theory of CO2 having a strong probability of increasing temperatures somewhat is better supported.
Bret: There certainly is theory for the proposition that CO2 is causing global warming, but is it strong theory.
CO2 is a greenhouse gas, but it is only .038% of the atmosphere. Is that number really sufficient to have a measurable effect on observed global temperature? Is that a strong theory? Atmospheric CO2 released by human action is about 35% of all atmospheric CO2. Is the difference between .025% and .038% really sufficient to give rise to a strong theory of AGW?
We don't really have to worry about this because of the lack of supporting evidence, but I don't really consider it to be a strong theory.
CO2 is a greenhouse gas, but it is only .038% of the atmosphere. Is that number really sufficient to have a measurable effect on observed global temperature? Is that a strong theory? Atmospheric CO2 released by human action is about 35% of all atmospheric CO2. Is the difference between .025% and .038% really sufficient to give rise to a strong theory of AGW?
This is one of the more clearly refuted objections. Without any greenhouse gasses the earth would be some 33 degrees C colder (http://en.wikipedia.org/wiki/Greenhouse_gas). It is true that water vapour (0.5%) is the major contributor but the 0.025% is also a significant part (it is hard to separate out contributions because they are not additive). So it is not unreasonable that another 50% increase in CO2 would increase temperature by a few degrees.
Another way of thinking of it is that is the amount of greenhouse gasses that matters. It doesn't matter how much of the other gasses are present (not quite true - if the CO2 proportion becomes very high than other effects kick in)
Mark: No one (by which I mean scientists in the field) thinks that.
The direct effects of doubling CO2 in the atmosphere is thought to be about 1 degree and 1 degree is not associated with catastrophe. The entire, you should excuse the expression, science of catastrophic AGW requires what you dismiss as add-on effects; that is strong positive feedback.
For the record, though, I entirely accept that CO2 is a greenhouse gas.
Molecular nitrogen is a greenhouse gas.
'That would be an alarmist theory for which there is no solid evidence.'
I agree there is no solid evidence for the theory, but I have solid evidence that that is the theory. I have just finished Schneider's 'Science as a Contact Sport,' for example, and that is his theory.
I would go so far as to say that it is the theory of all the modelers, all of whom believe that their models are sensitive to rather small changes in inputs.
In reality, large changes in inputs seem to produce only small changes in outputs, which is why I consider climate to be, unlike weather, antichaotic.
In technical terms, "chaotic" doesn't mean "widely varying", it means "unpredictably varying". Climate could be chaotic even if the mean global temperature never varied more than 1°C.
David
I am sorry. I did not mean to say that increasing CO2 by 50% would directly increase temperature by a few degrees. I should have said:
So it is not unreasonable that another 50% increase in CO2 would increase temperature by a degree or so.
My point was simply to put to bed that the argument that because the concentration of CO2 in the atmosphere is so low it cannot have a large effect. The concentration is irrelevant.
I think the concentration is relevant, just not important at current levels and anything near them, either way.
My understanding of mathematical chaos is not only that outputs are unpredictable in chaotic systems, but that very small variations in initial conditions can (but are not obliged to, I guess) result in very large changes on later conditions.
If the outputs were necessarily small for small changes in initial conditions, who would care? Not Professor Lorenz.
David asks: "Is the difference between .025% and .038% really sufficient to give rise to a strong theory of AGW?"
With the "all else being equal" caveat, yes.
The percentage of CO2 in the atmosphere is irrelevant since O2 and N2 are largely transparent to long wave radiation leaving water vapor, CO2, and a few other gases with low concentations as the only gases significantly impeding long wave radiation.
At the earth's surface, water vapor overwhelms other GHC's. Indeed, virtually no heat is radiated directly from the earth's surface because of water vapor. Instead, the surface air heats up, then rises, then cools as the pressure drops, then the water vapor falls out, then CO2 plays its main role in reducing outgoing long wave radiation.
The only question is the "all else" part, which I suspect consists of overall negative feedbacks, while most climate scientists believe the feedbacks are strongly positive. If all else were equal, the increase in global temperature would be somewhere in the neighborhood of 1C per doubling.
Harry Eagar wrote: "Molecular nitrogen is a greenhouse gas."
N2 is not a greenhouse gas. N2O and NO are. Are the oxides what you mean by molecular nitrogen?
Mr. Eagar;
"large" is measured in terms of the state space of the system, not by human scales. If the total variance of the system is 1°C, then 0.5°C is large in terms of chaotic systems even if it doesn't seem large to you.
Bret, the way I understand it, N2 is a greenhouse gas, it's just that it is in such oversupply that it intercepts all the possible photons, so its effect on overall greenhouse warming is stable.
Same, as I understand it, with O2.
Harry Eagar wrote: "N2 is a greenhouse gas, it's just that it is in such oversupply that it intercepts all the possible photons..."
If N2 intercepted "all the possible photons", wouldn't it be dark here on earth?
Do you have a reference that explains why you think O2 and N2 are greenhouse gases?
'All possible' means 'all possible.' Atoms can absorb photons only of specific energies.
For abundant gases like nitrogen, all the photons of appropriate energy are absorbed and the greenhouse effect is 100%.
For trace gases, like carbon dioxide, if there are excess photons, they escape.
Lubos Motl had a chalk talk on this some time back.
This could perhaps be the best and longest temperature series available anywhere.
And, so far as I can tell, it is not from source notorious for denialism.
There's some 'splainin that needs doing.
This could perhaps be the best and longest temperature series available anywhere.
And, so far as I can tell, it is not from source notorious for denialism.
There's some 'splainin that needs doing.
The contiguous USA is far from being the longest trend - that's Central England which is monthly from 1659, and daily from 1772.
However, it is one of the best recorded.
But I am intrigued as to how you got this chart. If I go to the noaa website and simply ask for the contigouos USA temperature series up to 2009 I get this which looks very different.
What parameters did you enter to get this graph?
Hey Skipper,
How come you chose to just do Octobers?
Harry Eagar wrote: "Lubos Motl had a chalk talk on this some time back."
Lubos Motl wrote: "The requirement that low-energy transitions must be allowed within the molecule is why the mono-atomic inert gases such as argon or even di-atomic molecules such as nitrogen are not greenhouse gases."
So Lubos and I are in agreement that N2 is not a greenhouse gas.
Mark:
I used this: NOAA contiguous US temperature 1895 2009.
The motivation came from reading a post somewhere else entirely, which showed this chart; however, the url looked suspect.
Anyway, the above search string led to a comment section, which contained the NOAA link to the same chart. That was when I decided it was real enough to use.
++++
You are right about England's temp record being longer; I knew that, but, in the heat of typing, forgot.
Bret:
I didn't use October for any particular reason, other than it is what I stumbled upon.
It is surpassing odd that, with weather being as chaotic as it is, that October trend would stand out in any particular way from the annual trend.
Mark and Bret:
You seem to be mistaking "possible" or "not inconsistent with" with compelling. What's the strong theory of causation?
Of course, your arguments cut the other way: implicit in what you say is that CO2 caused warming is not linear and will be capped. That is, a single proton passing through two CO2 molecules doesn't heat the planet any more than a single proton passing through a single CO2 molecule.
So, given that CO2 increases have always followed temperature increases by about 800 years, that direct effects are weak and capped and that we don't even have theoretical explanations of positive feedback loops, how is the theory of CO2 caused warming compelling?
Hey Skipper wrote: "It is surpassing odd that, with weather being as chaotic as it is, that October trend would stand out in any particular way from the annual trend."
I don't know about "surpassing odd". Maybe slightly odd.
The signal to noise ratio is fairly low. One would expect the signal to be considerably harder to see in an arbitrary smaller sample.
Also, one would expect most of the warming to occur in the winter, though the slightly odd thing is that I would've expected more or less average warming in October.
David asks: "What's the strong theory of causation?"
This is starting to feel like a semantic argument. I believe I've outlined the theory of causation. I'm not sure which part your not agreeing with. Let's take it one step at a time.
First question: do you believe that the temperature of the earth would be the same regardless of the composition of the atmosphere?
David,
Actually, scratch the last comment. Looking back over my other comments I can see that I've left out far too many details to have described AGW theory adequately. Unfortunately, this comment forum is not the appropriate place to try to convince you.
I've done a lot of reading on the subject and I'm convinced AGW has been and will continue to happen and that the theory is sound.
If you've read enough that you've convinced yourself that adding CO2 to the atmosphere is not going to affect the climate, I'm just going to have to leave you to your beliefs.
Where we do (seem to) agree is that CAGW is not likely to happen (the 'C' is for Catastrophic). That's all I really care about anyway.
AGW is a fine thing, in my opinion. After all, I didn't move to San Diego because I like it cold.
I tried some different ways to find the total series for each month, to little avail.
The October chart comes courtesy of http://www.ncdc.noaa.gov/sotc/get-file.php?report=national&image=timeseries02&byear=2009&bmonth=10&year=2009&month=10&ext=gif&id=110-00
Changing the month parameters to 11 brings up November. But 12, 1, and 01 (all the ones I tried) choke. Truncating the url to http://www.ncdc.noaa.gov/sotc is no help, or at least not to me. I couldn't find a way to specify that chart at all.
There were other oddities, but one worth noting was that Southern hemisphere ice extent is near a record high.
Enquiring minds want to know: why has that not gotten as much press as Arctic ice extent?
Ah I get it. I didn't notice that your chart was only for October - while mine was for all months averaged.
I guess someone went through looking for a month which did not show a warming trend and highlighted that one.
This article explains why antarctic sea ice has increased slightly while artic sea ice has declined rather more.
Bret;
The problem with your view of AGW is similar, in my opinion, to that of water swirling down a drain. There is no doubt that coriolis forces a forcing function for the direction of rotation. However, in practice, the effect is so small on small scales (such as a sink) that it is, for practical purposes, non-existent. You have a clear, indisputable physical theory of causation that is irrelevant.
As I read Mr. Cohen, he's asking whether the same is the case for AGW. Yes, the physical causal chain is clear and indisputable, but does is it large enough to have any practical relevance?
Susan's Husband wrote: "...the physical causal chain is clear and indisputable, but does is it large enough to have any practical relevance?"
Ahhh. So that's what David is asking. C is my first language and English is a distance second, and as a result, I sometimes have trouble deciphering what people are trying to say. :-)
The Coriolis effect and water going down the drain is reasonable example. Water does spin down the drain in one direction very slightly more than the other and if it chooses the "wrong" direction it spins very slightly slower than the other direction. Adding CO2 to the atmosphere makes it more likely to get warmer than it otherwise would've and if other factors overwhelm the warming effects of CO2, it will likely get cooler at a slower rate than it otherwise would've.
Since the climate system is a bit more complex than your sink, it's also possible that this significant impulse to the CO2 input will cause unpredictable results. For example, it may (though I doubt it), after a brief warming period, trigger the next ice age. Who knows? Anything is possible. But I think that the probabilities are that either increased warming or decreased cooling will occur on the timescales that anybody cares about. And I think that the mode of the probability distribution is at approximately 1 C per doubling of CO2 (which is about 1/3 what the IPCC thinks).
Ah, I see I misunderstood Motl.
Perhaps I misunderstood the sea ice press release, as well, but it makes my head hurt to figure out how the somewhat stabilized ozone hole warmed one side of Antarctica and cooled the other.
There's an ozone hole over the Arctic, too, though smaller, but evidently is it not being blamed for retarding the warming there.
There seems a great deal of ad-hockeystickness to it all.
Bret:
You mistake me. I accept that the Earth is warming, although it depends on what time range we use. I accept that CO2 is a greenhouse gas and that the Earth is warmer than it otherwise would be because of greenhouse gases.
I thus understand the theory that adding CO2 to the atmosphere could increase global average temperature. I accept that raising temperatures are associated with increases in atmospheric CO2. Thus, I understand a theory that increased atmospheric CO2 is causing increased temperature.
1. The temperature is increasing.
2. CO2 concentrations are increasing.
3. CO2 is a greenhouse gas.
4. Historically, increases in temperature are associated with increases in atmospheric CO2;
Therefore, increasing atmospheric CO2 increases global temperature.
But this is still a weak theory and not compelling because: CO2 increases in the past have come after increases in temperature, CO2 increases have been small, CO2 causes relatively small changes in temperature, the changes in temperature that could be caused by CO2 are capped, etc.
You seem to be saying that you find AGW compelling based solely on two facts: CO2 is a greenhouse gas, the amount of CO2 in the atmposphere is increasing due to human activity. Is that it? And if so, what do you find so compelling about that that you feel able to draw a causal conclusion.
[By the way, in my field the reviewers will not let us make any causal statements.]
David,
I think we have subtly different definitions of AGW (and yours is more mainstream).
For example, I think that the globe would've warmed over the past 150 years whether or not humans increased CO2 concentrations (or even existed for that matter) and that the globe may well continue to warm whether or not humans continue to increase CO2 concentrations.
So if "AGW = humans -> more CO2 -> global warming", then no, I don't consider the theory to be strong, because the counterfactual of no humans and/or no more CO2 would not necessarily imply no global warming.
But if "AGW = humans -> more CO2 -> globe warmer than it would've otherwise been", I think the theory is strong.
I use the latter definition of AGW.
I think the mainstream definition is in between the two: "AGW = humans -> more CO2 -> most of the observed global warming so far, continuing into the future". I don't believe this causation is strongly supported by theory either, though it's plausible.
'But if "AGW = humans -> more CO2 -> globe warmer than it would've otherwise been", I think the theory is strong.'
My position, too.
However:
AGW = farming -> globe warmer than it would've otherwise been is also a pretty strong theory, and I don't see multitudes clamoring to do away with farming (though there are some).
Mark:
This article explains why antarctic sea ice has increased slightly while arctic sea ice has declined rather more.
The problem with this article is that it is inherently post hoc. Ten years ago, or even five, AGW would have predicted decreasing ice Antarctic extent. When the exact opposite happens, there is a study to show why AGW is consistent with that, too.
In 1998, AGW would not have predicted the second derivative turning south, but it did. As a consequence, AGW became ACC, which explains everything, no matter what.
Put differently, valid scientific theories are hypothetical constructs, from which must come deductive consequences. For example, for evolution to be true, the earth must be very old; otherwise, the theory fails (and there are probably at least a dozen other examples). Of course, that deductive consequences exist and are satisfied does not mean the theory is true, only that it can, in principle, be demonstrated false.
AGW/ACC does not have one deductive consequence; it is a religion.
Bret:
But if "AGW = humans -> more CO2 -> globe warmer than it would've otherwise been", I think the theory is strong.
While I tend to agree with you here, that must mean there is an answer to this question:
What would the Earth's average global temperature be if CO2 concentration remained at 280 ppm (pre-industrial level), ceteris paribus?
If there is not an answer, or at least an answer with an error bar substantially smaller than observation, then the theory doesn't seem so muscular.
Hey Skipper wrote: What would the Earth's average global temperature be if CO2 concentration remained at 280 ppm (pre-industrial level), ceteris paribus?
A bit more than 0.5 C cooler (log2(385/280) * 1.2).
That's the calculation, but, unfortunately, the difference is much too small to be observed.
Although nobody seems to have noticed it, the dustup over Eschenbach's survey of the Darwin temperature series elicited a comment from the Australian Bureau of Meteorology that the adjusted temperatures by the BOM (0.6 C) and the adjusted temps by NOAA (1.0 C) were 'within the margin of error.'
I don't know the internals of the two adjustments, but the result tells me all I need to know.
That's the calculation, but, unfortunately, the difference is much too small to be observed.
Hence my leading question.
I am beginning to understand Peter's gripe about scientism.
There was a little press release (didn't save link) a couple weeks ago in which some Canadians proposed that they could recover past temps very accurately by isotope proportions in wood.
If true, it might answer a lot of questions.
As I understand it, you can recover temps pretty well from things like globergerina ooze but the chronology is imprecise, while you can recover chronologies precisely from wood but not the temps.
Combine the two and, bingo!
Maybe.
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