Bishop Hill Met insignificance
May 27, 2013 Climate: Statistics Climate: Surface This is an ultrasimplified version of Doug Keenan's post this morning.
The Met Office has consistently said that the temperature rise since 1850 is too large to have been caused by natural causes. Questioning from Lord Donoughue elicited the information that they came to this conclusion by modelling temperatures as a straight-line trend (global warming) plus some noise to represent normal short-term variability.
However, would a model in which temperatures went up and down at random on longer timescales, but without any long-term trend at all, be a better match for the real temperature data? Doug Keenan has come up with just such a "temperature line wiggling up and down at random" model and it is indeed a much better match to the data than the "gradual warming plus a bit of random variation" model used by the Met Office. In fact it is up to a thousand times better.
In essence then, the temperature data looks more like a line wiggling up and down at random than one that has an impetus towards higher temperatures.* That being the case, the rises in temperature over the last two centuries and over the last decades of the twentieth century, look like nothing untoward. The global warming signal has not been detected in the temperature records.
*Here I'm only referring to the two models assessed. This is not to say there isn't another model with impetus to higher temperatures which wouldn't be a better match than Doug's model. It's just nobody has put such a )third model forward yet. (H/T JK in the comments)
Reader Comments (193)
rhoda
For a detailed discussion of energy imbalance try this paper.
http://www.atmos-chem-phys.net/11/13421/2011/acp-11-13421-2011.pdf
For numerical values for imbalance and total irradiation try Figures 7 and 17.
Diogenes
Way past my bedtime, so I'll have to keep this short.
Climate sensitivity is the effect of changing something on the equilibrium temperaure of the climate system, land sea and atmosphere. You might regard the Milankovich Cycles as having a climate sensitivity of 5C between maximum and minimum temperatures in glacial and interglacial cycles.
The sensitivity of climate to changes in incoming radiation is generally accepted among the scientists as 3.7W/C.
Most of the currentdebate centres around the effect of increased atmospheric CO2 on temperatures. This is usually defined as the temperature rise likely to result from a doubling of CO2 concentration.
This has two components. First is the direct effect of extra CO2 in slowing heat loss from the surface and troposphere. The other is the secondary effects of cloud cover changes, methane and extra CO2 release, water vapour etc.
The combined effect is the overall climate sensitivity. The processes involved vary locally, but the overall sensitivity is for the planet as a whole, and can be studied using global temperature averages.
"things happen in the atmosphere which we cannot describe qualitatively let alone quantitatively, so we call it sensitivity and assign it a coefficient."
You give up too easily. The proccesses can be observed and quantified. You'll find a lot of papers in the literature describing just that, complete with uncertainties and 95% confidence limitsso you can judge how reliable or unreliable they are.
You do not strengthen your muscles by complaining they are weak. You exercise.
Similarly you do not learn by complaining how impossible it all is. You do science and keep doing it to improve your understanding. At any one time that understanding is imperfect, and improving.
I take the research done at face value, and draw the best conclusions I can from it. As further research improves our knowledge, so my conclusions change.
Goodnight
Richard Betts (May 31, 2013 at 11:47 PM):
Figure 1(b) of the Met Office paper gives the forcings per GISS. However, GISS forcings are significantly different from those of AR5 figure 8.18, most notably in its larger aerosol factors. I assume that the MO are aware of the differences between GISS forcing figures; perhaps you could inquire why the GISS values were chosen rather than those of other sources which are relied upon in AR5.
EM: "The sensitivity of climate to changes in incoming radiation is generally accepted among the scientists as 3.7W/C."
First off, I assume that the units contain a typo, and that you intended 3.7 Wm-2/K (deg C if you insist). However, I believe you do your cause a disservice; as you computed, that figure results in a climate sensitivity of about 1 K/doubling, which certainly does not correspond to AR4's value. Hansen, for example, suggests a value of 0.75 K/(Wm-2); inverting it to match your units gives 1.3 Wm-2/K.
However, your approach is a mishmash of equations; if you are trying to estimate the sensitivity from observations, you should be using equation (1) or (2) from Otto et al. rather than pulling a value of 3.7 from somewhere.
Good Grief - you guys have been at it all night!
EM, thank you for your detailed reply. I will need some time to condider it, along with Harlod's comments, and all of the references that have been quoted. At this point I would be particularly interested to know which of these numbers the Met Office are using - Richard, are you still around?
Thanks to all who have been providing hard numbers.
EM, thanks for the link. I skimmed the paper. Evidently it would take a lot of time and knowledge to properly understand it but a few 'dig here's came out. They are taking large estimates and subtracting other estimates and modelling outputs to get a small result. Surely that approach is fraught with danger because the errors of the first guesses are larger than the result. Now, there are a lot of conceptual problems and methodological questions and apparent non sequiturs too, but I can't in honesty separate them from my overall suspicion of the convenience of the result for warmists and the name at the top. I can't be fair, my BS alarm is ringing too loudly. I have an observation or two which I am going to rephrase as questions and put on the discussion page. Leaving that aside, I think even their result falls into the category of 'not much is happening', which is my own hypothesis at the moment.
Rhoda,
In his calculation of net forcing Hansen says (in his paper) that forcing due to GHGs is "known accurately", but that forcing from aerosols is "practically unmeasured". He then equates them as being almost equal and opposite over the last decade, and rambles on about other "known unknowns" such as clouds and ocean heat uptake.
I gave up reading at that point. This is nothing to do with science, as I know it...
Entropic Man, thanks for supporting this thread with rational discussion; as I’ve said before, it’s quite a rare thing in relation to CAGW. However, what follows is more of a personal ‘rant’ than a point-by-point rebuttal of your comments as I think we’ve reached the point where we can only agree to disagree.
Give your comments and those of the other contributors, I think we all have defendable reasons to support our conclusions but the key discriminator is our belief in both the fidelity of the data and the balance of risk associated with mitigating actions.
My personal view is that there may be problem but that its scale and urgency has been far overstated and, worst of all, used in a very cynical and immoral way to exploit the fears of ordinary people in order to achieve both political and financial gains. Moreover, the old story of ‘ Cry Wolf’ seems very applicable because, if we ever should find that there really is a serious problem, no one is going to believe the science until it’s too late. Indeed, that was what got me both interested in and concerned about CAGW theory back in 2006 when I first saw ‘An Inconvenient Truth’, which left me muttering to myself the words “a prostitution of science in the name of political correctness” and nothing I’ve learned since has given me any reason to change that view – on the contrary, it’s actually reinforced it.
Although I’m an engineer, I was trained as a scientist and so I appreciate there are many competing theories and some, like String Theory, are defended strongly by many even though they cannot yet be tested in the real-world. However, such theories are not being used to justify major national and international policies on both energy and the environment that have both direct and immediate impacts upon millions of people (e.g. preventing third-world countries from utilizing cheap fuels like coal). Therefore, scientists cannot and should not let their theoretical ideas be hijacked to justify such policies while there is serious doubt about their correctness; especially if alternate policies, such as adaptation, offer far less draconian ways forward but are ignored for the sake of political expediency… “there is a problem; we must do something; this is something, therefore we have to do it”.
Rhoda
THere are two ways of deriving enrgy flows.
The first is energy budgets. Measure and calculate the energy required to expand seawater, melt ice sheets, warm the atmosphere etc each year as observed.Add them together and you get the extra energy required.
The second method is to take the external approach. Use satellites to measure the solar input and sample the outward energy flow from different parts of the Earth to integrate them into an overall value, mostly for the OLR.
Roger Longstaff
The satellite designed to measure the effect of aerosols was destroyed when it failed to reach orbit. Until it can be replaced aerosols remain a "known unknown". We're stuck with incomplete information and have to infer what's happening as best we can.Care to lobby for a new satellite?
David Salt.
Too much to say. I'll get back to you later.
David Salt
"Just about everyone thinks they are doing the right thing.Or they've convinced themselves that they're doing the right thing, and that others must be both wrong and self serving."
Jack Campbell
This is behind a lot of the political side of the debate. If the other guy opposes your position there is always a temptation to think they have an ulterior motive. Out of that comes the concepts of the "rent money" climate scientist, the oil company stooge and the politicians bribed ( Sorry, "given campaign donations") to support either position. This is important to the political and economic interests involved, who stand to gain or lose according to the policy decisions made.
I'm not much interested in the politics. I want to know what the planet's doing.The information for that comes from scientific research with its limitations and uncertainties.
Rhoda, Roger and David have all expressed an unhappiness with the scientific papers. This comes across as a distrust of the evidence and presents a problem. I perceive myself as using scientific evidence to support my arguments. If all the scientific evidence is unreliable, on what evidence do you base your positions?
Most of you hypothesise that climate is relatively stable and that our CO2 release is not a problem. If you have no evidence, that becomes an assumption based on faith, rather than an evidence-based opinion. The famous "null hypoothesis" of stability is also an assumption, based on your perceived lack of evidence for any alternative.
Without evidence, how do you distinguish between "We're going to freeze!", We're going to fry!", or any of the positions in between?
HaroldW
Watts/M^-2/K is indeed the preferred unit.
My mishmash of equations comes from a habit of using back-of -the envelope calculations to check that something more complex is about right. For example, I encouraged my pupils to check eg. 97*203 done on a calculator by doing a mental sum of 100*200. This gives them an approximate idea of the answer (20,000) and warns them of mistakes like getting 196,910 because of a decimal place error.
My calculation here was not intended to be definitive, just to get an idea of the right ballpark to find the real answer in.
Entropic Man (Jun 2, 2013 at 6:15 PM) said "Rhoda, Roger and David have all expressed an unhappiness with the scientific papers. This comes across as a distrust of the evidence and presents a problem."
For my part, there's certainly distrust of the likes of Mann and Hanson. However, the majority of my 'scepticism' is based upon the quality of the empirical data (i.e. the signal to noise ratio) and, more importantly, the fact that there's still major uncertainties in both the chain of physical processes and the processes themselves that contribute to CAGW. I therefore tend to align myself with Freeman Dyson, who makes a very persuasive case for this type of 'scepticism'.
What struck/shocked me most particularly was when I read through the AR4 WG1 papers and saw the candid statements about uncertainty, especially related to the effect of clouds and vegetation, along with the incompleteness of the models (see my comment on this thread on May 28, 2013 at 10:08 AM). Moreover, when I posted my concerns over at Real Climate (I can provide the links if you're interested) I met with rather 'negative' comments and told to decide which side I was on... not a very scientific way to debate the subject, in my opinion!
EM: "Care to lobby for a new satellite?"
Yes, I would. Davr Salt and I have worked in the space industry for many years, and he would have a better idea, however, this is what I already posted over on the discussion thread:
"I have often thought of ways to measure a global TOA radiation budget. One idea is to place two spacecraft at the L1 and L2 Lagrangian points respectively (permanently facing the illuminated and dark faces of the Earth respectively). They could continually monitor the total radiation budget of the planet, integrated over all frequencies, and detrive any imbalance that would shift the diurnal thermodynamic equilibrium of the Earth. This would cost something like $2 - $3 billion, over a period of about 15 - 20 years, but at least it would give hard answers."
They could also directly measure albedo, presumably including any aerosol effects.
Dave would probably have a better idea / estimate, but in my opinion this would be money well spent if it saves humanity from bankrupting itself on what is probably a non-existent problem.
Dave |Salt
There are people on both sides who tend to climb into their bunkers and regard any contrary comments as warfare. You met them on RealClimate. I meet them here.
It doesn't help the science.
All science is uncertain. Good scientists are candid about it and try to manage it. They give 95% confidence limits and define areas where their understanding is incomplete. IPCC was tasked with summarising the science and forecasrting future conditions for policy makers. Defining the uncertainties was part of their job. Their output was a survey of the evidence, followed by a set of possible climate outcomes, with probabilities arttached. This is what they were asked for.
The potential trap is to take a two valued approach. If you say " There is uncertainty so it is impossible to infer anything", you veer too far into the assumption that nothing can be known.
If you say" The uncertainty is not significant, so we can confidently make exact predictions", you veer too far into dogmatism and overconfidence.
In fact, there are infinite shades of grey between these two positions. One skill of a good scientist is to walk the line between them. Uncertainty should be a tool to guide priorities in further investigation, not a debating weapon.
You are probably familiar with cognitive dissonance and confirmation bias. We all tend to give higher weight to anything that appears to confirm one's own opinions and disregard anything that contradicts them. When challenged, we can all manufacture rational reasons why.
How,then, does one objectively judge evidence for climate change while climate change advocates apply confirmation bias and climate change sceptics apply cognitive dissonance to the same evidence and both sides regard themselves as correct?
To what extent is my acceptance of the evidence confirmation bias and your distrust cognitive dissonance? How do we get around both and get a genuine picture of what's actually happening under the sky?
This is not just a problem for climate science. You should watch economists argue sometime!
EM, I am conscious that I may not be right and that most of us, all of us probably, form our opinions first and justify them later. The more intelligent the easier to justify anything. That's how very clever well-educated people may have opposite opinions
"Most of you hypothesise that climate is relatively stable "
Not quite. I think there is a top limit to temps which is apparently not dangerous and a bottom limit which definitely is. I fear an ice age but I am not bothered by the prospect of a bit more warmth. That the climate moves between two limits is consistent with what we see in the paleo record. Not exactly stable but not easily perturbed.
EM, you ask: "If all the scientific evidence is unreliable, on what evidence do you base your positions?"
I would say on the evidence for colder (LIA) and warmer (MWP) periods in the past. Surely you do not dispute this? If you do not, would you not naturally expect up be in the middle of a natural warming cycle between colder and warmer conditions? If so, there is no need for AGW, and definitely no need to panic about CAGW.
We really should be looking for an explanation for the LIA and the MWP. Planetary dynamics could be a good place to start.
Entropic Man (Jun 2, 2013 at 8:07 PM) said "How,then, does one objectively judge evidence for climate change while climate change advocates apply confirmation bias and climate change sceptics apply cognitive dissonance to the same evidence and both sides regard themselves as correct?"
I think you're overly concerned with tackling extremist views and not considering the more common sense view. If this is science, then let's judge it via the scientific method: use the theory to develop a hypothesis; propose a real-world test/observation that can unambiguously verify or falsify the hypothesis; modify the theory accordingly and develop another testable hypothesis... repeat until funding/patience/time runs out :-)
I believe that several tests for CAGW have been proposed (e.g. global temperature projections, tropospheric 'hot spot', Antarctic warming) but none have yet proved conclusive, though many believe they tend to falsify the theory. Anything else is just guesswork and so, if I ruled the world, I'd be spending money on better and more comprehensive data collection systems. I’d also invest in research into practical renewable energy sources and more efficient energy transmission/conversion systems. There are good reasons to wean ourselves of fossil fuels and become more energy efficient… it’s just that, in my opinion, CAGW isn’t one of them.
Once again differences in interpretation of evidence leads us in different directions.
Rhoda
I would like to be wrong on this. It would be comforting. Unfortunately I have been unable to overcome my own confirmation bias. :-)
"That the climate moves between two limits is consistent with what we see in the paleo record. Not exactly stable but not easily perturbed."
Unfortunately the two limits are 5C and 80ppm CO2 apart for the full glacial/interglacial alternation. One hypothesis is that 1C is due to Milankovich variation and the other 4C to temperature /CO2 feedback. That implies a change up or down of 1C for every 20ppm CO2 . We've put in 120ppm since 1850. I hope "not easily perturbed" is a powerful constraint!
Roger Longstaff
We may already have explainations for both.
The warmth and gradual decline from the MWP fit the pattern seen in Marcott et al and elsewhere, as we are past the peak of the current interglacial and should be cooling.
The LIA coincides with the Maunder Minimum, a prolonged sunspot minimum which, if modern behaviour is a guide, would have accompanied a reduction in solar energy output.
Radiation budget satellites at L1 and L2 would be an excellent idea. Each satellite would see any point on Earth once daily under the same conditions.. An alternative would be three satellites in geostationary orbit, each giving 24 hour coverage of its target area.
Both share the same problem. The fastest and slowest warming areas on the planet are in the Arctic and Antarctic, and either orbital option would only give shallow slant coverage in those areas. Would an extra satellite in high polar orbit be viable?
There would also be another possibible opportunity here. Could operation and data collection were delegated to different agencies? It would avoid the current funnelling of so much satellite data through NASA and reduce the resulting unease of Dave Salt and others.
Have you noticed another developing problem? One NASA GOES satellite went offline during Hurricane Sandy and had to be temporarily replaced by a backup. It went down again last month. None of the three GOES satellites is expected to last much past 2015, much of the polar orbit satellite network is due to disappear around the same time and their replacements are delayed by design and budget issues. The US is due to lose a lot of its weather and climate change data input for at least the latter half of the 2010s
"If this is science, then let's judge it via the scientific method: use the theory to develop a hypothesis; propose a real-world test/observation that can unambiguously verify or falsify the hypothesis; modify the theory accordingly and develop another testable hypothesis... repeat until funding/patience/time runs out :-)"
Lots of people are trying. Somehow I doubt that a final result unambiguous enough to satistfy everyone is likely to appear soon.
Global temperature projections are only testable by direct observation after the fact.
East Antarctica is isolated from the rest of the planet by altitude, latitude, the Polar Vortex and the Southern Ocean. CAGW or no, it is in the most literal sense the last place you would expect to see warming. West Antarctica is warming.
The tropospheric hot spot is a grey area It is due to a change in the lapse rate and has been observed in the short term, but whether it would persist in the long term is still uncertain.
And so to bed.
Entropic Man (Jun 3, 2013 at 12:29 AM) said "Global temperature projections are only testable by direct observation after the fact."
I don't understand your statement. If you mean things happened after the forecast (e.g. a major volcanic eruption) and so made it invalid then why not simply re-run it, after the fact, with these corrections to prove just how accurate it would have been? I know of some attempts at doing this but the results seem unconvincing and rely on factors that are either poorly understood (e.g. aerosols) or boarder on magic (e.g. disappearing the heat into the deep ocean).
Entropic Man also said "West Antarctica is warming."
Yes, but isn't that due to sea currents, rather than global air temperatures?
Entropic Man (Jun 2, 2013 at 8:07 PM) said "All science is uncertain. Good scientists are candid about it and try to manage it. They give 95% confidence limits and define areas where their understanding is incomplete. IPCC was tasked with summarising the science and forecasrting future conditions for policy makers. Defining the uncertainties was part of their job. Their output was a survey of the evidence, followed by a set of possible climate outcomes, with probabilities arttached. This is what they were asked for."
I strongly disagree about the use of 95% confidence limits since this number was effectively based upon gut feelings and a show of hands among a select and rather small subset of contributors, I rather than any meaningful statistical assessment of the true uncertainties/errors within the data.
What would have been wrong in saying that there is insufficient evidence to draw a strong conclusion about the validity of CAGW, especially when such conclusions will be used to justify major political and economic policy decisions whose immediate impacts on most of society will almost certainly be negative (i.e. the drastic reductions in energy consumption that will be needed to achieve >80% cuts in CO2)?
EM, I was seeking an "explanation for the LIA and the MWP". What you say is not an explanation:
"The warmth and gradual decline from the MWP fit the pattern seen in Marcott et al and elsewhere, as we are past the peak of the current interglacial and should be cooling. The LIA coincides with the Maunder Minimum, a prolonged sunspot minimum which, if modern behaviour is a guide, would have accompanied a reduction in solar energy output"
Remember, my thesis is that as we are in a natural warming cycle between LIA and MWP conditions we have no reason to be concerned about CAGW. But this is not an explanation. However, the sun is a fusion reactor, constrained and maintained by a gravitational field. Anything that effects the field will presumably effect the fusion process. Some have mapped planetary ephemaris and may have found a correlation with anthropogenic records, for example:
http://www.fel.duke.edu/~scafetta/pdf/Scafetta_JStides.pdf
It this correct? I don't know, but at least it seems to be a plausible hypothesis - and much more plausible to me than the AGW hypothesis based upon CO2.
May 29, 2013 at 7:57 PM | Unregistered CommenterEntropic Man "If you want to falsify CAGW using the natural variation argument AND HAVE IT GENERALLY ACCEPTED BY THE SCIENTISTS you need to have an alternative explaination showing how and why the energy changes we have seen occurred; one which fits the evidence better than CAGW."
........................................
There are, however, candidates. Global surface temperatures are likely to be controlled by oceans and their heat content and its relocation, through currents, upwellings, overturnings and the like. It is problematic that the instrumentation to properly and closely characterise just ocean heat content is too new and too sparse to bring prediction to acceptable levels. BTW, I was particularly impressed by Willis Eschenbach's plot that I filed on my web site in early 2013 - http://www.geoffstuff.com/Willis%20flat%20SST.PNG The platykurtic distribution appearance causes thought as to mechanisms.
It is not my argument that ocean heat movement is the explanation. I mention it to show that alternatives to CO2 exist. The hows and whys that you seek will take some more years to accumulate data.
As an aside, the correlation behaviour of Tmax at a given site can be rather different to Tmin. When they are averaged to get a Taverage, I think that some invalidity enters the analysis of autocorrelation.
It’s good to see Entropic Man (EM) and BH commentators engage in a proper debate. The problem is that the issue isn’t really a technical one. Or I should say, isn’t an issue that can be solved solely by technical argument.
For me Mike Haseler, earlier on in this blog’s commentary, made the telling point that the temperature change over the last 150 – 200 years could simply be noise in the climate system. There are regular large scale oceanic cycles such as PDO and AMO. There are ocean current circulations that take place over thousands of years. There’s clear evidence of rapid climate swings during the last ice-age. And looking back even further, there’s little clear correlation of atmospheric CO2 (which has risen into the thousands of ppm for prolonged periods) and temperature. That climate changes in unquestionable, but the role of human impact on a large scale is very much moot.
There are at least two practical reasons why we shouldn’t focus, and take wide-scale action, on the alleged dangers of CO2 emissions.
Firstly, knowing what we know about the Earth’s climate, it’s natural, and sometimes chaotic variability over long and short timescales, the null hypothesis (if it has to be called that) should be that what we see/experience is natural. i.e. the opposite of the IPCC’s, UK Met Office and Parliament’s assumption that, somehow, human-related CO2 emissions seriously affects the climate.
Secondly, there’s a critical policy-related issue. The whole of modern civilisation, since the 17th century, has relied upon replacing human and animal power with, initially, coal, and more recently oil and gas power. Our whole society is built on using fossil fuels, not just for power, but for chemical feedstocks too. For the world to agree to shut-down, or severely curtail the use of fossil fuels, would require overwhelming evidence of catastrophic harm from their continued use.
To plan to shut down modern society, and close off the possibility of attaining such a society to millions of poor people, the evidence that human-related emissions CO2 will lead to catastrophe, needs to be overwhelming. And it isn’t, any near overwhelming.
EM himself says, “I'm not much interested in the politics. I want to know what the planet's doing. The information for that comes from scientific research with its limitations and uncertainties.”
That’s all well and good, and I’m interested, in general terms (especially if it directly affects me) about “..what the planets doing”. But EM’s starting at the wrong end of the problem which, in truth, is perceptual, cultural, economic and political.
Roger Longstaff
An interesting article from Scarletti et al. The section analysing the relation between solar insolation, sunspot cycles and the possibility of a grand minimum from 2020 rings true and echos other work elsewhere.
The attempt to match the Sun's behaviour to a pattern of fidal forces from Jupiter and Saturn seems forced. Jupiter's orbital period is a little over 11 years, as is the solar cycle. It would be easy to jump from there to saying one causes the other. If the two stayed in phase I might accept it, but the solar cycle varies so much that they keep shifting phase. I would also want to see a more specific and demonstrated mechanism to expain the propesed link.
Geoff Sherrington
Tallbloke and I once did some parallel energy calculations on the AMO and both concluded that it could, at best store enough energy to produce a 0.3C oscillation over 60 years. Looking at the temperature record there is some indication of maxima around 1880, 1940 and 2000 with minima around 1910 and 1970. Unfortunatley for your idea, these are small variations on a larger long term trend.
Oceanic cycles are also energy neutral over their full period, which makes it difficult to use them when explaining longer term trends. Note that over the three AMO peaks observed since 1880, each peak has been higher than the one before.
Has anyone shown that the energy budget involved in your ocean movement hypothesis is sufficient to explain the observed global changes? Having done a few calculations in this area over the years, I would suspect not. Many a promising hypothesis has evaporated when exposed to the harsh light of numerical analysis.
EM, I agree with most of your comments about the Scafetta paper, but don't forget, I was seeking any explanation - even if partial - to explain the LIA and MWP cycles, as there is no explanation at all forthcoming from AGW theory.
In the abstract you will see: "The major beat (harmonic) points occour at 115, 61 and 150 years, plus a quasi-millenial large beat cycle around 983 years". My point is that the 983 year harmonic cycle is coincident with anthropogenic records of the LIA, the MWP, and also the Roman warm period. The coinsistent solution is just based on mathematics - it is either right or wrong and can be checked - but I agree with you that a firmer explanation of the nuclear physics is required for the theory to gain acceptance.
However, as far as I am aware, at present it is the ONLY partial explanation for the LIA and MWP climates, which as I have opined, set purely natural boundary limits on interglacial temperatures, and are nothing at all to so with human activity - they are defined by planetary dynamics.
EM, a further thought occours - if (and I agree it is a big if) the planetary harmonics theory is correct we could run the model further backward in time (another 10,000 - 15,000 years) and compute planetary alignments for the last ice age. We could then run the model forward in time to search for similar conditions, and predict the onset of the next ice age.
Perhaps a job for the Met Office "supercomputer" ?
Just to illustrate how much we still have to learn about atmospheric physics, the term 'ignorosphere' is jokingly used to describe the mesosphere and lower thermosphere because we have no way of directly sampling this zone on a frequent (e.g. several times per day) basis: it's too high for balloons, too low for satellites and sounding rockets are too expensive and infrequent (e.g. >$1m cost and flying once every few months, at best). Yet this is the first part of the atmosphere to 'couple' with the fields and particles emitted by the Sun and so is likely to host some very interesting and potentially important phenomena that may well have significant impacts upon the behaviour of Earth's climate.
Fortunately, we are now seeing the development of suborbital reusable launch vehicles that promise frequent (e.g. 4 flights/day) and relatively cheap access (e.g. ~$10k) to this region, which may soon provide the necessary data to help us understand this missing piece of the climate jigsaw.
If Dr Betts still monitoring this thread, would the Met Office be interested in using such capabilities?
I like the concept of testing planetary alignments against ice ages. but am cautious of trying lots of possible cycles until one fits, as Scafetta did. The danger is that you fall into the error I see regularly on Tallbloke's site, which is a regular haunt of the cycle enthusiasts.
They say that if you have a hammer every problem looks like a nail. If you start thinking of everything in terms of cycles, you tend to see matches even where there are none, a scientific equivalent of seeing the Virgin Mary's face in a stain on a church wall.
The Milankovich cycles are one exception. They provide a coherent explaination for the last two million years of climate, with a good fit to the physics and with considerable predictive power. If you wish to invoke Jupiter's influence, look there for a possible contribution to the cyclic changes in Earth's orbital eccentricity and precession.
Unless Scafetta et al can come up with something stronger I'll go with Occams razor. Theoretical explainations of observations should be no more complex than absolutely necessary. After all, we already have a successful physical model for the changes which drive recent Ice Age cycles.
It's one reason why I like the paradigm of climate changes being initiated by internal or external forcings such as orbital variations and solar isolation which change temperature. These are then amplified by feedback interactions with CO2 concentration. The same basic physics explains the broad outline of the Snowball Earths, the Miocene, Pliocene, Ice Ages and anthropogenic global warming. No epicycles neecessary.
Regarding possible explainations for the MWP and LIA, I feel that my paradigm already explains them. If you look at Marcott et al's graph you see a peak at 280AD, followed by a steady decline. and a downward blip at the LIA.
The MWP is not an unusually warm few centuries, just the normal temperature for the Earth at that stage in the current interglacial, as slowly decreasing Summer insolation at 65N latitude due to orbital changes reduces temperature slightly and reducing CO2 amplifies the downward trend.
The LIA begins as solar insolation reduces worldwide due to a 1 part in 1000 reduction in radiation from the Sun's surface. This drops temperatures below the trend line. The Law Dome ice core also shows a drop in CO2.
When the normal solar cycle restarts temperatures and CO2 return to the trend line during the latter 1800s, before CAGW reverses the trend from a natural decline in temperature to an artificial rise.
You, I think, expect the Marcott et al downward trend to have reversed naturally after the LIA, but I am uncertain where you find evidence for that expectation. My interpretation of the record is that the LIA accelerated a trend which was already reducing temperature, rather than reversing a potential natural warming trend.
"looking back even further, there’s little clear correlation of atmospheric CO2 (which has risen into the thousands of ppm for prolonged periods) and temperature."
Mark Piney
Look at the Miocene with both high temeratures and high CO2, then the Pliocene which shows a gradual decline in both as the Himalayas form, the Arctic Ocean is enclosed and Antarctica covers the South Pole, and orbital changes force cooling. Just before the onset of the current Ice Age the late Pliocene shows 400ppm CO2 and temperatures several degrees warmer than today, both declining towards the first glacial period.
EP, please could you reference the Marcott et al paper that you refer to?
This paper was a hot topic in March. I cant find the source of my full copy, but I've given you two reviews, one from each side of the fence and the original Science reference, alas paywalled. My main interest is the overall shape of the graph. The sceptics were mostly unhappy with the 20th century upturn.
http://www.skepticalscience.com/news.php?n=1928
http://www.thegwpf.org/earth-cooler-today-28-11300-years/
http://www.sciencemag.org/content/339/6124/1198
Dear EM Will get back to you tomorrow. Family medical emergency's intervened.
Regards Mark
Oh, that one! Yes, I remember the row about the "hockey stick splice".
It is all from proxies, and almost certainly wrong as it contradicts anthropogenic records - eg dairy farming in Greenland in the MWP, which must have been considerably warmer than current conditions - not colder by 0.5 degrees, as shown. In any event, I seem to remember that it was discredited at the time, but let's not fight that battle again.
My interest in Scafetta et al, and similar work, is that it is based upon a mathematical analysis of sunspot records, the derived theory from which hindcast scenarios that correlate with anthropogenic records - LIA, MWP, DACP, RWP.
Note that both the Greenland colonies failed. Even the name was a propoganda move by Eric to ncourage settlers.
I found an interesting graph accompanying Wikipedia's History of Greenland. One coloby may have failed due to cold. The other fades out in a warm patch.
http://en.wikipedia.org/wiki/History_of_Greenland
EM, from your wiki reference: ".....during the so-called Medieval Warm Period, the vegetation there was very different from what it is today. Excavations have shown that the fjords at that time were surrounded by forests of 4-to 6-metre-tall birch trees and by hills covered with grass and willow brush."
I repeat my point: Greenland in the MWP must have been considerably warmer than current conditions, not colder by 0.5 degrees, as shown by Marcott et al. To me this invalidates Marcott (apart from the "trick" of splicing modern instrumental records).
In the past you have said that if the facts change you will change your opinion (or words to that effect). As this thread seems to be drawing to a close may I ask if there is anything you have seen here that has changed your opinion at all? This is a genuine question, and not meant as a "dig".
EM Apologies for not replying sooner.
In answer to your question about the evidence showing a poor correlation between CO2 levels and temperature. I can’t immediately lay my hands on my folder of evidence but, to save time, I came across Vincent Gray’s recent href="http://wattsupwiththat.com/2013/06/04/dr-vincent-gray-on-historical-carbon-dioxide-levels/>Summary Similar points are made by Al Simmons and Doug L. Hoffman in more detail href="http://theresilientearth.com/?q=content/grand-view-4-billion-years-climate-change>Link This evidence seems pretty convincing to me.
There’s also the issue correlation versus causation. My understanding is that CO2 levels and the Earth’s temperature are strongly correlated. But the timing is key. The evidence suggests that CO2 rises after the temperature has risen, and this is due to the reduced solubility of CO2 in warmer oceans. The argument is made that somehow the CO2 acts as a strong positive feedback. No doubt there will be some warming but probably slight, and this doesn’t address the problem of timing. The future CO2 levels cannot determine the past Earth temperatures.
I think there’s a need to see the obsession with CO2 in context. Something’s happened to modern thinking, since the 1950s, whereby complicated phenomena are ‘explained’, completely, by simple ideas focussing on one substance, or family of substances/materials. CFCs are the sole cause of the ozone hole that appears over Antarctica every winter. Neonicotinoid pesticides are the main (sole?) cause of disappearing bees. This monomaniacal focus on one thing to explain all, is probably not as new as I think. It was probably given a boost by Cold War fear of radioactive fallout, and the rise of environmentalism on the back of dread fear of what damage humans can do. The monomaniacal focus on CO2 as the thermostatic gas, controlling the Earth’s temperature, is all of a part with this new environmental ‘politics’.
Finally, I want to return to Mike Haseler’s important point made earlier in this blog-post, that all we may be witnessing is noise in the climate system. Don Easterbrook summarised just how variable temperature can be, examining temperatures towards the end of the last ice age href="http://wattsupwiththat.com/2013/06/02/multiple-intense-abrupt-late-pleisitocene-warming-and-cooling-implications-for-understanding-the-cause-of-global-climate-change/>Link The variation is large and can be very rapid, and it’s all naturally generated. Seems to me that the climate system is quite capable of generating the temperature changes we’ve witnessed this last couple of centuries, all by itself.
Roger Longstaff.
This discussion has changed one area of my thinking.The expected tropospheric hot spot showed weakly in radiosonde data, but has not increased as models expected. Dr. Spencer has speculated that they are overestimating water vapour. That's making me happier with the sensitivity estimate by Otto et al of 2.0, from my previous personal estimate of 2.5.
You talk of warm Greenland conditions on the basis of dairy farming. This begs two questions.
1) How do you know and is your source reliable?
2) What is the minimum temperature at which dairy farming can take place?
I am unhappy with this method of temperature measurement by anecdote. One example is the argument that conditions were colder because they had forast fairs on the Thames. Nobody quantifies what the temperatures actually were , and the effect of old London Bridge as a barrier to river flow is neglected.
Since you regard the scientific evidence of post 900AD temperatures as unreliable, could you provide a reference for your temprature estimates, and indicate why you find them more reliable than the ice cores and other proxies?
Mark Piney
Under natural conditions the main long term drivers of temperature are the amount of incoming solar radiation, the orbital variations of the Milankovich cycles, and the position of the continents, particularly relative to the poles.
These produce the long term warmer or colder periods observed in the geological record.
Shorter term changes include solar cycles and glitches, vulcanism and oddities like the disruptive effect of the Tibetan plateau on atmospheric circulation. It also includes catastrophic events like impacts. A recent paper described finding impact spherules in NW North America and Northern Europe, dating from the beginning of the Younger Dryas and consistent with an impact in the Arctic Ocean. It may have caused the Younger Dryas.
I see problems with ascribing all changes to natural variation. Every little change needs its own explaination, with no underlying pattern. None of these are quantified by their proponents. Remember that temperature do not just change, They are driven by changing energy budgets which need to be enumerated to be credible.
Noise as an explaination for 20th century changes shares the same problem. Even though it appears random, noise is driven by physics, in this case the same energy budgets and energy flows. To be credible, this also has to be quantified and shown to be sufficient to explain the observations.
If you want me to seriously consider either, show me numbers.
In the modern context, CO2 is regarded as the main driver because there is a physically credible mechanism describing its effect, which is consistent with the observed changes. There is also a lack of observed alternative drivers shown to be.capable of producing the same effect.
The apparant obsession with CO2 in paleo research is because, once again, it provides a consistent mechanism operating over a wide range of past climates.
CO2 sinks of various kinds exist, from dissolved CO2 in the oceans to stored material in tundra, peat bogs, biomass, etc. When temperature rises these sinks tend to release CO2 into the atmosphere. When temperature falls the sinks tend to take up CO2. This is how temperature changes affect CO2 concentration.
CO2 itself affects temperature. Increased CO2 decreases the rate of heat loss from the surface and troposphere. The temperature rises until increased outward radiation establishes a new equilibrium. Decreased CO2 allows increased heat loss and cooling.
Put the two together and you have a feedback system in which an initial natural temperature change induces a change in CO2. The effect of the CO2 is to amplify the change. Normally this takes place gradually over millenia and the system rarely moves far out of equilibrium.
Occasionally CO2 drives temperature. The prime example is the Snowball Earth, in which whole world glaciation creates such a high albedo that the system runs to its cold limit and stays there. The warming that eventually comes is due to two effects. The ice cover prevents rock weathering and photosynthesis, so CO2 is no longer removed from the air. Vulcanism gradually increases CO2 until the reduction in heat loss becomes strong enough to start melting the glaciers. this takes a couple of million years.
Three things make the 20th Century warming anomalous.
The first is that, like a Snowball Earth, the initial change is due to CO2 rather than temperature. Secondly the rate of change is very fast. An interglacial would se a change of 80ppm in 10,000 years. We have produced a similar change in 1/100 the time.
Thirdly the CO2 level has moved out of the normal 200-280ppm variability range. At 400ppm it is at levels not normally seen in an Ice Age at all, but in warmer perids like the Miocene. There is no prehistorical precedent for this rapid and massive change in CO2 without a preceding temperature change. If the previous feedback loops prevail, an equally rapid change in temperature is likely to follow .
The magnitude and timescale of this change is outside our previous experience, as are the incidental effects.
In summary, temperature normally drives CO2 in slow, long term feedback loops. In the 20th century CO2 produced by our industrial civilization is driving temperature in ways which we have no easy way of predicting.
EM, there are several MWP / Greenland references here:
http://wattsupwiththat.com/2011/06/01/greenland-and-agw/
LIA records abound, not just for the Thames, but other frozen rivers (eg. the Hudson). I am afraid I do not have time today to compile a proper list, but I doubt that this is a point of serious dispute? We have discussed before why I think that ice core data should be viewed with extreme caution (earlier in this very thread, I think).
In your reply to Mark Piney you say: "In the modern context, CO2 is regarded as the main driver because there is a physically credible mechanism describing its effect, which is consistent with the observed changes. There is also a lack of observed alternative drivers shown to be.capable of producing the same effect."
I disagree. The CO2 AGW hypothesis is NOT consistent with observed changes, which are flatlining temperatures while atmospheric CO2 has risen. Solar activity seems to be a much more credible "climate driver", as we have discussed in some detail above. If temperatures remain static, or indeed fall over the next few years, the AGW hypothesis will have been falsified. Some think that it already has been.
Roger Longstaff
All data should be treated with extreme caution! Be careful of taking your data from sites like WUWT , which has a propoganda agenda to promote, with no equivalent of peer review to constrain them or crosscheck their accuracy and reliability.
The best correalation with temperature in the recent data is the reduction in solar insolation in solar cycle 24 from 2005 on. This is pushing temperatures down as fast as the change in CO2 is pushing them up, hence the flattening seen in the last decade.
Nothing in the basic physics has changed, and it is premature to assume that there is no longer a CO2 effect on the basis of 10 years data, when the response time is normally measured in millennia.
There is also the problem of the imbalance in energy flow, which persists despite the reduced insolation. The imbalance indicates that energy is still entering the system and accumulating, though where is not clear on current information. If you wish to entirely remove CO2 as a driver, you need to supply an alternative explaination for the continuing imbalance.
Thanks again for the reply EM.
However, as you are aware, I do not agree with your "imbalance and missing heat" argument, for all of the reasons given above, and Occam's Razor gives us quite different explanations for the empirical data. Therefore, as I have said before, we will simply have to agree to disagree. It would be pointless to go through it all again unless we have more data, or more likely explanations.
Thank you for an interesting discussion.