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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Recommended supplemental reading:

Nuclear fuel plant under gun to improve safety in wake of uranium buildup, explosion concerns by Sammy Fretwell, The State (Columbia, SC), Aug 12, 2016

sauerj at 07:24 AM on 15 August 2016

Climate inertia

Tom @7: I understand everything you have written and all the math on the ATTP site, which would ultimately work down to T_s = fx(F) and he explained that a singular net 'F' comes from the RCP₁₁ dataset. All very interesting.

Thanks for explaining the F_feed term (feedback component). I jumped to the ATTP site right away & read it and was puzzled by the F_feed term. Then, I read your 2nd paragraph; your explanation of F_feed was timely. And, thanks for explaining how the F_feed term is developed here; thus explaining that delta-forcing due to delta-humidities are not modeled directly. That's likely OK and doesn't hurt accuracy as F_d-humidity is likely near linear (w/ respect to T_s) in the temperature ranges that we are talking about.

Also, thanks for explaining the n-box detail. I assume the different time constants on Cowtan's 'model tool' correspond to the surface layer for box-1 (constant=1/yr) and the ocean layer for box-2 (constant=30/yr). And, I assume the 3-box model breaks the ocean layer into two separate boxes: possibly into 1) an upper ocean layer for its box-2 (30/yr) and 2) a deep ocean layer for its box-3 (100/yr). The 1:100 ratio here (box-1/box-3) was the same ratio used by ATTP for the heat capacity ratio.

And, thanks for heads-up on the SkS course. I did enroll for it and will start watching the course videos. You've been very helpful. Thank you!

Tom Curtis at 02:19 AM on 15 August 2016

Climate inertia

sauerj @6:

1) The difference between the 1 box, 2 box, and 3 box models comes down to the number of time constants used. If you want more details, I believe the model is discussed in the SkS online course, which started Aug 9th but which you can probably still enroll in. Alternatively, Kevin Cowtan has in my experience always been helpful to those interested in learning more. Finally, And Then There's Physics gives the equations for a two box model here. Others have done similarly. No doubt there will be small changes in the exact form of the equations from model to model.

2) n-box models such as Kevin Cowtan's do not model feedbacks directly, and certainly not as a component of any of the forcings. Rather, the feedbacks along with thermal inertia are handled by a feedback constant (see ATTP's first equation). As a result such models are useful for giving emperical estimates of TCR and ECS, but do not demonstrate the physics.

3) I agree that the tunability of the forcings is one of the best features of Kevin Cowtan's model. I think anybody trying to argue that "it's the sun" or some other such theory should really adjust the weightings of that model to match their theory and show us why the resulting, poor fit is preferable to the good fit from the default settings.

Glad I could help.

sauerj at 01:11 AM on 15 August 2016

Climate inertia

Tom @5. Thank you for taking the time to explain all of this to me. I understand everything you wrote. I checked out the Dr. Kevin Cowtan model and was thoroughly impressed (very easy to use and understand). Of course, I am ignorant on the details of the equational differences between the 1-box, 2-box and 3-box model variations, but that's OK. Someday, if I keep reading, I might understand what this means.

It was interesting how I could set the weighting of, say, 'Solar' to zero, just to see the difference to the 'fit'. One interesting tid-bit, the 'H2O(strato)' line is hidden exactly behind the 'BlackCarbon(snow)' line, in the forcing charts (I noted that there was 10 lines in the legend, but only 9 in the charts). But, then, when I changed the weighting of the 'H2O(strato)' line, then it appeared. One question: Is it correct to assume that rising humidities ['H2O(troposhere)'] (which would occur as a natural consequence of rising temperatures and a significant positive feedback component) is packed in the 'GHG(mixed)' line?

I was about to ask about RCP, but then found the SkS 3-part post (HERE) on that subject. I skimmed thru the whole thing; and need to return and read it in detail. This in-depth article looks amazing, and something that a person like myself should read in order to take the next appropriate step in learning.

I am a chemical engineer & very active in the local CCL chapter, which I think is the best thing out there for remediation vision, spirit and policy. ... Thanks again for your time!

HK at 00:32 AM on 15 August 2016

Water vapor is the most powerful greenhouse gas

old sage @250:

"I repeat, what physical process shuts down the alleged entrapment of heat by CO2 insulation after it has reached its target temperature per concentration thickness. If you can show that, you will see the rise is snuffed out from the outset and T does not rise whatever the concentration thickness."

Ergo: Insulation has no impact on temperature, and all the producers of house insulation, thick winter clothes and so on are just making profit from a hoax.
BTW, furry mammals started that hoax about 200 million years ago, followed by feathered dinosaurs and birds, so it has obviously been going on for a very long time!

Tom Curtis at 00:10 AM on 15 August 2016

Water vapor is the most powerful greenhouse gas

KR @252, the initial decrease in IR with the increased CO2 is the "entrapment" that Old Sage refers to. I mention it again in the last sentence of the first paragraph. The rise in IR radiation to space that I mention in second sentence of the first paragraph is a consequence of the rise in surface temperature. So, not a typo, but that second sentence was poorly, and confusingly worded. Specifically, I mention that the rise in IR radiation follows the increase in CO2 (meaning in terms of time sequence) and follows on from the rise in temperature (meaning as a direct causal consequence). Clearly that makes the sentence ripe for confusion. Thank you for seeking clarrification.

KR at 23:59 PM on 14 August 2016

Water vapor is the most powerful greenhouse gas

Tom Curtis - Typo? An increase in CO2 leads to a _decrease_ in IR to space, an energy imbalance that causes an accumulation of energy, an increase in temperature, until the warning climate once again emits an amount of energy equal to that coming in.

Ceist812534 at 12:50 PM on 14 August 2016

It's cosmic rays

A new paper published in the Journal of Atmospheric and Solar-Terrestrial Physics in August 2016 finds:

"There is a significant correlation only between cosmic ray (CR) intensity (and sunspot number (SSN)) and the cloud cover of the types cirrus and stratus. This effect is mainly confined to the CR intensity minimum during the epoch around 1990, when the SSN was at its maximum.This fact, together with the present study of the correlation of LSCC with our measured CR intensity, shows that there is no firm evidence for a significant contribution of CR induced ionization to the local (or, indeed, Global) cloud cover.

Pressure effects are the preferred cause of the cloud cover changes. A consequence is that [b]there is no evidence favouring a contribution of CR to the Global Warming problem.[/b] Our analysis shows that the LS data are consistent with the Gas Laws for a stable mass of atmosphere."

Relevance of long term time – Series of atmospheric parameters at a mountain observatory to models for climate change

Tom Curtis at 09:46 AM on 14 August 2016

Climate inertia

sauerj @4, I have responded to your comments by subject rather than by where you located the discussion. In particular, some of the points you raise under ESS are more correctly related to ECS, and so I have discussed them under that heading:

TCR: The TCR is strictly defined only for the 1% increase per annum experiment. It approximates to the real world temperature increase because most of the initial response to a forcing occurs in the first few years and the net forcing is variable in a short to medium time span (<10 years) due to the solar cycle, volcanic activity, and the effects of ENSO and other oceanic oscillations on albedo and water vapour concentrations in the atmosphere. If, however, you had a steady increase of CO2 concentration of 0.5% per annum, the temperature achieved at the 70 year mark would be higher than that predicted from an expectation based on the TCR.

Going into more detail, I compared the BEST LOTI temperature data to a prediction based on the sum of forcings from Kevin Cowtan's two box model of global temperatures (default settings). The correlation was 0.855, the Root Mean Squared Error was 0.176, and the linear trend was 0.914 of the observed values. In a monotonic 0.5% increase we would expect the linear trend to be greater than the observed values, so the perturbations more than compensate for the difference. For what it was worth, weighting the TCR prediction based on the difference in trend (ie, eliminating that difference) increased the RMSE by 0.001, decreased the mean error (which was still negative) but increased the standard deviation of the errors.

Given that, using TCR plus ENSO as a predictor of temperatures gives a reasonable approximation, but an approximation only.

ECS: Correct, with the provisio that in the approximately 200 year time frame to reach the ECS, there will have been some albedo change from changes of ice sheets and vegetation cover - so the balance will not not be perfect. The assumption is that the change small over that time frame, so the approximation is good enough on that time scale.

As an aside, the 1.5-4.5 C range for ECS is the likely (66.6%) certainty range. According the the IPCC AR5, the probability that ECS is 1 C is less than or equal to 5%. The probability that it is less than 6 C is greater than or equal to 10%. And assuming the probabilities are symmetrically distributed, the probability that it is less than 1.5 C is less than or equal to 16.7%, while the probability that it is less thanr than 4.5% is greater than or equal to 83.3%. Here are three Probability Density Functions (PDF) that more or less satisfy those conditions:

Strictly Roe and Baker (2007) is a PDF from the time of AR4 (although it better satisfies the AR5 constraints than the AR4 constraints). However, its high probability of low values comes at the expense of substantial probabilties of very high values of ECS. Rogelj et al (2014) is a representative PDF pubished in the scientific literature, and represents a best fit to the above constraints using a log normal curve. In accomplishing the good fit, however, it violates the requirement that the probability that ECS is less than than 4.5 C be greater than or equal to 83.3%. The alternate has adjusted values to ensure compliance with the above conditions, but as a result its threshold values diverge more from the stated limits than does Rogelj et al. For what it is worth, here are the 95% confidence range, mean, median and modes for the three distributions:

Value Alternate Rogelj Roe & Baker
2.5% 1.8 0.9 1.1
97.5% 7.8 7.8 29
Mean 3.03 3.07 2.66
Median 2.56 2.53 2.20
Mode 1.85 1.74 1.65

You will note that the median value (the 50:50 split) is around 2.5 C for all three distributions, and the mode below 2 C. The more reasonable climate skeptics are not wrong in expecting these lower values as the reasonable expectations (although they tend to artificially deflate the probability of higher values). In risk assessment, however, the mean value is more relevant. To exclude reasonable and dangerous possibilities from consideration, just because their probability of occuring is only 6.5% (6+ C using the alternate PDF) is unreasonable, but that is what concentrating on the median (or still worse, the mode) does. On the other hand, in popular discussion of climate risks, many people who want to take action forget that most probably (61.6% chance on alternate), ECS will be below 3 C. Of course, all of these PDFs give an artificial precession to the probability estimates.

ESS: In order to avoid overwhelming complexity, climate models do not typically vary ice sheet extent, and land cover (other then anthropogenic changes introduceds as forcings). That is justified because of the long time spans required for the melting of ice sheets. Using ESS for short term estimates is merely an artificial, and IMO misleading way of inflating percieved risk.

nigelj at 08:56 AM on 14 August 2016

Six charts show UK progress towards low-carbon energy

One planet only forever

Burning wood is indeed compensated by growing more trees, but this is a poor quality strategy. Better to stop burning wood where possible, and use new tree planting simply to reduce total atmospheric CO2 levels.

However subsistence farmers in the third world and developing countries rely on wood just to survive, and wood pellets do emit less CO2. It would be morally absurd to expect them to stop burning wood, and the contribution of burning wood appears to be less globally than burning oil and coal. So we have to accept some wood burning in some countries, unless someone comes up with some alternative.

I agree that the western world is indeed selfish at times, and is ruled by profit and short term goals. However plenty of people realise that destabilising the planet creates problems for poor and rich alike ultimately. We just need more people to see this.

Ironically most economists recognise that profit can have a negative downside, and business and individuals cannot operate in a completely unrestrained way. Our problem is politicians, lobby groups and selfish individuals who are short sighted, and don't see the bigger picture.

Tom Curtis at 08:20 AM on 14 August 2016

Water vapor is the most powerful greenhouse gas

Very briefly for Old Sage @250, the "entrapment" of heat by CO2 never ceases. However, following an increase in CO2 concentration, and as the temperature increases, the IR radiation from the surface and atmosphere also increase, thereby increasing the amount of radiation to space. After the temperature has increased a certain amount the amount of radiation to space returns to the the amount which balances incoming solar energy, at which point the temperature increase ceases. The temperature increase required to do that is a function not only of the reduction in radiation to space as a result of the increase in CO2 but also any further changes to the energy balance that result from the increased temperature.

This is so basic to understanding the greenhouse effect that it is stated, in one form or another, in any serious exposition of the greenhouse effect (other than those by some AGW deniers). If you did not know this, you do not understand the theory at even the most schematic level. Playing 'devil's advocate' requires actually understanding, and criticizing the theory being discussed. It also requires accepting the basic observational data. Old Sage does neither. Rather, his verison of 'devil's advocaccy' is the intellectual equivalent of a child putting their fingers in their ears, and shouting "Nah, nah, nah, nah nah-nah - can't hear you." Nobody mistakes that child for playing devil's advocate, and nor does such a response result in stimulating discussion.

old sage at 05:43 AM on 14 August 2016

Water vapor is the most powerful greenhouse gas

As a research scientist, the most stimulating discussion was got from others playing devil's advocate - sloganeering, is that how this particular column shuts down unwelcome thoughts. No wonder I haven't bothered to tune in for years. I repeat, what physical process shuts down the alleged entrapment of heat by CO2 after it has reached its target temperature per concentration. If you can show that, you will see the rise is snuffed out from the outset and T does not rise whatever the concentration.

Moderator Response:

[PS] Moderation complaint snipped. If you are research scientist, then you could try arguing like one, with accurate data and logic and especially a demonstration that you have understood the theory you are arguing against. At the moment, it is not clear that you even understand response being made to you. If you are have not read Ramanathan and Coakley 1978 then I suggest it is high time you did. Continuing to assert statements about physics of gases without backing evidence (and in defiance of well-established experimental evidence) is simply sloganeering. Put up evidence to back your assertions- otherwise your comment will be deleted.

sauerj at 05:31 AM on 14 August 2016

Climate inertia

Tom @3. That helps; I think I get it.

TCR would be like the real temp rise (I assume that TCR could also be based on %increases CO2 other than 1%/annum as we are now increasing in the 0.5%/annum range). The TCR would be like my crude model mentioned above in @2 [Tactual = fx(CO2)], which, yes, with the right constants, would hit the RED line.

ECS is the Tequil temp. The point at which global temperature has reached the point where Qin = Qout.

And ESS is the fully integrated model with all the real-life biosphere feedbacks played out. ... But, I had always assumed that these feedbacks (all of them ... stuff like warming oceans releasing more CO2, higher humidities adding to GHG's, ice sheet albedo changes, land cover impacts, etc.) were already packed into the ECS sensitivity curve. Was that assumption wrong? Note, many SkS articles clearly indicate a sensitivity # in the range of 2.5 - 4.5C. Is this range of sensitivity #'s only referring to ECS #'s and ESS #'s are even higher?

Note: To hit the lowest point of the grey region (2.1C on a 400/290 ppm rise), the gain# would be 4.5C; and to hit the midpoint (2.6C), the gain # would be 5.6C. Maybe the range indicated on the SkS articles did go up to 6.0C (?); but I do remember that the most probable value was ~3.0C.

So I'm a little confused on the discrepancy on past SkS articles on this sensitivity # compared to this ESS curve. Note: If it's too difficult to explain this, don't worry about it; its not that important that I understand this detail. A sensitivity # of 3.0C at our current trend of carbon emissions is plenty bad enough!!!

One Planet Only Forever at 03:16 AM on 14 August 2016

Six charts show UK progress towards low-carbon energy

JWRebel,

In addition to my previous comment, there would be a limit to the sustainable burning of wood. It would need to be limited to creating CO2 at a rate matching the CO2 taken in by new wood growth deliberately being grown as the offset of the burned wood.

Another point would be that wood pellets from harvesting deadfall that would eventually burn in a wildfire would be a sensible way to get usable energy. However, all of the renewable energy options should be competing to be regional winners without needing to compete with understood to be unsustainable damaging alternatives.

The failure of socio economic political systems to ensure that unsustainable and damaging alternatives are discouraged and are rapidly terminated whenever those are gotten away with being developed is clearly a major impediment to the advancement of humanity.

One Planet Only Forever at 02:41 AM on 14 August 2016

Six charts show UK progress towards low-carbon energy

JWRebel, Though burning wood pellets can result in pollution other than CO2, at least the carbon in the CO2 is not new carbon added to the recycling surface environment of the planet. Fossil fuel burning simply must be terminated earlier than the free action of people in the pursuit of popularity and profitability would end the activity.

old sage at 00:01 AM on 14 August 2016

Water vapor is the most powerful greenhouse gas

M A Rodgers please stop quibbling, the absorption of 70 w/m2 by vapourising water is a very significant proportion of the energy arriving at the surface. If you cover 1 hectare of surface with concrete and drain it, the resulting surface area presented by 1cms of rainfall shrinks from 10,000 sq m to 100 sq m as it is collected in drains. Therefore, the amount of vapour is significantly reduced.

I repeat what every schoolboy should know, that reduces cloud cover and lets more solar energy into earth's environment. The form factor and altitude of cloud formations radiate externally far more than vertically downwards.

Finally, I ask Tom Curtis to explain why when a given amount of CO2 has raised earth's temperature by t degrees - as we are asked to believe by theIPCC - it then stops retaining a single calorie of energy despite everything being in place to keep the 'blockage' of outgoing energy effective?

And please don't try to drown me in a deluge of 'off the point' rambling over radiation from gases at STP, they scatter, they absorb, but most definitely they do not spontaneously radiate from their translational kinetic energy to any significant extent. All they do is convey energy from one place to another in an energy neutral fashion.

Moderator Response:

[JH] Your argumentative, word-salad responses to MA Rogers and Tom Curtis constituite sloganeering which is prohibited by the SkS Comments Policy.

JWRebel at 14:52 PM on 13 August 2016

Six charts show UK progress towards low-carbon energy

There are some modestly positive trends here. The switch from coal to wood pellets for electrical generation (mainly based on European tax rules) is no sinecure, switching one set of problems for another, albeit with a reduction in CO² emitted — burning trees is not a global solution.

Tom Curtis at 00:11 AM on 13 August 2016

Water vapor is the most powerful greenhouse gas

old sage @245 @246:

1) I quote again:

"Comparing the radiative rate kR (the inverse of the lifetime) to the collisional deactivation rate kM[M], provides a quick estimate that only one out of 100,000 CO2 molecules excited into the (0,10,0) by collision or absorbing a photon, will emit."

It follows that on average, where CO2 absorption equals CO2 emissions, out of every 100,000 molecules dropping from a (0,10,0) state by emission, 99,999 will have been excited to that state by collision. Your statement that "Vibrational excitation most certainly cannot arise from mutual collisions" is nonsense. Classically, there is no better way to induce vibrations in an object than to subject it to a collision. Within quantum mechanics, the vibrational mode must have a particular energy level, so that the proportion of collisions conveying that level comes into question. However, as temperature rises, the mean energy of motion of the gas molecules rises and hence the proportion of collisions having the correct energy also increases. I quote more fully:

"At 300K (27 C) ground state CO2 molecules are continually colliding with oxygen, nitrogen and other molecules. The average collision has an energy equivalent to kT where k is Boltzmann’s constant. In units usual to the field this is ~200 cm-1 (multiply by the speed of light in cm/sec and Planck’s constant to get Joules) but some of them have much more energy. A few of the energetic collisions can vibrationally excite the CO2 to the same 650 cm-1 excited vibrational level. Because collisional processes are fast wrt radiation, the number of vibrationally excited CO2 molecules can be characterized by a Boltzman distribution. At 300 K about 6% of the CO2 molecules in the atmosphere are vibrationally excited and can radiate."

Note that the Maxwell-Boltzmann distribution that governs this is a function of temperture, not of ambient radiation. The upshot is that your claim is entirely wrong.

2) Again, you are merely arguing against well established emperical data. In that, you are like the flat earthers who, in an era of international flights and GPS insist that the Earth is flat based on misunderstood scientific principles. This is made graphic by the use of IR cameras filtered to 4.2 to 4.4 microns at which wavelength CO2 absorbs and emits radiation, but H2O and other major atmospheric components do not. Using a better quality, IR filtered camera, we can see CO2 production in a variety of circumstances:

Note the CO2 coming from exhaust pipes have come from conditions of near complete darkness. Their high rate of emissions shown by their bright temperatures, therefore are almost entirely the product of thermal collisions. As a side note, the lack of visible smoke or water vapour from the stacks (1:30 on the video) confirm that they are not emitting H2O and are emitting limited quantities of soot and hence that it is primarilly CO2 that is emitting the radiation. The CO2 from peoples breath is relatively cool, and typically cooler than the background and shows up as slightly dark. Again, level of radiation is temperature dependent.

As a technical note, this sort of footage relies on wavelengths near the edge of the absorption band so that CO2 has a low emissivity other wise distant shots would be impossible. As a consequence, the low levels of radiation associated with room temperatures do not show emissions in these cameras. Using a 15 micron filter, they would but so also would H2O.

3) Each meter cubed of dry air at standard pressure and 300 K results in the emission of about 7 Joules of energy per second, but a stack of such cubes will result in absorption of some of the emissions which limits the total amount transmited. At the the 15 micron emission peak for CO2, such absorption may well occur within the first meter, so that the total amount leaving each cubic meter may be a little less than the 7 joules.

More importantly, the CO2 emits the energy, it does not generate it. It is only able to emit the energy because it is continuously absorbing an equivalent amount of energy from thermal radiation and collisions. Therefore it cannot heat a room anymore than the high emission from room temperature walls will heat a room. In short, the laws of thermal emission do not violate the laws of thermodynamics (and if you think they do, move your discussion to the Second Law of thermodynamics thread).

MA Rodger at 00:00 AM on 13 August 2016

Water vapor is the most powerful greenhouse gas

old sage @246,

I'm disappointed by your responses. What you're telling me is that you were wrong to write @340 that "according to wikipedia, the average solar energy 24 hrs/day per unit area is 141 w/m2." In itself this is fine. Who does not make unfortunate mistakes from time to time? But you sadly dodge any explanation/apology. That is poor do's.

My reason for asking for a link was that it would provide us with the same hymn-sheet to sing from. As it is you provide no link and instead @244 provide the vaguest of description - "The average surface energy per m2..." and attach the vaguest of values to it - "...is of the order 150w."

Can I cut through your reticence and suggest that the graphic above @236 provides a source of this data. The 1360/4 = 340W/sq m of TSI you sign up to @ 245/46 is given there. We also have the average solar energy absorbed at the surface "of the order of 150w" = 161W/sq m. And your 70W/sq m is also within the given range of 70-85W/sq m. (I should point out that 99cm of precipitation would require more than 70W/m sq to evaporate from the surface unless the evaporating water was at 100ºC, which is why the graphic gives a range running higher than your 70W/sq m.)

So are we happy with the graphic @236?

old sage at 22:21 PM on 12 August 2016

Water vapor is the most powerful greenhouse gas

M.A. Rogers - oops 1360/4 w/m2, not kw.

old sage at 22:08 PM on 12 August 2016

Water vapor is the most powerful greenhouse gas

Just a couple of points of clarification:

M.A. Rogers - the gross incident energy is of course 1360/4 kw/m2. But I agree, the Google results are somewhat suspect and need further inspection.

Tom Curtis: The 6% of excited molecules you allege must come about from externally derived illumination. Vibrational excitation most certainly cannot arise from mutual collisions. It's a question of the difference between absorption and emission, your number, if true, varies with the strength of source rather than temperature of the gas.

old sage at 20:03 PM on 12 August 2016

Water vapor is the most powerful greenhouse gas

M.A. Roger- do a google search and you will find the average surface energy per m2 is of the order 150w. This is to compare like with like for average surface rain fall of 99cms taking up 70w/m2.

Tom Curtis - 7w /m3 for radiation by CO2, 40 times as much H2O vapour of similar characteristics in the air means 280 w/m3. My living room is 90m3 so why do I bother heating it. Have you even considered how the tiny weight of CO2 in a m3 could generate 7 watts?

This column needs to be renamed so as to include surreal.

stevecarsonr at 15:34 PM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

Tom,

Thanks for the paper. It doesn't look like it made it through peer-review - well, I can't find it published anywhere. I was looking so I could see the figures referenced (that don't appear in the draft online paper).

Interesting paper. The question posed is an good one, but more interesting would be the comparison with a naive forecast, i.e. the skill. So, for example, if the UK has outperformed Germany for 5-years in a row, then the sensible naive forecast is to say "UK will outperform Germany this year". When you win, you get a tick. As far as I can see the paper says "yes, win = tick". But like with the naive forecast which says "the weather tomorrow will be the same as today" you don't get a tick for skill unless you beat the naive forecast. That is, you need to have skill.

My weather forecasting has a brilliant track record, but it has no skill over the naive forecast.

How good are forecasts at predicting a change? For example, when we look at forecasts of GDP growth, the "forecasts" are great when the economy has been growing at 1-3% each year and the next year the growth is 1-3%. Hurray for the forecast!

When last year was 2% and next year is -1%, the forecasts (mostly) turn out to be rubbish. Likewise, when last 3 years were -1%, -2%, -3% and next year is +5% the forecasts turn out to be (mostly) rubbish. Not all of them though. A few are always right. Like many people visting the casino, there are always a minority that make money. Just different ones each time.

How were the forecasts of the UK not joining the Euro vs the countries that did join the Euro?

UK was predicted to do worse than the Euro block. How did that one turn out?

Some papers predicted very large growth in "intra-Euro" trade based on economic fundamentals. The results were basically - slight improvement vs the past. Compared with forecast, awful.

I'm happy to learn more here about economics forecasting: i) the comparison with reality; ii) the skill. A few more papers, even ones that are published in peer-reviewed economics journals will be appreciated.

1. Some examples of predictions of gloom in the midst of hope that were right - economy tracking up, majority of economists said "it's going to be real bad next year" and they were correct.

2. Some examples of predictions of hope in the midst of gloom that were right - economy in recession, majority of economists said "next year will be great" and they were correct.

But I'm sure my anti-intellectual bias in not placing faith in economics forecasting will be easy to demonstrate.

Tom Curtis at 14:24 PM on 12 August 2016

Climate inertia

sauerj @2, there are three climate sensitivity values it is helpful to know about.

First, the Transient Climate Response (TCR) is the temperature in the 70th year after when the only change in forcing consists of a 1% increase in CO2 levels per annum. The 70th year is when CO2 levels double under that condition. TCR is approximately 1.5 C per doubling of CO2, or 0.4 C/(W/m^2). It is important because it closely approximates to the immediate temperature response to forcing when forcing is increased more or less steadilly. It corresponds, more or less, to the red line in the graph above.

Second, the Equilibrium Climate Sensitivity (ECS) or Charney Climate Sensitivity is the temperature increase following a doubling of CO2 that is experienced once radiative/convective equilibrium is reestablished, but with no changes to land cover, or ice sheet extent as a result of feedbacks. It is approximately 2.8 C per doubling of CO2, or 0.76 C/(W/m^2). It is also the temperature we will achieve in 50-200 years if we increase CO2 concentration to a given level and hold it constant. The above graph is confused in that it purports that that is the brown line, but at ECS thermal equilibrium in the ocean has been established, so it should also be the yellow line.

Finally, if you allow forests to become deserts (or vice versa), and ice sheets to melt, you get the Earth System Sensitivity (ESS). That is not well constrained, but is likely 33% or more greater than the ECS. The grey shaded area is the ESS as determined from a particular period. Again, it is only relevant if we hold CO2 concentrations constant at their peak value.

In practise, if we should bring net anthropogenic emissions to zero, the ocean and chemical weathering will absorb CO2 at a rate that approximately balances the rate at which temperatures approach, first the ECS and then the ESS. The result is an approximately constant temperature near the TCR. Therefore with rational climate policy, ECS and ESS are more or less irrelevant. Even a continuation of 10% of emissions, however, will hold CO2 levels constant in the short term (up to 200 years) and rising in the long term so that temperatures will increase to ECS and then ESS values. Indeed, greater than ESS values because of the rising CO2 levels. That is why zero net emissions within the next 50 years is a must for any sensible climate policy.

sauerj at 13:35 PM on 12 August 2016

Climate inertia

I'm a bit confused, and need help understanding. Hansen's and other articles say that there is one equilibrium average global surface temperature based on CO2 concentration, and that it is ~3.0C (2.5 - 4.0) rise for every doubling of CO2 above a base concentration. This can be expressed as Teq = 3.0 x (Ln(CO2_new/CO2_base) / Ln(2)). If I apply this math to 400ppm (new) and 290ppm (base), I get 1.39C rise, which is the brown line in the lower chart. I understand that this is the average global surface temp increase, and that it would be more in the higher latitude regions, etc. And, I understand that this is the equilibrium temperature and that it will take ~135+/- years to reach full equilibrium based on a SkS chart I saw several months ago (from that I surmised that the 1st-order process lag is about 45 years); although another SkS article suggested this lag time is much less.

If I do the calculus, I get a the following crude model expression: Temp = Teq (above) x [1 - exp (- time_yrs/45 years)]. If I apply this expression to actual temps since 1955 (LINK), this fits very well, in terms of hitting the actual annualized or 30-year avg temps (lines in above chart). One could go on & find the best fit 'gain' multipler and 'lag time constant' using SOLVER for the minimum sum of squares of error; a project for another day.

All the above concepts are simple, straight forward and easy to understand. But, this article introduces two new temperatures (much higher than the Tequil that I've learned about so far). I don't understand what the RED and gray region temps represent, and how they are are applicable to benchmark temperatures like UNFCCC's agreed +2.0C limit; or Hansen's chart in 'Storms' that shows that the Antarctica ice formation started to develop at +4.5C. Are these RED and gray region temperatures on a different scale (apples-to-oranges) vs these latter benchmark temperatures? Are these RED and gray temps actually applicable to apples-to-apples comparison with the temperatures used in the bulk of scientific documents.

Bottom-line, what exactly do the RED and gray region temps represent in a tangible sense and in comparison to the normally discussed brown curve temps? Thank you!

nigelj at 12:26 PM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

Tom Curtis @24

Singapore, Taiwan, Japan and Hong Kong are all high wage asian economies, most with strong manufacturing bases.

Will London really lose its financial capital status? I thought this came mainly from strength in insurance etc and Brexit won't change that much.

It's probably pointless to speculate on what form of Brexit will prevail. However regarding free trade, most of Europes tariffs are on farm products. Britian doesn't export significant agricultural products. Britian exports some manufactures but the EU tariffs on non member countries are not large for manufactured products. Ditto for services.

Don't get me wrong, Brexit will hurt financially, but maybe not that much longer term. Britain could join the TPPA as an alternative fta.

I agree "scexit" is a worry. Theres a further possibility that the entire EU could unravel.

However Britain does gain some things. They can run a tighter immigration policy, and there are some monetary savings. I have grown sceptical about immigration, although I basically lean liberal. The OECD did a huge study on past immigration in Europe and concluded it hasn't given any real economic benefits as below:

www.telegraph.co.uk/news/uknews/immigration/10844765/Mass-immigration-not-the-secret-to-economic-growth-says-OECD.html

I don't know exacly what economists think, and havent seen a poll, but certainly in my country of NZ, the predominant opinion of economists in the media and treasury and reserve bank is in favour of free markets, privatisation etc. It's like a religion.

However a couple of comments in favour of economists. They do recognise some regulation is required to correct market failures, and the IMF has recently recognised that "neoliberalism" hasn't worked in some respects. To some extent it's politicians that make a mess of economic policy, or get captive to lobby groups wanting regulations removed etc. I half agree with you. It's not a simple issue.

Tom Curtis at 11:16 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

nigelj @23, I would not trust your common sense too much on this issue. First, the countries in Asia that do very well economically are those with low wages which give them an advantage in manufacturing. Unless Britain is prepared to follow that low wage route the comparison is not apt. Admitedly Australia is also doing reasonably well at the moment, but that is based on a vast resource base being sold cheaply to Asia. As Britain does not have that resource base, again the comparison is not relevant.

Personally, I don't think anybody can exactly predict the economic impact of Brexit, and I doubt serious economists will try. It will almost certainly be negative, but how negative depends on:

1) To what extent some city within the EU supplants London as the financial capital of Europe. London has been the financial capital in part, at least because it has been a convenient, English speaking location through which the US has channelled its European investments. With the UK's withdrawal from the EU, it is not clear it can continue to serve that role, and almost certainly not as well. Further, the ability to speak English is now sufficiently widespread on the continent that the UK provides the US no particular advantage in terms of communication anymore.

2) The nature of the final exit agreement. Those which will preserve close economic ties will also preserve the European regulatory structure (as with Norway). That will result in little negative impact, but great political cost to a government pursuing it. The alternative will be terms of trade no better than, for example, Australia or Canada, which will come at a moderate economic cost.

3) Can the UK preserve its unity. It is all very well for May to claim that no new referendum on Scottish independence is required or appropriate, but given the Brexit vote was (if anything positive) a vote for sovereignty, it would be hypocritical to not likewise allow sovereignty to the Scots - something the Scottish nationalists will be keenly aware of. Refusing a second referendum on Scottish independence is likely to greatly reduce cooperation between the Scotish parliament and the British government. Allowing it, on the other hand may result is Scexit which again would have a large negative impact on the English economy.

So, while there may only be a small to moderate negative impact, there is plenty of room for a very large negative impact.

With regard to economic experts, I think you will find that experts obtaining media exposure are filtered in the sameway as are climate "experts". They are almost certainly more representative of actual economic expertise, but they are by no means a fair sample. A large proportion of macroeconomists are not fans of neo-liberalism in any form. What proportion I could not say, but there is certainly no consensus of macroeconomists in favour of it.

nigelj at 10:37 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

Tom Curtis @ 21

There's a lot of sense in what you are saying about economists and Brexit, in general terms.

However you make the point economists are predicting that with Brexit Britian will have reduced gdp growth. Even a trained ape should be able to see Brexit will hurt Britain economically in terms of raw gdp performance. Whats concerning is that economists cant really put a reasonably accurate, proven figure on this. They can only really claim it will hurt . Sure I agree with you that what economists say is better than nothing, but it just isn't very good either.

However commonsense suggests Brexit may not hurt that much. Plenty of other countries are not part of the EU and do well economically, especially in Asia.

However it appears to me the economists kind of got drowned out in the Brexit debate. It was politicians on both sides of the debate making blatantly outrageous claims about economic aspects of Brexit, and I think they just made it up as they went along, probably ignoring the advice of their own economists!

Regarding frustration with "economic experts". The economics community has promoted an ideology of neoliberalism that promotes very free markets, privatisation and deregulation, etc. The economists and politicians told us all that it would lead to higher wages and a trickle down effect. This clearly hasn't happened in places like America and this is proven by hard data discussed in the Economist Journal. I'm not sure about Britain but I suspect maybe it hasn't happened much. People are understandably frustrated and have lost faith in the experts.

Neoliberalism also promotes very free immigration and we were all told everything would be marvellous. However this has produced at least some downsides, so again can you understand why people loose faith in the experts?

Free markets are fine in many cases and immigration obviously has value, but I think a borderless world is a fantasy with huge problems. There have to be at least some controls. Brexit was caused by a failure of the ruling establishment to acknowledge this sort of thing.

BC at 10:20 AM on 12 August 2016

Climate scientists make a bold prediction about sea level rise

A paper reassessing the satellite altimeter estimates of global mean sea level rise was published in May 2015 by the Uni of Tasmania, CSIRO and others in Nature Climate Change.

This graph from the paper shows that when possible biases in the early satellite record are taken into account, firstly the sea level rise becomes about 10 mm less over the last two decades. Secondly there has been an acceleration of the rate of sea level rise over this period. They say ‘our revised record indicates that the rate of rise has increased over the last 2 decades (independent of how we estimate the vertical land motion), consistent with other observations of the increased contributions of water and ice from Greenland and West Antarctica.’

Sea Level graph last two decades

The two papers taken together presumably provide more confidence in the conclusion that sea level rise has accelerated over the last two decades and give an even higher estimate of this acceleration.

nigelj at 10:01 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

stevecarsonr @20

I just meant that we can have some faith in economists in terms of microeconomics and supply demand curves etc.

I agree we should certainly be very suspicious of any economic "forecasts"and I certainly am, especially gdp growth or wage growth. The record in this area is very poor. Macroeconomics certainly has some grey areas that are not convincingly resolved.

I'm not an economist but find it pretty interesting. If you are interested in forecasting and macroeconomis in general I suggest the book "Post Capitalism" by Paul Mason. This book clearly suggests capitalism is evolving into a new form of capitalism, but it also goes over economic history and economic cycles, and analyses why predictions often haven't worked. I think the book also touches on climate change in the later chapters and how capitalism relates to this. The book is not promoting communism or anything so dont be put off.

One of the big problems is that economics is based on a set of assumptions on how people behave as I'm sure you would be aware of. But people simply dont behave rationally. However incorporating human behaviour in economic modelling is hard, but there are some good recent attempts to do this.

However some of the problem is politicians. Economists are right about some things, but politicians ignore their findings when it suits.

Tom Curtis at 09:36 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

stevecarsonr @20:

As can be seen below, economic forecasts can be accurate.

"Looking at Table 3, we can see that in 455 out of 567 observations, the forecasted relative growth differential was the same as the outturn differential. This means that considering the aggregate forecasts, the OECD’s forecasts of the relative growth of G7 countries was correct on over 80% of occasions. The statistic for Table 3 is 207.5 – significantly above the 1% critical value of 10.83 – and indicating that we can reject the null hypothesis that the forecasts and observations are independent. There is therefore a statistically significant link between forecasts of relative growth and the outturn growth differential. This indicates overwhelming evidence that the OECD’s forecast of the relative annual growth of G7 countries over the sample period can be useful to users of these forecasts seeking to understand countries’ relative growth prospects over the horizon we have used."
(Source)

This is a particularly relevent study, as it studies the ability of economists to forecast which of two economies will perform better. That is equivalent to forecasting under which policy an economy will perform better given particular choices in policy. Based on that, when economists universally predict that the UK economy will perform worse under Brexit, there is a significantly better than chance that it will perform worse under Brexit. Based on the study above, they have a 1 in 5 chance of being wrong, but that is significantly better than the predictive accuracy of wishfull thinking (the alternative to economic forecasts in this area).

Personally, I believe the fundamental economic issues for Brexit are sufficiently clear that the forecasts for worse growth with Brexit are more likely to be true than that study indicates. That is not guarantteed. The UK may enter a Norway like agreement with Europe werein it retains the same favourable trade arrangements as members of the EU on condition of maintaining compliance with EU regulations, in which case the Brexit impact will be negative in the short term due to uncertainty, but otherwise irrelevant. Such an agreement, however, is politically unlikely given the reasons for the "yes" vote to Brexit; and that being the case the downside of more expensive exports to and imports from the largest nearby trading block are pretty much a foregone conclusion. Couple that with the fact that Brexit removes the major reason for London to be the financial capital of Europe and the downside starts looming very large.

Further, even in the example from Nate Silver you provide, forecast accuracy is significantly better than chance; and that It is not that the experts are proven worthless, but that they are proven less accurate then they think they are. In the mean time, the nonexpert predictions in economics do tend to be worthless, and to the extent that they are better than that, it is based on their relative expertise in economics.

Given this, if all economists think Brexit will be an economic negative for Britain, odds on it will be. Therefore it should be of concern that the Brexit campaign was not conducted on the basis that there would be an economic cost, but that it would be worth it for "increased sovereignty" (although even that later claim is dubious). That it was instead conducted in denial of the economic advice and on the basis that "people in this country have had enough of experts" certainly shows the Brexit campaign was based on a rejection of expertise as a guide to policy, just as is the Clexit campaign.

nigelj at 09:23 AM on 12 August 2016

As nuclear power plants close, states need to bet big on energy storage

Michael Sweet @ 18 and 21.

Thank's for those details on the Jacobsen research. Its certainly very compelling and I'm convinced.

I was wondering in my post above how a totally renewable grid caters for days with little wind in parts of a country, and whether having a surplus of renewables power would be sufficient. It appears Jacobsen have proposed a surplus of renewables, along with some storage, but apparently not much surplus or storage is required.

We should also not let "perfection become the enemy of the good". No grid is going to be 100% reliable in all circumstances regardless of the power source. So long as reliability of renewables is high and this appears feasible if its properly done.

stevecarsonr at 08:17 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

nigelj,

"One could also say it has a truly dismal record at forecasting anything. But we cant just totally ignore economists. There are parts of economics that are reasonably soundly proven. It's the best we have."

Yes, there are parts of economics that are reasonably sound. Microeconomics, for example. Macroeconomics, not so much consensus. So what? I don't ignore microeconomics or macroeconomics. I'm fascinated by the subject.

The actual question is, "Is it anti-intellectual to ignore the forecasts of people who have been just as much wrong as right with their forecasts?"

I say, no.

You say, yes, because they are "the best we have". Sounds hopelessly fluffy to me.

Back when doctors used leeches to cure people, there was a crowd saying "well, it's the best we have". Applying reason to problems is what I believe in rather than fluffy optimism.

Critical thinking is why there has been so much progress in science, medicine and economics. Accepting rubbish from inappropriately-titled "experts" because "it's the best we have" is - my unproven hypothesis - one of the ways that has held back much progress.

Tom Curtis at 08:09 AM on 12 August 2016

Water vapor is the most powerful greenhouse gas

old sage @238:

"Any other body, earth included, will discharge its energy with a modified spectrum and gases, which obey quantum mechanics and are below the threshold for excitation do not radiate except with a very low probability."

Indeed, "Comparing the radiative rate kR (the inverse of the lifetime) to the collisional deactivation rate kM[M], provides a quick estimate that only one out of 100,000 CO2 molecules excited into the (0,10,0) by collision or absorbing a photon, will emit." (source) The collisional deactivation rate is "~ 10⁵ s^-1" (same source). Further, "At 300 K about 6% of the CO2 molecules in the atmosphere are vibrationally excited and can radiate." (Source) Multiplying out, that means approximately 6% of CO2 molecules will radiate in any given second at 300 K at 15 microns wavelength in any second. But with 9.52 x 10^21 molecules of CO2 per meter cubed at standard atmospheric temperatures and pressures, that is 0.572 x 10^21 photons emitted per second from gaseous CO2 per meter cubed per second across the 15 micron band.

At 15 microns wavelength, each photon has 13.25 x 10^-21 Joules of energy, so that each meter cubed of air at standard pressure and 300 K radiates approximately 7.58 Joules per second, or 7.58 Watts, with the energy divided equally among all directions. Added up over the thickness of the troposphere and the the resultant radiation is very significant.

The upshot is that while the probability of any given molecule radiating between excitation and collision is very small, the probability of each molecule radiating in a given second is only moderately small (6%) and there are a very lot of molecules. Of course, we don't need this maths because this is just another attempt by old sage to prove that the observed IR radiation from CO2 in the atmosphere does not exist. No matter how many times he hides his eyes from the observational data, it does not go away.

nigelj at 07:15 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

Regarding experts, economics and Brexit.

Economics is called the dismal science, because it deals with dismal things. One could also say it has a truly dismal record at forecasting anything. But we cant just totally ignore economists. There are parts of economics that are reasonably soundly proven. It's the best we have.

Brexit had a lot of lies and scaremongering on both sides of the debate, especially on costs. The truth is likely in the middle. Look at it logically. Britain is leaving a free trade zone so there must be costs in this. But look at what Britain actually exports and the costs should not be large.

Brexit was an ideological war and a very confused one. The first casualty of war is truth.

I think Brexit happened because certain problems with the EU and immigration, etc, etc were left unresolved and even ignored, and things boiled over. Im not sure if Brexit was wise but I certainly see why it happened. The "establishment and governing elite" only has itself to blame for ignoring reasonable concerns by the general population.

nigelj at 07:09 AM on 12 August 2016

Rejection of experts spreads from Brexit to climate change with 'Clexit'

One Planet Only Forever

I agree climate sceptics expressing concern for suffering of poor people is missleading. I would go further and say in my experience many (but not all) climate sceptics couldn't care less about poor people.

There seems to be a strong anti social welfare and anti income support agenda with many climate sceptics in my experience. Climate scepticism is driven by certain world views, as well as a sense of entitlement as you have noted.

michael sweet at 06:47 AM on 12 August 2016

As nuclear power plants close, states need to bet big on energy storage

Nigelj,

Jacobson et al (2015) Low-cost solution to the grid reliability problem with100% penetration of intermittent wind, water, and solar for all purposes won the Cozzarelli prize awarded "for outstanding scientific excellence and originality” to 6 out of ~3,000 papers published in 2015 in the Proceedings of the National Academy of Sciences. His simulations of the US power grid showed that renewable energy could provide 100% of all power (all power, not just all electricity) with high reliability. While I am not expert and cannot assess Jacobson's work, it seems to me that he would not have won the Cozzarelli prize from the National Academy of Science if the paper was not solid work.

Read the references to this paper and you will find out about peer reviewed work supporting renewable energy. Jacobson 2008 identifies the most promising non-fossil power supplies. It had 600 citations a year ago. Some of the conclusions have modified because of technical developments (Jacobson 2015 is state of the art). By contrast, virtually nothing is published in peer reviewed journals supporting nuclear.

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