Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


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.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
Keep me logged in
New? Register here
Forgot your password?

Latest Posts

Archives

Measuring Earth's energy imbalance

Posted on 20 September 2009 by John Cook

When the Earth is in energy imbalance, with more energy coming in than radiating back out into space, we experience global warming. How do we know if there's an energy imbalance? This can be determined empirically in two ways. Firstly, by using satellites to directly measure the difference between incoming energy from the sun and outgoing radiation from the earth. Secondly, by adding up the energy content of the atmosphere and ocean over time. The newly published paper An observationally based energy balance for the Earth since 1950 (Murphy 2009) does both.

Adding up the Earth's energy content

To calculate the Earth's total heat content, the authors took data of ocean heat content from the upper 700 metres. They included heat content from deeper waters down to 3000 metres depth. This is not insignificant  - the heat increase in waters deeper than 700 metres is around 40% of the heat increase in waters from 0 to 700 metres. They computed atmospheric heat content using the surface temperature record and the heat capacity of the troposphere. Land and ice heat content were also thrown into the mix.

A time history of the energy going to heat the Earth requires differentiating the heat content. As the heat content data was too noisy for single year differences, successive linear fits were performed to running 8-year segments of data. Eight years was chosen as it's the longest period that still separates the dips due to the El Chichon and Mt. Pinatubo volcanic eruptions. The resultant energy imbalance time series is seen in Figure 1:


Figure 1: Time history of energy flow into Earth's climate, calculated from the derivative of the Earth's heat content using Domingues 2008 for upper ocean heat (Murphy 2009).

We see that since the mid 1970's, the planet has been in positive energy imbalance. This is consistent with satellite measurements which also find more energy coming in than radiating back into space. This energy imbalance is what is causing global warming.

Empirically calculating climate sensitivity

Climate sensitivity is an expression of how much global temperature changes for a given radiative forcing. The general consensus of peer reviewed estimates of climate sensitivity (both modelled and empirically determined) tend to cluster around a global warming of 3 ± 1°C for doubled CO2.

As the ERBE and CERES satellites measure the net energy imbalance, this data can be combined with temperature records to place constraints on climate sensitivity. Because the ERBE satellite record covers only 15 years, it doesn't encompass slower feedback processes such as receding Arctic sea ice. Hence the data provides only a weak upper bound of climate sensitivity (a maximum of around 10°C warming for doubled CO2). However, the analysis rules out climate sensitivities lower than 2°C. This finding is consistent with the general consensus estimate of climate sensitivity (in addition, the author Dan Murphy informs me he's currently doing follow-up work to calculate a more precise lower bound).

Cumulative energy budget

Possibly the most interesting section of the paper (at least to me) is analysing the various contributors to the energy imbalance and where the energy is going. Figure 2 shows the sum of positive, long-term climate forcings.


Figure 2: Cumulative energy budget for the Earth since 1950, showing mostly positive and mostly long-lived forcing agents from 1950 through 2004.

To close the energy budget, the authors also calculated how the positive forcings have been balanced by various negative forcings, as seen in Figure 3. Note that outgoing radiation is on the increase - another indication that the planet is indeed warming and consequently radiating more energy back into space.


Figure 3: Cumulative negative forcings such as stratospheric aerosols, direct and indirect aerosol forcing, increased outgoing radiation from a warming Earth, and the amount remaining to heat the Earth.

Of particular note is comparing the heat capacities of the land and atmosphere to the heat capacity of the ocean. The land and atmosphere contribution is not even visible in Figure 3 so here is a magnified look at the bottom corner of the graph:


Figure 4: cumulative energy storage of the ocean compared to land + atmosphere. 

It's worth remembering that global warming occurs over the entire globe - land, atmosphere and oceans. Consequently, to focus on one very small piece of the puzzle (eg - surface temperatures) while ignoring the larger picture can lead to misguided conclusions.

Internal variability is apparent in the surface temperature record - a measure of atmospheric heat content. This is no surprise from an energy budget point of view. Small changes in heat transfer into or from the ocean into the atmosphere can create significant changes in surface temperature. But when you look at the entire planet's heat content, a clearer picture emerges. The planet is steadily accumulating heat due to its energy imbalance.

0 0

Bookmark and Share Printable Version  |  Link to this page

Comments

1  2  Next

Comments 1 to 50 out of 51:

  1. Hi John, I don't follow completely the reasoning behind this paper (or maybe that of your excellent summary).

    You start your post saying: "When the Earth is in energy imbalance, with more energy coming in than radiating back out into space, we experience global warming."

    But then, you say: "Note that outgoing radiation is on the increase - another indication that the planet is indeed warming and consequently radiating more energy back into space."

    But if Earth is both warming and also radiating more energy out, it means that the energy coming in is also increasing. Where does this extra energy come from?
    0 0
    Response: Very good questions and apologies for the confusion. There is a lot more to the paper than what I outlined above - I focused on just a few of the main points of the paper in an effort to be concise and accessible - perhaps not successfully!

    No, the energy coming in isn't increasing. In fact, that's another important point to make. We have satellite measurements of incoming solar radiation and it shows little to no long trend over the past 50 years. What is happening is the energy coming in is relatively constant but the energy radiating back out into space is being partially trapped by increasing greenhouse gases. Hence less energy going back out = energy imbalance.

    In fact, the paper explains some of the basics of this process by imagining what would happen to global temperatures if there was a sudden increase in greenhouse gases (a hypothetical simplified situation for the purpose of understanding the physics involved):



    If greenhouse gases suddenly increased to a new level, the planet would suddenly be in energy imbalance. The energy out would be less than the energy in and the planet would start accumulating heat. Hotter objects radiate more energy. Therefore, as the planet gets hotter, it radiates more energy so the energy imbalance lessens. Eventually the planet will have accumulated enough energy so that the energy out approaches the energy in. Eg - the system approaches equilibrium.

    This is why we talk about there being 'warming in the pipeline'. Even if we completely stopped all our CO2 emissions right this moment, we would still be left with a significant energy imbalance. It would take several decades of warming before the planet reached equilibrium. And that's a best case scenario. Of course we're not going to immediately stop CO2 emissions so the energy imbalance will only increase in the years to come.

    I tried explaining this process in the Climate Time Lag post but people seemed confused there too - I might have to rework my explanation of the whole process :-)
  2. Hi John, I also had a bit of a hard time following everything, but for a different reason than Manuel. For me the steady increase in cumulative forcing from solar and from ozone are problematic. In addition I'm surprised that most important negative forcing ("aerosol direct + indirect + other forcings") doesn't get a fuller description. Is the paper explicit about these things?
    0 0
    Response: The stratospheric and tropospheric ozone forcing is taken from NASA GISS data - there's a page on the NASA website going into details on how this is calculated. Re "aerosol direct + indirect + other forcings", this is actually one of the major points of the paper - I chose to concentrate on the simpler issue of energy imbalance (the reasons become evident if you read comment #3).

    Aerosol forcings are one of the major areas of uncertainty with climate models. So what this paper does is place empirical constraints on aerosol forcing by working out the total energy imbalance, then pruning away other forcings that we know with greater certainty. What is left is "aerosol direct + indirect + other forcings".

    If you'd like the full paper, contact me and I'll email it to you.
  3. A couple of points:

    1) If the earth has been heating since the 1970s due to other factors than greenhouse gases (eg less low level clouds due to eg long term solar magnetic trends, delayed tipping points/feedback loops from longer term solar lag effects etc), the apparent 'energy imbalance' (ie the factors used to calculate it) would still be there(Figure 1).

    E.g. less clouds- warmer earth/ oceans/atmosphere= 'apparently' more energy in than out.

    If the oceans warmed due to less clouds, this would absorb heat coming in, without it going out, but greenhouse gases would not be producing the warming.

    2) The warmer oceans from 1950s for example could be eg either 1) a lag effect from long term temperature trends, or 2) a result of less low level cloud cover.

    Figures 1,2,3 are models/interpretations, not data. Figure 4 appears to be data.

    3)One would have to check the papers and data in more detail etc, but one suspicion is, is that ocean/land heat/atmoshpere content etc has been measured correctly, but modelled using assumptions about greenhouse gas forcing and not other possible factors, to create an apparent 'imbalance' that is not there.

    (The also the attached Murphy 2009 paper requires subscription).
    0 0
    Response: To answer your points:

    1. I intentionally don't go into much detail on what's causing the energy imbalance (apart from touching on it briefly in Figure 2). That's a topic for a future post or two (or more). I'm taking baby steps here - just to accept that there's an energy imbalance is a big step for some :-)

    2a. The increasing energy imbalance since the 1950's cannot be a lag effect. In my response to Comment #1 and the climate time lag post, we see that if there's a change to the planet's energy imbalance (eg - increase in solar activity, increase in greenhouse gases), the planet will gradually approach equilibrium. This is not the case here - we're seeing the energy imbalance actually increasing in time since the 1950's.

    2b. Figure 1 is based on direct empirical observations of heat content. Narry a model is seen or used. Figure 2 is based on radiative line-by-line calculations, not climate models - nevertheless I only touch on this in passing as my main point is the overall energy imbalance, not the individual contributors. The various factors of Figure 3 are all calculated from empirical observations apart from stratospheric aerosol forcing which again is calculated from radiative line-by-line calculations. Nevertheless, my main point from Figure 3 is to compare the heat capacity of ocean to atmosphere which is hardly a controversial point to make.

    3a. Ocean/land/atmosphere heat content is based on empirical measurements. Modelling or greenhouse gas assumptions are completely irrelevant. We're talking about direct observations here. With all due respect, thingadonta, you need to switch off the cognitive dissonance here.

    3b. Sorry, I've been unable to find a link to the paper online yet, it was emailed to me. If anyone would like to read the full paper, contact me and I'll email it to you.
  4. John,

    Thank you very much for your clarification. I think I can follow the idea of energy imbalance and why it requires a higher equilibrium temperature, or more specifically, a combination of higher local temperatures that make the radiation going out equal to the radiation getting in. I say combination of temperatures and not global temperature, because it is still very hard for me to understand the physical meaning of an average temperature.

    I still don't understand the term "outgoing radiation" on figure 3. On your reply to my comment you say:

    "What is happening is the energy coming in is relatively constant but the energy radiating back out into space is being partially trapped by increasing greenhouse gases. Hence less energy going back out = energy imbalance."

    What is then, the "outgoing radiation" shown on figure 3?

    I hope this clarifies my previous question. And, in any event, I am going to take advantage of your offer to get the full paper.
    0 0
    Response: The outgoing radiation in figure 3 and the outgoing radiation that gets trapped by greenhouse gases are one and the same. The earth radiates longwave radiation. As the earth gets hotter, it radiates greater amounts of longwave radiation. Greenhouse gases partially trap the longwave radiation on the way out to space.
  5. Manuel, see if this thought experiment helps:
    Say you have a stove in a very leaky one room cabin with broken windows and the door off the hinges. The stove always puts out the same amount of heat (the energy going into the stove is always equal). It's cold, with the heat energy quickly escaping from the cabin, so you nail boards over the windows and fix the door. At first the heat from the stove escapes less quickly, and the cabin starts to warm ... but it doesn't warm forever. Eventually a new equilibrium is reached. Again, the added heat from the stove is balanced by the heat escaping the cabin, but because of the extra time spent by the heat in the cabin, you're more comfortable there. If you continue to improve the insulation, then the equilibrium temperature in the cabin will continue to increase. There is a slow down in the heat leaving the cabin with each increase in insulation, but that only lasts until the temperature inside has increased. Eventually the rate of heat production by the stove is still equal to the rate of heat emitted by the cabin.

    I hope this analogy is more helpful than harmful.
    0 0
  6. further to 5.
    the cabin won't keep heating up forever but it will keep heating up as long as the insulation keeps increasing.
    although normally with insulation you think of turning on the central heating, so the air warms up, then the building fabric, and if it is well insulated, then it takes a long time to reach equilibrium, by which time you have probably turned the heating down.
    Not sure where I am going with this, but presumably the increase in greenhouse gases is slow and so on average around the planet the heating is roughly constant and the insulation is gradually increasing so there is no time lag waiting for the fabric to heat up, oh except there is, its the sea - maybe like having a big sculpture made of lead in your front room, by the heater, except the lead is fluid and transfers heat around the room and makes things really hot and steamy in some places. I'm gong to bed.
    0 0
  7. I'm also a little confused by the cumulative increase in "outgoing radiation". I have an idea what it might but it isn't very clear:

    1. Even though the Earth warms up, the outgoing radiation at equilibrium must equal the incoming radiation. In an enhanced-greenhouse warmer world at equilibrium, even 'though the Earth's surface is warmer and thus emits a higher radiative flux to the atmosphere, the IR radiative flux emitted to space will not increase, since it is essentially emitted at the same temperature as previously (i.e before the enhanced greenhouse), but at a higher altitude on average that corresponds to the same temperature as before. Whenever equilibrium is reached the incoming and outgoing radiation must be equal whatever the Earth's surface temperature and size of the greenhouse effect.

    2. However, after a step increase in greenhouse gas concentration (as in John Cook's response to post #1), there will be a reduction in outgoing radiation, until the Earth warms up sufficiently to "force" the emission of IR back to the level that balances the incoming solar radiation....

    ....so does the cumulative increase in "outgoing radiation" correspond to an increase relative to the temporarily suppressed outgoing radiation that results from the enhanced greenhouse gas concentration? In other words the "outgoing radiation" is increasing due to the recovery of the radiative imbalance as the climate system tends towards re-equilibrium.

    In other, other words some of the radiative imbalance is "leaking away" (as it must do) due to the tendency to progress towards a new equilibrium...

    ...that's how I see it...not sure 'though if it's a correct interpretation of the paper. Expressing these forcings as "cumulative forcings" is conceptually difficult to me.
    0 0
  8. ah, morning, so if you have a domestic wall 'radiator' and it is on a constant temperature and you keep adding blankets to it, surely it will keep reaching a new equilibrium as the heat is trapped inside until it is hot enough to compensate for the blanket being there, but it will never 'radiate' more heat than it did to start with. so i don't understand yet.
    0 0
    Response: And thus we see the dangers of using analogies - eventually the comparison breaks down and they confuse more than clarify. The earth is not like a domestic radiator because its not on a constant temperature. It gets hotter as it accumulates heat. And as it gets hotter, it radiates more heat. This is why I prefer to explain the science straight.
  9. canbanjo: were you thinking of a balanced heating system or TRVs fitted?

    John: thank you for another good article. I guess the point is that here is further evidence (as if it were needed) consistent with the Earth currently heating up. And it's empirical so it can't be blamed on 'unproven computer models'.

    Okay, so this isn't proof that CO2 is the cause of the imbalance; so what, plenty of other evidence exists for that. Nor does it say anything about the hypothesis that cosmic rays enhance cloud formation. But it is another nail in the coffin of the 'urban heat island' myth along with the 'it's the Sun' myth. And probably some other myths as well....
    0 0
  10. Re Canbanjo @8: John, I agree that we should be wary of analogies, but explaining why an analogy doesn't apply should enhance understanding. Unfortunately, I thought Canbanjo had it right -- nothing is keeping the radiator at the same temperature but the outside energy input is the same. If the Earth received constant solar energy, this would be analogous.

    Maybe the problem is use of the word "heat"? Incoming solar energy per second equals that which leaves (at equilibrium), but in a warmer Earth rather than so much visible light being reflected straight back (not as heat), it is converted to infra-red which is trapped and can only leave as heat. But that can't be the whole problem.

    I guess I'm also having a problem with "cumulative" and who knows how many other concepts. I'll read the paper!
    0 0
  11. John,

    Thank you for sending me the paper. I think that I understand better what are different the components of the three figures, including the somewhat misnamed "outgoing radiation".

    My impression is that the paper deals with two unrelated issues.

    On the one hand, an analysis of the warming that has occurred in the last half of the 20th Century. It seems reasonable and the results consistent with other sources I have seen.

    On the other hand, a very interesting way of presenting the implications of the radiative forcings of different greenhouse components as estimated by sources like the IPCC reports. It shows that the effect of greenhouse gases is much bigger than the observed warming. Therefore, either their true radiative forcings are smaller or there exist other factors that are “masking” their effect.

    Unfortunately, the paper does not present any evidence to support either case. But, as I said, it provides indeed an interesting approach.

    As an aside, I agree with you that analogies have to be used with great care.
    0 0
  12. Figures 2 and 3 don't have any low level cloud data, which are reduced during a warmer earth, as well as during greater sunspot activity (eg 20th century), especially in temperate climes, where most surface warming has occurred.

    Reduced levels of low cloud cover enhances any warming trends (approx 2.5 times the solar irradiance during sunspot cycles), as well as allowing more heat to be absorbed into the oceans and thus enhancing any radiative imbalance, but note all cloud data is conveniently absent, alomg with any discussion, in Figures 2 and 3.

    There are plenty of papers and research to attest to the reduced levels of low level clouds during eg the 11 year sunspot cycles (enhancing the sunspot cycles approx 2.5 times what would be expected from the irradiance alone-where is this in Figure 2?? -and where is the asscoiated 20th century climate forcing from increased sunspot acivity if they have increased markedly over ~hundred years from ~1800s, along with associated longer term effects on clouds and the radiative imbalance, known to be roughly 2.5 times solar irradiance effects throughout the 20th century??)

    (And before someone says sunspot effects are way too small, we KNOW the effects from sunspot cycles on earth are enhanced ~2.5 the solar irradiance alone (eg due to less low level clouds), this therefore is a longer term forcing agent that is absent in Figure 2.
    0 0
  13. Looking again at figures 1, 2 and 3, I have a couple of observations to make:

    1) If the average of the curve depicted in figure 1 were 4x10^21 J/yr, which looks like it could be, the total imbalance during the 50 year period would be 200x10^21 J which is the observed increase in the heat contents of the system (the line blue on figure 3). The blue line also seems to follow the shape of figure 1. BTW, this is what one would expect, wouldn't it?

    Heat increase = Cumm. radiation in - Cumm. radiation out

    2) On figure 2, we see that about half of that increase (100x10^21 J) can be explained by an increase in solar input. Note that I am just reading what the figures say.

    That leaves the other half to explain (100x10^21 J).

    Rather, the author prefers to assume that in fact the cumm. effect of radiative forcings is of the order of 1,600x10^21 J, but there exist many negative feedbacks that counteract the effect of greenhouse gases.

    In other words:

    Explanation 1)

    200 of actual heat increase = 100 coming from the increase in solar radiation + 100 coming from unknown sources and measurement errors.

    Explanation 2)

    200 of actual heat increase = 100 coming from the increase in solar radiation + 1,600 from greenhouse gases effects – 300 from stratospheric aerosol effects – 350 from outgoing radiation that really isn’t going anywhere because of the greenhouse gases – 950 from mostly unknown (or not yet quantified) causes.

    [Note that the above figures have uncertainties that in some cases are of the order of 25% or more of the calculated value. And the real figure is totally unknown in the case of the 950 sundry effects figure and in fact is the result of the other calculations added to match]

    Which one do you prefer?

    I have two specific question for John.

    1) I have read with interest your recent comments about the correlation between CO2 and atmospheric temperature. I agree with you that trying to disprove the AGW theory based on the fact that during the last 10 years there is no correlation. On the other hand you present a correlation during 100+ years. Looking at figures 2 and 3, don’t you think that any correlation between the tiny white sector of figure 3 (representing the variation of atmospheric, land and ice heat) and the big gray sector on figure 2 (representing the effect of the increase in CO2) is in fact meaningless?

    2) I understand from the text of the paper, that it uses a linear method to compute the now famous "outgoing radiation". But the increase in radiation is not linear but rather proportional to the the fourth power of the increase in temperature. What do you think are the consequences of this "simplification"?
    0 0
    Response: Good questions. In fact, upon reflection, this post on energy imbalance gives a richer perspective on the two previous posts on short term CO2 correlations and long term CO2 correlations.

    Question 1. The correlation between CO2 and temperature is not meaningless. It's not a mathematical abstraction but grounded in physical reality. The earth radiates infrared (or longwave) energy back out to space. Atmospheric CO2 absorbs the longwave radiation, some is turned into heat and some of the longwave radiation is radiated back down towards earth. So this will have a direct effect on atmospheric temperatures hence the correlation.

    I'm not trying to downplay surface temperature record, just put it in it's proper context. It's important to realise that atmosphere is just one small piece of the climate puzzle. Much of that longwave radiation that gets radiated back down to earth is absorbed by the ocean. Figure 3 reminds us that the ocean has a much great heat capacity than the atmosphere. Then you have internal variation from phenomena like El Nino where the ocean exchanges heat with the atmosphere. This internal variation is superimposed on the long term warming trend caused by the energy imbalance. Internal variation doesn't add any extra energy to the planet - it just moves the energy around. This is the point I make in my post on short term CO2 correlations.

    In my post on long term CO2 correlations, I make the point that CO2 is not the only forcing that affects climate. You have solar variations, stratospheric aerosols (from volcanoes), methane, ozone, etc. Figures 2 and 3 are good reminders of this, even breaking down the various components based on empirical measurements.

    Question 2. Not sure about this, still wrapping my head around that part of the paper but in the part of the paper I think you're looking at (Section 3. Surface temperature and radiation), I don't think he's talking about outgoing radiation but net radiation balance. I could ask the author about it but I've nagged him enough asking questions and requesting data (to be used in an upcoming post), I don't want to push the friendship! Feel free to follow up with the author yourself :-)
  14. Manuel, your "explanation 2" has to be the correct one in the context of the study. The negative forcings (note these are not "negative feedbacks" as you describe them), are individual components of forcings, the summation of which gives the total forcing (that yields the cumulative 200 x 10^21 J). The total greenhouse gas-induced forcing is obviously much larger than the solar one, and any negative forcing acts to counter all of the positive forcings – one can't single out a single forcing (solar) and consider that its contribution is somehow left "unopposed" by negative forcings.

    (incidentally, and rather in line with the annoyingly vague descriptions in the paper, there is no reference to the source of the solar forcing contribution. The published data indicate that solar contributions have not only been very small since the 1950's, but have been in a cooling direction for around the last 20 years. However Murphy's data [Fig 2 above], indicates a (admittedly small) solar contribution that continues to increase during the 15-20 years up to 2004. The authors refer to global dimming effects, and I wonder whether these (i.e. recovery from "dimming") is included in the solar contribution…the authors give us no insight on this!).

    On you specific question #1:

    Firstly we should be careful how we're using the term "correlation". It's not a mathematical/statistical correlation, and one shouldn't be expected in the CO2/surface temperature relationship. At best we can say that in line with the rather slow early 20th century increase in greenhouse gas, the surface temperature rose slowly, and following the very rapid rate of increase in CO2 emissions from around the mid 60's the temperature increase has been faster. But the effects of CO2 on surface temperature are mixed in with the effects of all the other forcings [***], and are further "discorrelated" by lags in the response times of the various elements of the climate system (atmosphere, land, ocean surface, ocean depths), and so strict "correlations" in the statistical sense aren't expected.

    That there is a qualitative "correlation" as described by John Cook here…..

    http://www.skepticalscience.com/The-correlation-between-CO2-and-temperature.html

    ….is due to the fact that increasing the greenhouse effect does cause the Earth's surface to warm, and there haven't been any truly humungous events (massive changes in solar outputs or truly dramatic volcanic events etc.), that have overcome the dominant greenhouse contribution. In any case even 'though the tiny atmosphere/surface ("tiny white sector of figure 3") is indeed tiny with respect to the CO2 effect ("big gray sector on figure 2"), the ocean effect does clearly "correlate" with the CO2 effect, and we expect the land surface effect to "correlate" with the ocean effect since the latter has a strong influence on the former. So I don't think the "correlation" (using the term broadly!) is unexpected.


    [***] a very interesting paper on this is just published in PNAS – it's very apposite:

    http://www.pnas.org/content/early/2009/09/09/0908699106.abstract
    0 0
    Response: I queried the author re where his solar data comes from, it comes from Gregory and Forster (2008). Re the PNAS paper you link to, I just received a copy about a week ago and plan to do a post on it shortly.
  15. Re: #13 by Manuel:

    Manuel, your Explanation 1 is incorrect, because all those non-solar positive and negative forcings you say the author "assumed," instead are real, concrete, physical, measured phenomena that must be accounted for just as much as the solar forcing and the resulting temperature must be accounted for. Even if the global temperature was not increasing, the exact same analysis would be done using empirical facts for all those forcings, and in that non-warming case the accounts would have to balance.

    Your misunderstanding is understandable, because the popular media and especially the denialist ones try to create the impression that climatologists noticed that the temperature increased and in response started guessing at what might be causing it, without any empirical evidence.

    It's like your home budget. Receipts for spending, and paychecks, all are empirical facts that must be accounted for in the overall balance. Yes, there is uncertainty about some of your spending, and maybe about some of your income if you didn't keep good records of your garage sale. But you can't ignore the actual receipts and paychecks.
    0 0
  16. Thank you very much for your detailed answers. I agree with Tom that Explanation 1 (corresponding to the "it’s the Sun" hypothesis) is too simplistic to be correct. But I have to disagree with Chris and maintain that Explanation 2 (the "CO2 is gonna kill us" hypothesis) is also almost surely to be incorrect, if only because of the degree of uncertainty with which the different components of radiative forcings, positive or negative, are being "estimated" or "asumed".

    I have to maintain "estimated" or "assumed" because few things in Climate can be really "measured" and the paper itself recognizes that the big white chunk of figure 3 is a result, not a calculation.

    My personal impression (which I understand has little or no value) is that radiative forcings of greenhouse gases have been overestimated. Leaving a much more manageable situation on the right side of the equation once they are adjusted to their true value (less unknown effects to be accounted for). Furthermore, many of the claims made by both sides of the debate seem to me to be too opportunistic and self-contradictory, like rising temperatures prove CO2 warming, but when they apparently stop rising, other factors should be acknowledged for, even though they weren’t considered before. By the way, I am happy to concede that on the other side it is also easy to spot bogus arguments, if only because the skeptics’ front is less organized.

    I am sorry Chris, but "qualitative" correlations have little or no value for me at this point. They hardly prove or disprove anything, or rather they can "prove" anything you like them to "prove".

    That’s why I think that the only "correct" explanation at this point is that we still don’t know enough and everybody is free to make her own bets, but please let's try to be at least consistent with the implications of our hypothesis.
    0 0
  17. John,

    Thank you very much for your reply.

    Re. correlation. As per my previous post, my main point is that correlations have to be taken with great care as they provide very poor basis to prove or disprove anything.

    Re. linear modelization. Yes, I am looking at the following formula which, as you say, refers to net radiation:

    N = F - lambda x Delta T + epsilon

    One of the concerns I have when I look at climate papers is how linear relationships are being used for phenomena which don't seem to be linear. By the way, that's also why I find suspicious linear correlations to begin with.
    0 0
  18. Manuel, Of your two explanations, your explanation 1 is clearly incorrect (see mine and Tom’s explanation)…you agree with this. Explanation 2 is simply and unequivocably correct in the context of the paper. After all, these forcings are independent and thus an unbiased summation is the correct means of coming to a conclusion about the residual forcing and its contributions. Obviously there is uncertainty over the magnitudes of these, but that doesn’t negate the fact that an unbiased overall summation is appropriate.

    I’m curious about your extrapolation from the fact that the evidence very strongly supports a strong enhanced greenhouse forcing (which is very obviously much stronger than the solar forcing as indicated by a substantial evidence base), to an interpretation that explanation 2 corresponds to a "CO2 is gonna kill us" hypothesis” . That seems a very strange (and false) emotionalization of a quantitative analysis!

    “Qualitative correlations”. This is an interesting point. One of the difficulties with establishing attribution of forcing contributions to 20th century and contemporary warming is that the sort of “correlation” that you desire (presumably something like a mathematical/statistical linearized relationship between variables) isn’t appropriate for assessing attribution of 20th century warming to its contributing forcings. However we would be in a very sorry position if were to conclude that attribution was therefore not accessible nor robust. We can assess attribution via modelling based on known/estimated magnitudes of the forcings coupled with knowledge of climate responses and their time constants, and reintroduce a quantitative (‘though non-linear) element into the relationships.

    Notice that we can assess climate responses (earth temperature) and greenhouse gas concentrations with quantitative correlations of the sort you desire via analysis of paleoproxy data (e.g. as compiled, for example, here [***]) where the relationship between temperature and CO2 concentrations can be linearized since the temperature can be reasonably assumed to have come to equilibrium with the forcing in these analyses.

    Incidentally, although this is a semantic point, the use of the word “ correlation” certainly doesn’t imply that the correlation between variables is quantitative. Here’s a dictionary definition of the term “correlation”, and I suspect that the term is used in that sense in the page I linked to on this site in my post just above. However, as I indicated above, a quantitative analysis via mathematical modelling can be used to extract attributions of 20th century warming (rather in the manner of the quantitative analysis in the Murphy paper we’re discussing).

    correlation n. A causal, complementary, parallel, or reciprocal relationship, especially a structural, functional, or qualitative correspondence.

    [***]Royer, D. L. CO2-forced climate thresholds during the Phanerozoic. Geochim. Cosmochim. Acta 70, 5665–5675 (2006).
    0 0
  19. Manuel, it's worth going back to your explanation 2 since that's what you're disputing (it seems you raised it just to knock it down!)

    Explanation 2:

    200 of actual heat increase = 100 coming from the increase in solar radiation + 1,600 from greenhouse gases effects – 300 from stratospheric aerosol effects – 350 from outgoing radiation that really isn’t going anywhere because of the greenhouse gases – 950 from mostly unknown (or not yet quantified) causes.



    Two things that might help:

    i. The "350 from outgoing radiation" really is going somewhere. It's escaping from the atmosphere into space. I'm pretty sure this does not refer to long wave IR emitted from the earth's surface, but to the enhanced emission of IR to space as the climate system tends towards equilibrium with the enhanced (greenhouse) forcing (see my post #7). I welcome input on whether I've interpreted that correctly.

    ii. The 950 isn't mostly unknown nor "not yet quantified". It's largely aerosol direct and indirect effects, and these have been quantitated (see e.g. [***]). Of course there is signifcant uncertainty in these analyses.

    [***] V. Ramanathan & G. Carmichael (2008)Global and regional climate changes due to black carbon, Nature Geoscience 1, 221 - 227 (2008)

    Ramanathan's analysis can be read in a similar form from this Senate committee hearing document here:

    http://www-ramanathan.ucsd.edu/testimonials/BlackCarbonHearing-testimony.pdf
    0 0
  20. I still don't get the idea of increased radiation into space due to to the earth becoming hotter.

    If the earth is getting hotter due to greenhouse gases trapping outgoing longwave radiation, then there must be a decrease in outgoing radiation not an increase. The relative increase would only occurr once the system is returning to equilibrium.
    0 0
  21. Re: #20, canbanjo

    Greenhouse gases don't trap all the outgoing radiation. They trap some, which causes the temperature to increase, which causes the Earth to "try" to radiate more energy. Only some of that increased radiation is trapped by greenhouse gases; the rest escapes. Of course, the portion of that increased radiation that is trapped, raises the temperature even more, which in turn causes the Earth to "try" to radiate more, and so on.

    But that process does not run away; the increases in attempted radiation and in trapping are only fractional, so their absolute amounts become progressively smaller until they become effectively zero; that's equilibrium.

    But equilibrium lasts only if the amount of greenhouse gas stops increasing. Since greenhouse gases keep increasing, equilibrium is a moving target.
    0 0
  22. Tom, thank you for trying to explain.

    Unfortunately I come back to the fact that the earth is heating up, that energy is coming from outside, so overall there is more energy coming in than is going out.
    the energy coming in is not increasing, so the energy going out cannot be increasing.

    there must be something else to this that is not being explained.
    0 0
  23. Re: #22 canbanjo

    Poke a small hole in the bottom of a bucket. Put a water hose in the bucket. Turn on the water so the amount of water going into the bucket is slightly more than can leave through the hole. Over time, the amount of water in the bucket will increase, which will increase the weight of the water, which will increase the pressure of the water at the bottom of the bucket. The higher pressure will push a larger quantity per second of water through the hole.

    Result: The input is constant, but the amount of water in the bucket increases at the same time the amount of water escaping from the bucket increases.

    The extra water going out of the bucket is a fraction of the water that is accumulating in the bucket.
    0 0
  24. A flaw in my metaphor of water-bucket for energy-Earth is that there are no laws of physics compelling the bucket system to reach equilibrium. The hole's size and position, the bucket's size and shape, the rate of water input, would have to all be exactly the right combination for the system to stabilize at some high enough rate of water spurting out the hole, to prevent the bucket from overflowing. It can happen, but it's unlikely.

    In contrast, objects are constrained by laws of physics to radiate more the hotter they are, until they put out as much as they get in.
    0 0
  25. Tom, thanks again but wouldn't a more accurate analogy be

    at equilibrium - the water being added is equal to that which is leaving through a hole.

    AGW equivalent - the hole is decreasing in size, but the water being added stays the same.

    So the bucket starts to fill up. The speed of water through the hole increases but it is not enough to compensate.

    ?
    0 0
  26. Chris,

    "That seems a very strange (and false) emotionalization of a quantitative analysis!"

    I was just trying to characterize the two most extreme factions of the AGW debate I have met. On the one hand those that say "It's [only] the sun" on the other side the most exaggerate proponents of AGW that say "CO2 is gonna kill us [we have no time left to act]".

    My personal view, as I have already expressed is that both extreme views are probably wrong, and I am sorry if my phrase sounded like an insult to you.

    With respect to correlations: A strong "quantitative" correlation between two variables can serve as an indication to try and find a relation between them. It does not prove a relation indeed exists. I am sure you agree with me. A weak "qualitative" correlation is just the expression of the desires of the person that makes the graph.

    This reminds me of what a coworker told me many years ago. His first employment, as an intern in an investment bank, was mainly to try and find the specific kind of deals for which his bank was the market leader. He succeeded quarter after quarter. (And, yes, the "bank" was a small local operation, more a financial boutique than a real bank)

    With respect to the degrees of uncertainty involved in the issues we are discussing: It is huge. As an example, the last IPCC report says that total anthropogenic radiative forcing has a 90% confidence of being between 0.6 to 2.4 (with a central value of 1.6). That's a 4x factor between the lowest and highest values, and nearly 3x between the lowest and medium.

    I used to make my living selling companies. If I had told my clients that their businesses were valued something between 1 and 4, most probably around 3 ... I wouldn't have had many clients, would I?
    0 0
  27. Re #13 and #17

    Manuel, your interpretation of the linearization of the relationship between temperature change and radiative forcing as used by Murphy et al (2009) (their equation 1 that you reproduced in your post #13) isn't correct. Thus the concern you raise in your post #17 is misplaced in this instance.

    Your suggestion that the increase in radiation is proportional the the fourth power of the increase in temperature (Stefan-Boltzmann law) is fine, but not relevant to what Murphy et al (2009) are investigating. The Stefan-Boltzmann law relates the radiation emitted from the surface of a body at a defined temperature and does indeed have a fourth power relationship. However Murphy et al (2009) are estimating the radiative forcing F which is essentially the net radiation once the energy balance is "accounted" (i.e. top of the atmosphere radiation in minus radiation out). It turns out that this net radiation does have a generally linear relationship with the change in the earth's surface temperature (more sensibly, the earth's surface temperature change is roughly proportional to the radiative forcing). This could be investigated further by reading the following paper:


    Gregory JM and Forster PM (2008) Transient climate response estimated from radiative forcing and observed temperature change. J. Geophys. Res. 113, D23105

    Abstract (my highlights): Observations and simulations (using the HadCM3 AOGCM) of time-dependent twentieth-century climate change indicate a linear relationship F = rho Delta T between radiative forcing F and global mean surface air temperature change Delta T. The same is a good description of Delta T from CMIP3 AOGCMs integrated with CO2 increasing at 1% per year compounded. The constant "climate resistance'' rho is related to the transient climate response (TCR, Delta DT at the time of doubled CO2 under the 1% CO2 scenario). Disregarding any trend caused by natural forcing (volcanic and solar), which is small compared with the trend in anthropogenic forcing, we estimate that the real-world TCR is 1.3-2.3 K (5-95% uncertainty range) from the data of 1970-2006, allowing for the effect of unforced variability on longer timescales. The climate response to episodic volcanic forcing cannot be described by the same relationship and merits further investigation; this constitutes a systematic uncertainty of the method. The method is quite insensitive to the anthropogenic aerosol forcing, which probably did not vary much during 1970-2006 and therefore did not affect the trend in Delta T. Our range is very similar to the range of recent AOGCM results for the TCR. Consequently projections for warming during the twenty-first century under the SRES A1B emissions scenario made using the simple empirical relationship F = rho Delta T agree with the range of AOGCM results for that scenario. Our TCR range is also similar to those from observationally constrained model-based methods.
    0 0
  28. re #26

    A strong "quantitative" correlation between two variables can serve as an indication to try and find a relation between them. It does not prove a relation indeed exists. I am sure you agree with me.


    Yes that's fine as a general philosophy Manuel. However we often have independent evidence of causality (I'm using "causality" in place of your "relation"). For example (despite the efforts of a separate set of scientific misrepresenters!), we know that the statistical correlation between lung cancer and ciggie smoking indicates a causality since we can examine the lung cells of smokers and determine the carcinogen-induced DNA damage that leads to loss of cellular control of unconstrained proliferation.

    A similar case may be made for the correlation between hugely enhanced atmospheric CO2 level and enhanced surface temperature. Simply put, the correlation is pretty much what we expect from the known properties of CO2 as a greenhouse gas, our understanding of the greenhouse effect and a rather large amount of evidence form empirical analysis of paleodata on the relationships between atmospheric CO2 levels and earth surface temperature. So while the observed correlation doesn't prove causality, it is highly consistent with the expectation of causality, and clearly one should not leave out pre-existing empirical and theoretical understanding from the analysis of correlations when addresing causality.

    With respect to the degrees of uncertainty involved in the issues we are discussing: It is huge. As an example, the last IPCC report says that total anthropogenic radiative forcing has a 90% confidence of being between 0.6 to 2.4 (with a central value of 1.6). That's a 4x factor between the lowest and highest values, and nearly 3x between the lowest and medium.


    That's not quite right. Remember that the likelihood of the "correctness" of a particular value in a normal (Gaussian) distribution falls as one moves away (in either direction) from the most likely value. So while the central value has (by virtue of the mathematics of Gaussian distributions) a probability near 0.7, the 90% confidence level values in the wings of the distribution have a probability near 0.1 or less.

    And of course uncertainty works in both directions. So while one might feel relieved by the possibility that a rather low anthropogenic radiative forcing might apply in reality (with very low probability), we have to accept the same probability that an anthropogenic radiative forcing on the high wing of the distribution is equally likely. In fact the high end of the distribution of anthropogenic radiative forcing is considerably less poorly constrained, and in fact recent evidence indicates that the probabilities of anthropogenic radiative forcings on the low side are less likely than considered to be the case in the rather conservative IPCC assessment reports of 2007.

    Of course talking about normal distributions is unsatisfactory without actually looking at them! A recent paper analysing the reduction in uncertainty in anthropogenic radiative forcing is cited below. Figure 1 of this paper illustrates the Gaussian distribution defining the probabilities of values of anthropogenic radiative forcing, and gives a much better idea of what the error range actually means with respect to the likelihoods of particular values of the anthropogenic radiative forcing. Unfortunately I haven't been able to find a freely downloadable version.


    J Haywood and M. Schulz (2007) Causes of the reduction in uncertainty in the anthropogenic radiative forcing of climate between IPCC (2001) and IPCC (2007). Geophys. Res. Lett. 34, L20701, doi:10.1029/2007GL030749

    Abstract: Mechanisms that drive climate change are quantified by the radiative forcing which is the perturbation to the global energy balance of the Earth/atmosphere system. These mechanisms may be of anthropogenic or natural origins and each has an associated level of scientific uncertainty. Until recently, even the sign of the anthropogenic radiative forcing has been in doubt because strong, poorly quantified negative radiative forcings such as those from aerosols act to oppose the strong, well quantified positive radiative forcings from well mixed greenhouse gases. We present an analysis of the probability distribution function of the anthropogenic radiative forcing for the individual forcing mechanisms identified by IPCC (2001) and IPCC (2007). We conclude that significant progress in reducing the uncertainty of the anthropogenic radiative forcing has been made since IPCC (2001). The single most important contributor to this conclusion appears to be the reduction in the uncertainty associated with the aerosol direct effect, followed by the provision of a best estimate for the aerosol cloud albedo indirect effect.
    0 0
  29. Manuel #26, let's put it another way -- if you were a stock broker and you said you weren't very certain about a bunch of stocks, but one you were very certain of should increase in value from 60% to 240% over the next five years, would you have any takers? [I'm not arguing that this is a good analogy. But I think it's just as good as yours.]
    0 0
  30. Chris,

    Thank you very much for your highly detailed answers. Unfortunately, I am unable to access most of the papers you cite.

    "It turns out that this net radiation does have a generally linear relationship with the change in the earth's surface temperature."

    I fear that this is precisely what I was suggesting. Does the linear relationship you mention correspond to a proven consequence of physics laws? or is it an observed phenomenon? Unfortunately, I do not have access to the paper you cite.

    With respect to the degrees of uncertainty. I understand that there is a normal distribution involved, but I still maintain that the degree of uncertainty is too high.
    0 0
  31. Steve,

    Examples and analogies usually cause problems, as already mentioned in this thread. Anyway. My point is that if I were to tell my clients that I really have no idea of what is the market value of their companies, I would lose them.
    0 0
  32. My point is that (a) the value of information provided is relative to what else is available (you'd lose clients because others in your field could provide more certainty in their estimates, but we're not talking about a field with competitors legitimately claiming greater certainty); and (b) they have a very good idea what the anthropogenic radiative forcing is -- it is positive and nowhere near zero.
    0 0
  33. Steve,

    "We're not talking about a field with competitors legitimately claiming greater certainty"

    Are you sure? I am not.
    0 0
  34. Yep, I'm pretty sure. Why don't you cite a competing estimate (complete with uncertainty) if you think it really challenges the estimates published by the IPCC?
    0 0
  35. For all of the above, there are still deep uncertainties in the models, which climate scientists are willing to admit privately if not publicly. For instance:

    From: Kevin Trenberth
    To: Michael Mann
    Subject: Re: BBC U-turn on climate
    Date: Mon, 12 Oct 2009 08:57:37 -0600
    Cc: Stephen H Schneider , Myles Allen , peter stott , "Philip D. Jones" , Benjamin Santer , Tom Wigley , Thomas R Karl , Gavin Schmidt , James Hansen , Michael Oppenheimer

    Hi all
    Well I have my own article on where the heck is global warming? We are asking that here in
    Boulder where we have broken records the past two days for the coldest days on record. We
    had 4 inches of snow. The high the last 2 days was below 30F and the normal is 69F, and it
    smashed the previous records for these days by 10F. The low was about 18F and also a
    record low, well below the previous record low. This is January weather (see the Rockies
    baseball playoff game was canceled on saturday and then played last night in below freezing
    weather).
    Trenberth, K. E., 2009: An imperative for climate change planning: tracking Earth's global
    energy. Current Opinion in Environmental Sustainability, 1, 19-27,
    doi:10.1016/j.cosust.2009.06.001. [1][PDF] (A PDF of the published version can be obtained
    from the author.)
    The fact is that we can't account for the lack of warming at the moment and it is a
    travesty that we can't. The CERES data published in the August BAMS 09 supplement on 2008
    shows there should be even more warming: but the data are surely wrong. Our observing
    system is inadequate.
    ***
    Kevin

    Respectfully, if our leading scientists "can't account for lack of warming", then the science isn't "settled" on this matter.

    To be clear, I (and most other fair-minded skeptics) concede that the earth has warmed, but we are much less certain that the "consensus" as to:

    1) How much it has warmed;
    2) How much of that warming is man-made;
    3) How sensitive the climate is to additional CO2 forcing;
    4) How many liberties we should all be prepared to sacrifice to counter the threat.

    On these points, there are great uncertainties and the science most certainly isn't settled. This is especially true with regard to the issue of climate sensitivity.

    And regrettably, I find little on this website that seeks to resolve these uncertainties. Instead, the site seems to be primarily designed to attack the straw man argument that "skeptics" deny warming altogether.
    0 0
  36. sgking,
    that email has absolutely nothing to do with models, it's about data on energy balance. Then the first three points you made have nothing to do with it. (No comment on the fourth point).

    One thing I do not understand of you comment. What you mean by "science isn't settled"? That we do not have numbers for all the quantities we like with a precision to the tenth decimal digit? Or, instead, that the basic physical processes involved are understood and we are able to quantitatively describe the real world with a good aproximation?

    There's a sea of difference between the two, the former being true just for a small set of the physical constants we know. We'd have to throw away maybe 99% of the known physics ...
    0 0
  37. Riccardo,
    Look at #23-#29 (Tom and canbanjo)... I didn't see them before.

    I like the analogy, but the bucket should have two holes - one representing the CO2 band at 15um and the other the other represents the much larger non-CO2 OLR.

    As the CO2 "hole" is made smaller, the rate of water exiting the bucket is reduced (i.e. OLR goes down) and the water level starts going up. The increased pressure causes more water to exit the non-CO2 "hole". There is less water exiting the CO2 "hole" (has to be, since when the CO2 "hole" is completely closed, no water will be exiting! You don't get more water exiting a smaller hole.)

    The total water exiting the two holes will only start going up again when you STOP shrinking the CO2 "hole" - then it will go up until it equals the input and you are back in equilibrium.

    Moral of the story: OLR should be going down with increasing greenhouse effect.
    0 0
  38. guinganbresil, the bucket analogy is only that--an analogy. It's not nearly a perfect one. I'm not going to try to improve it, because that will yield diminishing returns. But consider what I wrote in #24.

    The real atmosphere behaves on a continuum, but with a delay. Insulation causes energy accumulation which increases temperature which increases outgoing radiation. That takes a little while, but not very long. Blackbody radiation laws that fit really well to nearly all condensed matter.

    Of course, a portion of that outgoing radiation gets absorbed and re-emitted, which raises the temperature, and so on.
    0 0
  39. Tom,
    I hate to be in a position of defending an analogy, but it does get to the root of my point.

    The OLR spectrum covers more than just the CO2 band. The total OLR (integrated over the spectrum) is the term that will affect the radiative balance - not just the CO2 band. If CO2 is the causative factor in radiative imbalance, it will need to dominate the overall OLR behavior. If the CO2 is not dominating the behavior of the total OLR then it could/would be an aggravating factor to other causative factors. This is CRITICAL to evaluating the applicability of predictions made by climate models.

    The figure 1C (Harries 2001) shown in "How do we know CO2 is causing warming?" is only showing the effect of trace gases. It gives the false impression that total OLR is going down. If you look at Harries figure 1B, it shows an increase in the range 750-1000 cm^-1 that clearly exceeds the decrease in the CO2 band. That is the "Non-CO2 hole" in the bucket.

    Harries explains the increase in this range as due to the effects of ice crystals not completely removed from the data set due to the differences in FOV between the IRIS and IMG detectors. This does not explain how the same effect is seen by Griggs 2004 and Chen 2007 with the addition of AIRS and TES data with different FOV's. Chen asserts that the behavior in the window region is not due to cloud contamination. Satellite measurements of total OLR also indicate an upward trend.

    To boil it down - looking at only the decrease in the CO2 15 um band and concluding that the overall energy balance of the Earth is controlled by that decrease neglects the effect of the non-CO2 regions of the OLR spectrum.

    The argument that the decrease in CO2 warms the Earth which causes the other regions of the spectrum to increase even more does not conserve energy. To go back to the dreaded analogies it is like saying that you wrap a space heater in insulation and the heater inside heats up (I agree) and the room outside of the insulation also heats up (I disagree.) I would agree with CO2 being the causative factor if the increase in the window region was less than the decrease in the CO2 band - that would make sense both with increased blackbody from a warmer Earth and still conserve energy. If more IR is being trapped by GHG's then the total OLR must decrease - this should be basic stuff - I am missing something?

    Look at Venus, OLR is ~150 W/m^2 compared to Earth's ~235 W/m^2...

    Riccardo mentioned an observed increase in OLR due to the recovery from a past transient and referenced Murphy (seen in response to #1 above). I am not aware of any historical records (Vostok etc.) indicating that we should be recovering from a large transient. The step response in Murphy shows an increase in OLR but ONLY AFTER the increase in CO2 stops. The OLR should be decreasing while CO2 increases if the CO2 is the causative factor.
    0 0
  40. guinganbresil, I think maybe your (admirably!) deeply detailed and technical thinking on this topic has distracted you away from the more plain and fundamental physical fact that an imperfect insulator will continue to let out a portion of energy that is accumulating.
    0 0
  41. Tom, as the insolating capability of the 'imperfect insulator' is increased it should let less heat out - not more. Also pretty plain and fundamental.
    0 0
  42. guinganbresil,

    An improved but still imperfect insulator will let out a smaller proportion of the energy that is trying to escape. Not necessarily a smaller absolute amount of energy, because the amount of energy trying to escape is increasing.

    The balance between those two phenomena--more trying to escape, less proportion escaping--is what determines the absolute amount that escapes.

    But the analogy is not working well, because a boiler is not the same as a blackbody that gets all its energy from outside of itself.
    0 0
  43. guinganbresil,
    i was not quoting any large ancient transient, in particular not old as the Vostok ice core record; it is a dynamical process.
    What I was just trying to explain is how you can have an increasing OLR. Indeed, you will have an increasing OLR during a warming phase whenever the the rate of increase of the forcing is lower than that of increasing thermal emission toward balance.
    0 0
  44. Tom, Riccardo,
    Thanks for the stimulating dialog!
    Tom - I agree you on w/#42 completely if the temperature increase is due to some other factor than increasing insulation. I will have to think some more about whether I agree whether a temperature increase due to increasing insulation alone would increase the heat loss from the system (it sounds to me like it doesn't satisfy conservation of energy...)
    Riccardo - I agree 100% on #43. With CO2 concentrations very consistently increasing at an increasing rate during this warming phase can you see how the increasing of the forcing is lower than the thermal emission toward balance? I could agree if there was some other large factor driving the system (such as a large past CO2 transient or a forcing term not correlated with CO2 concentration.)
    0 0
  45. guinganbresil,
    the temperature increase after a forcing is roughly proportional to the temperature anomaly and it also has a time lag. Then, thermal emission, proportional to the 4th power of absolute temperature, will keep up "later".
    Each year we increase the forcing a little bit (i.e. more radiation absorbed in the CO2 band) and the thermal emission (i.e. what is seen as background in the IR spectrum) need to increase. Add that there are feedbacks at work and what you'd expect is a more or less steady increase in thermal emission.

    This is the nice theoretical picture. The reality is much harder to grasp because the heat goes across the climate system in complicated and irregular ways. We still don't know the details and i would not be surprised to see no increase in thermal emission for a while. In Kevin Trenberth words from one of the now famous emails "Our observing system is inadequate."
    0 0
  46. What is dirturbing is that more than half of the greenhouse warming is masked by aerosols.

    This doesn't imply:
    1) A climate sensitivity much bigger than the commonly assumed value of 3ºC per doubling of CO2, maybe 6-7ºC per doubling of CO2?

    2)There is a lot of forcing (I said forcing,not warming) "in the pipeline" from the greenhouse gases, that will emerge as the aerosol emissions drop(these will be regulated before CO2 because them are highly toxic)?

    I suspect that the "Dangerous Antropogenic Influence" treshold was passed long ago, because according to paleoclimate studies, this levels of C02-equivalent are more than enough to melt away ALL GREENLAND, ALL THE MOUNTAIN GLACIERS AND THE WEST ANTARCTIC ICE SHEET.
    0 0
  47. I said:
    "this levels of C02-equivalent"
    with "this" I refer to the current ones, now near 450 ppm.
    0 0
  48. The truth is out there

    CERES solar calibration was done using a reference radiometer on the ground, with 13 year old mirrors that were never measured, see peer reviewed 2009 G. Matthews, “In-flight Spectral Characterization and Calibration Stability Estimates for the Clouds and the Earth’s Radiant Energy System” Journal of Atmospheric and Oceanic Technology. Vol 26, Issue 9, pp 1685-1716. The climate records can be fixed and the imbalance is easily explainable by the paper given that the reference standard was never actually measured. Read it and assess for yourself.
    0 0
  49. Thanks for the pointer Moldyfox.

    Abstract:

    It is essential to maintain global measurements of the earth radiation budget (ERB) from space, the scattered solar and emitted thermal radiative fluxes leaving the planet. These are required for the purpose of validating current climate model predictions of the planet’s future response to anthropogenic greenhouse gas forcing. The measurement accuracy and calibration stability required to resolve the magnitude of model-suggested cloud–climate feedbacks on the ERB have recently been estimated. The suggestion is for ERB data to strive for a calibration stability of ±0.3% decade−1 for scattered solar, ±0.5% decade−1 for emitted thermal, and an overall absolute accuracy of 1 W m−2. The Clouds and the Earth’s Radiant Energy System (CERES) is currently the only satellite program to make global ERB measurements, beginning in January 1998. However, the new climate calibration standards are beyond those originally specified by the NASA CERES program for its edition 2 data release. Furthermore, the CERES instrument optics have been discovered to undergo substantial in-flight degradation because of contaminant issues. This is not directly detectable by using established calibration methods. Hence, user-applied revisions for edition 2 shortwave (SW) data were derived to compensate for this effect, which is described as “spectral darkening.” Also, an entirely new in-flight calibration protocol has been developed for CERES that uses deep convective cloud albedo as a primary solar wavelength stability metric. This is then combined with a sophisticated contamination mobilization/polymerization model. The intention is to assign spectral coloration to any optical degradation occurring to the different CERES Earth observing telescopes. This paper quantifies the stability of revised edition 2 data. It also calculates stability, which the new protocols could give CERES measurements if used. The conclusion is that the edition 2 revisions restore the originally specified stability of CERES SW data. It is also determined that the climate calibration stability goals are reachable by using the new in-flight methodologies presented in this paper. However, this will require datasets of longer than approximately 10 yr. It will also require obtaining regular raster scans of the Moon by all operational CERES instruments.
    0 0
  50. For everyone's general amusement: George White, aka co2isnotevil, has now posted his theories on Jonova. Previously he hijacked the Lindzen and Choi thread here, which got to ~450 comments before he got consistently moderated for being off-topic.

    These theories include some very odd numbers for energy budgets (compared to Trenberth 2009), stating that a 3.7 W/m^2 TOA forcing for doubling CO2 is halved, as CO2 radiates in all directions, etc.

    Sigh. This discussion feels like a Whack-a-Mole game sometimes.
    0 0

1  2  Next

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.



The Consensus Project Website

TEXTBOOK

THE ESCALATOR

(free to republish)

THE DEBUNKING HANDBOOK

BOOK NOW AVAILABLE

The Scientific Guide to
Global Warming Skepticism

Smartphone Apps

iPhone
Android
Nokia

© Copyright 2014 John Cook
Home | Links | Translations | About Us | Contact Us