Climate Sensitivity and Transient Climate Response

Guest essay by Marcel Crok, Climate Dialogue

Climate sensitivity is at the heart of the scientific debate on anthropogenic climate change. In the fifth assessment report of the IPCC (AR5) the different lines of evidence were combined to conclude that the Equilibrium Climate Sensitivity (ECS) is likely in the range from 1.5°C to 4.5°C. Unfortunately this range has not narrowed since the first assessment report in 1990.

An important discussion is what the pros and cons are of the various methods and studies and how these should be weighed to arrive at a particular range and a ‘best estimate’.  The latter was not given in AR5 because of “a lack of agreement on values across assessed lines of evidence”. Studies based on observations from the instrumental period (1850-2014) generally arrive at moderate values for ECS (and that led to a decrease of the lower bound for the likely range of climate sensitivity from 2°C in AR4 to 1.5°C in AR5). Climate models, climate change in the distant past (palaeo records) and climatological constraints generally result in (much) higher estimates for ECS.

A similar discussion applies to the Transient Climate Response (TCR) which is thought to be more policy relevant than ECS.

We are very pleased that the following three well-known contributors to the general debate on climate sensitivity have agreed to participate in this Climate Dialogue: James Annan, John Fasullo and Nic Lewis.

The introduction and guest posts can be read online below. For convenience we also provide pdf’s:

Introduction climate sensitivity and transient climate response
Guest blog James Annan
Guest blog John Fasullo
Guest blog Nic Lewis

Climate Dialogue editorial staff
Bart Strengers, PBL
Marcel Crok, science writer

About these ads

45 thoughts on “Climate Sensitivity and Transient Climate Response

  1. Seems to me we know pretty well what TCR is by simply correlating
    observed temperature trends with estimated GHG forcing.
    That excludes flux into the ocean, but the oceans will smooth out that
    imbalance for a very long time.
    By this measure, TCR is about 1.6K per CO2 doubling equivalent.

  2. If the theory of a nuclear reaction in the Earth’s core is correct (WUWT article) then all these forcing calculations seem to get tossed into a cocked hat.

  3. …(ECS) is likely in the range from 1.5°C to 4.5°C. Unfortunately this range has not narrowed since the first assessment report in 1990.

    Global warming will be less than 1.5ºC from current levels. Probably much less. The real threat is global cooling.

  4. The NIPCC also reviewed:
    1.1.5 Climate Sensitivity
    Climate Change Reconsidered II, Physical Science pp 24-30

    WUWT posts on climate sensitivity e.g.
    Impact of the Atlantic Multidecadal Oscillation (AMO) on deriving anthropogenic warming rates from the instrumental temperature record, G. R. van der Werf and A. J. Dolman, Earth Syst. Dynam. Discuss., 5, 529-544, 2014 doi:10.5194/esdd-5-529-2014 PDF

    Our results indicate that both the high- and low end of the anthropogenic trend over the past 30 years found in previous studies are unlikely and that a transient climate response with best estimates centred around 1.3°C per CO2 doubling best captures the historic instrumental temperature record.”

    Spencer, R.W. and Braswell, W.D. 2011. On the misdiagnosis of surface temperature feedbacks from variations in Earth’s radiant energy balance. Remote Sensing 3: 1603–1613.

    It is concluded that atmospheric feedback diagnosis of the climate system remains an unsolved problem, due primarily to the inability to distinguish between radiative forcing and radiative feedback in satellite radiative budget observations.

  5. How much warming occurs after 15 years of huge increases in man-made CO2?

    None.

    How much warming occured from 1945 to 1980 agter smaller increases in man-made CO2?

    None.

  6. “Climate models, climate change in the distant past (palaeo records) and climatological constraints generally result in (much) higher estimates for ECS.”

    What is is about paleo records that leads to high ECS estimates?

  7. As usual, when you ask the wrong question, you get the wrong answer … the right question is, why have billions of dollars spent and hundreds of thousands of man-hours invested in the question NOT been able to narrow the estimates of climate sensitivity at all over the last third of a century? Every other field of scientific endeavor has moved forwards in the last thirty plus years, but climate science has made no progress on this question at all?

    Why no progress?

    To me, thirty years of no progress means you’ve asked the wrong question. But it’s like the old joke about what’s the difference between a rat running a maze, and a mainstream climate scientist running a maze?

    I hold that the reason for no progress is that the concept of climate sensitivity is an outgrowth of an erroneous understanding of how the climate works. The misunderstanding lies in the fundamental claim that the changes in global temperature are a linear function of the changes in forcing. The erroneous equation is

    ∆T = λ ∆F

    where T is temperature, F is forcing, and lambda ( λ ) is climate sensitivity.

    Asking the wrong question guarantees nobody will agree on the answer …

    w.

    PS—Oh, yeah. The difference between a rat running a maze, and a mainstream climate scientist running a maze, is that if you take the cheese out of the maze, the rat stops running …

  8. Marcel, you did not invite a denier expert to write anything; like CS is indistinguishable from zero.

  9. Joe Born says:
    May 13, 2014 at 11:02 am
    —————————————————
    You get a high ECS from the ice-core if you willfully misinterpret the lead-lag relationship between temperature and CO2. What would happen to a pharma company that stated pain causes tumors, and what would happen to a regulator that approved ASA for chemotherapy?

  10. Joe Born

    “What is is about paleo records that leads to high ECS estimates?”

    Over geologic time frames warming increases the atmospheric CO2 concentration, therefore, it is difficult (especially with low resolution data) to discern whether the CO2 is causing a warming or caused by a warming.

  11. Willis says: ∆T = λ ∆T

    where T is temperature, F is forcing, and lambda ( λ ) is climate sensitivity.

    ================

    Where is F?

    [Fixed. w.]

  12. Willis : “PS—Oh, yeah. The difference between a rat running a maze, and a mainstream climate scientist running a maze, is that if you take the cheese out of the maze, the rat stops running …”

    Well if we removed the cheese (grant money) from the climate maze, there’d be a lot fewer rats running around after it, too.

    No difference.

  13. “To me, thirty years of no progress means you’ve asked the wrong question. ”

    And the (wrong) question they’ve been asking is “how can we prove that man-made CO2 is the primary driver of climate”.

    If they’d been paid to ask “what drives climate” they would surely have got somewhere by now.

    The 30 years of failure on the first question means it has been answered, they just don’t want admit it. Sometimes negative results are just a important as positive ones.

  14. Willis said:

    ∆T = λ ∆T

    where T is temperature, F is forcing, and lambda ( λ ) is climate sensitivity.

    I have solved the equation. Climate sensitivity = 1.0 .

  15. ‘As you can easily see,’ Samuelson said, ‘we’ve been getting better and better. The trend is clear.’ He looked at us expectantly in the dim conference room, his outstretched left hand illuminated by the glare of the projector. Silence, then Irene spoke up: ‘Well, what you’re calling a trend only goes back several weeks. If you went back several quarters the graph would actually show an overall decline with a slight improvement at the end….’

  16. Martin A,

    I have just completed an exhaustive peer-review of your answer.

    1.0 it is!

  17. Actually, the climate sensitivity is 1.000000000000000000000000000000000000000000
    The T measurement error bars cancelled out.

  18. Willis Eschenbach says:
    May 13, 2014 at 11:02 am
    <<>>

    Many other fields of science demonstrate similar stagnation and are taken over by charlatans. In astrophysics mysterious term in Einstein’s equation was “explained” by meaningless dark matter and dark energy, in quantum physics meaningless string theory became combatively dominant (see Lee Smolin’s book “Troubles with physics..”, in nonlinear optics the Maxwell’s equations were solved with gross errors (what?!) leading to wicked theory of optical soliton, the “reputable” (sarc.) journals publish articles that, to any educated physicist, are obvious nonsense (see S.J. Byrnes, R. Blanchard, and F. Capasso, “Harvesting renewable energy from Earth’s mid-infrared emissions” (2014) PNAS vol. 111, no. 11, pp 3927-3932), etc. etc. The scientific progress was always fragile frequently falling victim to incompetence, arrogance and intrigue (see Stephen Brush’s “Should the history of science be rated X?” (1974) Science, New Series, V. 183, No 4130, pp. 1164-1172). However, it seems that, in past 30-50 years the sciences (at least most of the physical sciences) and also the funding of research (i.e. spending taxpayer’s money) became overtaken by fraudsters and incompetents on unprecedented level. Climate “science” is just another victim in the long list.

  19. “Joe Born says:
    May 13, 2014 at 11:02 am
    “Climate models, climate change in the distant past (palaeo records) and climatological constraints generally result in (much) higher estimates for ECS.”

    What is is about paleo records that leads to high ECS estimates?”

    In some cases its the error bars. in other cases its the assumptions.

  20. “I have solved the equation. Climate sensitivity = 1.0 .”

    Well that would lead to an sensitivity of 3.71 to doubling c02

    climate sensitivity is the system response to any increase in forcing.

    Say the sun goes up by 1 watt.
    The Plank response says temperature will go up by around .4C for a sensitivity of
    .4C/wattsm^2

    typical figures for lambda run from .4C/wattsm^2 to say 1.5C/watts^2

  21. It seems to me that in the largely inhabited part of the world, when the sun comes up in the morning, on a more or less clear day, everything starts to warm up.

    The ground starts to warm up; the ocean surface starts to warm up, the lower atmosphere (troposphere) starts to warm up, and the upper atmosphere starts to warm up.

    Where ice and snow exist, their surface layers melt to some extent.

    By late afternoon; everything is much warmer than it was at sunrise, in fact it is too warm, so when the sun sets, everything starts to cool down again, and the 24 hour temperature range cycling can easily be 10 to 20 deg. C, or more.

    So what this demonstrates is that as thermally massive as the earth is, it can still shift in Temperature in a few hours, much more than all the overall Temperature shift believed to have happened over the last 150 years.

    I would say that the earth response to “forcing”, by EM radiation, is darn near instantaneous. There is no 800 year delay between sunrise, and global warming.

    What this tells me is that ANY radiative “forcing” due to an increase in atmospheric CO2, such as me running my car engine and putting out H2O and CO2 green house gases, will also cause a virtually instantaneous increase in the Temperature (of something). It may be too small to register on instruments, but it will happen very quickly.

    It won’t wait a month or 30 years, or any other extended period; the planet will respond today. before my engine can even cool down after I shut it off.

    So the idea of looking over long intervals for something to happen seems pretty silly to me. It has already happened within minutes to hours of the “forcing” being turned on.

    So a plot of the daily data from any site, would seem to me to be an accurate account of what really happens at that location.

    Plotting trends, or thirteen month running averages, is simply throwing away, weather and climate information, that was obtained at great public expense, and replacing it with false information that was never observed or measured, by anyone at any time in any place.

    Now I can’t fault anyone who enjoys doing such machinations and reporting their output; particularly if someone else pays the bill for throwing away all that information.

    But the last straw, is when they assert that their faux “information”, will somehow tell them what will happen next.

  22. Jim Cripwell says:
    May 13, 2014 at 11:08 am
    Marcel, you did not invite a denier expert to write anything; like CS is indistinguishable from zero.

    #############
    err neither did he invite people who doubt we landed on the moon.

    CS = dT/dF

    its not indistinguishable from zero.

    To make a claim that it is, you have to actually do and show math.
    You have to show temperatures, you have to show forcings. you have to show that dT/dF
    is statistically indistinguishable from zero.

    in short.

    A) you can as willis does make a forceful argument that the concept, the CONSTRUCT,
    is confused or that the assumptions of construction are not valid.

    B) you can claim that we dont know dT, or that we dont know dF.

    C) you can claim that dT is uncertain (state your ranges) or dF is uncertain

  23. It’s really a stupid question to begin with. How long before co2 doubles? And doubles from what base point? and how fast will the doubling take place? The climate scientists have some of you chasing your tails over a question that has no real world value.

  24. “””””…..Greg says:

    May 13, 2014 at 11:23 am

    Willis : “PS—Oh, yeah. The difference between a rat running a maze, and a mainstream climate scientist running a maze, is that if you take the cheese out of the maze, the rat stops running …”…..”””””

    Well the difference between using rats, and using M$ climate $cientists, or even lawyers for that matter, is that there ARE some things, that you just can’t get rats to do !

  25. R. Taylor, John West, and Steven Mosher:

    Thanks for the responses regarding paleo bases for sensitivity estimates.

    Even after all this time, I found myself briefly thinking, “but surely they wouldn’t have made the statement without a better rationale than that”–and I know better.

  26. The existence of the equilibrium climate sensitivity (TECS) is a part of the bedrock on which modern global warming climatology is founded. Unfortunately for modern global warming climatology this part of the bedrock is logically faulty.

    Supposedly a posterior probability density function maps each of the possible numerical values for TECS to the associated probability density. The existence of this PDF is a consequence from the existence of a prior PDF, empirical data and Bayes’s theorem.

    An argument of this form is an application of Bayesian parameter estimation. As in other applications of it, this one falters on the issue of the prior PDF. Is it uniform? Is it curved? If curved, what is the formula for this curve? What is the range in which the value of TECS is non-zero? These questions lack answers.

    The lack of answers may be traced to the infinite multiplicity of uninformative prior PDFs. The uniform prior is uninformative but so are nonuniform priors that are of infinite number. Each prior PDF generates a different posterior PDF. The multiplicity of prior and posterior PDFs violates the law of non-contradiction. Non-contradiction is one of the three classical laws of thought. Thus, this part of the bedrock of modern global warming climatology is illogical.

  27. Steven Mosher says:

    May 13, 2014 at 12:03 pm

    “I have solved the equation. Climate sensitivity = 1.0 .”

    Well that would lead to an sensitivity of 3.71 to doubling c02
    =============

    Mosher maybe you should read the equation carefully.

  28. @Willis Eschenbach

    They don’t ask that question because they don’t want the public to know the answer.

  29. Computation of man-made vs natural warming components based on RSS satellite data.

    The trend from 1979-2005 during the +PDO was .16C/decade. The cooling from 2005 until present during the -PDO was .06C/decade. This gives us two equations with two unknowns if we assume the natural variation is equal and opposite.

    1) X + Y = .16
    2) X – Y = -.06 => X = Y – .06

    Substituting for X in 1): Y – .06 + Y = .16 => 2Y = .22 => Y = .11
    Substituting for result in 1): X + .11 = .16 => X = .05

    CO2 has gone from ~340 to ~400 ppm yielding a TCR around .9C.

    PS. I doubt TCR is a constant or that we understand all the factors with enough accuracy to make any computation. The one above is simply another way to look at the data which tells us TCR is not likely to be a problem.

  30. Willis Eschenbach said at 11:02 am
    The erroneous equation is
    ∆T = λ ∆T
    where T is temperature, F is forcing, and lambda ( λ ) is climate sensitivity.
    Asking the wrong question guarantees nobody will agree on the answer …

    I don’t see F in the equation. Maybe that’s the point.

  31. James Ard says:

    May 13, 2014 at 12:16 pm

    It’s really a stupid question to begin with. How long before co2 doubles? And doubles from what base point?

    When it doubles to twice as much as it was when it was half as much. The starting point is when it was half as much as when it is double.

  32. Steven Mosher says:
    May 13, 2014 at 12:15 pm

    “You have to show temperatures, you have to show forcings. you have to show that dT/dF is statistically indistinguishable from zero.”

    Or, you have to show that assuming it is significantly different from zero would lead to a runaway positive feedback which would have caused the Earth to fry eons ago. It does. It didn’t.

  33. If climate sensitivity is a function of multiple interacting feedback mechanisms (some positive, some negative), each of which varies in its intensity under different climactic conditions, why would any sane person expect that the sum total of all of these feedback mechanism should be a constant?

    Should it be any surprise that different methods of estimating climate sensitivity from different historical periods yield different results from current observations?

    My hypothesis: Climate sensitivity was higher in the earth’s past, when temperatures were cooler and ice sheets extended to mid-latitudes. Now that ice has receded to the poles, ice-albedo feedback is diminished (with the transition zone covering less surface area and receiving less insolation) and as a result feedback and climate sensitivity are lower today.

  34. “Climate sensitivity is at the heart of the scientific debate on anthropogenic climate change.”

    This is much too limited a statement. Willis Eschenbach’s several works (‘The Thermostat Hypothesis’ put his name in the search box of WUWT), Richard Lindzen (the iris effect), Roy Spencer and some others have written papers that present mechanisms in the climate that counteract warming or cooling of the planet (negative feedback) and produce long term stability in climate. Eschenbach’s upper limit for ocean temperatures of 29-30C is well supported by sea surface temperature observations and satellite readings. When these temperatures are approached, evaporation, convection and condensation increases creating clouds that shade and build up into chains of thunderstorms that further cool the sea surface (most of the sun’s energy enters the climate within the tropical convergence zone). If the sea surface is cool, cloud buildup is delayed to later in the day allowing warming. If warm, the clouds form earlier cutting off the heating.

    The well documented papers have attracted a lot of ad hominem attacks, but few antagonist arrows have been able to stick into the vital core of the idea. With this idea, the ECS doesn’t matter. If definitive experiment absolutely demonstrated a high sensitivity, the models relying on it would still fail miserably because the effect is counteracted by these mechanisms. Indeed, the ECS is probably as high as the IPCC estimates or maybe higher but it is irrelevant.

    Imagine a planet that is heated by electrical elements like that of a stove. Climate scientists would measure how much heat we should have by the voltage amperage and resistance of the elements they’ve measured. To ignore the pots of water over the elements which restrict temperature emitted by the pots to 100C and then to ignore the rising steam, its condensation and falling back as cooled water (much of the heat at elevation being lost to space) would have them projecting future temperatures a way too high because of models divorced from reality. They would be adamant that it is physics based (it partly is) and would be perplexed at the failure of these models. They would also become frustrated and angry at opponents of the idea.

  35. I’m sure the comments above were just having fun at the typo in the equation, but the one that Willis meant to write was:

    ∆T = λ ∆F

    where T is temperature, F is forcing, and lambda ( λ ) is climate sensitivity.

    • In the equation

      ∆ T= λ ∆F,

      T is an equilibrium temperature rather than a temperature. A distinction should be maintained between an equilibrium temperature and a temperature because a temperature is an observable feature of the real world but an equilibrium temperature is an unobservable feature of a theoretical world. To confuse the two concepts is to confuse the real world with a theoretical world.

  36. Marcel, Google Chrome was unable to pull down either Climate Dialogue or the three guest bloggers you introduced. The unsigned article on climate sensitivity etc.did come through, however, so I know at least what you are talking about. I have bad news for you: climate sensitivity, no matter how you choose to define it, is zero because the enhanced greenhouse effect simply does not exist. To understand why there are some facts of nature you have to acquaint yourself with. The first one is that the greenhouse effect as defined by Hansen does not exist. He simply failed to detect it in 1988 but nevertheless has been pushing it for the last 24 years. The second one is that the greenhouse warming theory based on Arrhenius is simply wrong and must be replaced by the Miskolczi greenhouse theory (MGT). You have to digest the meaning of these two facts to understand their connection to sensitivity. First, lets take Hansen. He reported to the Senate in 1988 that the greenhouse effect exists. What he did was to show a rising temperature curve, going from a low in 1880 to a high in 1988. That high 1988 peak, he said, was the warmest temperature within the last 100 years. There was only a half a percent chance that this could happen by accident. Hence, there was a 99 percent probability that this warming was greenhouse warming, thus proving that the greenhouse effect is real. But when you check the Congressional Record you find that he includes a non-greenhouse warming, from 1910 to 1940, as part of his 100 year greenhouse warming. Radiation laws of physics dictate that to start an enhanced greenhouse warming you must simultaneously increase the amount of carbon dioxide in the atmosphere. This did not happen in 1910, so this warming is not greenhouse warming. The same conclusion follows from its sudden cessation because greenhouse warming cannot be stopped without removing the absorbing molecules from the air. It follows that this particular warming period must be subtracted from his claimed 100 year greenhouse warming. More than half of the total warming for the entire twentieth century goes out with it. What is left of his 100 year warming after this amputation is a see-saw temperature curve of 25 years of cooling that is followed by 23 years of warming.You don’t have to be a rocket scientist to understand that this will never prove the existence of the greenhouse effect. Hansen’s claim that he has observed the greenhouse effect is simply false. But nobody checked his science and he has been able to get away with this fiction for the last 24 years. As a consequence, we have the IPCC built upon the belief that greenhouse warming caused by carbon dioxide exists. In view of the absence of the greenhouse effect this belief must now be considered pseudo-science. They rely upon the Arrhenius hypothesis that adding carbon dioxide to air warms the atmosphere by absorbing outgoing longwave radiation. But now we find that even this is not true because we have not had any warming for 17 years while carbon dioxide constantly increased. This by itself is enough to prove Arrhenius wrong. But more direct evidence is available from Ferenc Miskolczi. He used NOAA weather balloon database to observe the absorption of IR by the atmosphere over time. And found that absorption was constant for 61 years while carbon dioxide at the same time increased by 21.6 percent. That is sufficient to prove the absence of the greenhouse effect and take the feet right out from under the anthropogenic global warming theory. There simply is no such thing as AGW. But how do you then reconcile this and the fact that carbon dioxide is a greenhouse gas that absorbs energy? The answer is very simple. When you add carbon dioxide to the atmosphere it starts to absorb just as Arrhenius says. But Miskolczi greenhouse theory tells us that when carbon dioxide and water vapor simultaneously absorb in the IR there exists a joint optimum absorption window which they jointly maintain. Its optical thickness is 1.87, calculated by Miskolczi from first principles. Addition of carbon dioxide will increase the optical thickness but as soon as this happens water vapor will begin to diminish, rain out, and the optimum optical thickness is restored. This is the explanation of why we have the warming pause – as more carbon dioxide is added to the atmosphere its expected greenhouse warming effect is simply blocked by this condensation of water vapor. It is completely parallel to observations of the NOAA database where no warming took place for 61 years. Note that this behavior is the exact opposite of what IPCC is telling us. They found that their calculated temperature rise from carbon dioxide alone was not big enough to be threatening, so they added positive water vapor feedback effect to make it appear more dangerous. As a result, more than half, and possibly two-thirds, of the greenhouse warming they report is caused by nothing more exotic than water vapor. This cannot happen according to the Miskolczi greenhouse theory.
    See E&E 21(4):243-262 (2010).

  37. TCR is the response function to a step-like doubling of CO₂ averaged over the first 70 years, nothing more fancy than that. Of course we have no idea how that response function looks like, this is how all the uncertainty comes about.

  38. ***
    Steven Mosher says:
    May 13, 2014 at 12:03 pm

    Say the sun goes up by 1 watt.
    The Plank response says temperature will go up by around .4C for a sensitivity of
    .4C/wattsm^2

    typical figures for lambda run from .4C/wattsm^2 to say 1.5C/watts^2
    ***

    OK, I’ll play.
    The sun going up 1 watt is SW & can be partially stored under water & will indeed have a significant-time TCR and ECR.
    1 watt of GHG IR however, isn’t stored and results in immediate (couple days to a week) sensible and latent “heat”. No significant storage. Thus, TCR=~a day & ECR=~a week for GHG IR. IOW, insignificant.

    Stop treating all watts the same.

  39. “””””…..Terry Oldberg says:

    May 13, 2014 at 8:11 pm

    In the equation

    ∆ T= λ ∆F,

    T is an equilibrium temperature rather than a temperature. A distinction should be maintained between an equilibrium temperature and a temperature because a temperature is an observable feature of the real world but an equilibrium temperature is an unobservable feature of a theoretical world. To confuse the two concepts is to confuse the real world with a theoretical world……”””””

    The only place where earth has an EQUILIBRIUM TEMPERATURE is in Kevin Trenberth (et al)’s cartoon earth ENERGY budget.

    Earth is not, and never has been in thermal equilibrium; and likely never will be. It is NOT surrounded by a uniform spherical ersatz 6,000 K EM radiant energy emitter supplying 342 W / m^2 at all times all over the earth.

    I’ll leave it to the math whizzes to calculate what the diameter of such a hollow spherical surface “sun” at 6,000 K BB temperature has to be to produce 342 W/m^2 on the earth.

    I don’t even know if there actually is a solution that fits Trenberth’s model.

    • george e. smith

      Thanks for the support. By the way, people on all sides of the controversy over CAGW are unaware of the fact that a relation between an unobservable variable and an observable variable, such as ∆ T= λ ∆F, conveys no information to a maker of governmental policy about the outcomes from his or her policy decision. This is clear from the form of the mathematical function known as the “mutual information.” Getting information from ∆ T= λ ∆F is as likely of success as getting information from an HDTV whose power plug has been pulled. In effect, the designers of global warming climatology have robbed the makers of governmental policy of all of the information that these makers think they have and the makers don’t know it..

  40. Russ R. says:

    My hypothesis: Climate sensitivity was higher in the earth’s past, when temperatures were cooler and ice sheets extended to mid-latitudes. Now that ice has receded to the poles, ice-albedo feedback is diminished (with the transition zone covering less surface area and receiving less insolation) and as a result feedback and climate sensitivity are lower today.

    But, as James Hansen has pointed out, this is already accounted for: In the climate sensitivity that is generally talked about today, ice-albedo is considered a feedback; however, in comparing the Last Glacial Maximum (LGM) to now, it is considered a forcing. As Hansen has argued, if you consider it as a feedback, you get an estimate of climate sensitivity from the LGM that is about 6 deg C.

    I think there is a compelling argument to be made that this 6 deg C estimate is probably too high for the current climate and ice sheet locations…but, what you have to realize is that you are arguing against a 6 deg C estimate, not a 3 deg C estimate, with your hypothesis.

  41. The Sun is back again in the news.

    Abstract
    “Evidence for solar wind modulation of lightning ”

    http://iopscience.iop.org/1748-9326/9/5/055004/article

    “Solar wind ‘triggers lightning on Earth’”
    He explained: “It’s unexpected, because these streams of particles bring with them an enhanced magnetic field – and this shields Earth from the very high-energy cosmic rays from outside of the Solar System – these are generated when supernovae explode, and they accelerate particles up to the speed of light.”

    Previous research has shown that cosmic rays from space can boost the rate of lightning, and it had been thought that an increased shielding effect from the solar particles would cause a decrease in the number of strikes.

    http://www.bbc.com/news/science-environment-27406358

Comments are closed.