Dr. Roger Pielke Senior posted this today, since he has no comments on his blog, I felt it would be good to repost it here to allow discussion – Anthony
There is an excellent collection of interviews posted by Sam Patterson on April 23 2011 on the weblog Climatequotes.com titled
I have reposted his very informative set of interviews and commentary below.
_________________________________________________
From: Climatequotes.com
Note: I wrote this post many weeks ago and never posted it because I was waiting for some more feedback. However, Pielke Sr. has posted specifically on this issue recently and Watts ran it also, so I feel now is a good time to post it.
This post deals with the the question of whether or not climate sensitivity should be measured by global average surface temperature anomaly. I asked multiple climate scientists their opinion, and their responses are below. First, some background.
Over at The Blackboard there is an interesting guest post by Zeke. He attempts to find areas where agreement can take place by laying out his beliefs and putting a certain confidence level on them. This idea was commented upon by several blogs and scientists. Judith Curry, Anthony Watts, Jeff Id, and Pielke Sr. all contributed. I want to focus on Pielke’s response, because he challenges a core assumption of the exercise.
In Zeke’s post, he gives his position on climate sensitivity:
Climate sensitivity is somewhere between 1.5 C and 4.5 C for a doubling of carbon dioxide, due to feedbacks (primarily water vapor) in the climate system…
Here is Pielke’s response to this claim:
The use of the terminology “climate sensitivity” indicates an importance of the climate system to this temperature range that does not exist. The range of temperatures of “1.5 C and 4.5 C for a doubling of carbon dioxide” refers to a global annual average surface temperature anomaly that is not even directly measurable, and its interpretation is even unclear…
Pielke goes on to explain that he has dealt with this issue previously in the paper entitled “Unresolved issues with the assessment of multi-decadal global land surface temperature trends.” Here is the main thrust of his response:
This view of a surface temperature anomaly expressed by “climate sensitivity” is grossly misleading the public and policymakers as to what are the actual climate metrics that matter to society and the environment. A global annual average surface temperature anomaly is almost irrelevant for any climatic feature of importance.
So we know Pielke’s position. He is adamantly opposed to using surface temperature anomaly when discussing climate sensitivity, for various reasons, not the least of which is it ignores metrics which actually matter to people.
I haven’t heard this view expressed very often, so I decided to contact other climate scientists and find out their opinions on this issue. I asked the following questions and invited them to give their general impressions:
1. Do you believe that global annual average surface temperature anomaly is the best available metric to discuss climate sensitivity?
If yes to Question 1, then:
2. Could you briefly explain why you consider global annual average surface temperature anomaly the best available metric to discuss climate sensitivity?
If no to question 1, then:
2. What do you believe is the proper metric to discuss climate sensitivity, and could you briefly explain why?
John Christy
1. Do you believe that global annual average surface temperature anomaly is the best available metric to discuss climate sensitivity?
No. The surface temperature, especially the nighttime minimum, is affected by numerous factors unrelated to the global atmospheric sensitivity to enhanced greenhouse forcing (I have several papers on this.) The ultimate metric is the number of joules of energy in the system (are they increasing? at what rate?). The ocean is the main source for this repository of energy. A second source, better than the surface, but not as good as the ocean, is the bulk atmospheric temperature (as Roy Spencer uses for climate sensitivity and feedback studies.) The bulk atmosphere represents a lot of mass, and so tells us more about the number of joules that are accumulating.
Patrick Michaels
I think it is a reasonable metric in that it integrates the response of temperature where it is important–i.e. where most things on earth live. However, it needs to be measured in concert with ocean measurements at depth and with both tropospheric and stratospheric temperatures. For example, if there were no stratospheric decline in temperature, then lower tropospheric or surface rises would be hard to attribute to ghg changes. Because we don’t have any stratospheric proxy (that I know of) for the early 20th century, when surface temperature rose about as much as they rose in the late 20th, we really don’t know the ghg component of that (though I suspect it was little to none).
Having said that, I suspect that where we do have such data, it is indicative that the sensitivity is lower than generally assumed, but not as low as has been hypothesized by some.
Gavin Schmidt
Your questions are unfortunately rather ill-posed. This is probably not your fault, but it is indicative of the confusion on these points that exist.
“Climate sensitivity” is *defined* as being the equilibrium response of the global mean surface temperature to a change in radiative forcing while holding a number of things constant (aerosols, ice sheets, vegetation, ozone) (c.f. Charney 1979, Hansen et al, 1984 and thousands of publications since). There is no ambiguity here, no choice of metrics to examine, and no room for any element of belief or non-belief. It is a definition. There are of course different estimates of the surface temperature anomaly, but that isn’t relevant for your question.
There are of course many different metrics that might be sensitive to radiative forcings that one might be interested in: Rainfall patterns, sea ice extent, ocean heat content, winds, cloudiness, ice sheets, ecosystems, tropospheric temperature etc. Since they are part of the climate, they will be sensitive to climate change to some extent. But the specific terminology of “climate sensitivity” or the slightly expanded concept of “Earth System Sensitivity” (i.e Lunt et al, 2010) (that includes the impact on the surface temperature of the variations in the elements held constant in the Charney definition), are very specific and tied directly to surface temperature.
People can certainly hold opinions about which, if any, of these metrics are of interest to them or are important in some way, and I wouldn’t want to prevent anyone from making their views known on this. But people don’t get to redefine commonly-understood and widely-used terms on that basis.
I sent a response to Gavin clarifying my questions, and including Pielke Sr’s comments. Here is his response to Pielke’ comments:
I disagree. Prof. Pielke might not find the global temperature anomaly interesting, but lots of other people do, and as an indicator for other impacts, it is actually pretty good. Large-scale changes in rainfall patterns, sea ice amount, etc. all scale more or less with SAT. (They can vary independently of course, and so ‘one number’ does not provide a comprehensive description of what’s happening).
Kevin Trenberth
1. Do you believe that global annual average surface temperature anomaly is the best available metric to discuss climate sensitivity?
This is not a well posed question. This relates to definition: the sensitivity is defined that way. It is not the best metric for climate change necessarily
If yes to Question 1, then:
2. Could you briefly explain why you consider global annual average surface temperature anomaly the best available metric to discuss climate sensitivity?
I think the best metric overall is probably global sea level as it cuts down on weather and related noise. But global mean temperature can be carried back in time more reliably and it is reasonably good as long as decadal values are used.
If no to question 1, then:
2. What do you believe is the proper metric to discuss climate sensitivity, and could you briefly explain why?
However, it is all variables collectively that make a sound case
Pielke Sr.
We have already discussed Pielke’s position, but I contacted him to find out what metrics he would prefer to use. Here is his response:
1. Do you believe that global annual average surface temperature anomaly
is the best available metric to discuss climate sensitivity?
NO
If yes to Question 1, then:
2. Could you briefly explain why you consider global annual average
surface temperature anomaly the best available metric to discuss
climate sensitivity?
If no to question 1, then:
2. What do you believe is the proper metric to discuss climate
sensitivity, and could you briefly explain why?
The term “climate sensitivity” is not an accurate term to define how the climate system responds to forcing, when it is used to state a response in just the global average surface temperature. This is more than a semantic issue, as the global average surface temperature trend has been the primary metric used to communicate climate effects of human activities to policymakers. The shortcoming of this metric (the global average surface temperature trend) was discussed in depth in
“National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp. http://www.nap.edu/openbook/0309095069/html/“
but has been mostly ignored in assessments such as the 2007 IPCC WG1 report.
A more appropriate metric to assess the sensitivity of the climate system heat content to forcing is the response in Joules of the oceans, particularly where most the heat changes occur. I discuss this metric in
Pielke Sr., R.A., 2008: A broader view of the role of humans in the climate system. Physics Today, 61, Vol. 11, 54-55.
http://pielkeclimatesci.files.wordpress.com/2009/10/r-334.pdf
Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335. http://pielkeclimatesci.files.wordpress.com/2009/10/r-247.pdf
More generally, in terms of true climate sensitivity, more metrics are needed as we discussed in the 2005 NRC report. The Executive summary includes the text [http://www.nap.edu/openbook.php?record_id=11175&page=4]
“Despite all these advantages, the traditional global mean TOA radiative forcing concept has some important limitations, which have come increasingly to light over the past decade. The concept is inadequate for some forcing agents, such as absorbing aerosols and land-use changes, that may have regional climate impacts much greater than would be predicted from TOA radiative forcing. Also, it diagnoses only one measure of climate change “global mean surface temperature response” while offering little information on regional climate change or precipitation. These limitations can be addressed by expanding the radiative forcing concept and through the introduction of additional forcing metrics. In particular, the concept needs to be extended to account for (1) the vertical structure of radiative forcing, (2) regional variability in radiative forcing, and (3) nonradiative forcing. A new metric to account for the vertical structure of radiative forcing is recommended below. Understanding of regional and nonradiative forcings is too premature to recommend specific metrics at this time. Instead, the committee identifies specific research needs to improve quantification and understanding of these forcings.”
It is, therefore, time to move beyond the use of the global annual average surface temperature trend as the metric to define “climate sensitivity”.
Differing views
There are clearly differing views on this subject.
John Christy does not support the metric. He points out that the surface temperature is affected by numerous things other than greenhouse forcing, and then gives two metrics which he prefers. The first is the change in joules in the system, with particular emphasis on the oceans. The second is bulk atmospheric temperature.
Patrick Michaels supports using the metric. He points out that the metric is important because it addresses the area where people live. However, he emphasizes that the surface temperature must be taken in concert with measurements such as ocean temperature at depth, and tropospheric and stratospheric temperatures. Without these other measurements, it would be difficult to assess the impact of GHGs on surface temperature.
Gavin Schmidt supports the metric unreservedly. He and Trenberth rightly point out that climate sensitivity is defined by global average surface temperature anomaly. Of course, the point of my question is challenging whether or not this is the best definition. Gavin seems to think so, and points out that the metric is “commonly-understood and widely-used”. He states that other metrics such as rainfall patterns and sea ice amount track very well with surface air temperature.
Trenberth is very brief, but states that global average surface temperature anomaly is not necessarily the best metric to use for climate change. He considers that global sea level is a better metric because it cuts down on weather related noise. However, he also points out that global average surface temperature anomaly is useful because it can be applied to the past more reliably. He also states that all variables taken together make a sound case.
Pielke Sr. is adamantly opposed to using this metric. We’ve already discussed his reasons. He also proposes a different metric for assessing climate sensitivity, “A more appropriate metric to assess the sensitivity of the climate system heat content to forcing is the response in Joules of the oceans”. He supports these claims with several of his own papers as well as a NRC report.
Conclusion
Pielke and Christy want to stop assessing climate sensitivity by using global average surface temperature anomaly, and both recommend using a change of joules (particularly in the ocean) as a better metric.
Michaels and Trenberth support the metric while emphasizing that other metrics must also be taken into account. Schmidt does not mention any drawbacks and emphasizes that the metric is already widely used and it works well with other metrics.
It seems to me the main problem here isn’t the metric itself, but the emphasis placed on it. I don’t believe that Pielke or Christy believe the metric has no value at all, only that it is a poor choice to use as the main metric when discussing CO2′s impact on climate. In Pielke’s case, the emphasis on CO2 itself is a problem, as he believes that other human impacts are far more important.
Climate science so frequently focuses on CO2 and temperature that it seems natural climate sensitivity would be measured by global average surface temperature anomaly. A shift away from this metric seems unlikely. However, if it can be shown in the future that a change in joules in the ocean directly contradicts other metrics then I’m sure this discussion will come up again. Pielke’s paper mentions an apparent contradiction found by Joshua Willis of JPL, although the measurements are only taken over a four year period. Only time will tell which metric is most valuable.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
I have a problem with that graph you put up. Tamino told me that the models show acceleration in warming; your chart shows deceleration.
Gavin and Trenberth are trivially correct and I believe we should all welcome their engagement on the subject. However, the problem with this metric is that in a deterministically chaotic system the knowledge of what the “climate sensitivity” is yesterday tells us nearly nothing about what it is today or will be tomorrow. What it is not, is constant on any time scale.
The problem with basing any attempted determination of climate response on any temperature, and especially an “air” temperature, is that energy moving around within the system will confound attempts to determine the magnitude and sign of even an instantaneous sensitivity parameter. The “global mean surface temperature” can change on both short and medium time scales and it doesn’t tell us what we think it tells us about what external and internal forcings are doing.
KevinK says:
April 26, 2011 at 6:36 pm
“As long as the climate scientists insist that they can calculate “net energy gains” and use temperature as their means for ”observing” these gains they are just travelling further down their own little rabbit hole.”
Well put! For basic physical reasons that few in climate science seem to understand properly, the entire question of “climate sensitivity” to CO2 changes is largely an empty one. Because they produce no energy, GHG’s cannot “force” anything in any strict physical sense. What we should be asking is what the effect of different concentrations may be upon the rate of thermal energy transfer from atmosphere to space, when the principal mode of transfer from surface to atmosphere is moist convection. In other words, is the climate system’s Lyapunov exponent being affected? Globally averaged surface temperatures do not address that crucial question.
Mike Hodges – Thank you for your comment. In the oceans, layer averaged temperatures (i.e. mass weighted) are used to compute Joules. Similarly, John Christy’s suggestion to use tropospheric temperatures is a mass weighted average and can be directly converted to Joules of heat (although without the water vapor component). Mass must be part of any calculation of heat content.
The global annual average surface temperature trend (besides not considering water vapor trends) has inegligible mass associated with it. The use of such a temperature by itself is not the same as heat.
stevo says:
For how many years have you been reading English, stevo? Anthony wrote (at the very top):
In other words, Anthony is simply providing a service, a forum for discussion on an article he didn’t write and expressed no opinion about. You, OTOH, gave us:
“The graph you post is meaningless.” Do tell. I mean it: do tell. Explain why it is MEANINGLESS (as opposed to imprecise, wrong, inaccurate, misleading, leaves out crucial information, etc.). After all, when you insult the host of the blog with your condescending nasty little list of ‘alternatives’, you had better be accurate yourself. And since the invitation by Anthony was for discussion, not for baseless nastiness, you have posted under false pretences by not including any clear argument we can have a discussion about. Typical anonymous astroturfing coward.
Am I the only one who finds it remarkable that a meaningful discussion on CLIMATE SENSITIVITY does not anywhere (according to the Firefox “find” facility) include the name Lindzen?
The chart shows sensitivity at 1.2°C per doubling, often also called the no-feedback sensitivity. One could argue that the CO2 “equivalent” for all practical purposes is already at double (or it will be in a few years). So the 0.6°C change which is often quoted for the total surface temperature change since pre-industrial times, is the climate sensitivity, including all feedbacks, assuming that you’ve already discounted anything natural (which is almost by definition for any good AGW proponent). This, of course, also means that feedback is negative since the “no feedback” sensitivity is 1.2°C, and anything that reduces total system response must be a negative feedback (-0.5 in this case). So even assuming the entire change is caused by CO2 and equivalents, positive feedback is hopelessly missing.
The atmosphere responds virtually instantly to a forcing, compared with the time constant of the oceans (no matter what mixing assumptions you want to make). Ocean heat capacity is so vast you’re almost safe assuming any change in radiative forcing of the atmosphere has not been significantly buffered by it. In other words the time constant of air is so fast, and its mass so small in comparison to the oceans, that the total change in heat of the atmosphere is representative of the influence of the sum of the forcings at work. I don’t see evidence for positive feedback in any of it.
Using the Global Surface Temperature is like trying to estimate the runoff from snowpack using data obtained at a single altitude. Each season brings differing amounts of water content at differing altitudes.
On slide 26 of the following http://climategate.nl/wp-content/uploads/2010/09/KNMI_voordracht_VanAndel.pdf it is stated that Trenberth knows that the radiation window is 66W/m2 (as measured by statellites) rather than the 40 W/m2 in his heat balance papers (where is the missing heat). Is his non-correction of his paper then scientific fraud? Trenberth has no credibility in my eyes and it seems he has no understanding of the basic theory of heat transfer. Much the same applies to Gavin Schmidt. On another blog Nusselt numbers and the Schmidt number were mentioned. It appeared Gavin had to look up what the Schmidt number was on Wiki and then replied what did these numbers have to do with climate assessment.
Dr Pielke has it right that climate sensitivity to CO2 is a useless number. However, there is a more important reason, which is reflected in the lag of CO2 after temperature changes found in longterm (800yrs in icecores), medium term (about 5 yrs – Beck and some other researchers) , and short term seasonal and daily ( eg in Kreutz 1941), that there is practical zero sensitivity. This is indicated by Miskcolzci and Van Andel http://climategate.nl/wp-content/uploads/2011/02/CO2_and_climate_v7.pdf and also in Van Andel peer reviewed papers in Energy and Environment (same issue as Willis’s paper about thunderstorms). I have calculated the potentaial energy absorption of CO2 using Prof Hoyt Hottel’s equation and find it insignificant. Climate scientists appear not to understand heat transfer by radiation, convection and phase change (evaporation and condensation). As indicated in many papers all the climate models give wrong results because the authors included CO2 and leave out other important mechamisms.
Repeat the climate sensitivity to CO2 should be close to zero. Please anyone prove by unjusted accurate measurements that is significant ie greater than 0.2K/100 years
stevo (and others who have missed it), the graph is from Warren Meyers and is included in the post, I presume, for a catchy graphical representation of the sensitivity issue. For those who are interested in the substance of the graph, see Warren Meyers’ blog and related post, where he makes some interesting observations about the alleged climate sensitivity.
On slide 26 of the following http://climategate.nl/wp-content/uploads/2010/09/KNMI_voordracht_VanAndel.pdf it is stated that Trenberth knows that the radiation window is 66W/m2 (as measured by statellites) rather than the 40 W/m2 in his heat balance papers (where is the missing heat). Is his non-correction of his paper then scientific fraud? Trenberth has no credibility in my eyes and it seems he has no understanding of the basic theory of heat transfer. Much the same applies to Gavin Schmidt. On another blog Nusselt numbers and the Schmidt number were mentioned. It appeared Gavin had to look up what the Schmidt number was on Wiki and then replied what did these numbers have to do with climate assessment.
Dr Pielke has it right that climate sensitivity to CO2 is a useless number. However, there is a more important reason, which is reflected in the lag of CO2 after temperature changes found in longterm (800yrs in icecores), medium term (about 5 yrs – Beck and some other researchers) , and short term seasonal and daily ( eg in Kreutz 1941), that there is practical zero sensitivity. This is indicated by Miskcolzci and Van Andel http://climategate.nl/wp-content/uploads/2011/02/CO2_and_climate_v7.pdf
and also in Van Andel peer reviewed papers in Energy and Environment (same issue as Willis’s paper about thunderstorms). I have calculated the potentaial energy absorption of CO2 using Prof Hoyt Hottel’s equation and find it insignificant. Climate scientists appear not to understand heat transfer by radiation, convection and phase change (evaporation and condensation). As indicated in many papers all the climate models give wrong results because the authors included CO2 and leave out other important mechamisms.
Repeat the climate sensitivity to CO2 should be close to zero. Please anyone prove by unjusted accurate measurements that is significant ie greater than 0.2K/100 years
Dr. Pielke: Thanks
Mike Hodges
There is no ‘climate equilibrium’ on any time scale.
There is no climate sentitivity to CO2.
The changes in the meteorological surface temperature record are caused by changes in ocean surface temperatures, urban heat island effects and plain old ‘fixin’ of the temperature records – ‘homgenization’ etc.
Climate sensitivity to CO2 is part of climate astrology not climate science.
Firstly, the chart is nonsense. The red and blue lines for climate sensitivity should meet at 0 ppm CO2 and not 280 ppm.
Secondly, talk of surface temperature as a metric would be OK if the metrology (measurement) was any good, but it isn’t. You would think that with all the money spent on climate science there would be a grid of well placed, very accurate thermometers all around the would measuring temperature +/- 0.001 degree. But there isn’t as there is no budget for it. Instead we have a moving set of poorly placed, inaccurate thermometers with no calibration or quality control. All the charts of average temperature produced contain a different set of thermometers at the start and end – apple and pears charts – so are just useless. Averaging readings from 100 thermometers that are accurate to 1 degree and pretending the average is accurate to +/- 0.01 degree is deliberately misleading. This is NO usable record of average surface temperature.
Lastly, there is the problem of averaging, whether you are averaging min and max temperatures or temperatures from multiple sites. Take two places, one where min is 10 and max is 20, the other where min is 5 and max is 25. Both have an average temperature of 15. But apply the Stefan–Boltzmann law as you will see that the second place emits more LW radiation.
It’s as plain as day that climate sensitivity is highly non-linear and there is no single value for climate sensivity. Even if there was, you will never discover it from any available metric because the metrology is just not accurate enough.
I think that the best metric to use in order to detect the effect of increased co2 on the earths radiation balance depends on the time scale which you believe that it has an effect,if the effect is immediate we should see that in changing SAT but if that change will occur in a thousand years then the best place to look would be the oceans.I don’t believe we are seeing change in SAT that would increase SAT in 50 years by the amount predicted by AGW theory.
Lots of confusion in this thread. the various heavy weights are commenting from perspective of their own research, and there are a number of assumptions about what the IPCC says that have to be put into context. So quick physics lesson and quick deconstruct of what IPCC says in that context.
Joule – measure of energy. Takes about 4.2 joules to heat one cubic centimeter of water by 1 degree C assuming a starting temp of 20 C.
Watt – meaure of joules per second.
Forcing – Increase in joules per second per square meter by increases in CO2. So a doubling of CO2 results in a forcing of 3.7 joules per second per square meter of the earth which results in 1 degree of warming. Summarized, the IPCC position is that direct forcing from CO2 doubling is as follows:
CO2 Doubling = +3.7w/m2 = +1 degree C. Repeated all over AR4. Here’s the out of context stuff they don’t make easy to find:
1. That sensitivity calculation relies on the forcing of 3.7w/m2 against the “effective black body temperature of earth as seecn from space. This is explained in AR3 in some detail, but in AR4 they drop that explanatio and make vague references to the statement meaning “earch surface” . This is incorrent. Stefan Boltzmann Law defines how much a given body will change in temperature |(at equilibrium) if additional forcing in w/mw is added to it. The formula is P(w/m2)= 5.67 x 10 to the power of -8 times T in degrees K raised to the power of 4 or:
So P=5*67*10^-8*K^4 Working backwards from that, we discover that 3.7 watts results in a rise in temperature of 1 degree, provided that the starting temperature was -20C. But the average surface temp of earth is +15C. So the fine print in AR3 has been dropped and then misquoted in AR4. In fact, if you do the calcs, it should read like this:
CO2 Doubling = +3.7w/m2 = +1 degree at temperature of earth as seen from space which is -20C.
CO2 Doubling = +3.7w/m2 = +0.6 degree at earth surface which is +15C.
The next thing to keep in mind is that Doubling quote is almost always in the context of “if CO2 doubles from levels in 1920, temps will rise 1.0 degrees”. We’re not in 1920, we’re 90 years later in 2010. During the time period from 1920 to now, CO2 had gone from 280ppm to 390ppm. They quote the effects of doubling from 280, convenienty forgetting to differentiate who has already happened from what will happen in the future by bundling the two together as if they were one and the same. Bull. that’s not how is shoud be presented. there are two proper ways to present it.
1. CO2 doubling from 280 to 560 will result in an AT SURFACE temperature rise of 0.6 degrees. We’ve gone from 280 to 390 already, so over half (due to the logarithmic curve) should already have happened, about 0.4 of it. So saying 280 to 560 = +1 degree is meaningless. Saying 390 to 560 would describe how much we have left to go if we do double from 280 to 560, but prorating so we’re looking at 390 (where we are now) to 560 yields an increase of just 0.2 degrees at surface.
2. Doubling of CO2 from where we are now would add 3.7w/m2 = +1.0 as seen from space = +.6 at surface. That would be 390 doubling to 780 would cause +0.6 degrees at surface.
But the IPCC carefully avoids these far more practical and meaningfull ways to present the data. Consider the final numbers once we adjust for base starting point and if we are looking from space or at the surface. What does that yield?
In 1) above, going from NOW, 390ppm to 560PPM (double 1920) = 0.2 degrees at surface. At the higest rates of CO2 production that we have ever hit, that’s nearly two centuries from now. And 0.2 degrees, Whoopdeedoo.
But 2) becomes even more rediculous. We’re at 390 now. If we double to 780 ppm from where we are now, we’ll get another 3.7 w/m2 = +0.6 degrees at surface from where we are now. CO2 has been rising almost linearly at about 1.5 ppm per year. So in 250 years we could expect another 0.6 degrees higher surface temps.
But the IPCC would rather include what has already happened in their calculations of what is going to happen because not doing that exposes the fact that CO2 is logarithmic. Extend that to CO2 QUADRUPLING from 390 to 1670 ppm of CO2. How much temperature change is that at surface? 1.2 degrees higher than we are now and at 1.5 ppm per year, it will only take 1,000 years to achieve it. Whoopdeedoo.
I am also more inclined now towards thinking that the temperature of the oceans may be a better indicator of any “global warming” (yuck) than surface temperature on earth. Afterall, earth is 70% water and 30% land. However, can somebody here direct me to places where temps. of the seas and oceans are measured and where we have some good reliable records going back in time a bit?
HenryP
Try this:
http://climexp.knmi.nl/select.cgi
Almost any climate record you can think of downloadable from one site.
It’s obvious from Gavin’s response that he suffers from Climate Sensitivity !
I have to agree with DRs Schmidt and Trenberth. “Climate Sensitivity” is defined as the equilibrium temperature change for a doubling of CO2. It’s not like the term is just now being defined, it was defined in the past and as such is what it is.
Whether it is the best metric or not is another question. Heat content in joules of the ocean/atmosphere may be more accurate for some purposes, so perhaps some bright person can define a new metric using that figure. The downside to joules is the “So what?” factor. It gives a baseline figure but very little detail. Do the extra joules in the system mean the oceans are warmer? The winds stronger? The ocean currents faster? All these represent extra energy in the system, but which one is changing? It’s rather imprecise for practical purposes because it doesn’t tell you what you are measuring.
OTOH, using the GMST is using a usable metric, temperature. Yes there are problems with the surface temps, we know that, but at least it is measurable for change.
The thing is that climate (as everybody realises) is incredibly complex and as such I doubt that there is one single metric that can be applied. It is far more likely that a number of metrics are needed, each focussing on a different part of the climate system.
For example, I doubt that an engineer designing a boiler and steam transport system uses just one metric as temps, pressues, volumes and flow rates all come into play. Climate is a similar situation but a much more chaotic system.
So one of the metrics for climate, “Climate Sensitivity” has been defined in the general world. Rather than complaining that it might not be the “best” metric (is there a best one?) help work out what the others are and how they should be defined.
Because Gavin et. al. deals with surface temps, then the current definition of climate sensitivity is the “best” for his work because it’s about temperatures. Other climate scientists dealing with other facets of the climate would be expected to use other metrics. Rather than being condescending, that was all Gavin was getting at in his comment. There’s no “one number” that fits everything, but temps give a good starting point that other metrics can improve on in other areas.
I hope I made sense, but I’ve had the “Dreaded Lurgi” for a week, so I’m not sure.
Please describe the mathematical equations for the blue and red curves in the leader prepared by Warren Meyers. We are repeatedly told that these curves are (like) logairthmic or exponential curves. What is the X=zero intercept of curves on the Y-axis? How can they be different? Are the curves proven as logarithmic or are they exponential or of another form? What is the power(s) to which they are raised, and the equation coefficients? Doubling is a doubling of what? How do we know that we are not already on or passing the plateau part of a curve of diminishing returns? What evidence allows both curves to be pegged at 280 ppm pre-industrial? Why is there but one mention of the word “noise” in the articles, when the whole diagram might be within the range of natural variation? What assumptions are made about the change of rate of depletion of atmospheric CO2 with concentration? Why are ML values used when, in the valleys of land nearer sea level, CO2 can be 10 times as high as shown here, thereby adding to the mean (but not included)?
Surely this essay takes poor signal:noise ratios to a misleading simplicity.
How long are we supposed to wait until we can start talking about what is right and what is wrong with this theory.
CO2 increased above the equilibrium level of 280 ppm around 1800.
It is 211 years later and we should be able to start measuring this darn thing by now. It should be clear enough.
Someone mentioned Transient above. Even the definition of this is up in the air. Sometimes 7 years, sometimes 23 years, sometimes 30, sometimes 150 years and even 1500 years.
The top of the atmosphere emission layer, the lower troposphere, the surface, ocean heat content – we don’t even know what to measure.
What about water vapour which is supposed to contribute 2.0C of the 3.0C per doubling. We should at least have solid numbers on this given it is the most important aspect. My numbers going back to 1948 show no change at all in water vapour levels but nobody can agree on what numbers to use.
It is time to make the call on what we are going to measure and how it will be measured so we can start seeing how much of this theory is correct.
Geoff Sherrington says:
April 27, 2011 at 4:18 am
Please describe the mathematical equations for the blue and red curves in the leader prepared by Warren Meyers. We are repeatedly told that these curves are (like) logairthmic or exponential curves.
I believe the IPCC uses the following: dF = 5.35 ln(C/Co) So a change in forcing equals the natural log of the present CO2 reading (380 ppm) divided by the starting point reading (280 ppm) times a constant. So where the red and blue lines cross is 280 ppm. ie ln 1 = 0 and we go from there.
An instructive comment on Temperature versus Energy in the atmosphere – the Humidity makes a big difference, as shown in this comment
from – Max Hugoson says: June 7, 2010 at 9:49 am
http://wattsupwiththat.com/2010/06/07/some-people-claim-that-theres-a-human-to-blame/#more-20260
But to all the people playing “average temperature”, and in the spirit of trying to do GOOD ENGINEERING WORK… “average temperature” is a FICTION and MEANINGLESS. Here is why: Go to any online psychometric calculator. (Heh, heh, I use the old English units, if you are fixated on Metric, get a calculator!)
Put in 105 F and 15% R.H. That’s Phoenix on a typical June day.
Then put in 85 F and 70% RH. That’s MN on many spring/summer days.
What’s the ENERGY CONTENT per cubic foot of air? 33 BTU for the PHX sample and 38 BTU for the MN sample.
So the LOWER TEMPERATURE has the higher amount of energy.
Dave in Delaware says:
April 27, 2011 at 7:23 am
The weather channel gives a “feels like” temperature when it is humid. So even the weather channel knows, but won’t admit that water is far more important than CO2.