A few items of interest this week:
Katrina Report Card:
The National Wildlife Federation (NWF, not to be confused with the ‘National Wrestling Federation’, which has no stated position on the matter) has issued a report card evaluating the U.S. government response in the wake of the Katrina disaster. We’re neither agreeing nor disagreeing with their position, but it should be grist for an interesting discussion.
An Insensitive Climate?:
A paper by Stephen Schwartz of Brookhaven National Laboratory accepted for publication in the AGU Journal of Geophysical Research is already getting quite a bit of attention in the blogosphere. It argues for a CO2-doubling climate sensitivity of about 1 degree C, markedly lower than just about any other published estimate, well below the low end of the range cited by recent scientific assessments (e.g. the IPCC AR4 report) and inconsistent with any number of other estimates. Why are Schwartz’s calculations wrong? The early scientific reviews suggest a couple of reasons: firstly, that modelling the climate as an AR(1) process with a single timescale is an over-simplification; secondly, that a similar analysis in a GCM with a known sensitivity would likely give incorrect results, and finally, that his estimate of the error bars on his calculation are very optimistic. We’ll likely have a more thorough analysis of this soon…
It’s the Sun (not) (again!):
The solar cyclists are back on the track. And, to nobody’s surprise, Fox News is doing the announcing. The Schwartz paper gets an honorable mention even though a low climate sensitivity makes it even harder to understand how solar cycle forcing can be significant. Combining the two critiques is therefore a little incoherent. No matter!
Re 149: “Be careful with rhetoric — when rhetoric doesn’t match reality, people will use that to attack the message, even if it is otherwise valid.”
Et Tu Brute! I’m still in admiration of the plans and the steps you’re taking in using alternative fuels and energy efficiency. But there is a definite climate component to extreme meteorological events. Whether there’s a trend or not to more frequent cat 4 and 5 storms remains to be seen.One swallow doesn’t make a summer. But It does seem like we’re hearing about storms of greater magnitude even if the frequency of hurricanes has been lower in the past few years.
Politics unfortunately does get to decide who gets what slice of the pie in the protective stage and in the aftermath,since they control the pursestrings.
Rhetoric is sometimes described as showy and elaborate language that sounds effective but is mostly empty of ideas or sincerity. I’m a true believer that there’s a cause and effect relationship between the strength of storms and the warmer waters in the tropical Atlantic, just north of the equator where hurricanes are born and and gain in strength as they lumber across the now warmer waters in their path. There’s no disbelief or exaggeration for effect,(hyperbole) intended. It’s counter-productive as we learned by the deceptions of past and current administrations about going to war.
If there’s any doubt whether there is a strong correlation between the temperature of the Atlantic Ocean’s surface waters and the intensity of hurricanes click on the link to the graph below, based on an August 2005 paper from “Nature” by Dr. Kerry Emanuel of MIT.
http://www.cleartheair.org/hurricane_globalwarming_still.html
I’ve studied Schwartz’s paper more thoroughly. He gets a very low sensitivity value of about 0.3 (corresponding to about 1.1 C temperature change from a CO2 doubling). Very crudely this idea can be conveyed by his assertion of a 2.2 watt per sq meter greenhouse forcing in the 20th century and a 0.57 increase in temperature: 0.57 temp change/2.2 forcing = 0.26, even smaller than 0.3.
He gets the 2.2 watt per sq meter from this figure from IPCC 2001:
http://www.grida.no/climate/ipcc_tar/wg1/fig6-8.htm
I see about 2.0 I have detailed CO2, N2O and CH4 data. When I calculate using just CO2 I get only 1.2 watts per sq meter for 20th century forcing increase. But if I add N2O and CH4 using the IPCC 2001 simplified expressions I get 1.6. And if I then tack on CFCs forcings from IPCC 2001 I get 1.9, so the ~2.0 from the figure is materializing when I check it out.
Schwarz uses a 0.57 temperature increase for the 20th century. I use the HadCRUT3v data from here:
http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3vgl.txt
Now if I simply read the 1900 and 2000 temperature off this sheet I see they are different by 0.53. If you look at the CRUTEMv data the difference is 0.55 so I can see where the 0.57 might have come from.
But when I pass a trend line (a running 20-year linear regression) through the data and look at the 1900-2000 change I get about 0.77 C. And if I look at the 1905-2005 difference I get about 0.87 C. Since Schwarz finds a 5 year lag, it makes sense of compare 1905-2005 temperature change to a 1900-2000 forcing change. Even with this revised temperature change and the 1.9 forcing (instead of 2.0) the sensitivity value comes out at 0.46 (corresponding to a 1.7 degree increase from a CO2 doubling).
Now the IPCC 2001 report (same fig as before) suggests -0.2 net forcing from solar + aerosols. With their 2.0 watt/m^2 value for greenhouse gases this gives 1.8 for total forcing. With my 1.9 value it would come to a 1.7 watt/m^2 total forcing. Even with this reduced forcing and the 0.87 temperature change I get, sensitivity of 0.51 is obtained, which corresponds to 1.9 C for a CO2 doubling.
The consensus sensitivity is about 3 C for a CO2 doubling. To get that we need another 0.46 C temperature increase that is unrealized. This is what is considered “in the pipeline”.
The source of this delayed heating is the effect of the deep ocean. Using a simple model in which I divide the world into three compartments (1) land + atmosphere above land (2) surface ocean + atmosphere above ocean and (3) deep ocean I can explore the effects of lags on the system.
Each compartment has an interchange rate with the surface ocean compartment. The land compartment has a small heat capacity and so has little impact on system dynamics over a period of decades (which is the time scale of interest since my trend serves to produce a running 20-year smoothing).
Assuming a fairly rapid interchange between and land and ocean air masses, the effect of deep ocean interchange in system dynamics in the multi-decade time frame is not very important. What deep ocean *does* impact is the extent of the temperature change due to a forcing change. For example over a period of a few decades, the impact of a step increase in forcing will be about 85-90% of the full effect for a deep ocean exchange rate consistent with a ~2000-year equilibrium period. Increasing the exchange rate to what would produce equilibrium in say ~1000 years would reduce the impact to about 80% or so. That is, the *true* sensitivity would be 18-25% greater than the figures above suggest depending on the importance of deep water heat exchange.
Application of these correctives to my 0.51 sensitivity value from above and I get 0.6-0.64 for sensitivity, corresponding to 2.3-2.4 degrees for CO2 doubling. It’s still not 3 C, but if I assume larger deep ocean interchange rates I can make it bigger. The issue is this heating “in the pipeline” that reflects deep ocean effects isn’t going to show up quickly. It might take a couple of centuries to manifest so is this relevant? Obviously it will be relevant when looking at paleoclimate forcing versus response behavior, but is it relevant today?
Apropos of nothing in particular, I thought I ought to report this here.
I just got an unsolicited invitation in my email. I contacted them to see if it was spam, and they told me I was invited as an “influential blogger”. Shucks. Flattery will get you somewhere, but I am way behind on this proposal I need to get out, so I’ll pass.
A global shipping insurance concern is basically doing a global change for executives event. My sense is that this is for real. I’m not sure whether I’m supposed to tell my six billion closest friends more about the event or not, so I’ll just quote the interesting bit from the invitation:
Re 154,
I guess you could look at those numbers and conclude that the glass is half full. I’d also be curious to know which industries they represent.
Regards,from one of your six billion closest friends.
Re 154:”- An astounding half of executives surveyed do not believe that global climate change resulting in long-term environmental and economic impacts is likely to occur.”
There’s a story- I don’t know whether it’s apocryphal or not- that President Eisenhower was surprised to learn that half of the American people were below average in intelligence.(I’m aware of the difference between median and mean). Maybe this is the half that obeyed the ‘Peter Principle’ and rose to levels above their capabilities.
James Annan addressed Schwartz`s paper a week before this post. It`s a surprise that no one has noted it:
http://julesandjames.blogspot.com/2007/08/schwartz-sensitivity-estimate.html
James has also commented on Schwartz`s earlier Nature piece concerning the IPCC: http://julesandjames.blogspot.com/2007/09/pile-on.html#links
I just today listened to a lecture on active sun and its implications for climate change given by one of our physics professors (solar-magnetospheric physics). His main point was that sun’s poloidal magnetic field activity (geomagnetic field activity is used as a proxy) has increased and this has profound effects on climate. He did not identify any specific mechanism as to how (alluded to effects on cosmic rays and, of course, brought up Svensmark et al. paper, and effect on ozone layer and some vague other things).
He said that the solar scientists in the IPCC did not take this effect (the effect of the sun’s poloidal magnetic field on Earth’s climate) into account and therefore have underrepresented the solar influence on recent warming in the 4th IPCC report.
I challenged this idea (which I probably should not have done since he has a big influence here…), but got only a reply that it is only that the IPCC solar scientists have not taken the effect of this poloidal field effect into account in their estimates, because it is only during the past couple of years that scientist have even known about this effect. He was very specific that solar maxima, increased sun spot numbers etc are related to the sun’s toroidal field, but it is the poloidal field that seems to have more effect on Earth’s temperature.
How? In my opinion, this he did not satisfactorily explain.
And also, it seems that at least some scientists studying solar activity and geomagnetism put a lot of emphasis on the fact that geomagnetic activity index curve (for the poloidal component at least) seems to match Earth’s surface temperature curve, and hence the temperature increase is explained!
I would expect a bit more intellectual honesty…
So, what is the deal with the sun’s poloidal and toroidal field stregths and their effect on Earth?
I agree with Paul. Also, we should stop spending time, money and efforts in things like Iraq and start concentrating in this problem, that sometimes seems to be a lost cause..
Thanks,
fuser
[[So, what is the deal with the sun’s poloidal and toroidal field stregths and their effect on Earth?]]
What the hell does “poloidal” mean? I’ve studied astronomy since the 1970s and I never heard that term before.
[[What the hell does “poloidal” mean? I’ve studied astronomy since the 1970s and I never heard that term before.]]
Well, apparently it’s a real technical term — “A divergenceless field can be partitioned into a toroidal and a poloidal part.”
Google Scholar: Results — about 426 for +poloidal +climate.
170 articles since 2002; 16 articles during 2007.
This is behind a pay-wall; sounds like a current review, and a good reminder of how short-term our information is.
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1468-4004.2007.48223.x
“Following 20 years without satellite magnetic coverage, the first five years of the International Decade for Geopotential Field Research have provided the geomagnetic community with a wealth of high-quality data from several near-Earth satellites: Ørsted, SAC-C and CHAMP. Combined with ground-based and aeromagnetic data, this has opened numerous opportunities for studies ranging from core flow, mantle electrical conductivity, lithospheric composition and ocean circulation to the dynamics of ionospheric and magnetospheric currents using one or more satellites. Here, I review our current state of knowledge, and discuss the challenges to maximizing the utility of the satellite data.”
One full text article this year discusses what’s known:
http://arxiv.org/abs/physics/0703187
“Since the beginning of the 20th century, the correlation in the 11-year solar cycle between the sunspot number and geomagnetic aa-index has been decreasing, while the lag between the two has been increasing. We show how this can be used as a proxy for the Sun’s meridional circulation, and investigate the long-term changes in the meridional circulation and their role for solar activity and terrestrial climate. …”
I apologise posting this comment here, but I wanted to reply to Mr Barton Levenson (The CO2 problem in 6 east steps, post 253), and the original thread seems to have closed.
The equations Mr Levenson used relate incoming short wave solar radiation to outgoing long wave radiation, and via Stefan’s law and the geometry of the earth arrive at an equilibrium temperature of 254 degrees K. The 33 degrees K increase in temperature at the surface of the earth is then attributed, via one explanation or another, to the back radiation from the atmosphere.
What happens if we apply the same radiative equations to something which we can control, measure and understand – the real greenhouse effect.
A much simplified account, based on the earth’s greenhouse equations, follows:
Short wave radiation from the sun equal to W per square meter falls on the glass, passes through and warms the interior, which emits long wave radiation. In turn this warms the glass to a temperature T’, at which it emits long wave radiation, W, both outwards (balancing the sun’s input) and inwards.
To balance the back radiation, the greenhouse interior must warm, and emit long wave radiation 2W at a higher temperature T.
The ratio T/T’ = the fourth root of 2, or 1.189..
This looks plausible (when the ratio is applied to the earth the author calculates an increase due to “greenhouse” of 38 degrees K), but it is, sadly, nonsense. Nonsense to the fourth power, one might say.
The greenhouse interior is warmed by the direct sunlight and heats because the interior is insulated (the thermal conductivity of glass is low and convection is prevented). The radiation effect, which must be present, is negligible. The much derided G and T paper explains this at great length.
Mr R W Woods (who G and T quote as required reading for all climatologists) demonstrated the absence of a significant radiative effect by actually measuring the temperatures in a glass and a non-radiative greenhouse simultaneously.
So, my question to Mr Levenson is this. Why do we attribute our life-giving 33 degree K to back radiation? What is wrong with the adiabatic lapse rate which Mr O’Reilly laboured to explain, which we can see and feel whenever we use an a aerosol or drive up a hill?
TJT, (#158)Given the amount of handwaving he was doing, I’m surprised he didnt’ take flight. An assertion without a mechanism is meaningless. The only mechanism these solar types have come up with is GCR. Only one thing wrong: GCR fluxes aren’t changing. During the space era, they are remarkably consistent–to the point where the models we use to calculate bit flip rates in memories are basically the same as they were in the 80s. Neutron fluxes–a proxy for GCR–have also not been changing since the 1950s. If there were a solar/GCR mechanism, one would expect it to be active only when the GCR flux was changing, since it would act by changing the amount of solar radiation that makes it to Earth.
So, on the one hand, you have a mechanism that is known to be active (greenhouse heating by CO2) and is well understood and that we know should be increasing. On the other hand, you have a mechanism that nobody can quite parse out, the cause of which doesn’t seem to be present, but that solar types are just sure must be the real culprit. Hmm, which to believe?
Unfortunately, being an expert in one scientific field is no guarantee of competence in another–nor of being able to realize whether you are competent in that other field.
BTW, you can read about geomagnetism here:
http://www.phy6.org/earthmag/mill_5.htm
Specifically poloidal and toroidal fields:
“In a spherical geometry, like that of the Sun, magnetic fields can be divided into two classes, toroidal and poloidal fields. If the field is axially symmetric, poloidal field lines lie in meridional planes (like those of the dipole field) while toroidal field lines form circles around the axis of symmetry.”
Fred, this may help; an agricultural greenhouse isn’t in a vacuum.
http://www.ems.psu.edu/~fraser/Bad/BadGreenhouse.html
[[So, my question to Mr Levenson is this. Why do we attribute our life-giving 33 degree K to back radiation? What is wrong with the adiabatic lapse rate which Mr O’Reilly laboured to explain, which we can see and feel whenever we use an a aerosol or drive up a hill?]]
Because it’s the greenhouse effect that gives you the surface temperature from which you start counting off the lapse rate.
Mr Levenson’s comment, 166, is interesting.
If I understand it – which is by no means certain – he is saying that the earth’s surface temperature is increased from the “bare rock” level of 255 degrees K to 288degrees K by back radiation from the atmosphere. Adiabatic convection then cools the atmosphere and establishes the observed lapse rate from 288 back to 255 degrees K at the top of the troposphere. The role of the greenhouse gasses is presumably to increase the warming of the atmosphere by their enhanced absorption, and simultaneously to increase the back radiation.
But the atmosphere is warmed primarily by the earth; heat can flow only in one direction, and the earth’s surface is warmer than the atmosphere.
The ‘blanket’ theory (the atmosphere as a whole has a low thermal conductivity, so it is warmer on the inside) is more plausible, but has only a minor role for radiative effects, which is what Mr Woods found with his greenhouses.
The link from Mr Roberts, 165
[Response: edited–the reader has provided you with a link to a rigorous explanation of how the atmospheric greenhouse effect works. We’ll end this particular thread with that. If you’d like to try to overlaw the Planck radiation law, submit a publication to the peer-reviewed literature. We’ll be happy to feature it if gets published (well, anywhere but “Energy and Environment”). -mike]
Fred Staples (#167) wrote:
Actually greenhouse gases primarily cool the atmosphere by means of their direct effect of reradiating thermal radiation. The troposphere is warmed principally by moist air convection. Collisional energy from moist air convection is transformed into thermal radiation in addition to the thermal radiation which greenhouse gases absorb which is emitted both by greenhouse gases and by the surface.
Incidentally, I should point out that all of this is something which Levenson agrees with as he understands the scientific explanation of the greenhouse effect.
Fred Staples (#167) wrote:
“Heat” as thermal, kinetic energy flows in both directions even with non-greenhouse gases and with liquids and solids. To argue otherwise would be equivilent to presupposing the existence of entropy creating anti-Maxwell’s demon. However, it flows predominantly coldward. This too is statistical in nature.
As thermal energy flows back to the surface in the form of thermal radiation, slowing the rate at which the surface is able to cool, this is the proper application of a “blanket analogy,” one of the analogies by which the greenhouse effect is first explained to those who have not yet grasped the actual physics.
Fred Staples (#167) wrote:
If heat in the form of thermal energy in the form of kinetic, translational energy flowed in only one direction as you claimed above, then the atmosphere would have to be the same temperature as the surface since it would never be able to transfer this translational energy to the surface. And as I pointed out in comment #555 of the discussion to Part II: What Angstrom didn’t know, we have a great deal of detailed evidence for the radiative effects of greenhouse gases. In fact, we are able to measure the back radiation.
If you do the math rather than armchair theorizing which assumes that random kinetic energy can be transfered in only one coldward direction you will see that the mainstream view works. Yours does not.
[[If I understand it – which is by no means certain – he is saying that the earth’s surface temperature is increased from the “bare rock” level of 255 degrees K to 288degrees K by back radiation from the atmosphere. Adiabatic convection then cools the atmosphere and establishes the observed lapse rate from 288 back to 255 degrees K at the top of the troposphere. The role of the greenhouse gasses is presumably to increase the warming of the atmosphere by their enhanced absorption, and simultaneously to increase the back radiation.]]
The greenhouse effect heats the Earth from 255 K to what would be 336 K or so in the absence of sensible and latent heat exchange. That 81 K difference is cut back to only 33 K by conduction, convection, and evaporation of seawater.
[[But the atmosphere is warmed primarily by the earth; heat can flow only in one direction, and the earth’s surface is warmer than the atmosphere.]]
“Heat can flow only in one direction” is completely wrong if you’re talking about radiative effects. Cooler objects radiate to warmer ones all the time, as well as vice versa.
Barton and Fred, Might I suggest we amend Fred’s statement to “net heat transfer goes in only one direction” and of course we have to assume that no work is done to transfer heat in the opposite direction, etc.
The blanket analogy is quite imperfect, especially where convection and latent heat are important. Yes, I know I’ve used it, too, but what is really happening is that by altering the temperature profile of the atmosphere, ghgs change the net radiative cooling.
> 165, 168
Also recommended:
http://www.ems.psu.edu/~fraser/Bad/BadFAQ/BadGreenhouseFAQ.html