Whoops. Thanks for setting me straight so quickly. I've just done some further research on this
The poster is a denier, seemingly with no relevant qualifications http://www.desmogblog.com/willis-eschenbach The site is a denial blog https://en.wikipedia.org/wiki/Watts_Up_With_That%3F It's now on my mental 'banned list'. Sorry about this - it's not my area of expertise and the post came to me via a usually reliable channel - so I didn't see the need to do 'criminal record' checks on the author. Apologies. A major (if rare) screw up. A On 8 August 2015 at 17:25, Alan Robock <[email protected]> wrote: > Dear Andrew, > > Please refrain from posting pseudoscience from global warming deniers like > this to this list. > > Cloud feedbacks are incorporated into all climate models, and while they > vary a little in different models, overall, they provide a small net > positive feedback. This has been studied for decades, and handwaving > arguments like you posted, from someone with an agenda, only serve to > confuse those who are not involved in climate science. > > Your note, that this is important, is absolutely wrong. > > Alan > > Alan Robock, Distinguished Professor > Editor, Reviews of Geophysics > Department of Environmental Sciences Phone: +1-848-932-5751 > Rutgers University Fax: +1-732-932-8644 > 14 College Farm Road E-mail: [email protected] > New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock > http://twitter.com/AlanRobock > Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54 > > > On 8/8/2015 11:53 AM, Andrew Lockley wrote: >> >> Poster's note : Important concept suggesting negative feedback on >> albedo changes. Applicable, potentially, to all forms of SRM, but >> particularly SAI >> >> http://wattsupwiththat.com/2015/07/29/why-volcanoes-dont-matter-much/ >> >> Watts Up With That? >> Why Volcanoes Don’t Matter Much >> >> Willis Eschenbach / 5 days ago July 29, 2015 >> >> The word “forcing” is what is called a “term of art” in climate >> science. A term of art means a word that is used in a special or >> unusual sense in a particular field of science or other activity. This >> unusual meaning for the word may or may not be logical, but each field >> has its terms of art, and it’s useless to complain that they don’t >> make sense. The IPCC defines “radiative forcing” as follows: >> >> Radiative forcing >> >> Radiative forcing is the change in the net, downward minus upward, >> radiative flux (expressed in W m–2) at the tropopause or top of >> atmosphere due to a change in an external driver of climate change, >> such as, for example, a change in the concentration of carbon dioxide >> or the output of the Sun. Sometimes internal drivers are still treated >> as forcings even though they result from the alteration in climate, >> for example aerosol or greenhouse gas changes in paleoclimates. >> >> Now, the current climate science paradigm says that regarding the >> things that affect temperature, everything averages out in the long >> run except for any changes in total forcing. The current paradigm >> further says that the future evolution of the climate can be forecast >> by the simple linear relationship given as: >> >> Change in temperature equals climate sensitivity times change in total >> forcing. >> >> Me, I think that’s simplistic nonsense, but let’s set my opinion aside >> for a bit and compare their forcing claims to the actual observations >> of the changes in forcing. As an example, let me use the forcings that >> are the result of volcanic eruptions. The larger eruptions blast >> aerosols (various molecules and minerals) into the stratosphere, >> reducing the incoming sunshine. These forcings have been estimated by >> Sato as being of the following amounts: >> >> Figure 1. Volcanic forcings estimated by Sato et al. >> http://data.giss.nasa.gov/modelforce/RadF.txt Forcings are negative >> because they represent a reduction in available solar energy due to >> volcanic aerosols. The large eruption at the far right is Pinatubo in >> the Philippines, 1991, and the eruption to its left is El Chichon, >> Mexico, in 1982. >> >> You can see that some eruptions, like that of El Chichon, produced a >> much larger aerosol cloud in the northern hemisphere (red) than in the >> southern (blue), while others like Pinatubo were more equal in the >> distribution of the aerosols between the hemispheres. In all cases, >> the hemisphere where the volcano is located shows the greatest effect >> from the eruption. >> >> As I mentioned above, I think that the idea that the temperature >> slavishly follows the changes in forcings to be a fundamental >> misunderstanding of how the climate system operates. Instead, I say >> that although initially the temperature responds to the forcings, soon >> the climate system responds to the resulting changes in temperature by >> changing the forcings themselves, often in very non-linear ways. In >> particular, I have presented plenty of evidence that the climate >> system responds to increasing tropical temperatures by varying the >> timing and strength of the daily emergence of the cumulus cloud field. >> Part of the climate system response works like this: >> >> On warmer days, the emergence of the tropical cumulus cloud field is >> both earlier and stronger. This cuts down on the available solar >> energy by reflecting more of it back to space. The high cloud albedo >> means that less sunlight reaches the surface, so the surface cools. >> >> And on cooler days, the opposite occurs. The tropical cumulus field >> emerges later, and is weaker. As a result, the day warms up more than >> it would otherwise, because there is less cloud albedo and thus more >> available solar energy. >> >> All that is required to show that this effect exists is to show that >> tropical albedo is positively correlated with temperature … as I have >> done here, here, and here. >> >> Now, if we assume for the moment that my theory is correct, what kind >> of climate response would we expect to find from a volcanic eruption >> large enough to put aerosols into the stratosphere and cause some >> global cooling? Well, eruptions reduce available solar energy in two >> ways—increased reflection from white aerosols, and increased >> absorption from dark aerosols. >> >> So the first thing to happen after the eruption would be the reduction >> in incoming sunlight from the increased albedo and increased >> stratospheric absorption. Then after the decreased sunlight actually >> starts to cause widespread cooling, the climate system would respond. >> We’d expect the climate system response following such an eruption to >> have the following characteristics: >> >> • Right after the eruption, there would be a reduction in available >> solar energy, due to the volcanic aerosols in the stratosphere. >> >> • This initial eruption-induced reduction in available solar energy >> would be both deeper and sooner after the eruption in the hemisphere >> where the eruption occurred than in the opposite hemisphere. >> >> • As a result, the corresponding climate reaction in the eruption >> hemisphere would also both be deeper and occur sooner than the climate >> reaction in the opposite hemisphere. In other words there will be a >> dose-related effect, where a larger reduction is met with a larger >> climate reaction. >> >> • The form of the climate reaction will be an albedo reduction, which >> will cause increase in available solar energy. The increase in >> available energy will be of the same order of magnitude as the >> corresponding decrease due to volcanic aerosols. >> >> With those predictions derived from my theory about the nature and >> timing of the climate response, we can compare them to what actually >> happened when Mount Pinatubo erupted. I’ve taken the albedo records >> for the globe and for each hemisphere individually, and analyzed what >> happened after the eruption of Pinatubo in June of 1991. This gave me >> the anomaly in the amount of solar energy that is actually available >> to the climate system. Figure 2 shows three variables for the period >> 1984-1997, which includes the eruption of Mt. Pinatubo on June 15, >> 1991. >> >> First, in black, is a closer look at the same dataset shown in Figure >> 1. Black shows the global average of the Sato volcanic forcing data >> for the period 1984-1997. >> >> Second, in violet, is the aforementioned anomaly in the amount of >> incoming sunshine, in watts per square metre. This is the “available >> energy”, meaning the solar energy that remains after the albedo >> reflections. >> >> Third, in gold, is the amount of incoming solar energy that is >> absorbed in the stratosphere. Recall that volcanoes affect the >> sunshine in two ways—changes in reflection (violet line) and changes >> in absorption (gold line). The gold line shows the reductions from >> absorption of solar energy by stratospheric aerosols. >> >> Figure 2. Sato estimated volcano forcing (black), available solar >> energy anomaly after albedo (violet), and stratospheric absorption >> forcing (gold). The observed values (violet and gold) are expressed as >> anomalies around the value they had the month before the eruption. See >> below for methods and data sources. >> >> Now, the first thing I noticed is that immediately after the eruption, >> all three datasets agree with each other—as we would expect, there is >> a precipitous drop in downwelling solar radiation. However, after that >> they go their separate ways, so it’s hard to tell what the overall >> effect of the absorption and the reflection might be. >> >> For that kind of comparison, I use a running post-eruption average. >> This is the average forcing over the period from the date of the >> eruption to the date in question. So for example, the data point for >> January 1996 represents the average forcing from the date of the >> eruption until January of 1996. Figure 3 shows that type of >> post-eruption average applied to Figure 1, with the actual Figure 1 >> data shown grayed out in the background for reference. >> >> Figure 3. Post-eruption averages. Total observed eruptive forcing >> [reflection (violet) plus absorption (gold)] is shown in yellow. Other >> colors as in Figure 1 — black is the Sato estimate of total volcanic >> forcing; violet is available solar anomaly after albedo reflections; >> gold is stratospheric absorption anomaly. Each point on the graph >> represents the average forcing from the eruption until that date. >> >> The important thing to note is that from the eruption to the end of >> the record (end of 1997) the Sato forcing estimate (black line) has an >> average forcing of about minus one watt per square metre (W/m2). >> However, the observed change in total forcing of the period (yellow >> line, sum of purple (albedo forcing) and gold (absorption forcing) is >> a bit more than plus one watt per square metre. >> >> Also, the speed of the climate response is visible in Figure 3. The >> total forcing (yellow line) follows the Sato forcing estimate (black >> line) for the first four months or so after the eruption. But after >> that, while the Sato calculated forcing continues to become more and >> more negative, the observations show that the total observed forcing >> does not ever become much more negative than it was at four months >> after the eruption. Instead, it runs level for about a year, and then >> rapidly increases. By the end of 1993, the observed post-eruption >> average forcing has returned to pre-eruption values … while the Sato >> theoretical forcing is still at minus two W/m2. >> >> Now, Figures 2 and 3 show the global situation. We also have data for >> each hemisphere separately. This will let us observe the difference in >> the response of the climate in the two hemispheres. Here are the >> observed forcing and the Sato theoretical forcing for the northern and >> southern hemisphere. >> >> >> Figure 4. As in Figure 2 but by individual hemisphere. The two panels >> show the Sato estimated forcing (black), the solar absorption forcing >> (gold), and the available solar energy after albedo (upper panel, red, >> northern hemisphere; lower panel blue, southern hemisphere) >> >> The most notable difference between the hemispheres is the deep drop >> in available solar energy in the northern hemisphere (red line, upper >> panel) during the months immediately following the eruption. I note >> also that following that initial drop, the amount of available energy >> in the NH steadily increases in both the absorption (gold) and >> reflection (red) datasets. >> >> To conclude this analysis I looked at the post-eruption averages for >> the individual hemispheres. Figure 5 shows those results: >> >> Figure 5. As in Figure 3 but by individual hemisphere. These show the >> running average starting at the time of the eruption and moving >> forwards. >> >> In the northern hemisphere we can see that the initial drop in forcing >> was almost as large as the Sato estimate. However, from there, the >> climate response kicked in, and the amount of available energy started >> to rise rapidly. In the southern hemisphere, on the other hand, the >> response was smaller and initially slower. >> >> However, once the SH response began, the available solar energy rose >> very quickly. Both hemispheres took about the same amount of time, >> about two years, for the average forcing over the post-eruption >> interval to return to zero. >> >> And in both hemispheres, the eventual response was nearly >> identical—the average change in total available sunshine at the end of >> the record is about plus a watt and a half per square metre, compared >> to the Sato estimate which has an average change to the end of the >> record of minus one watt per square metre. >> >> Conclusions: The main conclusion that I draw from this is that the >> central paradigm of modern climate science is wrong—temperature does >> not slavishly follow the forcings. >> >> To the contrary, when the tropical temperature changes, the solar >> forcing subsequently changes in the opposite direction, negating much >> of the effect of the volcanoes. >> >> And in particular, the observations agree with the theoretical >> predictions, which were: >> >> • Right after the eruption, there would be a reduction in available >> solar energy, due to the volcanic aerosols in the stratosphere. >> >> • This initial eruption-induced reduction in available solar energy >> would be both deeper and sooner after the eruption in the hemisphere >> where the eruption occurred than in the opposite hemisphere. >> >> • As a result, the corresponding climate reaction in the eruption >> hemisphere would also both be deeper and occur sooner than the climate >> reaction in the opposite hemisphere. In other words there will be a >> dose-related effect, where a larger reduction is met with a larger >> climate reaction. >> >> • The form of the climate reaction will be an albedo reduction due to >> the temperature reduction, which will cause an increase in available >> solar energy. The increase in available energy will be of the same >> order of magnitude as the corresponding decrease due to volcanic >> aerosols. >> >> These theoretical predictions are all visible in the graphs above, and >> they lead back to the title of this piece. The reason volcanoes don’t >> matter much is that the climate rapidly responds to re-establish the >> status quo ante. Yes, eruptions do put loads of aerosols into the >> stratosphere; and yes, these aerosols do cut down available solar >> energy; and yes, this does have local effects in space and time … but >> because available solar energy in the tropics goes up as the >> temperature goes down, the balance is quickly restored. As a result of >> this and other restorative phenomena, the climate system has proven to >> be surprisingly insensitive to such variations in forcing. >> >> My best regards to everyone, >> >> w. >> >> The Usual Request: If you disagree with someone, please quote the >> exact words that you disagree with, so we can all be clear both who >> and what you are objecting to. >> >> Methods and Data >> >> Sato Theoretical Forcing: The Sato data is from here. Following Sato, >> I have used the aerosol optical depth (AOD) to estimate the forcing. >> Sato says that the forcing is estimated as a linear function of the >> AOD, which seems reasonable. I have used his formula for the >> “instantaneous” forcing (as opposed to the “equilibrium” or other >> forcings), since we are discussing the immediate effects of the >> eruptions. >> >> Available Solar Energy Anomaly After Albedo: For the albedo data, I >> digitized the albedo shown in Figure 5(b) of the most interesting >> study, Long-term global distribution of Earth’s shortwave radiation >> budget at the top of atmosphere, by Hatzianastassiou et al. I >> multiplied the monthly (1 – albedo) by the monthly TOA solar to get >> the absolute value of the available solar energy after albedo >> reflections. Then I subtracted the “climatology”, which means the >> monthly averages, from that dataset to get the anomaly in available >> solar energy >> >> Stratospheric Absorption: While researching for this post, I had an >> interesting insight about the increase in stratospheric absorption of >> solar energy after an eruption. This was that I could use the change >> in stratospheric temperature to calculate the amount of additional >> sunlight being absorbed, using the Stefan-Boltzmann relationship. For >> the stratospheric temperatures, I used the UAH satellite based >> estimate of the lower stratosphere, Version 6.0beta2, available here. >> Yes, I am aware that this is an uncertain estimate, but it’s accurate >> enough for a first-order analysis such as this one. >> >> Sensitivity to Assumed Emissivity: I used the most conservative >> assumption, that of a blackbody relationship with emissivity=1. If we >> assume a graybody, the change in solar absorption corresponding to a >> given temperature difference goes down in proportion to the change in >> emissivity. This reduces stratospheric absorption forcing. And this in >> turn increases the difference between the observed (yellow line) and >> the Sato theoretical forcings (black line) in the period immediately >> after the eruption, but makes little difference in the later years >> because the stratospheric absorption term is small. For an example of >> the change in the early years, using an emissivity of 0.5 reduced the >> largest total forcing decrease (reflected plus absorbed) to about >> minus one W/m2, rather than the approximately minus 1.75 W/m2 as shown >> after the eruption in Figure 3. >> >> Data: One of the bad things about this is that the dataset is so >> short. Can’t be helped, because as far as I know there’s no >> hemispheric estimate of the albedo during the time of the previous >> eruption, El Chichon in 1982. (If you know of such a dataset, please >> post a link). But the good side of short data is there’s not much of >> it, so it’s easy to move around … for example, I’ve been looking at >> one-minute radiation measurements from Mauna Loa, 31 million data >> points per year since 1980. That’s hard to download, and too big for >> me to put up on something like photobucket. >> >> But here we only have 14 years at 12 months per year = 168 records, so >> it’s small enough to put into an Excel spreadsheet, which I’ve done in >> .csv format here. The spreadsheet contains the TOA solar values, the >> albedo values, the Sato forcing values, the stratospheric temperature >> values, and as a special bonus, the hadCRUT4 records for the period >> both globally and for individual hemispheres. Enjoy. >> > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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