A. Either the climate sensitivity is around half a degree per doubling of CO2, and the time constant is under a year, or
B. The current paradigm of climate sensitivity is wrong and forcings don’t determine surface temperature.
Based on the actual observations, I hold for the latter.They don't make sense to me. A. seems like gobbledook. Can anyone explain what he means by 'the time constant is under a year'? B. seems very odd because he is using a definition (climate sensitivity) to contradict that same definition. That can't be done. Leaving aside the inexplicable meaning of them - on what does he base his conclusions? On his strange analysis of the impact of volcanoes. It looks to me that he has taken the short term impact of different volcanoes on global surface temperatures and drawn conclusions about the long term impact of all forcings, including the very long-lived forcing of carbon dioxide. He writes:
Unlike the situation with say greenhouse gases, we actually can measure how much sunlight is lost when a volcano erupts.Let's not wonder why Willis thinks sunlight is lost by greenhouse gases and focus on his wonderings about volcanoes. He goes on to talk about:
...the huge reductions in global forcing that volcanoes cause, the global temperature has steadfastly refused to cooperate. The temperature hasn’t changed much even with the largest of modern volcanoes.Well, that's not quite so. But modern volcanoes have only had a very short term impact globally. The cooling effect disappears in a matter of months to years, depending on the nature, composition and location of the eruption as well, one would imagine, as the prevailing weather conditions at least in regard to smaller eruptions.
Willis builds a strawman
The current climate paradigm says that the surface air temperature is a linear function of the “forcing”...Change in Temperature (∆T) = Change in Forcing (∆F) times Climate Sensitivity
What is climate sensitivity?
The climate sensitivity depends on the type of forcing agents applied to the climate system and on their geographical and vertical distributions (Allen and Ingram, 2002; Sausen et al., 2002; Joshi et al., 2003). As it is influenced by the nature and the magnitude of the feedbacks at work in the climate response, it also depends on the mean climate state (Boer and Yu, 2003). Some differences in climate sensitivity will also result simply from differences in the particular radiative forcing calculated by different radiation codes (see Sections 10.2.1 and 220.127.116.11). The global annual mean surface temperature change thus presents limitations regarding the description and the understanding of the climate response to an external forcing. Indeed, the regional temperature response to a uniform forcing (and even more to a vertically or geographically distributed forcing) is highly inhomogeneous. In addition, climate sensitivity only considers the surface mean temperature and gives no indication of the occurrence of abrupt changes or extreme events.What about this:
Note, however, that because of the inherently nonlinear nature of the response to feedbacks, the final impact on sensitivity is not simply the sum of these responses. The effect of multiple positive feedbacks is that they mutually amplify each other’s impact on climate sensitivity.The very fact that some feedbacks act more quickly than others plus the fact that feedbacks act on each other should be sufficient to demonstrate that surface air temperature is not a linear function of forcing. After building his strawman, Wondering Willis proceeds to chop it down, writing:
In lieu of a more colorful term, let me say that’s highly unlikely. In my experience, complex natural systems are rarely that simply coupled from input to output.By demolishing his own strawman, he's starting to sound more reasonable.
Willis invokes Gaia
I say that after an eruption, the climate system actively responds to reductions in the incoming sunlight by altering various parts of the climate system to increase the amount of heat absorbed by other means. This rapidly brings the system back into equilibrium.If I've understood him correctly than that's just plain weird. Where is the extra heat coming from? As Willis has already said, the aerosols from the volcanic eruption have temporarily reduced the amount of incoming radiation. There is no other source of 'heat' for the climate system to absorb.
Applying a long term equilibrium sensitivity to short lived eventWillis does some number crunching and draws some coloured charts and says:
To properly judge the response, however, we need to compare it to the expected response under various scenarios. Figure 3 shows the same records, with the addition of the results from the average models from the Forster study, the results that the models were calculated to have on average, and the results if we assume a climate sensitivity of 3.0 W/m2 per doubling of CO2. Note that in all cases I’m referring the equilibrium climate sensitivity, not the transient climate response, which is smaller.Why would he use the equilibrium climate sensitivity of an assumed 3° Celsius on a transient effect lasting only a few months or years at most and apply it in the same way to eruptions at different locations and of different magnitudes and chemical composition? The equilibrium climate sensitivity of 3° Celsius refers to the temperature after a doubling of CO2, all other feedbacks have run their course and the climate is at a new equilibrium. Willis does not appear to have calculated just how much incoming radiation was reflected back out by any of the volcanoes, so it doesn't seem to me that he's showing anything of value at all.
Leaving out inconvenient dataWillis leaves out inconvenient data. First to get the chop is El Chichon eruption, which Willis calls an 'outlier' - but not giving any reason for doing so. Later on he drops Krakatoa as another 'outlier'. That's two out of six dropped from his analysis or one third. Did they spoil his yarn?
Not considering differing impacts of different volcanoesWillis seems to assume that each eruption will have the same impact on incoming solar radiation. Consider this - the top three were part of Willis' analysis, the bottom one was a real beauty, but earlier in time:
El Chichon - released an unusually large volume of aerosols (7 Mt of SO2 compared to 1.0 for Mount St. Helens). El Chichon produced some climate effects. The temperature of the stratosphere increased by 4 degrees C. ...Impact on ground temperatures is harder to quantify but temperatures in the Northern hemisphere may have been 0.2 degree C less about 2 months after the eruption.
Pinatubo - produced the greatest volume of SO2 ever measured, 20 Mt, about three times more than El Chichon (McCormick, 1992). It is estimated that the gases caused a global temperature decrease of 0.5 degree C for about 2 to 4 years after the eruption.
Krakatau - Although Krakatau erupted a large volume, the magma was relative poor in sulfur, and the eruption had less climate impact compared to some small volume eruptions that were sulfur rich (e.g., Agung in Indonesia). ...Rampino and Self (1982) estimated that the temperature in the Northern Hemisphere decreased 0.3 C due to the eruption.
Toba - The eruption of 2,800 cubic km of magma at Toba caldera 75,000 years ago was the largest eruption in the last 2 million years. The eruption may have release as much as 10E12 kg of sulfuric acid, an order of magnitude more than Laki in 1783 and Tambora in 1815, two of the greatest Holocene eruptions. The Toba eruption may have caused about 3 to 4 degree C cooling at the surface but this impact is hard to detect because of concurrent glacial conditions (Sigurdsson, 1990).
This is from NASA, which suggests that Willis might need to dig a bit deeper:
With a single volcano it may be hard to identify a climate "signal" among the large amount of weather and climate "noise", that is, the unforced chaotic fluctuations of the atmosphere and ocean. So the Pinatubo team first looked at the average climate response after the five largest volcanos this century. They found (Figure 1) that there was a small cooling, about 1/4°C (1/2°F), which peaked 1-2 years after the eruption. This tends to confirm that volcanos do cause a small global cooling.
It's not the sun?
I say that the temperature is regulated, not by the forcing, but by a host of overlapping natural emergent temperature control mechanisms, e.g. thunderstorms, the El Nino, the Pacific Decadal Oscillation, the timing of the onset of tropical clouds, and others. Changes in these and other natural regulatory phenomena quickly oppose any unusual rise or fall in temperature, and they work together to maintain the temperature very stably regardless of the differences in forcing.
More on volcanoes
Willis put up some charts saying, "look see no impact". I can't tell what he did, so I plotted GIStemp and marked the volcanic eruptions. Click the chart to enlarge it.
Anyway, the standout is Novarupta, which is in the Arctic. The others are closer to the equator and their impact was spread through both hemispheres. Click here for a discussion of Novarupta and how its impact was contained because of where it is located.
Willis' magical ocean
While I'm here, I'll add a comment that caught my eye. It's about Willis saying how the oceans and clouds and thunderstorms all gang up and win a war against the laws of physics to offset a change in climate forcing - my bold and italics for emphasis:
David Longinotti says: May 25, 2013 at 4:17 am I think this is a strong challenge to the orthodoxy regarding climate sensitivity, but the posited correction mechanism doesn’t appear to cohere with the data shown. The claim is that “When the reduction in sunlight occurs following an eruption, the Pacific starts storing up more energy.” But the timing seems to challenge this assertion – in Figure 6 the change in the slope of the cumulative Best Index occurs about 20 months BEFORE the eruptions, and there is no change in slope around the time of the eruption. Is the implication that the Pacific starts storing energy in anticipation of the eruption, or have I misunderstood the proposed correction phenomenon (or its measurement)?Good to see it's not just me who wonders what prompts the Pacific to start 'storing up more energy' and where that energy could possibly come from, given there is less incoming energy. I hadn't bothered to check just when the ocean took it into it's head to 'store up more energy' to make up for the lack of incoming. Seems it can not only decide to create energy out of nothing, it can do so in advance of the event that prompts it to do so. What a clever little ocean, eh?
Update: In the comments Ashby alerted me to the fact that Willis is basing his assertion for oceans storing energy on an apparent association with El Nino. Problem is the ocean releases heat in its El Nino phase, it doesn't store it. So bang goes another bit of Willis' wonderings.
- Willis has read very little climate science and understands less.
- Willis suffers from the Dunning-Kruger Effect.
- Willis enjoys holding the floor.
- Willis has a veneer of 'hail fellow well met' but it's very thin. He can't take criticism or even polite questions from real sceptics and loses his cool easily - in fact he gets downright nasty. Supported by his patron when the going gets tough.
|Figure 6.14. Simulated temperatures during the last 1 kyr with and without anthropogenic forcing, and also with weak or strong solar irradiance variations. Global mean radiative forcing (W m–2) used to drive climate model simulations due to (a) volcanic activity, (b) strong (blue) and weak (brown) solar irradiance variations, and (c) all other forcings, including greenhouse gases and tropospheric sulphate aerosols (the thin flat line after 1765 indicates the fixed anthropogenic forcing used in the ‘Nat’ simulations). (d) Annual mean NH temperature (°C) simulated by three climate models under the forcings shown in (a) to (c), compared with the concentration of overlapping NH temperature reconstructions (shown by grey shading, modified from Figure 6.10c to account for the 1500 to 1899 reference period used here). ‘All’ (thick lines) used anthropogenic and natural forcings; ‘Nat’ (thin lines) used only natural forcings. All forcings and temperatures are expressed as anomalies from their 1500 to 1899 means; the temperatures were then smoothed with a Gaussian-weighted filter to remove fluctuations on time scales less than 30 years. Note the different vertical scale used for the volcanic forcing compared with the other forcings. The individual series are identified in Table 6.3.|