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Discussion > Evidence for Rhoda and Dung

Sigh!
The only way you can get a decent correlation between CO2 and temperature in the modern era is by taking the temperature in 1880 and the temperature in 2015 and the CO2 in 1880 and the CO2 in 2015 and drawing a pair of straight line trends.
RR is quite correct that the correlation (let alone the causation) between temperature and CO2 has been non-existent over most of the last 100 years.
We have all heard until we are sick to death that "Arrhenius says ..." and "Basic physics says ..." but it's not happening, guys! Wake up.
IF Arrhenius was right and IF the 'basic physics" is right, it can only be in theory and not in the real world which means that something else is going on out there that we haven't sussed yet and which 40,000 sheep congregating in Paris are going to keep trying to make sure we don't suss. Because when we finally do their gravy train hits the buffers and their plans for world domination (or whatever it is the are hoping to inflict on us) fall apart.

Nov 30, 2015 at 1:13 PM | Unregistered CommenterMike Jackson

Radical Rodent

I don't know where you get your figures from.

0.89 is a good correlation coefficient for real world data.

There is more here than a correlation. Measured radiative forcing and temperature are both rising, in agreement between theoretical projection and observation. Finally, none of the other forcings are generating much energy, leaving increased CO2 as the only probable explanation.

Nov 30, 2015 at 5:42 PM | Unregistered CommenterEntropic man

Mike Jackson

"Something we haven't sussed"

You are quite free to invoke cycling leprechauns as the cause of recent warming.
However the etiquette of scientific debate requires that you provide evidence to back up your hypothesis.

Nov 30, 2015 at 5:47 PM | Unregistered CommenterEntropic man

Mike, David Evans has a theory that answers your final paragraph.

Back in the days of Arrhenius, they realised that the earth was warmer than solar heating suggested. The GHG effect was equivalent to more energy being received. In fact it was easier to think of it in this way than to try to calculate the GHG effect and subsequent feedbacks.

The important thing was the overall energy balance and the model worked well during the warming years.

To be clear, the model treated the GHG effect as though it was additional sunlight being received. The atmosphere is transparent to shortwave sunlight. It warms the surface of the earth.

The GHG effect, on the other hand, is the blocking of long wave radiation from leaving the atmosphere in its journey to space. The heat is retained in the atmosphere by the carbon dioxide.

Clearly, the two mechanisms are completely different. While the notion of energy equivalence may exist, the mechanistic differences are large. For a start, the sunlight warms the surface but the GHG warms the atmosphere. The excited CO2 shares its energy kinetically with the massively more abundant water vapour and that water vapour is free to emit photons to space as well as in other directions.

The basic model, however, only contemplates extra heating of the surface.

The basic model has got it badly wrong. Calculated correctly, the warming caused by doubling CO2 is about 10 times less. The model worked fine in the final decades of last century (when solar activity probably dominated the warming) but today the model is a failure. The mistake also explains the missing hotspot. Water vapour cools the planet rather than warm it.

The basic climate model became the basis of the GCMs. As David says, the mistake became baked in the modern climate model cake.

Nov 30, 2015 at 6:36 PM | Unregistered CommenterSchrodinger's Cat

So, our little pet troll, if CO2 is the driving force of climate change /global warming / call it what you will, then why has CO2 had so little influence over the global warming / climate change / call it what you will for most of the past 70 years?

Stop your puerile witterings about cycling leprechauns and look at the most basic facts, none of which even you could refute: since 1945, while CO2 emissions from human consumption of fossil fuels has soared; the rate of increase of CO2 in the atmosphere has not – the rate of increase is about the same as it was for the 30 years before WWII, when human consumption of fossil fuels was considerably less than afterwards, up to and including today. So, as humans have been consuming fossil fuels at such an increased rate, not only has the increase in CO2 continued its more or less linear rate, but temperatures actually had a statistically-significant fall for 30 years (enough for the alarmists to bray about an oncoming Ice Age). During the past 70 years, when humanity has been consuming fossil fuels at an unprecedented rate, here have been just 23 years when there was a statistically-significant rise in temperatures. How you can overlook such simple, irrefutable facts, and bleat on about mysterious “forcings” and expect to be taken seriously? Wake up, and admit that this is a subject that we have only recently started to study with any real intensity, and it is a subject that is truly vast – as big as a planet! – so perhaps, Mike Jackson is right, and there might be something that we have yet to discover or isolate sufficiently to recognise that is having an effect on the climate – take up the gauntlet, and prove him wrong. To tell the truth, my only hypothesis is that it is a whole plethora of actions and interactions, both within and without the planetary sphere that influences the climate; one thing might be more influential than others, but I very much doubt that it is a trace gas in the atmosphere.

By the way, if you are so convinced that the rise in CO2 is the culprit, ’cos it correlates so closely, how can you be sure it is not the rise in the US debt, a curve that fits even more closely than that of CO2?

Where do I get my figures from? Try the latest paper by What Lysenko Spawned; this article gives you a link to it.

Nov 30, 2015 at 7:14 PM | Registered CommenterRadical Rodent

Just for the sake of interest I googled measured radiative forcing. It came up with a paper by Evans and Puckrin where they use radiative flux models to get a good match with emitted radiation in the atmosphere. That's good.

The bad is that they assume the concept of radiative forcing, as in that this change in radiative flux actually produced a change in heat of a surface connected to an atmosphere, has been demonstrated. This idea only comes about through a string of assumptions dating back all the way to Arrhenius. It's a circular argument.

Essentially a temperature change is being attributed to a change in Co2 radiative properties and that's it.

Which makes this thread interesting because that change in Co2 suggests another process at work.

Also EM, CO2 can also cause heating? How does that work? Did the 80 to 100 pmmv of Co2 have any effect on getting up out of the ice ages? And if so why is the same effect not present now? Heat caused 10 ppmv to be emitted following Ferdinands argument in recent years? Did that feedback on itself?

What stops the positive feedback?

Dec 1, 2015 at 7:44 AM | Registered CommenterMicky H Corbett

Micky H Corbett

Sorry, I forgot that the best response to the white blood cells is to ignore them.

Dec 1, 2015 at 11:04 PM | Unregistered CommenterEntropic man

Micky H Corbett

Ultimately it is all about equilibria. Energy flows in as solar insolation at 400-700nm visible and out as outward longwave radiation in the infra-red.

Ignoring mechanisms for the moment, I have found the tank analogy useful.

Imagine a 1000 litre tank of water. A tap at the top lets water in and a tap at the bottom let's water out. The tap at the top is half open and the tap at the bottom is set to maintain the water level halfway up.

The taps represent insolation and OLR. The volume of water represents the energy content of the system and the head of water is temperature. Initially the system is at equilibrium. The flow through the taps is constant and so are the volume and temperature.

In increase in CO2 concentration is analogous to closing the lower tap slightly. With more water entering than leaving, the volume and head of water increase. As the head of water increases the increased pressure increases the flow through the lower tap. When the two taps have equal flow the system stabilises again, but at a higher volume and head than initially.

With constant CO2 insolation and OLR are equal; heat content and temperature remain constant. Increase CO2 and OLR reduces, while insolation stays constantThe difference accumulates as extra heat leading to a higher temperature. The higher temperature increases OLR until it overcomes the extra insulating effect and a new equilibrium is reached.

What about mechanisms? There are several, but they all have an insulating effect, slowing the rate of heat loss.

IR radiating from the surface is absorbed by greenhouse gases. Some of the energy warms the atmosphere. Some is reradiated and eventually reaches the TOA or the surface. Both the atmosphere warming and the amount of energy returning to the surface increase measurably with increasing CO2.
Thirdly, the extra CO2 increases the emitting altitude for 15micrometre IR . The emission temperature remains the same , but the increased altitude means that the lapse rate but the lapse rate allows a higher surface temperature. IIRC increased downwelling radiation is the largest effect. Together they all raise the surface temperature. This raises the surface radiation, and ultimately restores the original OLR. Equilibrium returns at a higher surface temperature.


There is no runaway positive feedback because radiation from the surface increases as the 4th power of temperature. (Stephan-Boltzmann equation) while the greenhouse effect is only logarithmic. Thus a few degrees centigrade warming produces enough extra radiation to counter a !of of extra CO2.

It took me a long while to get all this straight in my own ahead. I am not surprised that it goes straight over the heads of some people here.

Dec 2, 2015 at 12:11 AM | Unregistered CommenterEntropic man

EM

Okay, I see you've basically reiterated what people like Hansen modelled, the underlying belief that balance in total outgoing emission is only achieved through an increase in surface temperature. The problem with this macro approach is that it directly predicts a troposphere hotspot which hasn't been observed.

Also CO2 in the ice core record does not ever appear to drive anything; it reacts with a lag which suggests its effect is limited. The proxy above does the same thing. Following the logic of the attribution argument it appears that temperature caused a change in CO2 and that temperature change is of the same magnitude as the change from 1850 to now.

But lets taken this simple model of the atmosphere. First off CO2 and absorption of radiation in the first say 50 metres effectively isolates the upper layers from interacting with the surface. In fact at pressures around 1 bar, atomic physics says that the mean free path precludes long scale interaction due to radiation. So the amount of radiation emitted by CO2 is due to the temperature of the surroundings. Plus CO2 can absorb and transfer incoming IR much faster than it can emit.

The initial surface absorption saturates at ppmv levels even below 200 ppmv, so that effect has long been baked into the atmosphere. The focus of the greenhouse effect is really how does CO2 get rid of its radiation at the top. The simple model just focuses on reduction of OLR without considering the basic law of physics that it is total spectral emission that needs to be balanced at TOA.

This also means that there never will be an imbalance of energy coming from the Earth if you observe far enough away as the boundary condition is set by the Sun not by the Earth. So then it comes down to what mechanisms result in that energy being emitted elsewhere.

The Hansen and others argument is that macro scale adjustments of the entire atmospheric column are what happens. The issue with this is that it goes against the Least Energy Principle. CO2 will transfer excess energy to other atmospheric components at a local level rather than cause a mass change in the atmosphere. It only becomes energetically favourable to change on mass when the distribution of energy at local level is higher than a mass organised movement. This behaviour is observed in lots of other coupled collective systems.

So to eliminate this local effect, you need to take detailed measurement of the entire spectrum of the Earth and at sufficient resolution since the predicted AGW effect is only 4 W or so. Measuring CO2 absorption in the atmosphere at different heights will only give you spectra not the effect of what that does in an atmosphere.

Lastly if you read Hansen et al 1981 it's clear that the CO2 relationship with temperature only comes about by curve fitting and by limiting factors that could cause temperature change. Something has to cause it; it can't be a mechanism we haven't seen. In that paper they also get a 400% range for climate sensitivity fitting the same data. That alone should give you pause to think.

If the low end is taken it also means less assumptions. A climate sensitivity of 1.4 degrees/doubling of CO2 doesn't require extra heat hiding in the oceans.

I think the problem is that your arguments about CO2 are predicted on the forcing idea which itself is predicted on "it has to be this because we can't think of anything else". And to return to the point of this thread, when you make the argument as to why current emissions are mostly man-made, a change in CO2 levels before that era appear to be driven by temperature. By demonstrating the effects of volcanoes and vegetation changes in recent years through argument it also can be applied to the past.

And as forcing over the years has evolved from assuming the temperature change from 1850 onwards is due to CO2 it can look very much like a case of misattribution.

Dec 2, 2015 at 6:18 AM | Registered CommenterMicky H Corbett

Micky H Corbett

I'll try to answr without getting 403'd, so I ll have to ration the links. Sorry if this makes me sound dogmatic.

"The problem with this macro approach is that it directly predicts a troposphere hotspot which hasn't been observed."

The tropospheric hot spot has been observed.

"CO2 in the ice core record does not ever appear to drive anything; it reacts with a lag which suggests its effect is limited."

Quite right Mostly CO2 acts as an amplifying feedback for another forcing.Consider the transition into the Holocene. The temperature warmed from 9C to 14C over 10,000 years, a 5C gain. CO2 went from 200ppm to 280ppm.

Look at it from the energy viewpoint. The orbital change produced an extra 4W. The CO2 greenhouse produced another 1.8W (5.35ln(280/200)). That Is a direct increase of 5.8W. If you take a mid-range climate sensitivity of 3.0, that becomes 17.4WW when you add in the various feedbacks.

The IPCC estimate that you need 3.7W to produce warming of 1C. 17.4W produces 4.7C warming.

Incidentally, this is why I like the forcing approach. Even back-of-the-envelope calculations produce a good match between theory(4.7C) and observation (5C).

"CO2 and absorption of radiation in the first say 50 metres effectively isolates the upper layers from interacting with the surface. "

Not quite. The first 50 metres absorbs photons from the surface.It therefore has more IR energy passing back and forth than the next 50 metres, so there will be a net upward transfer (1st law). The result is a net energy gradient transferring 13-17micrometre photons upwards from surface to TOA. Think of the energy of the initial push propagating along a line of dominoes.

"The initial surface absorption saturates at ppmv levels even below 200 ppmv, "

Yes. You can see it in the OLR spectrum too. At the spot frequency of 15 micrometres the emission is 60% lower than the expected Stephan-Bolzmann emission. 10% of this is water, the rest is because 50% has been retained due to saturation of the CO2. However, this only occurs at 15micrometres. Due to band spreading CO2 in the atmosphere absorbs across a band between 13 and 17 micrometres. Across the band absorption has not saturated.

I'll put this up before it gets 403'd.

Dec 2, 2015 at 11:37 AM | Unregistered CommenterEntropic man

EM

Concerning the absorption of radiation. Experiments and physics show that isotopic emission i.e back radiation is much weaker than primary directional radiation that is attenuated. Or in other words off axis emission including that which goes back is much less than the primary beam that propagates forwards. Secondly the absorption rate and relaxation is something like 1000 times quicker than re-emission. So the IR absorbed by CO2 is passed to other molecules very quickly leaving the background passive IR from CO2 itself.

The emission of 15 micron radiation is little changed with temperature over the Earth (45 to 55 W from poles to equator according to NIMBUS) You can see that from the spectra taken over different parts of the Earth. In the tropics the re-emission window is not 50%. The emission will be what comes out once the opacity is low enough. It is not primary surface radiation. Also in the Antarctic CO2 emits more than other components in the atmosphere.

I looked at an old paper by Newman and Dopplick (1978) where they estimate 0.25 K max for a doubling in CO2.

Manabe and Strickler get 2.5 odd but only because they assume a sea surface temperature larger than is physically possible; that any increase in energy at the surface causes an increase in radiation not latent heat; and importantly it only works if water vapour feedback is assumed. Newman and Dopplick didn't model forcing. They simply take the physical conditions and worked out the best case.

The extra feedback line of thinking has continued until now. Doesn't mean it's correct. And it doesn't have any experimental backing. Vostok cores show 10 degrees change and 100ppmv. Which matches Henry's Law as well as explains why there is a lag. Again Co2 is only being touted as a possible addition to orbital effects because of the apparent rapidity of temperature change. Yet it is not a definite thing. Nor does it explain the lag. If also does not explain the excursion of Co2 from 280 in a period before 1850.

As for a tropical hotspot I'll read the paper though I see Roy Spencer covered it a few months ago using actual data as opposed to statistical analysis.

Dec 2, 2015 at 12:58 PM | Registered CommenterMicky H Corbett

Micky H Corbett

To continue.

"it is total spectral emission that needs to be balanced at TOA.

This also means that there never will be an imbalance of energy coming from the Earth if you observe far enough away as the boundary condition is set by the Sun not by the Earth. "


I would disagree. If the Earth is warming, it is accumulating heat and this will show as an imbalance.

" So to eliminate this local effect, you need to take detailed measurement of the entire spectrum of the Earth"

The Earth orbiting satellites are too close and have to sample albedo and OLR. There is one satellite observing from Lagrange 1 and another satellite at L2 is discussed. Together they would give 90% continuous coverage.

You discuss the confidence limits of Hansen et al 1981. That was the first serious attempt to analyse the warming trend. 34 years later we can do better.

"Something has to cause it [temperature change]; it can't be a mechanism we haven't seen."
" as forcing over the years has evolved from assuming the temperature change from 1850 onwards is due to CO2 it can look very much like a case of misattribution."

I agree with the first point, but not the second.

Part of the argument for CO2 as the forcing agent for recent warming is the good match between projections from theory and observation. Another part is that there is no viable alternative source for the eextra energy. The planet is gaining 3*10^22Joules/year in ways consistent with the increasing CO2 greenhouse effect and its feedbacks. The climate system is now well enough monitored that an alternative energy source of this magnitude would be detectable.

As for the "missing heat". Direct measurement of temperature from ARGO buoys and their deep ocean equivalent, plus the indirect evidence of ocean thermal expansion, have shown that the apparent gap in the energy budget is filled by the increasing ocean heat content.

"when you make the argument as to why current emissions are mostly man-made, a change in CO2 levels before that era appear to be driven by temperature. By demonstrating the effects of volcanoes and vegetation changes in recent years through argument it also can be applied to the past."

Look back into the past and, most of the time, temperature changes forced by changes in insolation and albedo drive the climate. CO2 follows temperature, acting as an amplifying feedback.

There have been occasion when CO2 has forced temperature. Snowball Earths occured when CO2 levels got too low and increasing ice albedo caused runaway cooling to global temperatures near 0C. These persisted until the gradual accumulation of CO2 from volcanoes forced warming.

There is also evidence that shield volcano's, particularly the Deccan and Siberian Traps, can drive warming by releasing large amounts of CO2. IIRC one of them was also found to have burned off coal beds which added extra CO2.

Modern vulcanism is not a major factor. Volcanic CO2 emissions are 1% of our industrial CO2 production.Vegetation changes are presently a slight negative feedback, but in the longer term decay of permafrost peats looks likely to be a large positive feedback.

The PETM also shows a big increase in CO2 of biological origin( big drop in C13) and a big jump in temperature, though the details are still obscure.

"as forcing over the years has evolved from assuming the temperature change from 1850 onwards is due to CO2 it can look very much like a case of misattribution."

Remember the limitations of scientific method. The best fit between theory and observation over the last 150 years is CO2 forcing. This is generally accepted because of the match between CO2 theory and observation and the lack of any alternative source of energy. Proof, in the mathematical sense, is impossible.

If you want to consider an alternative, it would need to be consistent with observations and the measured energy budget and have a scientifically sensible mechanism. None of the alternatives suggested by various sceptics have met these minimal requirements.

If you think that recent warming has been misattributed, I wonder what you do attribute it to. I see no viable alternative to anthropogenic CO2. None of the other past drivers of increased temperature are in operation at present. If anything, the natural drivers should be producing a cooling trend.

Dec 2, 2015 at 1:10 PM | Unregistered CommenterEntropic man

EM

You should go read up on the modelling papers from the past. You still have not explained why there is a shift of 10ppmv before the industrial revolution which is apparent in ice cores and this dC13? And what causes it?

Also you are arguing from "how do you explain if it's not this". You don't prove a negative.

Extra heat in the deep oceans is theoretical. NASA admitted it couldn't be measured. Heat accumulating in the upper ocean is an observation. That's all. It would occur purely because the ocean is heating up. You cannot say that's predominantly because of Co2.
There have not been measured and verified snowball Earth events due to vegetation. It's a theory.

When Newman and Doppick calculated the effect of additional heat in the tropics due to radiative forcing they used actual conditions and data. Manabe and Strickler hypothesised an additional feedback only because they could not think of anything else. It had to be radiative forcing.

You seem wedded to CO2 as an amplifying feedback but don't explain how this fits when there is cooling but still high levels of CO2 as in the ice core record. Does CO2 amplify cooling as well?

Also how does your belief in Co2 forcing explain the 10 ppmv deviation?

Dec 2, 2015 at 2:13 PM | Registered CommenterMicky H Corbett

And just so we aren't just using Ferdinands data here is Co2 from Law Dome which matches recent CO2 increases but clearly shows variation of 10 ppmv in the centuries before the industrial revolution.

http://cdiac.ornl.gov/trends/co2/graphics/lawdome.gif

Dec 2, 2015 at 2:21 PM | Registered CommenterMicky H Corbett

Micky H Corbett

"how does your belief in Co2 forcing explain the 10 ppmv deviation?"

Indeed there are changes. Note the bump of increased C13 around 1560 in both datasets.

That coincides with two disasters for humanity. One was the Little Ice Age and the other was plague. The world population dropped by nearly half between 1350 and 1450 and only recovered in the latter 1600s.
Half the world's agricultural land was abandoned and reverted to forest. It was also a considerable C12 sink. That is why the proportion of C13 increased.

I think you underestimate how complex this whole thing is. There are a large number of factors which, over 3 billion years, have affected CO2 and/or temperature. Often several effects may be happening at the same time.

Consider the present. Henry's law is increasing the amount of dissolved CO2 in the ocean as its partial pressure in the atmpsphere increases. At the same time increased temperature is reducing the solubility of CO2 in the ocean and driving CO2 back into the air. Dissolved CO2 becomes Carbonic acid and then bicarbonate. Depending on pH and concentrations dissolved bicarbonate can also become atmospheric CO2.

Fossil fuel burning is increasing CO2. Decomposing permafrost soils are releasing CO2.
Where conditions are suitable plants are grreening and absorbing CO2 In Brazil the forests are being cut down or dying of drought and releasing CO2. In the Arctic methane clathrates are releasing methane which decomposes into CO2. Thawing permafrost is allowing peat soils to decompose and release CO2.

Since 1850 the world has seen an industrial revolution, an increase of 40% in atmospheric CO2 and a corresponding increase in in CO2 and decrease in pH in the oceans. Once again there is no natural source measured which can account for the change.

"You don't prove a negative."

Yet this is exactly what you are claiming.. You are claiming that the warming is NOT due to CO2, in the face of considerable evidence that it is happening.

"Does CO2 amplify cooling as well?"

Yes. How else can you move into a snowball earth or a glacial period.Consider how to move out of an interglacial. As you move away from the Milankovich sweet spot the amount of northern hemisphere insolation decreases. Temperature drops below 14C and the boundary of the Arctic permafrost starts to move South. Expanding taiga and tundra take up CO2 and the imbalance reverses. Outward radiation exceeds incoming radiation. The other feedbacks such as decreasing water vapour and increasing ice albedo pull the temperature back down.Heat bleeds out of the system until you are back to 9C

Dec 2, 2015 at 6:48 PM | Unregistered CommenterEntropic man

How else can you move into a snowball earth or a glacial period.

Asteroid strike?

Chaotic dynamics of ocean flows requiring no external stimulus ?

Nuclear winter?

Dec 2, 2015 at 8:11 PM | Unregistered CommenterMartin A

EM

"That coincides with two disasters for humanity. One was the Little Ice Age and the other was plague. The world population dropped by nearly half between 1350 and 1450 and only recovered in the latter 1600s.
Half the world's agricultural land was abandoned and reverted to forest. It was also a considerable C12 sink. That is why the proportion of C13 increased."

That is called a stretch my friend. First off what caused the Little Ice Age? The second was that by current understanding mankind's impact on CO2 is only noticeable after 1850. So there may have been a change in agriculture but we weren't producing enough CO2 to make a dent.

By stating that you believe in a Little Ice Age you are saying that Nature can produce temperature changes without CO2 forcing. But yet you don't think Nature can do the same thing now?

So basically you have contradicted yourself.

Dec 2, 2015 at 8:42 PM | Registered CommenterMicky H Corbett

Micky H Corbett

Best candidate for the onset of the Little Ice Age is a pulse of vulcanism in the 13th century .The LIA started before the Maunder Minimum but the MM may have extended he LIA.

"you are saying that Nature can produce temperature changes without CO2 forcing. But yet you don't think Nature can do the same thing now? So basically you have contradicted yourself."

There is a little thing called evidence. All the non-CO2 effects I mentioned left traces in sediments, peat bogs or ice cores. At present there is no evidence of any other process driving temperature change on the scale of AGW.

If a non-CO2 process were increasing temperatures by 1C in 135 years, we would see its signature.

Vulcanism is above average, the Sun is moving towards another Grand Minimum, albedo is increasing. We are moving off the Milankovixh sweet spot. None of the natural processes we have discussed are generating warming.

To be concise. There are a number of processes which have caused climate to change, in addition to CO2. They all leave evidence.

At present there is evidence that increased CO2 and its feedbacks are causing warming. There is no evidence that any other process is causing warming.

If you know of a natural process which is raising temperature at the present rate, provide convincing evidence and collect your Nobel Prize. If you cannot produce evidence you will be ignored.

Dec 3, 2015 at 12:02 AM | Unregistered CommenterEntropic man

Martin A

Good you are thinking. Perhaps you may help Micky H Corbett that CO2 is not the only agent forcing climate.

Note though, that all the events you mentioned leave traces in the record.and would be detectable if they were happening today.

Dec 3, 2015 at 12:09 AM | Unregistered CommenterEntropic man

He's on form today.

Dec 3, 2015 at 3:36 AM | Unregistered Commentermichael hart

EM

Sadly you didnt follow the original argument. To get a sustained change of CO2 you need to have a period of strong volcanic emissions followed by a period of little. And by sustained we are talking about decades.

The reason? Maths. You say there was a pulse of volcanism. One large volcano doesn't affect CO2 levels in a significant way nor does it produce the huge aerosol cooling that people are fond of. We see that today don't we?

And also the exponential residence time means that the CO2 levels variation can be discounted. That is the implication of Ferdinand's argument

Plus you have ignored your use of the Little Ice Age. You believe in a cooling period but with no mechanism.

So there was a non CO2 process that you invoke but that didn't have a signature.

Again you need to explain your use of a Little Ice age temperature variation. It can't be explained by Co2 forcing.

Dec 3, 2015 at 7:48 AM | Registered CommenterMicky H Corbett

To add, I looke into Gifford Millers work about volcanoes causing the Little Ice Age. The evidence is changes in vegetation and what appears to be a rapid change in climate in some places. He relates it to 4 major volcanoes, though still not as powerful as Pinatubo, and then uses a model to try and prolong their effect over decades.

So the same way we saw the effect of volcanoes today causing prolonged cooling? Oh wait they don't.

A model is not evidence EM

Dec 3, 2015 at 8:15 AM | Registered CommenterMicky H Corbett

Re the Little Ice Age.

What about the Solar cycle correlation with global temperature ?

Dec 3, 2015 at 10:42 AM | Unregistered CommenterRoss Lea

Micky H Corbett

Let's turn this around.

You have spent most of this thread challenging me to explain the last 1000 years of temperature change and then rejecting everything I put forward.

Time for you to put forward your own temperature record and your explanations for its variations.

Dec 3, 2015 at 11:06 AM | Unregistered CommenterEntropic man

Ross lea

"What about the Solar cycle correlation with global temperature ?"

Show me.

Dec 3, 2015 at 11:14 AM | Unregistered CommenterEntropic man