Scottish Sceptic

In this article I explain why the evidence shows we are unlikely to get runaway global warming in the present inter-glacial period and propose a simple mechanism.

Recap

So far I have proposed a timing mechanism explaining the long period of the ice-age cycle, a means by which CO2 (or other gases) could be released during this cycle due to expansion and contraction of the earth’s crust and then I have look at feedbacks and climate stability explaining that for the climate to go through cycles there must be positive feedback present.

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See also:

1. Introduction
2. Criteria for Cycles
3. Global warming and earthquakes
4. Thermal crust expansion, decomposition and the Carbon cycle
5. Overview of feedbacks
6. Climate stability

Hitting the buffers

To go back to figures 2.3 & 2.4 (see Criteria for Cycles) we saw that in a typical astable oscillator, the system can have very high levels of feedback such that theoretically it would continue to increase without limit, but that in a practical circuit, the signal is normally limited by the power supply voltages. Continue reading →

The last article discussed negative and positive feedbacks in the climate. Now I want to see how these impact the stability of the climate and also how the stability of the climate can tell us what kinds of feedback are present.

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See also:

1. Introduction
2. Criteria for Cycles
3. Global warming and earthquakes
4. Thermal crust expansion, decomposition and the Carbon cycle
5. Overview of feedbacks

Climate stability

I introduced the idea in the overview of feedbacks that negative feedbacks are rather like a driver on a road constantly correcting any small veer to one side or the other. I then suggested that positive feedbacks produce the kind of effect that would occur if an ordinary driver got into a car where the steering wheel acted in reverse. So that as they turn to the right to correct a drift to the left, rather than the car going right as intended, the car goes further and further to the left. As a result almost all normal drivers getting into such a car will go off the road and so would a climate with large positive feedbacks.
In general climates with positive feedback tend to be unstable and the higher the feedback the more unstable they become. Continue reading →

Although feedbacks and the resultant climate sensitivity are widely discussed, it is done so with reference to CO2 and warming. During the ice-age cycles feedbacks act when the temperatures are both cooling and warming. This will be obvious to many but as even sites like the UK Met Office focus almost exclusively on the effects of increasing CO2 and ignore feedbacks during cooling, to ensure everyone understands the concept of feedbacks relating to a complete ice-age cycle irrespective of whether CO2 is driving it, I will quickly cover the topic. Note, I’m not trying to introduce anything new or novel here.

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See also:

1. Introduction
2. Criteria for Cycles
3. Global warming and earthquakes
4. Thermal crust expansion, decomposition and the Carbon cycle

What are feedbacks?

I briefly introduced the theory of feedback in relation to a circuit in the article on cycles (see fig 2.1) but how do they manifest themselves in the real world?
All life is subject to feedbacks. When driving the car, if we are tending to veer to the right, we turn the wheel slightly to the left to bring us back  along our intended route. In such a way, even though the car will be constantly subject to various forces such as wind, camber, etc. which constantly tend to push it away from the intended direction we then act in the opposite direction to bring it back to our intended route. Moreover, the bigger the deviation, the large we turn the wheel.
This is a form of negative feedback. And as shown below in a schematic for climate temperature if the climate is subject to negative feedback, any change that tends to warm the climate is reduced is scale so that it does not warm as much as it would without these feedbacks. But also any change that tends to cool the climate is also reduced in magnitude. So negative feedbacks tend to reduce the impact of any change.

So negative feedbacks tend to make the climate stable. Or to turn that around a climate that hasn’t changed much for 100s of millions of years despite all the various changes that occur from meteorites to changes in the sun, such as ours, most have large negative feedbacks that tend to keep it as it is.

Positive Feedback

Continue reading →

In the last article I showed how the temperature change between Glacial and interglacial was sufficient to cause up to 2.3km of crust to be forced down into the earth’s core. In this article I examine how this could affect climate.

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See also:

1. Introduction
2. Criteria for Cycles
3. Global warming and earthquakes

CO2 production from Cement making

A windmill takes energy from the wind and in so doing it opposes its motion. To enable that, each windmills has several hundred tonnes of concrete make from cement which is in turn produced by heating limestone rock.

The breakdown of calcium carbonate from heat is called thermal decomposition and the equations for this thermal decomposition of calcium carbonate are:

calcium carbonate calcium oxide + carbon dioxide

CaCO₃ CaO + CO₂

This decomposition will occur at depths of around 100km or greater. So, although no ice-age cycle will be sufficient on its own to push crust down this far, the successive expansion and contraction will ratchet the rocket downward so that the rock moves another 2.3km downward toward the point where it decomposes.
Similar processes will occur for most carbon containing rocks so that overall  up to 2.3km of the 40,000 km of crust will be pushed down.
Carbon is found throughout the earth but particularly in Marine sediments and rocks as shown by the following table.
 
Continue reading →

We saw in the previous introductory article that the ice-ages appear to come and go about every 120,000 years. Their shape suggests a fast rise in temperature followed by a slow decline which is indicative of some kind of cyclic behaviour to the climate. This can occur for two reasons:

1. Because there is some form of driver whose effect is cyclic. Obvious ones are the yearly cycle of the earth around the sun which obviously forces the climate to follow a similar yearly cycle on top of any other changes
2. Because the climate is inherently unstable.

As no appropriate external cycle with a period of around 120,000 years capable of driving the climate has been found the first can be ruled out. Therefore is it likely the climate is in some way unstable. So what makes a system oscillate and imposes this kind of cyclic behaviour? The answer comes in terms of the criteria for a system to oscillate in this manner.
Continue reading →

This was a quick outline of a theory I’ve been developing since the summer on the cause and progression of ice-ages. As I started describing the theory and the background, it mushroomed and spawned into several articles and then  … I hit a snag.
Crucial to my theory was that temperature was controlled by CO2 (but not in the normal way). I knew CO2 lagged temperature, but I kept going hoping I could explain this. Then it all came unstuck, not on the CO2 lag, but when I realised that there were very significant falls in temperature occurring around 16,000 years after the peak of each inter-glacial. (See I’m a CO2 denier) and CO2 did not fall in the same way. So, CO2 could not possibly be causing this cooling, so, CO2 clearly did not directly cause the ice-ages.
(Note in my defence: this presumed CO2 induced positive feedback during the ice-ages is one of the main reasons for believing in positive feedbacks in today’s climate. So, it never occurred to me that it would be so obviously flawed).
I’ve now been thinking about this since Xmas and not really making much progress. So, I have decided to start publishing my articles, knowing the conclusion is wrong, but hoping that the discussions might suggest a way forward to me, or that at worst, they prove useful to others.

Current state of Knowledge

In 1742 Pierre Martel, an engineer and geographer saw erratic boulders in the valley of Chamonix in the Alps and the locals said these erratic boulders were from when the glaciers extended much farther. From that first step, the idea gradually developed that much of the North of Britain, Europe, Asia and America were once under huge ice sheets and that these ice-sheets had fundamentally moulded the character of northern places like Scotland. Today we now accept that U shaped valley, with wide bottoms, steep sides and broken rocky tops that are characteristic of Scotland are a consequence of the Ice-age. However, a few centuries on there is still no real understanding of what causes ice ages. Continue reading →