Something has recently appeared to me that I guess was in plain sight all along but yet was buried in an argument about CO2 attribution.

But due to the rigour of Ferdinand Engelbeen's arguments about CO2 growth he actually demonstrates an interesting fact. And the fact appears to show that CO2 has little effect on climate.

Now I know this is a bold claim and there a certain number of assumptions in this but humour me as I can demonstrate it and to boot, can use the very same graphs that are often used to blame humans for climate change

So briefly: Ferdinand had the patience of a saint but sometimes even Francis of Assisi decided to smack down a few foxes. Do to this Ferdinand published a post on WUWT called "About spurious correlations and causation of the CO2 increase…"

He basically demonstrates a few things about CO2, including the different processes that lead to a change in CO2 growth (or recession) rate. Recently it appears that the half-life for CO2 has been independently confirmed within a range of 8 to 9 years (I haven't seen the guts of this paper but it does appear to match other observations and basic theory). This puts the residence time at around 40 to 45 years - as in the time it takes to remove a pulse of CO2 to within 0.1%.

The process follows an exponential curve which implies that if you keep emissions constant the level of Co2 in the atmosphere saturates. This is important as if you assume volcanic activity can be said to be constant over decades, and that recent estimates still have this activity only contributing around 600 Mt per year, this residence time means that CO2 from volcanic emissions saturated a long time ago.

Variation in this level should be very small.

Now I know that people who follow Murray Salby don't like the idea that volcanoes and other natural processes don't really contribute to increasing emissions so that's why Ferdinand's CO2 rate equation is good. It is:

dCO2/dt = k2*(k*(T-T0) – ΔpCO2)

The rate of CO2 change over time is proportional to Henry's Law (first part) and partial pressure balancing. k is 16 ppmv but from ice cores k2 is approximately 10/16 - so 1 degree of temperature change can be related to a change of 10 ppmv

So if you read Ferdinand's post he basically describes how if you pump large amounts of CO2 into the atmosphere the second part of the equation tends to dominate. This results in just over half of the CO2 staying in the atmosphere mostly due to the ocean uptake. Vegetation plays a part but the ocean is dominant.

If you aren't pumping large amounts in the atmosphere, like before the industrial revolution, CO2 change is natural and should only be around 5 to 10 ppmv.

Now, I hope you are starting to see the obvious implications of this.

Here is a graph of dC13 which is often used to show that the variation in this isotope of C is proof that really old carbon is being introduced a greater rates than nature into the atmosphere. Or in English, that humans burning fossil fuels are the cause.

dC13 levels from sponges

Assuming that this proxy is picking up variations in CO2 without other factors at play (maybe a large assumption but one that those of the warmer persuasion like to make), we can see that indeed the drop off in 1/ppmv values matches the growth in industrial activity. So the last 150 years of so has resulting in us putting 120 ppmv into the atmosphere, more or less (280 to 400)

If I was rounding down I'd say 100.

Now look at the sponges graph again. Do you see how the CO2 levels vary in the past before humans were dumping more and more CO2 into the atmosphere. It varies between 0.00362 to 0.0035 (conservatively - it could be more).
That corresponds to a variation between 275 and 285 ppmv.

We have shown that if you assume the residence time of CO2 is correct (40 to 45 years) then natural processes that should be occurring regularly cannot produce such a variation of CO2, especially over decades. It would take prolonged volcanic activity then prolonged lack of activity to produce such a variation.

So we can say that within maybe 10% uncertainty that change in CO2 is related to temperature - specifically about 1 degree of change.

From 1850 to now we have been told by the Met Office and the like that we have witnessed 1 degree of change in temperature as well.

Before the Industrial Revolution - 1 degree of change as measured by change in CO2

After the Industrial Revolution - 1 degree of change as measured by thermometers and the like (note I'm not even talking about adjustments and how that value may be smaller).

So the SAME magnitude of change in temperature....BUT...and ORDER OF MAGNITUDE change in CO2.

10 ppmv versus 100 pmv (rounded down of course - it's larger than this)

Before the industrial revolution, natural processes produced this change in temperature if you believe the proxies. After the industrial revolution there is a similar change which under the laws of physics, yes even the basic ones, should also be due to Nature (as Nature doesn't just switch off) and yet we have added over 10 times more CO2 into the atmosphere.

The same temperature change occurs irrespective of levels of CO2.

And all there in the evidence that is used to attribute CO2 increase to humans. Also used to warn us of the cost of increasing such levels and how it will effect temperature.

So Rhoda and Dung, there's your evidence. If of course you assume that this proxy is relatively correct and that the current temperature record hasn't been adjusted to seem larger than it is.

EM

It's not that the 10ppmv causes anything, simply that following the logic and observations about Co2 residence time as well as using Henry's Law, this change in the record occurs because of a temperature change. If we use the dC13 to talk about human influence on CO2 we must also admit that before human influence it shows natural influence.

That natural influence appears to show a 1 degree change. How can you tell if the current 1 degree change is not all natural? The CO2 levels simply are there because we burned fuel. The recent change in temperature can be explained as natural as it exists prior to the industrial revolution. If you use the dC13 as a proxy for CO2 attribution.

It hinges on this as I pointed out.

EM

So many misconceptions? The only one is that the proxy gets worse as the age increases. That would mean temperatures didn't vary as much. If you take the proxy as is and are using it to show that dC13 levels change now then it also shows they varied centuries ago.

As I said and you can take it from the graph between 1350 and 1850, Co2 levels vary by 10ppmv, which using the ice core comparison is 1 degree. It's that simple.

If you believe that the dC13 in sponges are a good estimate of changes in CO2 in the atmosphere over the time period, you can see how since the industrial revolution there has been a dramatic increase in CO2. But before this period you can also see what is natural.

Because of saturation effects of natural emissions, again explained using the residence time of CO2 (namely 40 years rather than centuries), variation in CO2 should mostly come from temperature variations.

We see the same temperature variation from 1850 to now as can be seen in the time period of 1350 to 1850, if of course you use the CO2 as a temperature proxy.

So how do you remove natural variation from 1850 to now if the temperatures changes appear similar? How do you resolve the effects of more CO2?

That's the thing that is most interesting. If you accept that recent CO2 rise has to caused by humans then the same principles also mean that variations of CO2 in the past are mainly caused by temperature, which varied by itself and due to other processes that we don't know.

Martin

The first term is release by temperature. The second is decay to equilibrium from having a pressure difference. Because we have the extremes in CO2 change the idea is that the large majority of today's emissions can be mapped as being driven by the second term. The pressure difference is driven manually so to speak.

My point is if we follow that logic and it does appear to match changes in atmospheric concentration, the very same data implies that before large scale emissions nature demonstrated changes. But because the conditions for today's emissions require things like volcanic and vegetation to have limited effect, changes in CO2 before the industrial revolution should be mostly driven by temperature. The same limited effect would exist back then.

And if you use the same proxies it implies a natural 1 degree change.

Dung

I believe that the vegetation argument is that yes more green stuff grows and hence the cycled CO2 fraction goes up to match. But the rate at which it grows is nowhere as fast as the rate at which we see emissions grow.

So if we get more green stuff that will use a certain amount of CO2 and then the plants should continue to cycle this every year. It's only by changing the amount of vegetation that you change the amount it cycles. The residence time bit I believe is more related to how the excess pressure of Co2 finds equilibrium.

The argument I've seen before is that currently Nature cycles great amounts of CO2 but the values don't change as long as the plants are there. Euan Mearns also had a great post on this. It's also why plants are often not included in the attribution argument and also because of their dC13 signature.

But yes there may be holes in the whole thing. My point is that if you follow the logic of the attribution argument it appears that before human influence CO2 changes were natural and mostly driven by temperature as nothing stipulated by the attribution argument can result in such a ppmv change apart from out gassing.

EM

First off, I didn't say that the temperature change before 1850 was due to 10 ppmv change, simply that over the long term as can seen in some of the proxies I linked to (not all mind) there appears to be a change in temperature.

The global change per year is already accounted for in Engelbeen's calculations and post. A long term pre industrial revolution change in CO2 can be attributed mostly to Henry's Law even with annual variations. That after all is what climate versus weather arguments are. The same temperature argument is also used to lessen the increased emissions after 1850 due to temperature. That is the point of what I'm saying. If you use this argument for recent years you need to appreciate it works both ways.

And as for anthropogenic CO2 driven temperature increase, yes it may be there but the problem is that it is indiscernible from natural, if the previous change was there. And considering that 120 ppmv more CO2 doesn't produce significant change, it would suggest the CO2 heating effect was not the main driver of temperature change.

It is a rehash of the old argument about proxies. The difference is that the dC13 isn't measuring temperature but CO2 content. It's because Ferdinand's argument when worked through implies that if large quantities of CO2 are not being emitted temperature change drives long term change. That's why it's not immediately obvious.

EM

Long term as in for that specific sponges record, not in terms of overall record. I'm just talking about that as the very same proxy (comparison of shallow depth to deeper sponges) that is used for the attribution.

As for dC13 levels look at his comment near the start to Leo.

Ferdinand is basically saying that the change in dC13 is mostly from the oceans due to the levels involved. He goes into some detail about it and shows the proxy curve above. That's the reason why it's interesting because it implies a temperature change in the sponge record that matches the ice core CO2 data (plotted and scaled in the same graph I linked to)

Now like I said if Ferdinand's arguments are actually all just bollocks then so be it. If not, it's interesting.

Michael hart

I agree about the resolution in the proxies as I've stated above. My argument is simply a process of elimination once you accept the basic tenets of Ferdinand's argument. The way he accounts for various processes and CO2 variation leads to the question about what caused the variation in CO2 around 1500 to 1800.

The larger picture is if the dC13 levels are imprecise then attributing CO2 rises in modern times to humans has less weight and the implication is that Nature emits a lot more than we think. This lessens AGW too.

If however the dC13 is actually relatively correct then the ocean appears to be the cause of the variation back before humans emitted significant quantities. The prime driver of that in this scenario is temperature.

My argument is a simple scientific one: if you follow the logic and assumptions that lead to Co2 in recent years being due to man, the process of getting to this leads to the conclusion that when man was not emitting, temperature caused the CO2 release. Remember it only makes sense if you follow the assumptions as science arguments have anyway. Ferdinand has been at pains to dot the t's so to speak even with the difference in dC13 variation due to vegetation and ocean release.

I think a lot of people are focussing on his attribution argument in recent times. I just noticed the implication for what happened a few centuries before and that it was worth pointing out.