CO2 Residence Time (Soloman vs Segalstad)

[itsthesunstupid]

Sept 26, 2009 17:37:00 GMT glc said:

GLC,

So what you are saying is that you don't deny the LIA but that the historical documentation that supports its existence is less reliable than AGW models that can't reproduce past temperatures. Can't keep arguing with you based on that logic.

I haven't mentioned models. CO2 is a greenhouse gas. It absorbs IR radiation. It's likely that at least some of the warming over the past 30-odd years is due to it's increased presence in the atmosphere. By using well established phyical laws and equations, the absorption/transmission of radiation through the atmosphere can be calculated.

Meanwhile you (and others) seem to be relying on some vague period in history when some years may have been colder than other years. You presented the Thames freezing events as evidence (the only evidence) of the the existence of the LIA. I have shown that the Thames has frozen over in many years including years during the MWP. The last year the Thames froze was in 1963.

Do you have anything else to add on the LIA. I'm still waiting for someone (anyone) to define the period of the LIA. I'm happy to accept that some years in 18th and 19th centuries were cold but they quite often coincide with significant volcanic eruptions. There does not appear to be a strong correlation with solar activity. The Dalton Minimum was a minimum in terms of sunspot averages, but the climate does not appear to have been appreciably colder than the periods immediately before or after the Dalton period. This can be seen from long term temperature records.

Quite useless to go back in forth with opinon dynamics. For the sake of other interested posters let them go to realclimate.com to get your perspective and a source such as Wikipedia to get mine.

You may not have mentioned CO2 but neither did I mention solar influence. We both assumed those points however.

As people who read all of the boards on this site know, there are myriad influencers of climate - many of which our understanding has barely scratched the surface.

Having said all that, I still contend that to deny the LIA as it is historically understood to have evidenced itself, is simply a convenient way of dealing with major holes in AGW theory. Regardless of what caused the LIA or the MWP, their significance is that the observed climate changes were as or more variable (at least on a regional basis) than the warming of the late 20th century even without regard to exascerbated UHIE in modern societies.

Want "evidence"? You can browse and search on Wiki as easily as I can copy and paste. Be inquisitive, it won't be hard to find many, many studies and stories about both LIA and MWP. That information is infinitely more verifiable than CO2 modeling projections (which can't even replicate past climate).

[icefisher]

Sept 26, 2009 17:37:00 GMT glc said:

Do you have anything else to add on the LIA. I'm still waiting for someone (anyone) to define the period of the LIA. I'm happy to accept that some years in 18th and 19th centuries were cold but they quite often coincide with significant volcanic eruptions. There does not appear to be a strong correlation with solar activity. The Dalton Minimum was a minimum in terms of sunspot averages, but the climate does not appear to have been appreciably colder than the periods immediately before or after the Dalton period. This can be seen from long term temperature records.

Itsthesunstupid.

Eyeballing it. . . .Looks to me like a 1,200 year cycle; 300 flat, 300 decline, 300 flat, 300 rise of course with a lot of noise.

Is so we could be in store for 300 years of nice temperatures with a major cooling trend starting in 2300.

[socold]

Sept 26, 2009 13:19:01 GMT nautonnier said:

What you said in your initial post was that a CO₂ molecule had a life of 5 years in the atmosphere.

What you are NOW saying is

I am still saying a co2 molecule has a lifetime of about 5 years in the atmosphere.

[william]

Icefisher,

The is more than one mechanism by which solar magnetic cycle changes modulate planetary clouds.

Solar wind bursts remove cloud forming ions via the process electroscavenging. Due to electroscavenging, GCR and C14 production can be high, the planet can be warm, if there are solar wind bursts.

For the last couple of years the solar magnetic cycle has slowed down, which has resulted in an increase in GCR of 18% however during the same period solar wind bursts increased 3 times from previous solar magnetic cycle minimums. The solar wind burst removed cloud forming ions which makes it appear an increase in GCR does not cool the planet. Now the solar wind bursts have stopped and GCR is high, there will be two solar mechanisms working to cool the planet.

Based on the mechanism (see Brian Tinsley and Yu's paper for details) the planet there will be increased cloud cover particularly over the oceans which are ion poor due the higher GCR. The increased clouds is strongest at higher latitudes. The reduction in the high speed solar wind burst will cause an increase in cloud formation at both high and low latitudes.

GCR also inhibits the formation of high altitude clouds, with a result of very cold night temperatures.

See this paper for an explanation of the mechanisms.

www.utdallas.edu/physics/pdf/Atmos_060302.pdf

It has been known for some time that there is cyclic warming and cooling that correlates with solar magnetic cycle changes. What has not known however has how the solar magnetic cycle changes cause the planet to warm and cool.

www.essc.psu.edu/essc_web/seminars/spring2006/Mar1/Bond%20et%20al%202001.pdf

“A solar influence on climate of the magnitude and consistency implied by our evidence could not have been confined to the North Atlantic. Indeed, pervious studies have tied increases in the C14 in tree rings, and hence reduced solar irradiance, to Holocene glacial advances in Scandinavia, expansions of the Holocene Polar Atmosphere circulation in Greenland; and abrupt cooling in the Netherlands about 2700 years ago…Well dated, high resolution measurements of O18 in stalagmite from Oman document five periods of reduced rainfall centered at times of strong solar minima at 6300, 7400, 8300, 9000, and 9500 years ago.”

The geomagnetic parameter Ak is a measurement of the solar wind bursts. The 20th century warming and cooling (the observed temperature change graph) correlates with the Ak.)


sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

Once again about global warming and solar activity K. Georgieva, C. Bianchi, and B. Kirov

We show that the index commonly used for quantifying long-term changes in solar activity, the sunspot number, accounts for only one part of solar activity and using this index leads to the underestimation of the role of solar activity in the global warming in the recent decades. A more suitable index is the geomagnetic activity which reflects all solar activity, and it is highly correlated to global temperature variations in the whole period for which we have data.

In Figure 6 the long-term variations in global temperature are compared to the long-term variations in geomagnetic activity as expressed by the ak-index (Nevanlinna and Kataja 2003). The correlation between the two quantities is 0.85 with p<0.01 for the whole period studied.It could therefore be concluded that both the decreasing correlation between sunspot number and geomagnetic activity, and the deviation of the global temperature long-term trend from solar activity as expressed by sunspot index are due to the increased number of high-speed streams of solar wind on the declining phase and in the minimum of sunspot cycle in the last decades.

www.utdallas.edu/physics/pdf/Atmos_060302.pdf

[glc]

I'm interested in this statement by William

It has been known for some time that there is cyclic warming and cooling that correlates with solar magnetic cycle changes

What exactly has been known for some time and could you demonstrate the correlation.

[william]

The is correlation of C14 and BE10 isotope changes with the abrupt climate changes. The forcing mechanism is indirectly the sun.

What is happening is the solar magnetic cycle is interrupted. The interruption itself causes the planet to cool.

Now comes the complication. When the solar cycle restarts massive and repetitive coronal mass ejections are created. The CME generate a space charge in the ionosphere which in turn creates a charge difference from ionosphere to the surface of the planet.

That charge difference is equalized by a very large charge flow from the ionosphere to the surface of the planet. Depending on the tilt of the planet at the time of the strike and the timing of perihelion control which hemisphere the strikes occur in. As the core portion of the geomagnetic field response slowly to changes (period of around 1000 years.), it at first resists a change by creating a local geomagnetic anomaly similar to the Southern Atlantic magnetic anomaly. Now over time depending on the current orientation of the geomagnetic field and the hemisphere where the strike occurred the geomagnetic field is either strenghtened or weakened.

When the geomagnetic field is weakend the GCR effect moves down to lower latitudes and the planet is colder. The ice sheets are an insulator so when the planet is covered with ice sheets the strike moves down to lower latitudes which weakens its effect.

Thinking about the above described mechanism, read through the next papers.



cio.eldoc.ub.rug.nl/FILES/root/2000/QuatIntRenssen/2000QuatIntRenssen.pdf

Reduced solar activity as a trigger for the start of the Younger Dryas?

For climate fluctuations during the Holocene the role of solar variability as an important forcing factor becomes more accepted. Furthermore, two physical mechanisms were recently published that explain how relatively small changes in solar irradiance could have had a strong impact on the climate system. We discuss the possibility that an abrupt reduction in solar irradiance triggered the start of the Younger Dryas and we argue that this is indeed supported by three observations: (1) the abrupt and strong increase in residual 14C at the start of the Younger Dryas that seems to be too sharp to be caused by ocean circulation changes alone, (2) the Younger Dryas being part of an & 2500 year quasi-cycle * also found in the 14C record* that is supposedly of solar origin, (3) the registration of the Younger Dryas in geological records in the tropics and the mid-latitudes of the Southern Hemisphere. Moreover, the proposed two physical mechanisms could possibly explain how the North Atlantic thermohaline circulation was perturbed through an increase in precipitation together with iceberg in fluxes.

sciences.blogs.liberation.fr/home/files/Courtillot07EPSL.pdf

Are there connections between the Earth's magnetic field and climate?

Understanding climate change is an active topic of research. Much of the observed increase in global surface temperature over the past 150 years occurred prior to the 1940s and after the 1980s. The main causes invoked are solar variability, changes in atmospheric greenhouse gas content or sulfur due to natural or anthropogenic action, or internal variability of the coupled ocean–atmosphere system. Magnetism has seldom been invoked, and evidence for connections between climate and magnetic field variations have received little attention. We review evidence for correlations which could suggest such (causal or non-causal) connections at various time scales (recent secular variation approx. 10–100 yr, historical and archeomagnetic change approx. 100–5000 yr, and excursions and reversals 10^3–10^6 yr), and attempt to suggest mechanisms.

Based on newly acquired archeo-intensity data from archeological and historically dated material recovered from western Europe and the Middle-East, Genevey and Gallet [55] and Gallet et al. [56] observed rather sharp maxima in time variations of the intensity of the ancient field, associated with sharp curvature changes in direction. These features, which are stronger and faster than previously realized [57,58,53] have been called “archeomagnetic jerks” (Fig. 4). The name may be a bit misleading, as these are rapid, approx. 100-yr long increases in field intensity by 15–30%.

[glc]

Re: CO2 Residence Time (the title of this thread)

This seems to have gone quiet, so I assume everyone is clear on the issue. I stayed out of the argument until things quietened down a bit but I'd just like to add my 'tuppence' worth now.

Socold is right.

The average RT of a CO2 molecule in the atmosphere is not the same as the time taken to reach the CO2 equilibrium level if the production of fossil CO2 were stopped. Socold did an admirable job of trying to explain the issue but it's not easy and this is one of the reasons I stood on the sidelines. But if anyone's still interested I can give it a go.

PS to William. Ok, so we need to consider geomagnetic activity and ¹⁰Be and ¹⁴C observations. anything else we should look for, e.g. ak index or similar.

[icefisher]

Sept 27, 2009 13:16:44 GMT glc said:

But if anyone's still interested I can give it a go.

You betcha if you have calculations. If all you have is theory then forget it.

[glc]

You betcha if you have calculations. If all you have is theory then forget it.

There are calculations but it's really the concept that needs to be understood. Think about the pre-industrial period of 'CO2 equilibrium'. At that time CO2 concentrations were ~300ppm (I'm using simple numbers to illustrate a point - don't quote them). A concentration of 300ppm very roughly equates to ~600 GtC. If the carbon cycle meant that 120 GtC were being released annually from the oceans and biosphere then to maintain the 300ppm equilibrium 120GtC would need to be re-absorbed. So we have this cycle where 120GtC is released into the atmosphere and 120 GtC is absorbed by the various sinks. It should be obvious, in this case, that the average lifetime of the CO2 molecule is 5 years.

What happens when we add more CO2 by burning fossil fuels?

If the natural carbon cycle keeps recycling 120GtC per year then the additional CO2 should accumulate in the atmosphere. But it doesn't - not all of it, anyway. There is an increase in the atmosphere but not as much as might be expected. This means there is increased absorption - an 'extra' sink as it were. What's more this 'extra' sink appears to take up more carbon as the fossil fuel CO2 increases. In other words

The amount absorbed by the sink is a function of the total fossil fuel CO2 (C).

What happens if we stop all fossil fuel CO2 production. Two things happen: (1) The 'natural' carbon cycle will continue. (2) The extra sink will continue to absorb CO2 until we get back to the 300ppm level.

This is where the Maths comes in. As the sink is a function of the CO2 excess, the amount absorbed will reduce over time, i.e. it's a decaying function which can be represented by the following first order differential equation

dC/dt = -kC which has the solution C = C₀e^-kt

where C₀ is the intitial value of C and k is the rate of decay. We now need to decide on these values.

Currently there are ~750GtC in the atmosphere which means we have ~150GtC more than in the pre-industrial era, so C₀=150. What about k (the rate of decay)? A reasonable current estimate which also gives a nice easy number (this is for illustration purposes remember) is 3 GtC per year. The decay rate is, therefore, 3/150 = 0.02. If we plug these values into the above equation we get

C = 150 x e^-0.02t

If we want to find out how long it will be before C is half it's initial value (i.e. 75) then the equation becomes

75 = 150 x e^-0.02t or 0.5 = e^-0.02t

i.e. ln(0.5) = -0.02t therefore t =~35 years.

From which we can conclude that it will be about 35 years until the CO2 concentration is reduced to 675 GtC. But the important thing to note is that more than 120 GtC (123 GtC at peak) of carbon are being recycled which means that, even with the peak 750 GtC in the atmosphere, the average residence time of a CO2 molecule is still only ~6 years. This shows that the average residence time and the time taken to return to equilibrium are not (closely) related.

The numbers used in the above illustration were chosen for simplicity's sake but, as far as I'm aware, they are not a million miles away from the true values.

[magellan]

Note that glc does not give references for his "maths", nor does he give observational evidence supporting his self-created hypothesis.

Strange though, I didn't see John Finn setting Spencer straight over at WUWT ;D

wattsupwiththat.com/2009/09/26/the-2007-2008-global-cooling-event-evidence-for-clouds-as-the-cause/

P.S. glc's magical 35 year number goes back to the "committed" or heat "in the pipeline" (which doesn't exist) argument ala Hansen et al......

[glc]

Note that glc does not give references for his "maths", nor does he give observational evidence supporting his self-created hypothesis

Oh please. The "maths" is a standard differential equation for modelling the rate of decay. The numbers I used were observational evidence. I can't swear they're 100% accurate (e.g. the ppm <-> GtC conversion could be a bit out) but they're not far off. The point (which you've obviously missed) is that the molecule residence time is dictated by the 'natural' cycle and this has very little to with the reduction in the 'excess' CO2.

[magellan]

Sept 28, 2009 1:12:06 GMT glc said:

Note that glc does not give references for his "maths", nor does he give observational evidence supporting his self-created hypothesis

Oh please. The "maths" is a standard differential equation for modelling the rate of decay. The numbers I used were observational evidence. I can't swear they're 100% accurate (e.g. the ppm <-> GtC conversion could be a bit out) but they're not far off. The point (which you've obviously missed) is that the molecule residence time is dictated by the 'natural' cycle and this has very little to with the reduction in the 'excess' CO2.

Oh, so this isn't based on your own work? You know glc, anyone can give a lecture paraphrased (plagurized?) from unreferenced sources. Please, you are not impressing anyone....

Cite your sources.

[icefisher]

Sept 28, 2009 0:30:19 GMT glc said:

There are calculations but it's really the concept that needs to be understood.

So why did you ask?

[glc]

Oh, so this isn't based on your own work? You know glc, anyone can give a lecture paraphrased (plagurized?) from unreferenced sources. Please, you are not impressing anyone....

Cite your sources.

Sources for what? For the exponential decay? I don't know about the US, but here in the UK this is the sort of stuff which is taught every day in schools, colleges and universities.

But here's a link if you need one ...

en.wikipedia.org/wiki/Exponential_decay

As well as providing the differential equation, the wiki link states that "A quantity is said to be subject to exponential decay if it decreases at a rate proportional to its value".

This is pretty much describes the CO2 situation. In this case the "quantity" is the excess (fossil fuel) CO2 in the atmosphere. Using my figure this is 150 GtC.

As for the rest of my figures. The CO2 conversion rate for GtC -> ppm appears to be ~2 GtC per ppm (or ~0.5 ppm per GtC). [See www.john-daly.com/tar.htm for Jan Ahlbeck's figure of 0.471 ppm per Gt/C]

The numbers I used, therefore, represent a pre-industrial equilibrium of ~300 ppm (600 GtC) and a 'current' concentration of ~375ppm (750 GtC). My estimate for the extra fossil fuel 'sink' was 3 GtC per year which seems to be pretty close. The world is producing ~7 GtC per year of which about half remains in the atmosphere. In my example ~4 GtC remains which represents a ~2 ppm per year increase (i.e. in line with observations).

As for the natural cycle I probably didn't use the correct figure here. In his article, Segalstad writes "....Essenhigh (2009) uses the IPCC data of 1990 with a total mass of carbon of 750 gigatons in the atmospheric CO2 and a natural input/output exchange rate of 150 gigatons of carbon per year (Houghton et al., 1990...". But this just alters the average CO2 molecule residence time. It doesn't change the overall conclusion.

I'm not actually sure what you point is. If it's to say that my 'work' is not original then you're almost certainly correct. Similar (but much more sophisticated and accurate) calculations will have been done on countless previous occasions. I've just tried to use simple numbers to try to explain the difference between the mean residence time of CO2 and the atmospheric residence time of the excess CO2. They are not the same.

I'm not looking for any credit at all. Far from it. I was the 'coward' looking on from the sidelines while Socold valiantly put forward the arguments. I couldn't face it. I'd just like it acknowledged that Socold was, in fact, right.

[glc]

Yesterday at 7:30pm, glc wrote:
There are calculations but it's really the concept that needs to be understood.
So why did you ask?

My point is that the calculations are not to be taken at face value. They are merely intended to demonstrate that the average RT of a CO2 molecule is not the same as the residence time of the excess CO2. If we stopped burning fossil fuels tomorrow, most of the extra ~100 ppm would still be there in 5 years time. However the individual CO2 molecules would not be the same.