MarkR, sorry for the delay in reply (have a few very busy days…), as you could see, the largest differences are in forested areas, but also near tundra’s. And mainly in the NH. That is caused by biomass decay (autumn to spring) and biomass growth (spring to autumn). While this happens, the CO2 richer (or poorer) air travels around in the main wind direction, which in general is West to East and from the equator to the poles. But at the same time it is mixed to some degree with air that is less affected by CO2 changes (thus smoothed). And over the oceans, CO2 is exchanged between air and ocean surface (which again smooths the changes). The travel time of air over each hemisphere is a matter of weeks, that makes that the effect of the seasons is seen everywhere, but most at places with the largest changes…

As the exchange between NH and SH air masses is more limited, one will see some delay in trends and far less variation of CO2 levels in the SH, which is further counteracted by the (smaller, because of less land) seasonal variations there, which are in opposite direction.

My question is why the sawtooth, as the local conditions are very different? CO2 can’t be absorbed and released by the sea in central Germany, and can’t be absorbed by plant life on desolate island locations, so where is it going to and from? Even Mt. Waliguan, China, which probably has no vegetation, and certainly has no sea, but it has a sawtooth.

As Hans already provided, seasonal changes are much higher as measured on land based stations, especially when located in areas with a lot of forests. Further, the seasonal variation diminishes southward and is virtually absent at the South Pole. And there is a lag of 6-12 months between the average (yearly) concentrations between the NH and SH. This points to the NH as main source.

And it is a typical example of confusion between seasonal/yearly variations and a multiyear trend, caused by some continuous (in this case increasing) source. The seasonal variations (which is one independent variable) in the above example are up to 60 ppmv (6 ppmv for Mauna Loa), the yearly variations (around the trend) are about 1 ppmv (depends on the difference between uptake and release in oceans and biosphere, another natural variable, but partly depending on the first one), while the trend is only 2 ppmv per year (but mainly caused by a third non-natural independent variable). Despite that, the trend over 30 years is equal to much larger than the seasonal variations and 60 times higher than the variations in yearly average.

Last but not least, 13C trends are declining everywhere, but again with a lead of a year (to several years) in the NH against the SH, and with a lead of the atmosphere vs. the upper ocean layer. This again points to fossil fuel burning (which is 13C poor) mainly in the NH. Ocean degasing can’t provide the extra 12C, as the surface as well as the deep ocean is far more 13C rich than the atmosphere. Biogenic decay is 12C rich too, but that can’t be the source, as this should deplete oxygen faster than measured, while oxygen is depleted less fast than expected from fossil fuel use (+ land use change) alone…

For the second part, that still is under discussion, as several of the high spikes of CO2 (e.g. around 1940) are not visible in independent measurements of stomata index data. Further, I like to see some independent view/comment on the data from Prof. Jaworowski. It seems to me that many of the data are quite old, while most ice core measurements are from more recent times, when better treatment (relaxation) of the ice cores may give a difference…

See further a lot of comment on this topic at CA #820

but no such profile with that amplitude is known to have been reported at any mainland location.

Germany mainland enough?

more data:
http://gaw.kishou.go.jp/wdcgg/data.html

What do you think abiut this theory:

This interpretation of the sea as the major source is also in line with the famous Mauna Loa CO2 profile for the past 40 years, which shows the consistent season-dependent variation of 5–6 ppm, up and down, throughout the year”¢’‚¬?when the average global rise is only 1 ppm/year.

In the literature, this oscillation is attributed to seasonal growing behavior on the “mainland” (4), which is mostly China, >2000 mi away, but no such profile with that amplitude is known to have been reported at any mainland location. Also, the amplitude would have to fall because of turbulent diffusive exchange during transport over the 2000 mi from the mainland to Hawaii, but again there is lack of evidence for such behavior. The fluctuation can, however, be explained simply from study of solution equilibria of CO2 in water as due to emission of CO2 from and return to the sea around Hawaii governed by a ±10 °F seasonal variation in the sea temperature.

Link

I think maybe the use of ice core data from the recent past to support CO2 measurement is still open to question.

The data from shallow ice cores, such as those from Siple, Antarctica[5, 6], are widely used as a proof of man-made increase of CO2 content in the global atmosphere, notably by IPCC[7]. These data show a clear inverse correlation between the decreasing CO2 concentrations, and the load-pressure increasing with depth (Figure 1 A). The problem with Siple data (and with other shallow cores) is that the CO2 concentration found in pre-industrial ice from a depth of 68 meters (i.e. above the depth of clathrate formation) was “too high”. This ice was deposited in 1890 AD, and the CO2 concentration was 328 ppmv, not about 290 ppmv, as needed by man-made warming hypothesis. The CO2 atmospheric concentration of about 328 ppmv was measured at Mauna Loa, Hawaii as later as in 1973[8], i.e. 83 years after the ice was deposited at Siple.

An ad hoc assumption, not supported by any factual evidence[3, 9], solved the problem: the average age of air was arbitrary decreed to be exactly 83 years younger than the ice in which it was trapped. The “corrected” ice data were then smoothly aligned with the Mauna Loa record (Figure 1 B), and reproduced in countless publications as a famous “Siple curve”. Only thirteen years later, in 1993, glaciologists attempted to prove experimentally the “age assumption”[10], but they failed[9].

Link

As far as I know, all recent ice core data has been “age adjusted” to a greater or lessed extent.

I just don’t think that there is enough certainty about how CO2 behaves, and can be measured in recent ice core.

Steve M, have you read the article by Esper, Frank, Wilson and Briffa:
Effect of scaling and regression on reconstructed temperature amplitude for the past millennium? Seems interesting, as indeed the difference in amplitude is important for the attribution of solar vs. other forcings…

Francois, as there is a temperature dependent dynamic equilibrium between CO2 levels in air and water, the net in/outflow depends on temperature (long term average ~10 ppmv/K) and the difference in concentrations between air and ocean surface. In formula:

Fout = f(T)*(Cair-Csink(T)) + constants
(this is Fick’s law modulated by temperature)

Csink(T) is observed in ice cores (10ppmv/K)
f(T) is Ahlbeck’s CO2 thermometer.

As the concentration in the atmosphere increases, the equilibrium is shifting towards more absorption, but of course not 0% or 100%, somewhere in between. With a pulse emission, the absorption would decrease in time, until a new equilibrium is reached, but as there is a more or less linear increase in emissions, the result is a more or less linear increase in atmospheric concentrations and in increasing absorption by the ocean’s surface layer.
But as Csink (the concentration in the ocean’s surface layer) increases too, if the emissions remain constant, the % absorbed will diminish in time. Thus even with future constant emissions at some level, the atmospheric levels will increase and more will remain in the atmosphere as the ocean’s CO2 concentration increases.

Of course, this is not the complete story, as there is buffering in the upper layer and exchange with the deep layers of the oceans. The latter is a slow process (~1500 years overturning rate via the THC), about the first, we have already used about 1/3rd to halve of the buffer capacity (according to different sources).

For biogenic uptake/release, the equilibrium is more difficult to follow: the increase in temperature at one side increases (old) vegetation decay (and less optimal temperature/precipitation will reduce uptake in some parts of the world), while at the other side more CO2 (and more optimal temperature/precipitation for other parts of the world) will increase uptake. The net result in the past decade seems to be more uptake (the “greening” earth), which may be deduced from less O2 decrease than calculated from burning fossil fuel and land use change (both use oxygen, while uptake releases oxygen).

The problem which confuses many people is that the amount of CO2 (and oxygen) largely varies during a year, due to seasonal changes, and even from year to year. And the seasonal in/out flows are much larger than the changes in CO2/O2 due to human emissions. Nevertheless, the trends in CO2, d13C and dO2 over decade(s) are quite clear…

A couple of points. First while warmers make much of supposed acidification of the oceans, the fact is that the level of CO2 either as dissolved gas or bicarbonate or carbonate (mostly as shells as carbonate is pretty insoluble) will continue to increase. And the ocean currents will typically move a constant volume of ocean water to deeper levels yearly. This means that an increasing amount of CO2 will be moved to deeper waters. Though the fact is as I’ve mentioned before that we actually get more CO2 in the rising waters than in the falling waters at present. So what is happening is that the increase in CO2 from deep waters is decreasing relative to rising waters. But we’re close to the break even point so it could well be that there will be net movement of CO2 to deep waters before long.

In any case there is a constant flow of CO2 via shells and dead bodies directly to deep waters and this is likely to also increase both because there will be more net production in the surface waters as there is more CO2 in the waters and because if we continue to deplete fisheries more primary producers will die and rain down before being eaten. So we’re likely to have a continued uptake by the oceans roughly proportional to the total concentration of CO2 in the atmosphere.

On land the situation is more complex and humans are even more in the picture as a lot depends on the storage in forests which are subject to logging, burning, insect infestations, etc.

Finally, more CO2 in the atmosphere will increase the weathering affects on carbonate rocks which in turn will increase CO2 flow into the oceans. This isn’t gigantic, but it’s increasing and needs to be taken into consideration.