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Post by glc on Sept 29, 2009 23:15:55 GMT
Steve Where does the 3GtC value come from?The 3 GtC is my number, but it is a reasonable guess. It comes from the fact that we (humans) are currently emitting ~7GtC per year. The GtC->ppm conversion rate is 0.471. Therefore if all this carbon were allowed to accumulate in the atmosphere the annual increase would be ~3.3 ppm, but the recent annual increase is only ~2 ppm. The average over the past decade is ~1.7 ppm. This means that around half the amount that is emitted is removed by the extra 'sink'. This sink is additional to the natural cycle sink which absorbs and emits ~150 GtC a year. The 3 GtC represents the extra bit that is removed. Can you be sure that the absolute amount of uptake each year continues to be the same. What if there is a short term sink that fills up quickly as a function of atmospheric CO2 levels, but empties elsewhere slowly? I can't be sure of anything, Steve. There are bound to be fluctuations and variations. But the pattern of growth we've seen suggests that the removal rate (the extra 'sink') is roughly proportional to the excess CO2 in the atmosphere. By 'excess' I mean the amount above the pre-industrial level (currently ~100ppm). Eg. for illustration of my meaning only, suppose the top few metres of the ocean quickly reach equilibrium with the atmosphere as it absorbs the bulk of the 3GtC. This means that even if emissions cease, the ocean cannot absorb any more until either the atmosphere concentration starts to rise again or the top layers have a net loss of "dissolved CO2" to the deeper ocean through ocean circulation and/or biological activity.I understand your point but this is a bit beyond the point of my original post. I was actually just trying to show that the average residence time of a CO2 molecule in the atmosphere which is mainly determined by the natural cycle is not the same as the time taken for an injection of CO2 to be removed from the atmosphere. Given that CO2 levels have been sustained at much higher levels in the past, other people's suggestions that it could be so easily constrained now seems optimistic.Ok - but if what we've observed in the past ~50 years continues for the next ~50 years then I reckon my 'model' will be pretty near the mark. Of course we'd have to stop all anthropogenic CO2 production to find out. There's always a hitch  |
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Post by glc on Sept 29, 2009 23:31:50 GMT
What problem?
I would suggest your model does not provide for natural variation. Put together as if all other forces on the planet are static and forever in balance.
Such assumptions simply are irrational when dealing with natural systems. Its kind of a deterministic view that eventually humbles all natural scientists.
You may be surprised to find that I agree with you. However the "model" is simply intended to illustrate a point about CO2 residence time. It's also worth pointing out that if the model is wrong it's not likely to be wrong in a favourable direction. I don't see CO2 removal rates being much quicker than those implied in the model.
Also, in defence of the model, it is loosely based on the CO2 accumulation rates observed over the past ~50 years.
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Post by icefisher on Sept 30, 2009 2:13:00 GMT
What problem?
I would suggest your model does not provide for natural variation. Put together as if all other forces on the planet are static and forever in balance.
Such assumptions simply are irrational when dealing with natural systems. Its kind of a deterministic view that eventually humbles all natural scientists.You may be surprised to find that I agree with you. However the "model" is simply intended to illustrate a point about CO2 residence time. It's also worth pointing out that if the model is wrong it's not likely to be wrong in a favourable direction. I don't see CO2 removal rates being much quicker than those implied in the model. Also, in defence of the model, it is loosely based on the CO2 accumulation rates observed over the past ~50 years. However, your model completely discounts the idea that most of the CO2 increases in the atmosphere could be related primarily to the LIA recovery (the soda pop equilibrium theory), which if true means any resemblance between the model and actual times of atmospheric CO2 fluctuation is merely coincidental in that it is temperature change that determines the rate of the sinks and sources.. The fun stuff with natural systems is how many theories it supports with consistency in the numbers. Anyway according to your calculations where 1/2 of the anthropogenic emissions are removed each year, in 8 years for all intents and purposes all that carbon is going to be gone (99.6%) hardly seems consistent with a theory it will take a 100 years. I kind of like the soda pop theory a little better to explain longterm increases and decreases. |
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Post by glc on Sept 30, 2009 10:33:42 GMT
However, your model completely discounts the idea that most of the CO2 increases in the atmosphere could be related primarily to the LIA recovery (the soda pop equilibrium theory), which if true means any resemblance between the model and actual times of atmospheric CO2 fluctuation is merely coincidental in that it is temperature change that determines the rate of the sinks and sources.. The reason I discount that idea is because it's nonsense. Following the last ice age CO2 levels rose ~100 ppm but temperatures rose more than 5 deg. Hans Erren has looked at the vostok ice core record and found a relationship of ~10ppm CO2 per 1 deg. As we've only had ~0.7 deg increase since 1900 this cannot explain increase in CO2 since then. members.lycos.nl/ErrenWijlens/co2/howmuch.htmThe fun stuff with natural systems is how many theories it supports with consistency in the numbers.
Anyway according to your calculations where 1/2 of the anthropogenic emissions are removed each year, in 8 years for all intents and purposes all that carbon is going to be gone (99.6%) hardly seems consistent with a theory it will take a 100 years. I kind of like the soda pop theory a little better to explain longterm increases and decreasesNo - the ½ figure relates to the sink as a proportion of the annual increase, i.e. ~3 GtC out of ~7 GtC per year. It is not ½ of the total excess. You might have taken the frog analogy too literally. The 3 GtC sink represents ~2% of the ~150 GtC excess. If ‘my model’ is correct and we stop human CO2 emissions now then .. In year 1: 2% of ~150 GtC will be removed In year 2: 2% of ~147 GtC will be removed In year 3: 2% of ~144.06 GtC will be removed and so on Each year slightly less will be removed than in the previous year. After ~35 years about half the original excess will have been absorbed. After ~50 years around 63% of the original excess will have gone. In 50 years time atmospheric CO2 concentration should have fallen by 63 ppm. The assumption underpinning this ‘model’ is that the removal rate or ‘sink’ is proportional to the excess CO2. This is not unreasonable because that is what appears to have taken place over the past ~50 years - except in reverse, i.e. as we’ve increased emissions (and excess) the ‘sink’ has increased. Another assumption is that the pre-industrial CO2 concentrations were roughly in equilibrium with the natural cycle. In other words around 1/5 of the total CO2 in the atmosphere was absorbed and emitted each year. Steve has raised a couple of points which may be valid and which suggest ‘my model’, as you put it, leans towards the more optimistic scenario. My argument to that is that the model fits with observations. I have not taken into account other influences no matter how plausibe they may be.
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Post by icefisher on Sept 30, 2009 16:18:53 GMT
However, your model completely discounts the idea that most of the CO2 increases in the atmosphere could be related primarily to the LIA recovery (the soda pop equilibrium theory), which if true means any resemblance between the model and actual times of atmospheric CO2 fluctuation is merely coincidental in that it is temperature change that determines the rate of the sinks and sources.. The reason I discount that idea is because it's nonsense. Following the last ice age CO2 levels rose ~100 ppm but temperatures rose more than 5 deg. Hans Erren has looked at the vostok ice core record and found a relationship of ~10ppm CO2 per 1 deg. As we've only had ~0.7 deg increase since 1900 this cannot explain increase in CO2 since then. It may be nonsense to believe icecores chronicle long term gas content records accurately. Numerous issues have been identified with icecores. . . .not just icepack dynamics but also transport and handling of icecores. This is a rather dynamic medium as witnessed by my home freezer. I wouldn't necessarily jump on that theory with both feet without some kind of ground truthing to support the specific results to well within a factor of magnitude. I haven't really looked at the specific testing that has been done on the soda pop theory; but it at least operates as claimed in my refrigerator. The fun stuff with natural systems is how many theories it supports with consistency in the numbers.
Anyway according to your calculations where 1/2 of the anthropogenic emissions are removed each year, in 8 years for all intents and purposes all that carbon is going to be gone (99.6%) hardly seems consistent with a theory it will take a 100 years. I kind of like the soda pop theory a little better to explain longterm increases and decreasesNo - the ½ figure relates to the sink as a proportion of the annual increase, i.e. ~3 GtC out of ~7 GtC per year. It is not ½ of the total excess. You might have taken the frog analogy too literally. The 3 GtC sink represents ~2% of the ~150 GtC excess. That would be fine as long as you have hung your hat on the icecores and completely eliminated all but 10ppm CO2 coming from a source other than anthropogenic. There are some lynchpin assumptions being made that do not seem to be very robust. If ‘my model’ is correct and we stop human CO2 emissions now then .. In year 1: 2% of ~150 GtC will be removed In year 2: 2% of ~147 GtC will be removed In year 3: 2% of ~144.06 GtC will be removed and so on Each year slightly less will be removed than in the previous year. After ~35 years about half the original excess will have been absorbed. After ~50 years around 63% of the original excess will have gone. In 50 years time atmospheric CO2 concentration should have fallen by 63 ppm. The assumption underpinning this ‘model’ is that the removal rate or ‘sink’ is proportional to the excess CO2. This is not unreasonable because that is what appears to have taken place over the past ~50 years - except in reverse, i.e. as we’ve increased emissions (and excess) the ‘sink’ has increased. Another assumption is that the pre-industrial CO2 concentrations were roughly in equilibrium with the natural cycle. In other words around 1/5 of the total CO2 in the atmosphere was absorbed and emitted each year. Steve has raised a couple of points which may be valid and which suggest ‘my model’, as you put it, leans towards the more optimistic scenario. My argument to that is that the model fits with observations. I have not taken into account other influences no matter how plausibe they may be. Its pretty easy to take two upward curves and figure a gain rate of one from the other. But we should not confuse that with any evidence of it being the case beyond the fact the math works and it works because you made it work. Again we have that unidirectional correlation. . . .the never ending march to doom. . . .with a lot of folks seemingly overly impressed with their math skills. Again it comes around to ice and whether unfrozen gas migrates in ice. . . .like it does in my freezer. |
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Post by socold on Sept 30, 2009 19:51:26 GMT
It may be nonsense to believe icecores chronicle long term gas content records accurately. Yet you are happy to accept the 800 year temperature-co2 lag they show... Or are you saying you don't believe that anymore? Which argument do you want to keep? |
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Post by icefisher on Oct 1, 2009 0:53:15 GMT
It may be nonsense to believe icecores chronicle long term gas content records accurately. Yet you are happy to accept the 800 year temperature-co2 lag they show... Or are you saying you don't believe that anymore? Which argument do you want to keep? Perhaps there are reasons to question that also. Diffusion in the ice could I suppose could shift the timing as well as the amount of gas, but most processes of erosion tend to leave the peaks and valley in place while partially wearing down the peaks and partially filling the valleys without moving the entire mountain to the valley. So I don't see your dilemma clearly as an either/or. Perhaps you could elucidate a bit and prove you are not just playing devil's advocate. |
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Post by enough on Oct 1, 2009 1:17:11 GMT
Good discussion going on but...
I want to remind all that the claim of Soloman/NOAA was not a 100 years, but greater than a thousand years.
If need be I can go back and find the link to the paper.
NOAA has absolutely no credibility. Any body care to stand up for Soloman/NOAA?
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Post by Pooh on Oct 1, 2009 5:53:53 GMT
Posted by icefisher on Yesterday at 8:53pm Is this it?Solomon, Susan, Gian-Kasper Plattner, Reto Knutti, and Pierre Friedlingstein. “ Irreversible climate change due to carbon dioxide emissions.” PNAS 106, no. 6 (February 10, 2009): 1704–1709. www.iac.ethz.ch/people/knuttir/papers/solomon09pnas.pdf. "The severity of damaging human-induced climate change depends not only on the magnitude of the change but also on the potential for irreversibility. This paper shows that the climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop. Following cessation of emissions, removal of atmospheric carbon dioxide decreases radiative forcing, but is largely compensated by slower loss of heat to the ocean, so that atmospheric temperatures do not drop significantly for at least 1,000 years. Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450–600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the ‘‘dust bowl’’ era and inexorable sea level rise. Thermal expansion of the warming ocean provides a conservative lower limit to irreversible global average sea level rise of at least 0.4 –1.0 m if 21st century CO2 concentrations exceed 600 ppmv and 0.6 –1.9 m for peak CO2 concentrations exceeding ~1,000 ppmv. Additional contributions from glaciers and ice sheet contributions to future sea level rise are uncertain but may equal or exceed several meters over the next millennium or longer." |
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Post by socold on Oct 1, 2009 23:04:27 GMT
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Post by nautonnier on Oct 2, 2009 12:46:25 GMT
Why does every climate model I come across assume that CO2 is the driving force? The climate models assume that CO 2 is the driving force because that was the remit of the IPCC. It is presented in their AR4 report as 'the only explanation for the temperature rise' that they could think of. This is due to them playing with the parameters in the model to show that CO 2 can be the driving force. As I said in another thread this is the Kelvin Fallacy - that we know all there is to know - therefore the cause of some observation _must_ be something we know. Then play with models of the data to support your hypothesis. |
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Post by socold on Oct 2, 2009 23:12:57 GMT
The climate models show that doubling co2 causes a significant amount of warming.
The lack of model results to the contrary underlines the fact that this isn't simply an assumption that someone has programmed into the models or else someone could just as easily program a model to show no warming from co2.
No the lack of model results to the contrary show that the co2 warming from models is not an assumption, but an inescapable consequence of human understanding of climate.
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Post by sigurdur on Oct 2, 2009 23:30:08 GMT
The climate models show that doubling co2 causes a significant amount of warming. The lack of model results to the contrary underlines the fact that this isn't simply an assumption that someone has programmed into the models or else someone could just as easily program a model to show no warming from co2. No the lack of model results to the contrary show that the co2 warming from models is not an assumption, but an inescapable consequence of human understanding of climate. SoCold: I am still waiting for an explanation of why co2 keeps rising as temps fall at the end of each warming period. |
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Post by socold on Oct 2, 2009 23:55:00 GMT
And I am still waiting for you to give some numbers. How much did co2 change, over how long and how much did temperature fall?
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Post by icefisher on Oct 3, 2009 0:55:13 GMT
And I am still waiting for you to give some numbers. How much did co2 change, over how long and how much did temperature fall? Interesting you should ask that Socold. I was on the beach this afternoon and found a clam that has the answer to that. ;D |
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