The Low Down & Down Under of Carbon Dioxide

[Clifford]

Here are some notes I just put together on the equilibrium of Carbon Dioxide. It is nothing new, but I perceive that it is being grossly misrepresented in the popular press.

We have all seen far too many Temperature/CO₂ charts.

CO₂, however, is not driving the temperature. Instead, equilibria pressures are driving the CO₂.

Prior to Anthropogenic Release of CO₂, the concentration of CO₂ in our atmosphere was dictated by equilibria. In particular the relationship between the concentration of the CO₂ in our atmosphere vs the concentration dissolved in the oceans (in the various forms, dissolved CO₂, Carbonic Acid (H₂CO₃), ions from Carbonic Acid, and various carbonates).

From Henry's Law:

At 1 ATM, 25°C (water), CO₂ is distributed with concentrations of about 30(air):1(water) (except that air is also less dense than water), so we actually find the total ratio is about 2% atmosphere, 98% oceans (ignoring the carbon in living biota).

http://www.waterency...Atmosphere.html

If the temperature increases by about 8°C, the concentration in the air increases by about 50% due to an increase in partial pressures (think of it like boiling a pot of water or distilling moonshine).

http://en.wikipedia...._acid_solutions

http://en.wikipedia...._Henry_constant

So, in the previous ice age, the concentration of CO₂ in the atmosphere was about 200ppm.

An increase in ocean temperatures of about 8°C caused the concentration of atmospheric CO₂ to increase by about 50%, or to about 300ppm.

This increase is driven solely by the equilibrium.

The oceans will bubble out CO₂ as the temperature increases. The atmospheric concentration MUST increase as the ocean temperatures increase. And the outgassing is likely relatively rapid, somewhat like leaving a open bottle of soda on the counter... it quickly looses CO₂ and becomes flat.

Likewise, as the ocean temperatures decrease again, that “extra” CO₂ is reabsorbed back into the oceans. However, due to the heat sink effect of the oceans, and time to reach equilibrium, there may be a lag between the surface temperature decrease, and the absorption of the CO₂.

Earth's Crust temperatures have to reflect the average atmospheric temperatures. So, a decrease in the atmosphere temperature will cause an eventual response in the average ocean temperatures throughout the entire depth of the ocean, although not uniform, and a decrease in carbon dioxide.

There is nothing surprising about the Temperature/CO₂ correlation. It is a fixed relationship that MUST OCCUR.

Now.

If the temperature is held constant. One can change the concentration of CO₂ in the “system” and a new equilibrium will eventually be met. So, for example, if Carbon is buried (like in fossil fuels), then the concentration will decrease in both the atmosphere and the ocean and eventually a new equilibrium will be reached.

Now we bring Human Anthropogenic Carbon into the system.

In a relatively short period we have increased the Atmospheric concentration of CO₂ from about 300ppm to about 400ppm

If left to reach equilibrium, that extra 100ppm will eventually be sequestered in the ocean at the same approx 98:2 proportions. So, about 2ppm will remain in the air, and the rest will end up in the oceans.

That process is already happening. And, we are observing about 50% of the excess CO₂ we release each year is sequestered that same year, so perhaps one should consider it more likely as a 96:4 relationship.

And, thus a short-term increase in the atmospheric Carbon Dioxide of 100ppm from 300ppm to 400ppm will likely result in an equilibrium of an increase to 304ppm in the atmosphere.

The time to return to that 304ppm equilibrium, of course, will depend on the temperature response of the entire ocean heat-sink, as well as the time it takes to absorb and convey the CO₂ throughout the entire ocean depth.

If the carbonates are sucked up by “weathering”, it is possible that the oceans can buffer even more CO₂.

One could convert from atmospheric ppm to gigatons or petagrams. The conclusion would be the same.

Temperatures & Equilibria drive CO₂ concentrations rather than the other way around.

[BethesdaWX]

Good post.

The fear from alarmists will be that further buffering from the ocean will only add to the issue in the end. Not realizing the Co2 isn't a permanent residence without its original properties.

[WeatherRusty]

Here are some notes I just put together on the equilibrium of Carbon Dioxide. It is nothing new, but I perceive that it is being grossly misrepresented in the popular press.

We have all seen far too many Temperature/CO₂ charts.

CO₂, however, is not driving the temperature. Instead, equilibria pressures are driving the CO₂.

Prior to Anthropogenic Release of CO₂, the concentration of CO₂ in our atmosphere was dictated by equilibria. In particular the relationship between the concentration of the CO₂ in our atmosphere vs the concentration dissolved in the oceans (in the various forms, dissolved CO₂, Carbonic Acid (H₂CO₃), ions from Carbonic Acid, and various carbonates).

From Henry's Law:

At 1 ATM, 25°C (water), CO₂ is distributed with concentrations of about 30(air):1(water) (except that air is also less dense than water), so we actually find the total ratio is about 2% atmosphere, 98% oceans (ignoring the carbon in living biota).

http://www.waterency...Atmosphere.html

If the temperature increases by about 8°C, the concentration in the air increases by about 50% due to an increase in partial pressures (think of it like boiling a pot of water or distilling moonshine).

http://en.wikipedia...._acid_solutions

http://en.wikipedia...._Henry_constant

So, in the previous ice age, the concentration of CO₂ in the atmosphere was about 200ppm.

An increase in ocean temperatures of about 8°C caused the concentration of atmospheric CO₂ to increase by about 50%, or to about 300ppm.

This increase is driven solely by the equilibrium.

The oceans will bubble out CO₂ as the temperature increases. The atmospheric concentration MUST increase as the ocean temperatures increase. And the outgassing is likely relatively rapid, somewhat like leaving a open bottle of soda on the counter... it quickly looses CO₂ and becomes flat.

Likewise, as the ocean temperatures decrease again, that “extra” CO₂ is reabsorbed back into the oceans. However, due to the heat sink effect of the oceans, and time to reach equilibrium, there may be a lag between the surface temperature decrease, and the absorption of the CO₂.

Earth's Crust temperatures have to reflect the average atmospheric temperatures. So, a decrease in the atmosphere temperature will cause an eventual response in the average ocean temperatures throughout the entire depth of the ocean, although not uniform, and a decrease in carbon dioxide.

There is nothing surprising about the Temperature/CO₂ correlation. It is a fixed relationship that MUST OCCUR.

Now.

If the temperature is held constant. One can change the concentration of CO₂ in the “system” and a new equilibrium will eventually be met. So, for example, if Carbon is buried (like in fossil fuels), then the concentration will decrease in both the atmosphere and the ocean and eventually a new equilibrium will be reached.

Now we bring Human Anthropogenic Carbon into the system.

In a relatively short period we have increased the Atmospheric concentration of CO₂ from about 300ppm to about 400ppm

If left to reach equilibrium, that extra 100ppm will eventually be sequestered in the ocean at the same approx 98:2 proportions. So, about 2ppm will remain in the air, and the rest will end up in the oceans.

That process is already happening. And, we are observing about 50% of the excess CO₂ we release each year is sequestered that same year, so perhaps one should consider it more likely as a 96:4 relationship.

And, thus a short-term increase in the atmospheric Carbon Dioxide of 100ppm from 300ppm to 400ppm will likely result in an equilibrium of an increase to 304ppm in the atmosphere.

The time to return to that 304ppm equilibrium, of course, will depend on the temperature response of the entire ocean heat-sink, as well as the time it takes to absorb and convey the CO₂ throughout the entire ocean depth.

If the carbonates are sucked up by “weathering”, it is possible that the oceans can buffer even more CO₂.

One could convert from atmospheric ppm to gigatons or petagrams. The conclusion would be the same.

Temperatures & Equilibria drive CO₂ concentrations rather than the other way around.

Everything you state here may well be true, and I believe it is with the exceptions:

CO₂, however, is not driving the temperature. Instead, equilibria pressures are driving the CO₂.

Temperatures & Equilibria drive CO₂ concentrations rather than the other way around.

CO2 is an important greenhouse gas. It acts as both a forcing and a feedback.

[salbers]

I've read though that the equilibrium CO2 amount is higher than that, as per a paper by Archer. Judging from the plots it would be about 25-30% of the spike. The first paragraph in Section 4 summary explains this a bit better.

http://geosci.uchica...05.fate_co2.pdf

So I think that the 98:2 ratio doesn't really hold as the system reaches a new equilibrium.This is due to the "Revelle Buffer Factor" as the ocean Ph changes (section 3.1 of the text).

[BethesdaWX]

I've read though that the equilibrium CO2 amount is higher than that, as per a paper by Archer. Judging from the plots it would be about 25-30% of the spike. The first paragraph in Section 4 summary explains this a bit better.

http://geosci.uchica...05.fate_co2.pdf

So I think that the 98:2 ratio doesn't really hold as the system reaches a new equilibrium.This is due to the "Revelle Buffer Factor" as the ocean Ph changes (section 3.1 of the text).

The entire theory is a hypothesis on both sides, so it doesn't disprove the argument at hand.

[salbers]

Sorry, but I think it's a copout if you're unable to refute the Archer paper in a more detailed manner. I'd really like to know what the errors in reasoning are in this paper. It seems like a solid presentation, though it doesn't account for any land CO2 sequestration.

[BethesdaWX]

Sorry, but I think it's a copout if you're unable to refute the Archer paper in a more detailed manner. I'd really like to know what the errors in reasoning are in this paper. It seems like a solid presentation, though it doesn't account for any land CO2 sequestration.

Well I haven't read it yet, so obviously I cannot refute it.

My statement that the whole theory on both sides is a hypothesis, stands as is.

[salbers]

I'd note that many of the statements in this paper about ocean chemistry are more than hypotheses - as they can be proven by direct observation and experimentation. So I'd suggest you should go ahead and read the paper and think about what it's saying before trying to characterize the theory. I'd really enjoy an intelligent discussion about the important implications of this paper.

[BethesdaWX]

I'd note that many of the statements in this paper about ocean chemistry are more than hypotheses - as they can be proven by direct observation and experimentation. So I'd suggest you read the paper and think about what it's saying before trying to characterize the theory.

Depends what part of the theory you're speaking of. The AGW theory has many stemwinders.

Direct measurements don't always tie in the way you'd think, by the standards of correlation. Or what you'd peg such OBS on in the first place.

[salbers]

I'd suggest your posts are a waste of everyone's time until you can stay on topic and respond to this paper. While you're at it maybe take a chemistry class or do some background reading?

[BethesdaWX]

I'd suggest your posts are a waste of everyone's time until you can stay on topic and respond to this paper.

huh? I'm staying on the topic of the initiated thread by Clifford. Measurements contradict in all fields, I'm 100% on topic.

If my posts are a waste of time then don't respond.

I think you need to take an English course.

[salbers]

I stand by the logic and conclusions in the Archer paper unless you can refute it in some detail. Vague generalities about contradicting observations really don't help very much. These are very reproduceable observations - so there's not really much of a contradiction.

If your English skiils are that good you'd have read half of it by now

[BethesdaWX]

I stand by the logic and conclusions in the Archer paper unless you can refute it in some detail. Vague generalities about contradicting observations really don't help very much. These are very reproduceable observations - so there's not really much of a contradiction.

If your English skiils are that good you'd have read half of it by now

I never said mine were good, just that yours are bad. I cannot refute the paper until I have read it, which will not be this weekend.

All kidding aside, I'd perfer to spend my weekend not reading...as much.

[skierinvermont]

Everything Clifford says is true (or rather I can see no reason why it would be false and will take him/his sources as is) and is not at odds with the Archer paper you posted Steve.

The difference is Clifford is not accounting for temperature increase that would alter the equilibrium partitioning of CO2. If the temperature did not rise then it may very well be that 98% of the anthropogenic carbon we have released will eventually be absorbed by the oceans across several thousand years. However, because of the temperature increase the oceans will not be at equilibrium with the atmosphere until a much higher atmospheric concentration.

What Clifford said about temperature driving CO2 historically is, of course, also true as I think everybody here knows. CO2 also, of course, has amplified the warming of the inter-glacials. All this is well explained in the IPCC report. I don't really see much confusion about this in the popular press anymore.

In fact, I was just reading a NYT article where they say the interglacials were not caused by rising CO2, but the rising CO2 (due to the temp increase) amplified the warming.

[Clifford]

I've read though that the equilibrium CO2 amount is higher than that, as per a paper by Archer. Judging from the plots it would be about 25-30% of the spike. The first paragraph in Section 4 summary explains this a bit better.

http://geosci.uchica...05.fate_co2.pdf

So I think that the 98:2 ratio doesn't really hold as the system reaches a new equilibrium.This is due to the "Revelle Buffer Factor" as the ocean Ph changes (section 3.1 of the text).

Thanks,

Excellent article.

(and, to others I'd encourage attempting to understand the references before replying)

Archer presents these two figures:

In Metric, Gigatons and Petagrams are the same. In "Standard", they are off by 10% which is close enough

(not much different from the difference between a gigabyte and a billion bytes).

Archer's notes indicate:

300 Gigatons of Carbon Dioxide already released.

500 Gigatons equivalent of Carbon Dioxide left in Oil & Natural Gas

2000 Gigatons equivalent of easily acceptable Coal, Oil, and Natural Gas total.

5000 Gigatons equivalent is the total theoretical Coal Reserves.

5000 to 10,000 Gigatons equivalent of Deep sea Methane Reserves ... I don't even want to think of that one

On page 4 Archer notes the 50:1 Ocean:Atmosphere carbon ratio that I mentioned above.

750 Gigatons CO₂ currently in the atmosphere (From Water Encyclopedia Article Above)

37,500 Gigatons CO₂ currently in the ocean (calculated from the 50:1 ratio).

Ok...

So, with Archer's notes (Figure 1)

If we stop using Carbon Fossil Fuels Now (300 Gigatons)

Our atmosphere CO₂ will peak at about the current level of 400ppm or so, and will decay back down to below 300ppm relatively quickly.

If we hit a likely scenario of at least 1000 Gigatons total, then it should peak somewhere around 500ppm, and decay back to below 350ppm (below current levels) relatively quickly.

If we hit 2000 Gigatons, then it will drop down to maybe 450ppm, followed by eventually dropping below 400ppm.

Archer plotted everything on a scale that it is impossible to get a close estimate of the exact time scales, and I can imagine why . However, near the end he stated that the quickest drop will be in the first 300 years. I.E. If we stopped using Carbon sources now, in 300 years we would be hard pressed to find a difference between the CO₂ ppm and pre-industrial levels. If we waited a half century to a century before decreasing oil/coal usage, wait an additional 300 years, and we'll be back to below current levels.

Since everything is based on an Asymptote with absorption, as well as organic and inorganic sequestration, after the first half millennium, it could take thousands or hundreds of thousands of years to return to the 280ppm baseline if we ever reach it.

The Revelle saturation concept is important.... So there may be a limit as to how much CO₂ the ocean can absorb. And, of course, all the acidity equilibriums. At the moment we're probably not at a big risk of acidifying the entire ocean more than happened during the last glacial period. However, if we add 5000 Gigatons of CO₂ to the atmosphere, that will be a different story.

Here is the Takahashi Paper that discusses CO₂ absorption at the Ocean Surface, and local effects caused by it. I must admit that I skimmed it. Anyway, it does talk a lot about surface absorption of CO₂.

http://www.ldeo.colu...rs/taka2002.pdf

Anyway...

Back to the Archer Paper.

He does present an important concept, tucked away at the bottom right of Page 2.

The Change in Temperature (at Equilibrium) = 3°C * log₂(pCO₂/278) = (3°C * ln(pCO₂/278)) / ln (2)

He doesn't provide a derivation of this equation, but perhaps it is in some of the references.

So, on the Glacial Period end... this is saying...

The Change in Temperature (at Equilibrium) = 3°C * log₂(180/278) = (3°C * ln(180/278)) / ln (2) = -1.88°C

THIS IS NOT THE NET FORCING OF -8°C that one is often led to believe with the ice age examples.

Putting in the current levels of 390ppm CO₂, we get:

The Change in Temperature (at Equilibrium) = 3°C * log₂(390/278) = (3°C * ln(390/278)) / ln (2) = 1.47°C net forcing.

That seems a bit high, but one could always argue that we're not at equilibrium yet either.

I would say that the average temperature of the surface of Earth's Crust must be equal to the average temperature of the lower atmosphere at equilibrium. And that would include the oceans. There is some forcing by geothermal heat. But, that too is part of the atmospheric temperature.

In fact, in the Archer Diagrams, the peak temperatures don't seem to follow the peak CO₂ppm, but only the equilibrium concentrations. But, that would be explained by the enormous buffering capacity of the oceans and the ice caps. So, unless we pick an arbitrary pCO₂ cap such as 400 ppm, and maintain it at the cap for an extended period of time, we will never fully reach equilibrium, but rather we'll likely use all the easily accessible carbon up, then stop relatively abruptly.

All of this also predicts to some extent the delay that is seen between the the drop in temperatures and drop in CO₂ that is seen at the end of interglacial periods and the beginning of ice ages. And, with the -1.88°C "forcing", something else must be causing the rapid changes in temperatures during the ice ages or glacial/interglacial periods.

Anyway, I guess the next step is to try to understand the derivation of that logarithmic function.

[skierinvermont]

Thanks,

Excellent article.

(and, to others I'd encourage attempting to understand the references before replying)

...

Several problems with your post here.

Ok...

So, with Archer's notes (Figure 1)

If we stop using Carbon Fossil Fuels Now (300 Gigatons)

Our atmosphere CO₂ will peak at about the current level of 400ppm or so, and will decay back down to below 300ppm relatively quickly.

If we hit a likely scenario of at least 1000 Gigatons total, then it should peak somewhere around 500ppm, and decay back to below 350ppm (below current levels) relatively quickly.

If we hit 2000 Gigatons, then it will drop down to maybe 450ppm, followed by eventually dropping below 400ppm.

Archer plotted everything on a scale that it is impossible to get a close estimate of the exact time scales, and I can imagine why . However, near the end he stated that the quickest drop will be in the first 300 years. I.E. If we stopped using Carbon sources now, in 300 years we would be hard pressed to find a difference between the CO₂ ppm and pre-industrial levels. If we waited a half century to a century before decreasing oil/coal usage, wait an additional 300 years, and we'll be back to below current levels.

First you claim that it drops below 300/350 "relatively quickly" but then you admit that you can't actually read the X-axis. The X-axis is in thousands of years because the whole point of the paper is that it takes longer than most realize for the earth to absorb the carbon.

Then you falsely infer that just because most of the carbon is absorbed in the first 300, that we will be back to pre-industrial levels. In fact, he says at the end of the paper VERY EXPLICITLY (I guess you did not read this) that a good rule of thumb is that it takes 300 years to absorb most of it and then 25% lasts forever. That is representative of the very long tails on the graphs. That's a pretty overly simplistic rule of thumb though. See my below and other papers for a more detailed analysis of the lifetime of carbon over the next 1000 years.

Putting in the current levels of 390ppm CO₂, we get:

The Change in Temperature (at Equilibrium) = 3°C * log₂(390/278) = (3°C * ln(390/278)) / ln (2) = 1.47°C net forcing.

....

Anyway, I guess the next step is to try to understand the derivation of that logarithmic function.

That functions is simply the mathematical representation of the well known and well accepted climate sensitivity of 3C/doubling CO2 including feedbacks. The IPCC report is full of references and information that support a climate sensitivity in this range. The atmospheric response to CO2 is modeled to be 1.2C/doubling and then the rest of feedbacks. The response to CO2 alone is quite easily calculated and that number has been around for quite a while.

Anyways this paper is not really the best paper to use if we want to look at the atmospheric response over the course of the next 1,000 years because it is largely focused on the next 10,000-100,000 years.

To get a better idea of what is likely to happen with CO2 levels over the next 1,000 years, here is another paper by the same author (Archer) and a group of other researchers:

http://geosci.uchica...nn_rev_tail.pdf

As you can see from the chart on page 125, a 1000 Pg release of CO2, which is about what humans are expected to emit by 2100, it takes about 200 years to fall back to 500ppm, 400 years to fall back to 450ppm, and 1,000 years to fall back to 400ppm which is the current level. The model assumes a pre-industrial starting concentration of 278ppm, but even after 5,000 years the concentration is still 370ppm

Remember, this is the response to 1000 Pg, we have already emitted 300 Pg, and will emit at least 1000 Pg by 2100 probably more without very serious global legislation. If we don't stop emitting by then, obviously it will take even longer and the resulting equilibrium will be higher.

These numbers are roughly similar to those found in the IPCC report. As you can see in figure 10.35 b( on page 826 chapter 10:

http://www.ipcc.ch/p...1-chapter10.pdf

for an emissions scenario which takes us to roughly ~625-650ppm, which is a reasonable scenario and is where we are heading without major global legislation, it takes 300 years to fall back to 500ppm, and 900 years to fall back to 450ppm. Pretty similar to the Archer study I posted above, but slightly slower decline. Not sure exactly what the differences are but I think it may have to do with the fact that the carbon is being released over a longer period which allows more warming to occur. Archer's study uses a one time dump of 1000Pg much of which would be immediately absorbed by the very cold (relatively) oceans.

These are all based on scenarios which emit about 1000 Pg and then cease emissions.. if you burn more than that then it takes much longer to lower CO2.

Anyways.. from both of the above studies I posted they conclude that if we keep going at the current rate until 2100, and then cease emissions magically, we would still have 475-500ppm in the atmosphere in the year 2400. And then 1,000+ years to fall back close to current levels.

You are simply reading the X-axis of Archer's study wrong and misinterpreting/not reading his conclusions.

[nzucker]

The carbon we emit today will be with us for a long time, undoubtedly, sadly.

However, it probably won't matter much in the long-term since humans will figure out how to geoengineer the climate to return to past conditions, or at least a close approximation. With the cloud seeding going on in China and the various ideas presented about using mirrors to deflect solar radiation or using cellulose/plastic covers to protect ice sheets and glaciers, I can't imagine we're more than 100-150 years away from having a much better control of the global thermostat. I think the most serious threat is the acidification of the oceans (which may be accelerated by seeding them with iron to absorb more carbon dioxide) and the inevitable displacement of ecosystems from warming, which will be hard to reverse. Of course, none of this is any reason not to control emissions, since we haven't yet designed a reasonable method for mitigating climate change.

I'm not convinced we'll see 3C of warming with a doubling of CO2, just because other natural cycles seem to be heading towards colder such as solar activity. With carbon concentrations increasing from 280 to 400ppm since the Industrial Revolution, we've seen about 1C of warming, and this period of warming includes having all the natural factors aligned favorably for a milder climate with few volcanic eruptions of any magnitude, the highest solar activity in 70,000 years, and most recently a Pacific biased towards El Niño and a cryosphere in an unfavorable state for maintaining albedo. There's still a big question in my mind about how much warming we'll see in the next 30-40 years given the PDO and solar trends, and a plateau in global temperatures for such a long period could make it difficult to achieve the 3C doubling that is theoretically predicted.

[skierinvermont]

The carbon we emit today will be with us for a long time, undoubtedly, sadly.

However, it probably won't matter much in the long-term since humans will figure out how to geoengineer the climate to return to past conditions, or at least a close approximation. With the cloud seeding going on in China and the various ideas presented about using mirrors to deflect solar radiation or using cellulose/plastic covers to protect ice sheets and glaciers, I can't imagine we're more than 100-150 years away from having a much better control of the global thermostat.

I would love to see the evidence that these methods may one day in the future solve climate change and without severe undesirable side effects perhaps worse than the climate change itself. Otherwise all you seem to be saying is in the future we will be able to do anything. Yes no doubt great progress has been made, but that doesn't mean that in the future we will be able to do anything. Quite frequently researchers are able to at least hypothesize ways in which something might be done effectively and safely, but I don't see any evidence of that yet with regard to climate engineering. All of the methods you proposed have glaringly large problems with no plausible solution. The IPCC concluded of all proposed climate engineering methods to date that they were unproven to be effective and safe on a large enough scale. Studies which have considered possible climate engineering methods have made it quite clear that they are NOT a substitute for reducing emissions.

So given the lack of evidence that these methods are currently or even ever will be effective, your argument basically seems to be it doesn't matter we will be able to do pretty much anything in 100-150 years. By the same standard, why worry about the environment at all? Let's just burn everything, dump pollutants, kill all the animals.. after all surely we will be able to travel through space in a few hundred years and/or magically make all the pollution go away.

I would love to see the evidence that any of these climate engineering methods are even remotely close to being effective and safe on a large enough scale.

Given the failed and dangerous history of trying to control nature, this is not a path we should be going down intentionally. I can give you dozens of examples where humans have intervened in nature trying to "fix" it and make it better, but the unintended and poorly understood side effects were much worse than the original problem itself.

[BethesdaWX]

Several problems with your post here.

First you claim that it drops below 300/350 "relatively quickly" but then you admit that you can't actually read the X-axis. The X-axis is in thousands of years because the whole point of the paper is that it takes longer than most realize for the earth to absorb the carbon.

Then you falsely infer that just because most of the carbon is absorbed in the first 300, that we will be back to pre-industrial levels. In fact, he says at the end of the paper VERY EXPLICITLY (I guess you did not read this) that a good rule of thumb is that it takes 300 years to absorb most of it and then 25% lasts forever. That is representative of the very long tails on the graphs. That's a pretty overly simplistic rule of thumb though. See my below and other papers for a more detailed analysis of the lifetime of carbon over the next 1000 years.

That functions is simply the mathematical representation of the well known and well accepted climate sensitivity of 3C/doubling CO2 including feedbacks. The IPCC report is full of references and information that support a climate sensitivity in this range. The atmospheric response to CO2 is modeled to be 1.2C/doubling and then the rest of feedbacks. The response to CO2 alone is quite easily calculated and that number has been around for quite a while.

reading the paper was a complete waste of time for lack of relevance to my discussion with "Salbers".......... however...problems with your post.

1) Why don't you try reading? Quote "If we stopped Co2 emissions now"... even if 25% would remain, there would be very little difference between the dangerously low 275ppm Pre-Ind levels and what would outcome from the remaining Co2. (aka, 25% more from 275ppm.....303.75ppm vs 275ppm) wow!

2) BAD SCIENCE. 25% of emitted CO2 lasts "forever"....wtf?! There is no basis for such a claim, even in reading the whole damn article. This is another problem with these studies, they either make claims with no backup, or use Hypothesis as "evidence". There is a reason AGW studies need to throw out the SM in order to get the desired results. You can get data to show what you want....very easily.

3) Co2 correlation to temperature. This is where the flop is in the AGW debate, and is the reason AGW will be dead in 10-20yrs.

[salbers]

As for (2), it is stated as an approximate rule of thumb. In practical terms I find little distinction between "forever" and many thousands of years. Seems like good science to me.

Can you name a claim in the paper that isn't backed up, or a hypothesis used as evidence?

Otherwise, glad to see the thoughtful discussion in this thread

[BethesdaWX]

As for (2), it is stated as an approximate rule of thumb. In practical terms I find little distinction between "forever" and many thousands of years. Seems like good science to me.

Can you name a claim in the paper that isn't backed up, or a hypothesis used as evidence?

Otherwise, glad to see the thoughtful discussion in this thread

Well, I do! It bugs me.

1) Saying "25% of emitted Co2 will remain in the atmosphere for 10,000yrs", sounds alot better than "25% of Co2 will remain with forever in all of time".

Definitely a distinction, and it can effect how people view the article, and the author.

Although "bad science" was poor wording choice on my part. Remember, I need to make skier look as bad as possible.

2) My claims of hypothesis have always been on the Co2-temperature correlation....I've never argued the properties of the Co2 Molecule itself, and the fact that there is more C02 now than there has been in the past few million years.

[salbers]

Glad to see the followup paper by Archer et. al. with more details - thanks to Skier. It's still uncertain whether the lifetime of the "CO2 tail" would be 10000 years, or even 100000 years. They are both long lifetimes. Perhaps the main thing that might shorten this is increased sequestration in the soil, either via natural processes or via agricultural help, such as the use of biochar. Still, it's interesting that the second Archer paper suggests the vegetation's ability to draw down carbon may just be a short term thing. What's the story with that?

[skierinvermont]

The author explains his use of the word forever means any timescale relative to humanity. In reality it's not just 10,000 years, it lasts for 100,000+ years.

It makes perfect sense that based on the assumptions in the model it would take 100s of thousands of years to re-absorb the CO2. When you extract CO2 from deep in the earth's crust that has been there for 10s of millions of years it takes a long time to return it. The result is more CO2 in the ocean and atmosphere and the ocean and atmosphere must be in equilibrium. If there is more carbon in the ocean/atmosphere system the CO2 level will be higher. The only way to remove carbon from the ocean/atmosphere system is through very slow weathering of CaO to form CaCO3. However, even this process can only take you so far because CaCO3 is more soluble at lower pHs, and the pH of the ocean will be lower due to the higher pCO2. So the only way I see is to essentially reform the fossil fuel deposits which takes millions of years.

This is all based on a simplistic model of course which ignores things like ice ages. If we were to head into an ice age in 100,000 years it could speed the process along.

[BethesdaWX]

The author explains his use of the word forever means any timescale relative to humanity.

And what is that?

[nzucker]

I would love to see the evidence that these methods may one day in the future solve climate change and without severe undesirable side effects perhaps worse than the climate change itself. Otherwise all you seem to be saying is in the future we will be able to do anything. Yes no doubt great progress has been made, but that doesn't mean that in the future we will be able to do anything. Quite frequently researchers are able to at least hypothesize ways in which something might be done effectively and safely, but I don't see any evidence of that yet with regard to climate engineering. All of the methods you proposed have glaringly large problems with no plausible solution. The IPCC concluded of all proposed climate engineering methods to date that they were unproven to be effective and safe on a large enough scale. Studies which have considered possible climate engineering methods have made it quite clear that they are NOT a substitute for reducing emissions.

Here's the 2005 article from Popular Science that I was referring to; it's a great read and very informative:

http://www.popsci.com/environment/article/2005-06/how-earth-scale-engineering-can-save-planet

The authors' solutions (beyond the giant space mirror) are neither unrealistic nor inherently dangerous....they include very well-known methods for engineering climate such as sequestering carbon underground in used oil/gas fields, dumping small quantities of iron into the Southern Ocean to incite the development of carbon-consuming plankton, and using simple chemical reactions to transform carbon dioxide into magnesium carbonate, a relative of limestone. While none of these methods singlehandedly can solve the problem, together they may offer a solution. Carbon sequestration is already occurring in various EU-funded projects in European power plants, I'm personally friends with one of the developers of the "artificial tree" (carbon sequestration technique), etc. Here is an article about the EU's attempts and guidelines to sequester carbon, from 2007:

http://www.euractiv.com/en/climate-change/carbon-capture-storage/article-157806

If these ideas are already viable today, it seems ludicrous that the IPCC doesn't acknowledge that they'll be totally on the table in 50-100 years when climate change becomes more severe. I'm thinking we don't warm much for the next 30-40 years given the Maunder-style minimum and PDO state, so that gives us plenty of time to experiment with these plans, perhaps leaving the giant space mirror out.

[skierinvermont]

Here's the 2005 article from Popular Science that I was referring to; it's a great read and very informative:

http://www.popsci.co...can-save-planet

The authors' solutions (beyond the giant space mirror) are neither unrealistic nor inherently dangerous....they include very well-known methods for engineering climate such as sequestering carbon underground in used oil/gas fields, dumping small quantities of iron into the Southern Ocean to incite the development of carbon-consuming plankton, and using simple chemical reactions to transform carbon dioxide into magnesium carbonate, a relative of limestone. While none of these methods singlehandedly can solve the problem, together they may offer a solution. Carbon sequestration is already occurring in various EU-funded projects in European power plants, I'm personally friends with one of the developers of the "artificial tree" (carbon sequestration technique), etc. Here is an article about the EU's attempts and guidelines to sequester carbon, from 2007:

http://www.euractiv..../article-157806

If these ideas are already viable today, it seems ludicrous that the IPCC doesn't acknowledge that they'll be totally on the table in 50-100 years when climate change becomes more severe. I'm thinking we don't warm much for the next 30-40 years given the Maunder-style minimum and PDO state, so that gives us plenty of time to experiment with these plans, perhaps leaving the giant space mirror out.

Dumping iron in the ocean is basically what we already do to the gulf of Mexico already. It's called fertilization and most environmentalists know it as pollution. Iron fertilization basically involves doing this on a world wide scale continuously. It would completely destroy natural ocean ecosystems and have who knows what unintended consequences.

While carbon sequestration is likely to play a role in the future it is extremely expensive. What I objected to was your claim that "The carbon we emit today.... Probably won't matter much in the long-term since humans will figure out how to engineer the climate." It does matter because all of the proposed methods are either extremely expensive (sequestration) or dangerous to humans and the environment (iron deposition, SO2 in the stratosphere) and also require society to take climate change seriously in order to act. The only really viable, safe and potentially cost effective method of climate engineering is sequestration, but even that is extremely expensive.

The following study estimates that the "capture" portion of carbon capture and storage (CCS) will increase energy costs by 40-70% at your typical modern efficient coal power plant. This is because it requires burning 25-40% more fuel in order to store the carbon, and large amounts of money to build the carbon capturing portion of a power plant as well as to maintain it. NOTE: this is an estimate for the future on a mass commercial scale, presently it costs much more than this because it is done on a smaller less efficient scale. This is NOT an estimate of how much it costs now but an estimate of how much it WILL cost. Also note that this is the cost of a new plant with CCS technology vs a traditional plant. It costs much more to retrofit old plants and those costs are not included.

http://www.ipcc.ch/p...wholereport.pdf

Then you have the "transport and storage." These vary depending on how far you have to pipe and/or transport the CO2 via tanker. Some of this can be offset by using it to enhance oil recovery.

The net cost increase in power costs is 43-91% for your typical coal modern efficient coal power plant. See table 8.3a on p.347. Plants located near oil fields will have some of this cost offset because they can sell the CO2 for enhanced oil recovery.

Just to throw out some rough calculations given U.S. electricity demand of 4 billion MWh and generation costs of $60/Mwh (up from the $48/Mwh in 2002 which is the price the study used), multiplied by say a ~60% increase in costs(between the 43%-91% range), that comes to roughly $144 billion annually in the U.S. alone.

This will only sequester 85-90% of emissions from U.S. electricity generation alone. Electricity accounts for less than 40% of U.S. emissions. So you are basically paying $150 billion annually to sequester about one third of U.S. emissions. If the cost of coal/oil/gas goes up so will this price tag.

In other words it's extremely expensive and doesn't come close to solving the problem. In fact, present day wind and solar are cheaper than projected future sequestration costs and are becoming even cheaper. But you are still left with the other 60% of emissions that is not related to electricity generation. The other methods of climate engineering are much more expensive or extremely dangerous to humans and the environment. So I simply cannot agree with your claim that our emissions don't matter because we will be able to engineer the climate.

[nzucker]

In other words it's extremely expensive and doesn't come close to solving the problem. In fact, present day wind and solar are cheaper than projected future sequestration costs and are becoming even cheaper. But you are still left with the other 60% of emissions that is not related to electricity generation. The other methods of climate engineering are much more expensive or extremely dangerous to humans and the environment. So I simply cannot agree with your claim that our emissions don't matter because we will be able to engineer the climate.

I said "Our emissions won't matter much in the long-term" referring to the 200/500/1000 years timescales you guys were discussing with regards to the longevity of carbon in the atmosphere. I meant that a few hundred years down the road, our approaches to geoengineering and carbon sequestration will be much more refined, and much less dangerous to the ecosystem. The Popular Science article mentions several of these options, which may sound a bit far-fetched now but will probably seem normal in a few hundred years. I do think our emissions matter in the medium-term, say the next century or so, since we're unlikely to find a geoengineering solution that fast and certainly likely to suffer the effects of such emissions. So I think you took my point a little out of context...I simply intended to say I wouldn't worry about carbon staying in the atmosphere in the uber long term.

[skierinvermont]

I said "Our emissions won't matter much in the long-term" referring to the 200/500/1000 years timescales you guys were discussing with regards to the longevity of carbon in the atmosphere. I meant that a few hundred years down the road, our approaches to geoengineering and carbon sequestration will be much more refined, and much less dangerous to the ecosystem. The Popular Science article mentions several of these options, which may sound a bit far-fetched now but will probably seem normal in a few hundred years. I do think our emissions matter in the medium-term, say the next century or so, since we're unlikely to find a geoengineering solution that fast and certainly likely to suffer the effects of such emissions. So I think you took my point a little out of context...I simply intended to say I wouldn't worry about carbon staying in the atmosphere in the uber long term.

It will in all likelihood matter in the 200+ timescale as well since none of those solutions will ever be cheap, completely effective or safe. Really the only one that I would consider at all viable is carbon sequestration which will be expensive and can only remove at most 30% of our emissions if you put it on every single power plant in existence. It's also projected to be more expensive than wind or solar or hydro or nuclear are at present, all 4 of which are better more realistic options at this point and are becoming even cheaper (in the case of wind and solar).

Yes who knows maybe we come up with some brilliant invention in the future that we just have no conception of now, but that's not something I'm willing to count on. It would be one thing if we had some conception but just needed to do some more R&D, it's another to have no foreseeable solution other than adaptation which will be very expensive and chaotic.