Comments on: Atmospheric Residence Time of Man-Made CO2

By: Martin A

Martin A — Tue, 18 May 2010 20:35:41 +0000

No, he has not confused things. However, your view represents a common misconception, so it is worth explaining things a bit more.

There is a constant equilibrium interchange between atmosphere and the rest (biosphere/ocean). If I add a dollop of fresh CO2 to the atmosphere this has two effects:

[1] The eventual equilibrium levels are no longer the same because the total mass of CO2 in the system has changed. However, the changes in the equilibrium levels will be minuscule, even if my dollop had a mass of petagrams. This is because the ocean contains vastly (~50 times) the mass of CO2 that the atmosphere does. My dollop will represent a minuscule change to the total system even if it causes a significant change in the percent CO2 in the atmosphere.

[2] Because of the CO2 I added to the atmosphere, the system finds itself displaced from its (new) equilibrium state. It will now move towards its new equilibrium, getting halfway there in 5-7 years.

This is confirmed by the curve of the reduction of radioactive carbon 14 in the atmosphere following the atmospheric nuclear tests of the 50′s and early 60′s. The curve is consistent with an average residence time of 5-7 years:

http://cdiac.esd.ornl.gov/trends/co2/well-gr.html

Note that radiocarbon involved was totally new carbon created by interaction of neutrons from the explosions with nitrogen in the atmosphere – it played no part of the ongoing equilibrium exchanges of existing CO2 between atmosphere and the rest.

By: Derek

Derek — Sat, 27 Mar 2010 22:11:44 +0000

You’ve confused two things. The atmospheric residence time is how long a molecule stays in the atmosphere on average. This is around 5-7 years for CO2. But when it is absorbed by soil/plant/ocean, that does not take it out of circulation. Most will be re-emitted to the atmosphere over another few years. In terms of getting atmospheric CO2 levels back to normal, what matters is the residence time within this cycle. Long term removal, into rocks, is rather slower.
Pre-industrially, the annual exchange between atmosphere and land/ocean would have been around two thirds of the 200GtC it is now. If we stopped emitting CO2 tomorrow, that high rate of exchange would continue, with only about 2-3GtC more being absorbed than emitted each year. So it will take 70-100 years to remove the 200GtC we’ve added to the atmosphere.

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By: Michael Moon

Michael Moon — Tue, 05 Jan 2010 17:34:45 +0000

Magnificent. I am sending this to my Congressman even though I live in the bluest of blue states Illinois! For anyone willing to open up their minds this should put the entire question to rest.

By: admin

admin — Tue, 05 Jan 2010 17:05:49 +0000

Thanks Michael. There’s a graphic of some published atmospheric CO2 residence times here:

http://c3headlines.typepad.com/.a/6a010536b58035970c0120a5e507c9970c-pi

I thought it might be good news if CO2 resides in the atmosphere for less time that the IPCC’s claimed 50 to 200 years.

By: Michael Moon

Michael Moon — Tue, 05 Jan 2010 16:52:04 +0000

Did you guys read the article? He is saying IPCC was radically wrong in their Summary for Policymakers. He is saying that the residence time of CO2 is only five years. Let’s do a little arithmetic here. 750 Gt carbon in the atmosphere, five year residence time, each year arond 150 Gt goes in and out due to vegetation/algae growing/rotting and the oceans absorbing/spewing back in. We are putting in a maximum of 8 Gt/year, we are a pimple on Mother Nature’s posterior, lost in the natural standard deviation. AGW is a masssive hoax, wake up and smell the coffee people! Professor Essenhigh for Leader…

By: admin

admin — Fri, 01 Jan 2010 20:59:16 +0000

There’s not enough fossil-carbon fuels for atmospheric CO2 to get anywhere near toxic levels.

By: AutoBotMan

AutoBotMan — Fri, 01 Jan 2010 17:14:36 +0000

You only tell 1/2 the story……what happens when the air starts to get saturated with CO2 and plants can’t absorb it all? Do those plants keep growing? Do Humans keep growing?

“Plants need CO2 and, therefore, will thrive under more concentrated atmospheric conditions. These plants will absorb the excess CO2, but there is a level where plants can no longer absorb the gas, and CO2 becomes toxic. Too much CO2, like too much fertilizer, stunts the growth rate of many plants. ”

And

“Humans are affected by too much CO2 in the air more quickly than by lack of O2. Higher levels of CO2 are toxic to humans, primarily due to oxygen deficiency”.

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By: Anonymous

Anonymous — Tue, 01 Sep 2009 09:09:43 +0000

I should also have added that this very article basically says that the IPCC is drastically overestimating the CO2 effect to begin with, because of the false assumption of the duration of CO2 in the atmosphere. Which means that the calculated 0.2 degree reduction if cap and trade is fully implemented would also have been overestimated, and the effect of us reducing CO2 emissions would be far less.