The New Old News You’ve Never Heard…

The Climate Blogosphere is all a flutter over a recent study:

Knorr, W. (2009), Is the airborne fraction of anthropogenic CO2 emissions increasing?, Geophys. Res. Lett., 36, L21710, doi:10.1029/2009GL040613.

The gist that has people excited or concerned is that the portion of the CO2 we emit that stays in the atmosphere has remained more or less constant. It has been hypothesized by some that as warming increases, the earth will lose it’s ability to absorb our CO2 gradually. Since our emissions are increasing, if the sinks were constant, the ratio would be  increasing gradually. If sinks were absorbing less CO2 then there would be a rapid increase. But if the ratio has stated the same, that means that the amount of CO2 that is absorbed by the Oceans and biosphere etc. is increasing. In other words, we emit more, and the Earth’s capacity to absorb CO2 increases proportionally. This is exactly the opposite of the “CO2 feedback” hypothesis, that a warmer world will be less able to absorb CO2. Thus more of our emissions will stay in the atmosphere, which means more warming, rinse lather repeat.

But we already knew this. Search google for “missing sink” to find plenty of articles that explain that there is a bunch of carbon dioxide that is emitted into the atmosphere that carbon cycle modelers have no clue what happens to. There are a lot of hypotheses, but the issue at present is still unresolved. What’s more, it has long been know that our emissions are more than enough to account for the increase in CO2 concentrations, so that the “missing” amount of CO2 is increasingly large and difficult to account for.

One possible explanation is that the biosphere is absorbing more CO2 through photosynthesis. I don’t know if anyone is testing this but it would make sense and fits with studies indicating increases in primary productivity.

Yet in spite of this not being news, you haven’t heard it, most likely, until now. Well that’s probably because it is surprisingly good news. Logically as warmer oceans lose their ability to sequester CO2 and as higher temperatures presumably result in release of “trapped” carbon from permafrost (in the case of methane this is VASTLY contradicted by observational evidence). If that were the case then the airborne fraction would have to be increasing. Since it is not, it appears that the carbon cycle feedback hypotheses are not supported at present by the evidence.


6 Responses to “The New Old News You’ve Never Heard…”

  1. The Drain is Bigger than the Faucet « the Air Vent Says:

    […] Posted by Jeff Id on November 11, 2009 UPDATED:  I misread the graph, thanks to TTCA who has done a good post on it here. […]

  2. Dave Dardinger Says:

    Actually I’ve been aware of the basic facts here for a number of years. I have done a sort of analysis of the numbers and found there was a slight acceleration of the increase in CO2 in the atmosphere, but it’s pretty small. But if you want a suggested reason the % of CO2 retained in the atmosphere is more or less constant, it’s that the supposed “warming” of the oceans is greatly overestimated. This is because the majority of warming is just in the surface waters and this warmth can be purged periodically. (See recent stories about different sorts of el ninos.)

    Most of the cold water which moves from the surface to deep waters is produced at the ice edges (mostly in the Arctic I believe) where the winter production of new ice densifies the surface water allowing it to sink. This produces water which can maximally absorb CO2 and then sinks with this CO2 to the bottom waters. Now actually this water has less CO2 than that in the bottom waters it displaces, but it now has more CO2 than in the recent past, so the net difference in the waters up vs waters down is less. The “new” CO2 which rises is fertilized and promotes growth of plankton and related organisms. A lot of this organic CO2 is then returned to the deeps when the organisms die and sink.

    The net result is that the higher amount of CO2 in the atmosphere is absorbed by a roughly isothermal body of cold sea water avoiding the warmer tropical waters.

  3. rob r Says:

    What a surprise. Increasing emmissions and atmoispheric CO2 concentration lead to greater primary productivity! Who would have thunk it.

    Well actually heaps of people have suggested this to be a likely result. Nearly every week the Idso’s over at “CO2 science” predict this will occur. They have even been so good as to assemble a massive data base of experiental data on the subject.

    The IPCC alarmists seem to have thier fingers firmly planted in thier ears on this subject.

  4. timetochooseagain Says:

    Rob R-yes, the Idsos have been arguing for the importance of the CO2 fertilization effect for some time. What I mean is that I wonder if this is the explanation for the increasing sink. It certainly would help.

    Dave-thanks for the thoughts. Sounds like as good an explanation as any but I’m not up enough on the details to make a comment.

  5. Angels On The Head Of A Pin « Hypothesis Testing Says:

    […] incredible because it seemed me like they just found exactly the opposite was true. Golly science changes fast! Try to keep […]

  6. Something Else Curious… | Hypothesis Testing Says:

    […] something like this that people estimate the so called “airborne fraction.” We’ve discussed that before, (see also discussion at Jeff’s blog). At any rate, compare emissions from fossil fuel […]

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