Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation by M. A. Martínez-Botí, G. Marino, G. L. Foster, P. Ziveri, M. J. Henehan, J. W. B. Rae, P. G. Mortyn & D. Vance. Nature 518, 219–222 (12 February 2015) doi:10.1038/nature14155. As far as I can tell, no-one has covered this yet (well, all right, ScienceDaily did).

Its not that wildly exciting (so much so that I’m a touch surprised it made over-excitable Nature); but it is interesting. Another step on the Mystery of Deglaciations; the kind of stuff SoD has been banging on about a bit. Here’s the abstract:

Atmospheric CO2 fluctuations over glacial–interglacial cycles remain a major challenge… to explain glacial–interglacial atmospheric CO2 variations invoke changes in deep-ocean carbon storage, probably modulated by processes in the Southern Ocean, where much of the deep ocean is ventilated. A central aspect of such models is that, during deglaciations, an isolated glacial deep-ocean carbon reservoir is reconnected with the atmosphere, driving the atmospheric CO2 rise observed in ice-core records. However… Radiocarbon activity tracks changes in ocean ventilation, but not in ocean carbon content, whereas proxies that record increased deglacial upwelling do not constrain the proportion of upwelled carbon that is degassed relative to that which is taken up by the biological pump. Here we apply the boron isotope pH proxy in planktic foraminifera to two sediment cores… as a more direct tracer of oceanic CO2 outgassing. We show that surface waters at both locations, which partly derive from deep water upwelled in the Southern Ocean, became a significant source of carbon to the atmosphere during the last deglaciation, when the concentration of atmospheric CO2 was increasing…

So in broad terms, this is the same story as before: to explain the level and speed of CO2 changes at deglaciations, you probably need CO2 to ventilate from deep-ocean reservoirs (this also comes into the T/CO2 lead/lags stuff). Exactly what might cause that to occur is no clearer; there’s just a little bit more evidence that this actually occurred, rather than the somewhat more process-of-elimination there was before.

Attribution of Arctic temperature change to greenhouse-gas and aerosol influences, Najafi et al.

This one has been reported elsewhere, e.g. Aerosols dampen pace of Arctic warming for now, say scientists by CarbonBrief, so I don’t think I need bother say much. Aerosols offset warming. Who’da guessed?

Unprecedented 21st century drought risk in the American Southwest and Central Plains, Cook et al.

I sometimes wonder if I should take Unprecedented 21st century drought risk in the American Southwest and Central Plains type stuff more seriously. But there are so many Americans who are already doing so, I hardly need to.


* UAB – Carbon release from ocean helped end the Ice Age.
* Meanwhile, back in the real world, Rotating Eyeballs with Eli.


  1. #1 See Noevo

    Speaking of oceans…
    After billions of years of receiving salt-bearing flows from rivers and run-offs, why aren’t the oceans a heck of a lot saltier than they actually are?

  2. #2 Mike Haseler (Scottish Sceptic)

    [I’m somewhat surprised to see you here, after some of your earlier posts. I’m afraid a comment simply spamming links to multiple blog postings isn’t really acceptable; its over here if anyone wants to see -W]

  3. #3 JBL

    See Noevo, try
    for a quickie answer and pointers to more.

  4. […] Source: Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation. And… [Stoa… […]

  5. #5 See Noevo

    To JBL #2:

    Thanks, but not helpful to me.

    “A NASA-funded expedition, the Salinity Processes in the Upper Ocean Regional Study (SPURS), traveled to the North Atlantic’s saltiest spot to analyze the causes behind this high salt concentration and to validate Aquarius measurements.”

    I’m not aware of any studies that say that ocean salinity overall has declined or even could decline.
    How did the ocean get so salty to begin, and why couldn’t it get saltier?
    I wonder if the ocean salinity-studying NASA could answer my questions.

  6. #6 MobiusKlein

    See, can I ask what your point is here? YEC-ism is a bit off topic from boron levels in plankton.

    [That’s what I was wondering -W]

  7. #7 Nick Barnes

    The sodium thing, like a lot of nonsense from YECs, is palpably nuts. Sodium comes into the sea from rock erosion. Rocks are deposited by sedimentary processes in the ocean (and elsewhere). So duh.

  8. #8 BBD

    There’s a suggestion that a reduction in the extent of Antarctic sea ice cover might be the trigger which causes rapid CO2 release during deglaciation. The converse – that increased Antarctic (summer) sea ice cover prevented the upwelling of deep water and the release of CO2 to the atmosphere – is argued in Ferrari et al. (2014):

    In the modern climate, the ocean below 2 km is mainly filled by waters sinking into the abyss around Antarctica and in the North Atlantic. Paleoproxies indicate that waters of North Atlantic origin were instead absent below 2 km at the Last Glacial Maximum, resulting in an expansion of the volume occupied by Antarctic origin waters. In this study we show that this rearrangement of deep water masses is dynamically linked to the expansion of summer sea ice around Antarctica. A simple theory further suggests that these deep waters only came to the surface under sea ice, which insulated them from atmospheric forcing, and were weakly mixed with overlying waters, thus being able to store carbon for long times. This unappreciated link between the expansion of sea ice and the appearance of a voluminous and insulated water mass may help quantify the ocean’s role in regulating atmospheric carbon dioxide on glacial–interglacial timescales. Previous studies pointed to many independent changes in ocean physics to account for the observed swings in atmospheric carbon dioxide. Here it is shown that many of these changes are dynamically linked and therefore must co-occur.

  9. #9 Steve Bloom
    United States

    Had to look. Apparent;y SoD’s somewhat obsessive flight of fancy trying to find some sort of chaotic process underlying the deglacials got Haseler all excited.

    Thanks BBD, that’s what I was faintly recalling. The sea ice explanation is intuitively appealing, although later on it seems like the southerly shift of the westerlies would be important for squeezing out more CO2.

New comments have been temporarily disabled. Please check back soon.