As part of an ongoing study I have computed monthly deviations between CO2 level at each of the seven southern stations lying from 40 deg S to the Pole obtained from the NOAA record of monthly averages for ALL Southern Hemisphere stations and the NOAA (monthly) average global CO2 levels for the period 1982 through 2006.
I then computed the average annual deviations for all southern stations from the global annual mean CO2 levels. Note I used strictly ONLY complete year records for each station and dumped any year if it had missed a single month or more.
The outcomes are in the plot below. Error bars are ± one sigma as usual.
Please note the 2nd inflection around 1998 when global temperatures were last maximal - slight cooling or plateau since then.
Northern Hemisphere CO2 levels undoubtedly continued to climb monotonically on an annual scale over the period 1982 – 2006 and we can reasonably presume was accompanied by no significant attendant global warming since about 2000.
However, it appears that after a hiatus in the 1990s, Southern Ocean and Antarctic CO2 levels have continued to deviate increasingly, in the negative sense, in relation to the global CO2 average (dominated by data from Northern Hemisphere and Tropical Zone monitoring stations).
In my view, this southern offset from the global average CO2 level should be getting smaller, not larger, worldwide due to increasing global circulation to be in accord with present GCM theory.
Zones of blooming cyanobacteria directly back-scatter solar radiation due to calcite-producing coccolithophores, which are found everywhere but especially in subpolar regions (Coccolithus pelagicus), thereby decreasing ocean heat retention and cool the overall water column (Hansen et al. 1997; Hansen and Nazarenko, 2004).
By shading the deeper waters and trapping energy near the surface where it can escape to the atmosphere, it is suggested this cyanobacterial ‘canopy’ decreases heat input to the deep ocean.
Cyanobacteria also produce the sulfur compound dimethylsulfoniopropionate, which decomposes in sea water into dimethylsulfide, diffuses into the atmosphere, and is oxidized, leading to acidic aerosols that function as efficient cloud condensation nuclei. In areas where cloud condensation nuclei are scarce, this could increase planetary albedo by creating more and brighter clouds of greater longevity.
It is speculated that cyanobacteria in the Great Southern Ocean entered a phase of higher blooming rates in the early part of the millennium, thereby consuming CO2, increasing oceanic albedo and cloud cover (via dimethylsulfide emissions) and likely significantly cooling the southern hemisphere.
This ‘effect’ (if such is what it is) is found directly by deconvolution of the official NOAA CO2 data record, and doesn’t appear to have anything to do (that I can think of) with solar cycles etcetera.
Please note this information is preliminary and currently subject to discussion, checking and related computation by myself and several colleagues during preparation of a paper to be submitted most likely to Geophysical Research Letters. In the mean time, may I request that this new finding be fairly attributed to myself in this blog AND to Short et al. (in preparation) ‘Evidence for Increasing Negative Deviation of Southern Ocean and Antarctic Atmospheric Carbon Dioxide Levels from Global Average’ cited elsewhere.
References:
Hansen, J., Sato, M. & Ruedy, R. (1997) J. Geophys. Res. 102, 6831–6864.
Hansen, J. & Nazarenko, L. (2004) Proc. Natl. Acad. Sci. USA 101, 423–428.
Regards
Dr Steve Short
Director
Ecoengineers Pty Ltd
www.ecoengineers.com
It is even more pertinent to note that all current GCMs tend to:
. overestimate the positive feedback from water vapour over the Pacific in El Nino warming; and
. underestimate the negative feedback from cloud albedo in El Nino warming - particularly with respect to low altitude cloud.
These deficiencies are now well recognised. See for example:
http://cires.colorado.edu/science/groups/pielke/classes/atoc7500/sun.pdf
I note that both of these effects are precisely the effects one would expect from a warm sea surface with a significant near surface population of cyanobacteria producing:
. increased low level cloudiness (due to enhanced nucleation by dimethyl sulfide emissions); and
. increased ocean surface reflectivity (= less surface warming) and reduced evaporation (i.e. effect on the wet adiabatic lapse rate) as a consequence of the increased generation of monolayers of lipids, sterols etc at the surface resulting from zooplankton predation and lysis due to cyanobacteriophages. A good analogy is the use by CSIRO etc to reduce evaporation off reservoirs and dams using octanol etc.
I just wanted to say that while it is fascinating that a lot of climate scientists can give a lot of attention to the effects on albedo of:
1) regional soots and other particulates falling on snow and ice; and/or
2) regional expansion of creosote bush (for Aussies read 'woody weeds') across open rangelands,
refer:http://climatesci.org/2008/06/
they seem strangely reluctant to consider the effects on ocean surface albedo and marine cloud albedo induced by regional variations in cyanobacterial primary production across the oceans' surface!
Perhaps I have to wait until the Arctic ice is completely melted!
Thanks Luke - I was aware of the 'dead seas' phenomenon of recent years off the Pacific North West Coast as I spend time in California every year on business and often take a break to drive around a bit.
IMHO it is quite possible that an increased flow of melt water out through the Bering Strait commenced in the early part of the decade leading to an increased upwelling off this coast via the North Pacific subtropical gyre. This is a coast which traditionally has picked up lots of thongs from Japanese and Korean fisherman, Nike shoes etc etc!
However, 'it's a jungle out there' where the balance between photosynthetic production of O2 by cyanobacteria ('blue-green algae') and 'dark decay' by aerobes consuming dead cyanobacteria and O2 has often been a fine one.
For every bloom that does not get dispersed by adequate mixing there will also be a 'bloom' of bacterial dark decay of the dead cells of cyanobacteria. This is a common occurrence in lagoons, lakes, even farm dams etc.
It is also very probable that there were, in counter balance, massive increases in the number of fish etc elsewhere in the gyre where better mixing of the blooming cyanobacteria was occurring.
We shouldn't lose sight of just how much we owe to the evolution of cyanobacteria AND the whole biogeochemical system they partially created and are inextricably embedded-in.
Everyone interested in this stuff should read Red Earth, White Earth:
http://pr.caltech.edu/periodicals/EandS/articles/LXVII4/Kirschvink%20Feature.pdf
Steve - perhaps tangentially relevant http://www.sciencedaily.com/releases/2008/02/080214144547.htm
Enjoyed your story on climate affecting volcanism above. Interesting hypothesis.
And back on topic:
http://www.nature.com/nature/journal/v451/n7176/pdf/nature06441.pdf
Louis
Not as weird as it seems. I have already given the reference to the Bay et al. PNAS review which contained the following:
Kyle et al.(17) pointed out that abundant visible tephra layers found by Gow and Williamson (18) at Byrd Station (also near volcanic sources in West Antarctica), which were clustered during the late part of the last glacial period, might have been due to a thickening of the West Antarctic Ice Sheet that initiated the eruptions in nearby
Marie Byrd Land. Zielinski et al. (15) noted that in the sulfate record at GISP2 the periods of greatest volcanic activity seemed
to occur during changing climatic conditions, especially during the early Holocene. Maclennan et al. (19) found a link between deglaciation and volcanism in Iceland that they attributed to
increased melt generation rates in the shallow mantle caused by unloading of the ice sheet. Numerical studies have shown that mantle stress accumulation associated with glaciation or deglaciation and meltwater change may have triggered or accelerated active Quaternary volcanism of the circum-Pacific
(20). Eruptions might be induced by climatically driven atmospheric jolts to the solid Earth’s rotational angular momentum (21) or by crustal stresses resulting from ice-sheet loading
unloading effects on the planet’s distribution of mass.
17. Kyle, P. R., Jezek, P. A., Mosley-Thompson, E. & Mosley-Thompson, L. S.
(1981) J. Volcanol. Geotherm. Res. 11, 29–39.
18. Gow, A. J. & Williamson, T. (1971) Earth Planet. Sci. Lett. 13, 210–218.
19. Maclennan, J., Jull, M., McKenzie, D., Slater, L. & Gro¨nvold, K. (2002)
Geochem. Geophys. Geosys. 3, 1062–1086.
20. Nakada, M. & Yokose, H. (1992) Tectonophysics 212, 321–329.
21. Stothers, R. B. (1989) J. Geophys. Res. 94, 17371–17381.
One of my earliest mentors back in the early 1970s when I was busy carving out early career as a exploration geochemist using AAS-based stream sediment analyses was the wonderful Nelson (NZ) ecologist Roger Bray, an early pioneer of these notions:
http://www.sciencemag.org/cgi/content/abstract/197/4300/251