Thanks for the reminder, ASLR. It's definitely either the ocean doing something or photosynthetic plants (or their debris) doing (or not doing) something, as far as I can see...or some combination thereof. I can't quite see how any patterns of emissions variation would have that kind of effect on that short of a timescale.
It would be nice to see a study on it though, rather than just our guesses, intelligent thought those may be.
wili,
First, in Reply #131 Bruce provides the following evidence linking the CO₂ variations to changes in flux/sink into/out-of the ocean:
"Global Assessment of Carbon Export Using Satellite Observations:
New Approaches and Plans for the Future"
Presented by
Professor David Siegel
Abstract:
The biological carbon pump is thought to export anywhere from 4 to >12 Peta (10^15) gC each year from the surface ocean depth in the form of settling organic particles, and its functioning is crucial for the global carbon cycle. Assessments of the global export flux have either been through the empirical extrapolation of point measurements to global scales or the results of ocean system model experimentation. Satellites resolve relevant space and time scales, providing guidance to the empirical extrapolation problem, but they do not quantify directly carbon export. Here, I introduce a mechanistic approach for assessing global carbon export by synthesizing modeling approaches with satellite observations. The resulting export flux model does an excellent job of reproducing regional export flux observations, and it reproduces the basic patterns of export both spatially and seasonally. The talk concludes by introducing an on-going planning project for a major NASA field campaign on the quantification of the biological pump from satellite observations.
Second, In replay #128 of the 2014 El Nino thread in the Consequence folder, Bruce Steele provides the following excellent explanation:
"The different Co2 content of the upwelled or downwelled water is due to it's different sources. The intermediate water upwelled under normal conditions in the eastern equatorial pacific is older water that has accumulated Co2 due to bacterial decomposition of organic matter. Organic matter is
ballasted by calcium carbonate and sinks till it hits the saturation horizon which is at intermediate depths in the pacific. Once the calcium carbonate dissolves the organic surface supplied material is remineralized by bacteria. The warm water in the graphs above are downwelled in the western pacific. These waters are much younger and haven't spent much time at depth so they don't have the high Co2 content.
Under normal conditions the eastern equatorial pacific contributes about 72% of all oceanic Co2 ventilation. When the warm western supplied water is pushed to the surface by the Kelvin wave is suppresses the cold high Co2 water and because the cold water no longer has surface contact with the atmosphere it stops ventilating. So the immediate effects of an El Nino are a reduction in natural supplies of oceanic derived Co2 but later as drought and terrestrial conditions increase the terrestrial supplies of Co2 dominate.
http://www.pmel.noaa.gov/pubs/outstand/feel1868/feel1868.shtml"
Therefore, the Mauna Loa C02 readings can be seen as clear evidence that the Eastern Pacific cold water upwelling is dropping off, and that we are in the process of changing to El Nino conditions.
Best,
ASLR
Poll
