How does rising atmospheric CO2 affect marine organisms?

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Biology Rules: On Land and at Sea
Volume 5, Number 33: 14 August 2002

In our Editorial of 2 January 2002, we described the study of Eastman et al. (2001), who used a hybrid atmosphere/vegetation model composed of linked meteorological and plant growth sub-models to investigate the individual and combined consequences of the direct climatic effect of a doubling of the air's CO2 content (the so-called greenhouse effect), as well as the multi-faceted indirect climatic effect of that phenomenon, which is mediated by various plant physiological responses to atmospheric CO2 enrichment, including processes driven by CO2-induced changes in land surface albedo, leaf stomatal conductance, plant rooting profiles, fractional coverage of the land by vegetation, plant roughness length and displacement height, vegetation phenology, time of planting and harvesting (in the case of agricultural crops), and plant growth.

For the part of the planet included in this regional assessment, i.e., the area located between approximately 35 and 48 N latitude and 96 and 110 W longitude, it was determined that the net result of the simultaneous actions of the direct and indirect effects of the doubled atmospheric CO2 concentration was a 0.715C decrease in the area- and seasonally-averaged daily maximum air temperature and a 0.354C increase in the similarly-averaged daily minimum air temperature. Hence, what climate alarmists typically describe as detrimental, when only the greenhouse effect of atmospheric CO2 enrichment is considered, turns out to actually be beneficial, when several of the biological effects of this phenomenon are included in the calculations. During the time of greatest heat stress (mid-afternoon), for example, temperatures are lower; while during the time of greatest cold stress (pre-sunrise), they are higher. Likewise, the 1.069C reduction in the average daily air temperature range is indicative of a more thermally-stable environment; and a more thermally-stable environment is a less stressful environment. Last of all, the overall change in daily mean air temperature is not a dramatic warming, as climate alarmists are wont to claim, but a slight cooling.

It is also interesting to note in this regard that the study of Eastman et al. was by no means comprehensive, in that it did not include a number of other land-based biological phenomena that are known to temper the greenhouse effect of rising atmospheric CO2 concentrations, several of which are described in our Editorial of 10 October 2001, as well as elsewhere on our website. Yet even without these additional mechanisms, what Eastman et al. did include was sufficient to demonstrate that terrestrial plants have the ability to totally overpower any deleterious climatic consequences that, in their absence, would be expected to result from the greenhouse effect of atmospheric CO2 enrichment.

But what about the portion of the planet that is covered by the vast oceans of the world? Can the micro- and macro-algae that live in their waters do anything to counter the intensifying atmospheric greenhouse effect that is caused by the ongoing rise in the CO2 content of the air above them? Of course they can, as may be readily appreciated by scanning the materials we have listed under just the single heading of Dimethyl Sulfide in our Subject Index. In addition, the recently-published paper of O'Dowd et al. (2002) describes an entirely new phenomenon of this nature that may also have the capacity - all by itself, in fact - to totally thwart the CO2 greenhouse effect.

What O'Dowd et al. did, in the words of Kolb (2002), who writes about their work in a companion "news and views" article in Nature, was discover "a previously unrecognized source of aerosol particles" by unraveling "a photochemical phenomenon that occurs in sea air and produces aerosol particles composed largely of iodine oxides." Specifically, they used a smog chamber operated under coastal atmospheric conditions to demonstrate, as they report, that "new particles can form from condensable iodine-containing vapours, which are the photolysis products of biogenic iodocarbons emitted from marine algae." With the help of aerosol formation models, they also demonstrated that concentrations of condensable iodine-containing vapours over the open ocean "are sufficient to influence marine particle formation."

The significance of this work, of course, is that the aerosol particles O'Dowd et al. discovered can function as cloud condensation nuclei (CCN), helping to create new clouds that reflect more incoming solar radiation back to space and thereby cool the planet. With respect to the negative feedback nature of this phenomenon, O'Dowd et al. cite the work of Laturnus et al. (2000), which demonstrates that emissions of iodocarbons from marine biota "can increase by up to 5 times as a result of changes in environmental conditions associated with global change." Therefore, as O'Dowd et al. continue, "increasing the source rate of condensable iodine vapours will result in an increase in marine aerosol and CCN concentrations of the order of 20 - 60%." Furthermore, they note that "changes in cloud albedo resulting from changes in CCN concentrations of this magnitude can lead to an increase in global raidative forcing similar in magnitude, but opposite in sign, to the forcing induced by greenhouse gases."

Think about that. A previously unrecognized source of aerosol particles, which responds to global change in such a way as to possibly totally compensate for the radiative forcing induced by real-world increases in greenhouse gases, has just been discovered ... and it's only one of many such biologically-induced negative feedbacks that exist within earth's complex climate system. This development is indeed, as Kolb describes it, "big news to atmospheric scientists," who will need to rethink a lot of what they thought they knew about how earth's "biothermostat" operates. But will it cause the IPCC crowd to deviate in the least degree from their cherished-but-bogus objective of saving the planet from catastrophic CO2-induced global warming? Mark our words, it will not. And that must surely tell one something about their motives.

Dr. Sherwood B. Idso
Dr. Keith E. Idso
Vice President

Eastman, J.L., Coughenour, M.B. and Pielke Sr., R.A. 2001. The regional effects of CO2 and landscape change using a coupled plant and meteorological model. Global Change Biololgy 7: 797-815.

Kolb, C.E. 2002. Iodine's air of importance. Nature 417: 597-598.

Laturnus F., Giese, B., Wiencke, C. and Adams, F.C. 2000. Low-molecular-weight organoiodine and organobromine compounds released by polar macroalgae - The influence of abiotic factors. Fresenius' Journal of Analytical Chemistry 368: 297-302.

O'Dowd, C.D., Jimenez, J.L., Bahreini, R., Flagan, R.C., Seinfeld, J.H., Hameri, K., Pirjola, L., Kulmala, M., Jennings, S.G. and Hoffmann, T. 2002. Marine aerosol formation from biogenic iodine emissions. Nature 417: 632-636.