Saturday, October 10, 2009

CO2 Increase Impact - A Question of Complexity

CO2 is Green, a pending 501(C)(4) non-profit organization whose mission is to support scientifically and economically sound public policy on environmental issues. Currently, the non profit organization is attempting to sway public opinion by refuting “claims that CO2 is a pollutant…” To accomplish this CO2 is Green makes its own claim that facts support the position that “…lowering levels of carbon dioxide would actually inhibit plant growth and food production.” CO2 is Green claims the facts of carbon reduction advocates are “… a myth and are absolutely false.” CO2 is Green is not the only organization or group asking us to make decisions based upon their arrangement of information. What we have here, then, is a failure to communicate wrapped in a classic wicked problem, surrounded by a selective use of knowledge.

Challenged as to where to begin, a definition of carbon dioxide seems in order. From the web site of Lenntech Water treatment & purification Holding B.V we read:

“Joseph Black, a Scottish chemist and physician, first identified carbon dioxide in the 1750s. At room temperatures (20-25 oC), carbon dioxide is an odourless, colourless gas, which is faintly acidic and non-flammable. Carbon dioxide is a molecule with the molecular formula CO2. The linear molecule consists of a carbon atom that is doubly bonded to two oxygen atoms, O=C=O. Although carbon dioxide mainly consists in the gaseous form, it also has a solid and a liquid form. It can only be solid when temperatures are below -78 oC. Liquid carbon dioxide mainly exists when carbon dioxide is dissolved in water. Carbon dioxide is only water-soluble, when pressure is maintained. After pressure drops the CO2 gas will try to escape to air. This event is characterized by the CO2 bubbles forming into water.”

Glossing over the many uses that carbon dioxide offers to mankind including decaffeinated coffee, we turn to plants and man and the regulating function such as the gas cycles of ecosystems. Although this discussion is focused on carbon dioxide, we need to keep in mind that the “…principal greenhouse gas concentrations that have increased over the industrial period are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons CFC-11 (CCl3F) and CFC-12 (CCl2F2)” [Hansen et al., 1998; Schimel et al., 1996]. These increases are not in dispute but, importantly for this discussion, the mechanisms of the increase are contested by some. If the increases are by the hand of man there may be a way back from the brink; if the increases arise from a natural cycle then a much of humanity is in even bigger trouble.

CO2 is Green offers the proposition that more carbon dioxide is good and will have broad across the board positive benefits to plants and therefore mankind through increased production of ecosystem service resources. The ideas of more of anything is always better lurks beneath the claim and is supported by some plants benefitting from increased carbon dioxide. Some plants will benefit, however the CO2 is Green claim is a blanket statement of benefit, and assumes the reader will jump to the conclusion that carbon dioxide is good for all plants and plays upon most of us not recalling or ever learning about plant physiology and processes of photosynthesis.

Almost certainly, CO2 is Green is thinking of Sylvan Wittwer who observed in ‘Food, Climate and Carbon Dioxide’ that “[t]he effects of an enriched CO2 atmosphere on crop productivity, in large measure, as positive, leaving little doubt as the benefits for global food security …. Now, after more than a century, and with the confirmation of thousands of scientific reports, CO2 gives the most remarkable response of all nutrients in plant bulk, is usually in short supply, and is nearly always limiting for photosynthesis … The rising level of atmospheric CO2 is a universally free premium, gaining in magnitude with time, on which we can all reckon for the foreseeable future.”
( Thayer Watkins Silicon Valley & Tornado Alley USA)

It turns out that plants are not all alike and that there is a distinct worth considering between agricultural monocultures and diversity rich natural ecosystems. Leaving out the fact that too much carbon dioxide can harm a person directly through suffocation, kidney failure or even in extreme conditions, frostbite, more carbon dioxide is not necessarily a good thing for all plants. Because some species evolved solutions to hot dry climate conditions, some plants already maximize the carbon dioxide available and will not measurably benefit from increased carbon dioxide. These are the C4 and CAM plants, many grasses, succulents and cacti of mild and desert ecoregions. This of course does not negate the CO2 is Green claims, but does strongly suggest that in ecosystems with both plant types the C3 species may, if temperatures and light conditions remain the same, become more efficient and therefore dramatically out compete changing the resources of the system at hand. If that change results in top predator degradation or loss, the entire ecosystem will collapse.

The large elephant running freely through out CO2 is Green’s argument involves temperature and photosynthesis. Keeping in mind that photosynthesis and respiration, one the reverse of the other, play an important role in the carbon cycle and are at equilibrium with one another, and that carbon dioxide levels influence atmospheric temperature, we know that as temperatures go up photosynthesis goes down in plant species which most benefit from the extra carbon dioxide. It follows that CO2 is Green is allowing its target audience to assume that the additional carbon dioxide will be taken up by the plants as a super carbon sink thereby preventing the rise in temperatures. CO2 is Green’s imbedded claim is that increased carbon dioxide is a simple linear process with no feed back loops and no interaction with other processes such as temperature. And most tellingly, CO2 is Green fails to mention that for many terrestrial land plant species, there is a process called photorespiration which occurs at high light intensities and temperatures and competes with photosynthesis limiting further increases in the rate of photosynthesis, notably when the supply of water is limited. Thus CO2 is Green might correctly claim that a rising concentration of carbon dioxide will not materially augment, neither will it limit food production for ten billion people nor lessen the land that can be spared for Nature however, the effects on ecosystem outside of agriculture cannot be foreseen and the importance of limiting factors are not considered.

The claims of CO2 is Green are built upon a few broad based truths or facts that ignore inconvenient data or processes in order to justify an a priori desired outcome, the classic position of stakeholders in a wicked problem. The simple direct linear proposition that correlates better photosynthesis in some plant species to a better world; a complicated reality that falls a little short in the complex fuzzy fractal world of wicked problems. According to Farrar & Williams (1991), although “…[l]ittle information is available for interactions between temperature and CO2. Cold-adapted plants show little response to elevated levels of CO2, with some species showing a decline in biomass accumulation. In general though, increasing temperature will increase sucrose synthesis, transport and utilization for CO2-enriched plants and decrease carbohydrate accumulation within the leaf.” Bunce & Ziska (1995) measured carbon dioxide impact among soy bean cultivars and found that “…increasing atmospheric carbon dioxide concentration may reduce respiration in soybeans, and respiration may be insensitive to climate warming.”

But our carbon-dioxide-increase elephant is larger than even these important biochemical functions for every process is part of a higher level system, and current research strongly suggests that while in some plant species carbon dioxide certainly enhances photosynthesis, at the level of leaf canopy, the level of the plant as a whole, the increase carbon dioxide will lead to higher leaf canopy temperatures. And this increase in temperature will lead to an increase in sterility. If this were true just for annoying pest plant species, we would stop reading, however, the research is focused on and the sterility is in, grain species. At the very least this means more land to produce the same resource, and more likely it means just less food.

If we move to the next level of system complexity we enter the plant community, the biome. Here we must note that increased carbon dioxide will not only cause large leaf and plant structures for our desirable agricultural species, but of course for the weed species that have co-evolved with the crop and humans. The current reduction in farm out-puts (harvests) in Asia could feed over 50 million people. With larger and more vigorous growth of C3 plants including the weeds which compete with the desirable plants, our needed resource yields will go down and starvation will go up.

In closing, we must find a way to balance the intricate mechanisms and complexities of ecosystem services and try to refrain from making simple carte blanche statements of the one size fits all variety. Mankind must find ways to adapt or die; evolutionary forces have no moral grounding, and we must not be fall into the trap of paralysis through analysis. We need to find a pathway between doing nothing at all and waiting until there is nothing to be done.
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