Saturday, September 27, 2014

Atmospheric co2: a boon for the biosphere

Ready for a pop quiz? Name a colorless, odorless, tasteless gas that is found in the atmosphere in relatively minute quantities and is essential to nearly all life on earth. ___________. Time’s up! The answer is carbon dioxide.
Carbon dioxide, or CO2, was probably not the first molecule you thought to name. After all, in today’s world CO2 is given a bad rap. Ironically, some people even refer to the emission of this life-giving and life-sustaining gas into the atmosphere as “carbon pollution.” They fear its accumulation in the air because of computer model projections, which forecast a future of dangerous global warming and a host of other climate- and extreme-weather-related catastrophes if atmospheric CO2 concentrations continue to rise. And, therefore, in an effort to alleviate their concerns, these individuals seek government regulation of CO2 emissions as part of their overall objective to reduce the CO2 content of the air.
Efforts to regulate CO2 and reduce its concentration in the atmosphere, however, are way off the mark. Carbon dioxide is not a pollutant; and its increase in the air will have little, if any, impact on future climate. Literally thousands of scientific studies have demonstrated such. The recent work of the Nongovernmental International Panel on Climate Change (NIPCC), for example, highlights many of the problems, inconsistencies and outright contradictions that exist between climate model projections and real-world observations. In a 1,000-page report released this past September, the NIPCC concluded there is nothing unusual, unnatural or unprecedented about Earth’s current climate and that the impact of rising CO2 on future climate will be small, if not negligible, which conclusion is a far cry from climate catastrophe.
Another damning indictment of the rising-CO2-will-cause-dangerous-global-warming narrative is seen in the failure of the climate models to predict the current plateau in global temperature. Despite an eight percent increase in atmospheric CO2, over the past 17 years, the earth experienced no net increase in temperature, yet all of the computer models upon which the vision of dangerous global warming is based projected it should have warmed.
Aside from having a rather benign – or possibly even nil – effect on climate, there are other reasons for rejecting efforts to regulate and reduce carbon dioxide.
Atmospheric CO2 is the building block of life. It is the primary raw material or “food” that plants utilize during the process of photosynthesis to construct their tissues and grow. And, as conclusively demonstrated in the peer-reviewed scientific literature, the modern rise in CO2 is benefiting the biosphere in multiple ways.
In general, atmospheric CO2 enrichment endows plants with three main benefits. The first and most recognized is enhanced plant productivity. Typically, a 300-parts-per- million (ppm) increase in the air’s CO2 content (which is expected to occur by the end of this century) will raise the productivity of most herbaceous plants by about one-third and most woody plants by about one-half. Such stimulation is generally manifested by an increase in the number of branches and tillers, more and thicker leaves, more extensive root systems and more flowers and fruit, and it portends great benefits for the biosphere. One obvious consequence is greater crop productivity; and many researchers acknowledge the yield-enhancing benefits of the historical and still-ongoing rise in the air’s CO2 content on past, present and future crop yields. According to one recent study, rising CO2 concentrations boosted the value of global crop production over the past 50 years by a staggering $3.2 trillion. An additional $9.8 trillion in monetary gains are estimated to accrue in the future in response to the projected rise in atmospheric CO2 between now and 2050.
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The second major benefit is increased water use efficiency. Plants exposed to elevated levels of atmospheric CO2 generally do not open their leaf stomatal pores as wide as they do at lower CO2 concentrations. The result is a reduction in most plants’ rates of water loss by transpiration. The amount of carbon (biomass) they gain per unit of water lost – or water-use efficiency – therefore typically rises for a doubling of CO2 on the order of 70 to 100 percent. And as a result, at higher atmospheric CO2 concentrations numerous studies show plants need less water to produce the same or an even greater amount of biomass than they do at lower CO2 concentrations. One implication of this benefit is that plants will be able to grow and reproduce in locations where it was previously too dry for them to even exist; and they may therefore win back lands previously lost to desertification.
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The third major benefit of atmospheric CO2 enrichment is an amelioration of environmental stresses and resource limitations. Higher levels of CO2 tend to help reduce detrimental growth effects of high soil salinity, high air temperature, low light intensity and low levels of soil fertility. They also reduce the severity of low temperature stress, oxidative stress and the stress of herbivory. What is more, the relative percentage growth enhancement produced by an increase in the air’s CO2 content is often greater when comparing plants growing under stressful and resource-limited conditions than when growing conditions are ideal.
Altogether, with the plant productivity gains that result from the aerial fertilization effect of the ongoing rise in atmospheric CO2, plus its transpiration-reducing effect that boosts plant water use efficiency along with its stress-alleviating effect that lessens the negative growth impacts of resource limitations and environmental constraints, the world’s vegetation possesses an ideal mix of abilities to reap a tremendous benefit in the years and decades to come. And based on a multitude of observations, the future is now. As evidence from around the globe indicates, the terrestrial biosphere is presently experiencing a great planetary surge in growth, likely due in large measure to the approximate 40 percent increase in atmospheric CO2 that has occurred since the beginning of the Industrial Revolution.
Real-world evidence of such is apparent in the long-term observation of forests. Tree growth at locations all around the globe over the past two centuries, for example, reveals trends that are not consistent with the usual climatic variables attributable to growth stimulation, such as temperature or precipitation. In these instances, researchers acknowledge the steady influence of rising atmospheric CO2 concentrations on growth trends, which trends are often manifested as increases in both the density and aerial coverage of woody species.
Other evidence of a CO2-induced stimulation of vegetation in recent years is seen in grassland and desert ecosystems, as well as for the world as a whole. With respect to all land plants, for example, satellite-based studies reveal net terrestrial primary productivity has increased by six to 13 percent since the 1980s. Other research shows the annual global carbon uptake has doubled from 2.4 ± 0.8 billion tons in 1960 to 5.0 ± 0.9 billion tons in 2010. What makes these observations appear even more astonishing, however, is the fact that they occurred in spite of the many recorded assaults of both man and nature on planetary vegetation over this time period, including fires, disease, pest outbreaks, deforestation and climatic changes in temperature and precipitation. That the biosphere experienced any productivity improvement, let alone a doubling, is truly amazing; and it demonstrates, in part, the powerful impact atmospheric CO2 enrichment is exerting on global vegetation.
As a society, it is high time for us to recognize and embrace the truth. Contrary to misguided assertions, political correctness and government edicts, carbon dioxide is not a pollutant. It’s a colorless, odorless, tasteless atmospheric gas that is essential to nearly all life on earth. Please remember that, especially the next time you are quizzed about its virtues.