Going back in time to the final few years of the 20th century, Schaffer et al. (1997) grew two mango ecotypes – one evolving from a warm, humid tropical climate, and the other from a cool, dry subtropical region – for 12 months in glasshouses maintained at either 350 or 700 ppm CO2 in order to determine the effects of atmospheric CO2 enrichment on the trees’ growth and leaf mineral nutrient concentrations. In doing so, they found that in addition to the greater net carbon gains of the CO2-enriched trees, the elevated CO2 tended to decrease foliar concentrations of mineral nutrients (N, P, K, Ca, Mg, S, Cl, Fe, Zn, Mn, Cu and B) in both mango cultivars, most likely due to a dilution effect, since atmospheric CO2 enrichment increased leaf dry mass. But with respect to this latter finding, the scientists who conducted the study wrote that “given the slow rate at which global atmospheric CO2 concentration is increasing, it is possible that plants will adapt to this phenomenon over time with respect to mineral nutrition,” as actually was found to be the case in a prior study of sour orange trees after 85 months of exposure to elevated CO2 (Penuelas et al., 1997).
Water Use Efficiency of Agricultural Species
In some cases, the water-use efficiency increases caused by atmospheric CO2 enrichment are spectacularly high. De Luis et al. (1999), for example, demonstrated that alfalfa plants subjected to atmospheric CO2 concentrations of 700 ppm had water-use efficiencies that were 2.6 and 4.1 times greater than those displayed by control plants growing at 400 ppm CO2 under water-stressed and well-watered conditions, respectively. Also, when grown at an atmospheric CO2 concentration of 700 ppm, a 2.7-fold increase in water-use efficiency was reported byMalmstrom and Field (1997) for oats infected with the barley yellow dwarf virus.
Growth Rates of Old Versus Young Forest Trees
The planting and preservation of forests has long been acknowledged to be an effective and environmentally-friendly means for slowing climate-model-predicted CO2-induced global warming. This prescription for moderating potential climate change is based on two well-established and very straightforward facts: (1) the carbon trees use to construct their tissues comes from the air, and (2) its extraction from the atmosphere slows the rate of rise of the air’s CO2 content.
Although simple enough that a child can understand it, this potential partial solution to the putative global warming problem has been under attack for several years by people who seek to address the issue solely on the basis of forced reductions in anthropogenic CO2 emissions (seePearce, 1999).
The Global Medieval Warm Period
Between the 10th and 14th centuries AD, earth’s average global temperature may have been warmer than it is today, according to the analyses of Lamb (1977, 1984, 1988) and Grove (1988). The existence of this Medieval Warm Period was initially deduced from historical weather records and proxy climate data from England and Northern Europe. Interestingly, the warmer conditions associated with this interval of time are also known to have had a largely beneficial impact on earth’s plant and animal life. In fact, the environmental conditions of this time period have been determined to have been so favorable that it was often referred to as the Little Climatic Optimum (Imbrie and Imbrie, 1979; Dean, 1994; Petersen, 1994; Serre-Bachet, 1994; Villalba, 1994)
In July of 1987, as described by U.S. Department of Agriculture researchers Idso and Kimball (2001)
, eight 30-cm-tall sour orange tree (Citrus aurantium L.) seedlings were planted directly into the ground at the Agricultural Research Service’s U.S. Water Conservation Laboratory in Phoenix, Arizona, where they were enclosed in pairs within four clear-plastic-wall open-top chambers. Then, in November of that year, the two scientists began to continuously pump ambient air through two of the chambers via perforated plastic tubes that lay upon the ground beneath the trees, while through the other two chambers they began to pump air that was enriched with carbon dioxide to a concentration that was 300 ppm greater than that of the surrounding ambient air, which had an average CO2 concentration of 400 ppm. And thus was born one of the longest atmospheric CO2 experiments ever to be conducted anywhere in the world.
According to the IPCC, CO2-induced global warming will be net harmful to the world’s marine species. This summary examines this hypothesis for various fish species, presenting evidence in opposition to the IPCC’s point of view.
As the air’s CO2 content rises in response to ever-increasing anthropogenic CO2 emissions, and as more and more carbon dioxide therefore dissolves in the surface waters of the world’s oceans, theoretical reasoning suggests the pH values of the planet’s oceanic waters should be gradually dropping. The IPCC and others postulate that this chain of events, commonly referred to as ocean acidification, will cause great harm — and possibly death — to marine life in the decades and centuries to come. However, as ever more pertinent evidence accumulates, a much more optimistic viewpoint is emerging. This summary examines the topic of the potential impacts of ocean acidification on fish.
Most of the ocean acidification research conducted to date has focused solely on the biological impacts of declining seawater pH. Few studies have investigated the interactive effects of ocean acidification and temperature. This summary examines what has been learned in several such studies of various marine organisms that challenge the alarming and negative projections of the IPCC on the matter.
Since October 1996 there has been no global warming at all (Fig. 1). This month?s RSS temperature plot pushes up the period without any global warming from 18 years 1 month to 18 years 2 months (indeed, very nearly 18 years 3 months). Will this devastating chart be displayed anywhere at the Lima conference? Don?t bet on it.
By examining various properties of tree rings, researchers can deduce how historical increases in the air’s CO2 concentration have already affected tree productivity and water use efficiency.
As living entities, corals are not only acted upon by the various elements of their environment, they also react or respond to them. And when changes in environmental factors pose a challenge to their continued existence, they sometimes take major defensive or adaptive actions to insure their survival.
Climate alarmists predict global warming will increase human death rates, and nary a heat wave occurs but what they are quick to blame any concurrent excess deaths on the high temperatures associated with it. Much more deadly than hot weather, however, is cold weather; yet climate alarmists typically ignore the excess deaths that are caused by low temperatures, even though they are far more numerous than those caused by high temperatures. In the present summary we examine a number of papers investigating the relationship between temperature and human health for various locations in Asia.
Environmental stresses induced by exposure to pollutants, drought, intense solar radiation and high air or water temperatures generate highly-reactive oxygenated compounds that damage both terrestrial and aquatic plants. Ameliorating these stresses typically involves the production of antioxidant enzymes that scavenge and detoxify the highly-reactive oxygenated compounds. Hence, when stresses are present, concentrations and/or activities of antioxidants in plants are generally observed to be high; and a good question to ask, therefore, is how atmospheric CO2 enrichment impacts this relationship and what the observed results imply. A number of researchers have done just that, and in this summary we highlight what they have learned.