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Agriculture (Feeding the World) -- Summary
As world population continues to grow, so too must our capacity to produce food continue to expand (see Agriculture (Our Greatest Challenge) in our Subject Index). This challenge may seem especially daunting in light of the climate-alarmist claim that rising air temperatures and CO2 concentrations will adversely impact the agricultural enterprise due to numerous climate-related catastrophes they will spawn. Hence, it is enlightening to review the results of studies that describe how agriculture around the globe fared over the past century or more, when the world's radical environmentalists say that the air's temperature and CO2 concentration rose at rates (and to levels) not seen for thousands of years, which is likely true in the case of CO2 but likely false in the case of temperature.

Starting near the top of North America, Shen et al. (2005) derived and analyzed long-term (1901-2002) temporal trends in the agroclimate of Alberta, Canada, reporting that "an earlier last spring frost, a later first fall frost, and a longer frost-free period are obvious all over the province." They also found that May-August precipitation in Alberta increased 14% from 1901 to 2002, and that annual precipitation exhibited a similar increasing trend, with most of the increase coming in the form of low-intensity events. In addition, they note that "the area with sufficient corn heat units for corn production, calculated according to the 1973-2002 normal, has extended to the north by about 200-300 km, when compared with the 1913-32 normal, and by about 50-100 km, when compared with the 1943-72 normal."

These changes, in Shen et al.'s words, "imply that Alberta agriculture has benefited from the last century's climate change," and they note that "the potential exists to grow crops and raise livestock in more regions of Alberta than was possible in the past." They also note that the increase in the length of the frost-free period "can greatly reduce the frost risks to crops and bring economic benefits to Alberta agricultural producers," and that the northward extension of the corn heat unit boundary that is sufficient for corn production "implies that Alberta farmers now have a larger variety of crops to choose from than were available previously." Hence, they say "there is no hesitation for us to conclude that the warming climate and increased precipitation benefit agriculture in Alberta."

Also working in Canada, Bootsma et al. (2005) derived relationships between agroclimatic indices and average grain yields of corn, soybeans and barley obtained from field trials conducted in the eastern part of the country and used them to estimate the impacts of projected climate change scenarios on the yields of these commodities for the 2040-2069 period. Based on a range of heat units projected by multiple climate model simulations, they determined that average yields achievable in field trials could increase by 40-115% for corn and by 21-50% for soybeans by 2040-2069, when "not including the direct effect of increased atmospheric CO2 concentrations." Adding expected CO2 increases into the mix, along with gains in yield anticipated to be achieved through breeding and improved technology, these numbers rose to 114-186% for corn and 117-157% for soybeans.

Initial yields of barley, on the other hand, were predicted to decline, and by as much as 25% in areas with significant water deficits; but after reviewing the scientific literature on the subject, the Canadian researchers concluded that the direct effect of increased CO2 alone "would more than offset the yield reductions anticipated due to effects of rising temperature and changes in water deficit." All things considered, they thus concluded that "barley yields would increase by an average of about 15% under this scenario."

In light of these impressive findings, Bootsma et al. predict there will be a "switch to high-energy and high-protein-content crops (corn and soybeans) that are better adapted to the warmer climate." However, they say "there will likely still be a considerable area of land seeded to barley and other small grain cereals, as these are very desirable in rotation with potatoes." Consequently, if climate-change predictions prove correct (even though based on totally false presumptions), Canada will be immensely blessed by the incredible stimulus the changed conditions will bring to the country's agricultural productivity.

Dropping down to the United States, Hicke and Lobell (2004) calculated cropland net primary production (NPP) in the central part of the country (South Dakota, Nebraska, Kansas, Missouri, Iowa, Minnesota, Wisconsin and Illinois), using U.S. Department of Agriculture information together with crop-specific parameters that convert agronomic data into carbon fluxes for the period 1972-2001. This exercise revealed that the total cropland area exhibited no temporal trend over the study period, but that "both NPP (flux per unit area) and P (spatially aggregated flux) increased during the study period (46 and 51%, respectively)."

In spite of the "twin evils" of rising air temperature and CO2 concentration that climate alarmists decry so mightily, these results indicate that agricultural productivity in the central United States increased, and dramatically so, over the last three decades of the 20th century. Possible drivers of this increase, according to Hicke and Lobell, include "improved cultivars, better fertilizer and pest management, more favorable climate, shifts to productive crop types, and economic influences (Duvick and Cassman, 1999; Evans, 1997; Lobell and Asner, 2003)." Consequently, it would appear that if either of the twin evils of the climate-alarmist crowd had a negative impact on crop productivity - which is highly unlikely, considering that Hicke and Lobell attribute part of the increase in NPP to a "more favorable climate" and that carbon dioxide is an effective aerial fertilizer that also increases plant water use efficiency - it was miniscule compared to the positive impacts of all of the other factors cited by Hicke and Lobell. Based on these observations, therefore, we may expect to see more of the same in future decades, i.e., increased crop yields, even in the face of (and likely partly because of) continued increases in both the air's CO2 concentration and its temperature.

Also in the U.S., and focusing on the first of these last two environmental factors, Bunce (2008) grew adequately fertilized plants of four varieties of the common garden bean (Phaseolus vulgaris) -- Matterhorn (a great northern bean), Jaguar (a black bean), Red Hawk (a kidney bean), and Brown Beauty (a snap bean) -- from seed to maturity under standard field conditions at Beltsville, Maryland (USA) within open-top chambers, where photosynthetic measurements of mature upper-canopy leaves were made in full sunlight at midday during the pod-filling stages of four growing seasons, and where final seed yields and other plant characteristics were determined at harvest.

This work revealed that the extra 180 ppm of CO2 in the CO2-enriched chambers (a concentration increase of close to 50% during daylight hours) resulted in a mean long-term stimulation of midday net photosynthesis of approximately 18% in the Matterhorn and Jaguar bean varieties, but an increase of fully twice that much (36%) in the Red Hawk and Brown Beauty cultivars. In terms of dry mass seed yield, however, the Matterhorn variety led the way with a CO2-induced increase of about 39%, followed by Red Hawk at 21%, Brown Beauty at 18%, and Jaguar with an actual 10% decline in seed yield. What is more, as Bunce reports, "the highest yielding variety at ambient CO2 [Jaguar] was out-yielded by a different variety at elevated CO2 [Matterhorn]."

In light of these several observations, it is clear there is significant variability in seed yield response to atmospheric CO2 enrichment among the four bean varieties tested by Bunce. In addition, it is equally clear there was no a priori way of knowing which of the four cultivars would prove to be the best responder to an increase in atmospheric CO2 concentration, or that one of them would actually respond negatively to an increase in the air's CO2 content. Consequently, Bunce's experiment demonstrates the great need we have to perform a host of such experiments on our most important crop plants, in order to identify which of their many varieties should be selected for crop breeding work, in order to take full advantage of the significant increase in the atmosphere's CO2 concentration that will surely occur over the next several decades, irrespective of how rigorously the nations of the world might attempt to curtail their CO2 emissions. These important crop characteristic assessments must be made, in spite of everything else we might rightly -- or wrongly -- do concomitantly.

Moving all the way down to Argentina, Magrin et al. (2005) evaluated 20th-century changes in climate and the yields of the chief crops (soybean, wheat, maize and sunflower) of nine areas of contrasting environment within the Pampas region, which accounts for over 90% of the country's grain production. Then, after determining low-frequency upward trends in yield due to improvements in crop genetics and management techniques, as well as the aerial fertilization effect of the historical increase in the air's CO2 concentration, annual yield anomalies and concomitant climatic anomalies were used to develop relations describing the effects of precipitation, temperature and solar radiation on crop yields, so that the effects of long-term changes in these climatic parameters on Argentina's agriculture could be determined.

Although noting that "technological improvements account for most of the observed changes in crop yields during the second part of the 20th century -- which totaled 110% for maize, 56% for wheat and 102% for sunflower -- Magrin et al. report that due to changes in climate between the periods 1950-70 and 1970-99, yields increased by 38% in soybean, 18% in maize, 13% in wheat, and 12% in sunflower. Therefore, 20th-century climate change, which is claimed by climate alarmists to have been unprecedented over the past two millennia and is often described by them as one of the greatest threats ever to be faced by humanity, was definitely not a problem for agriculture in Argentina. In fact, it was a great help.

Skipping across the Pacific Ocean, as well as back across the equator, Liu et al. (2004) made detailed calculations of the economic impact of predicted climate changes for the year 2050 (a mean countrywide temperature increase of 3.0C and a mean precipitation increase of 3.9%) on agriculture in China via the methodology of Mendelsohn et al. (1994), based on agricultural, climate, social, economic and edaphic data for 1275 agricultural counties for the period 1985-1991. In the mean, they found that "all of China would benefit from climate change in most scenarios." In addition, they say "the effects of CO2 fertilization should be included, for some studies indicate that this may produce a significant increase in yield," an increase, we would add, that is well established and was not included in their analysis. These findings are particularly important, for Liu et al. note that "China's agriculture has to feed more than one-fifth of the world's population, and, historically, China has been famine prone," reporting that "as recently as the late 1950s and early 1960s a great famine claimed about thirty million lives (Ashton et al., 1984; Cambridge History of China, 1987)."

In a standard paddy culture FACE experiment conducted at Yangzhou, Jiangsu, China, over the period 2004-2006, Yang et al. (2009) grew a two-line inter-subspecific hybrid rice variety (Liangyoupeijiu) at ambient and elevated atmospheric CO2 concentrations of 376 and 568 ppm, respectively, at two levels of field nitrogen (N) application -- low N (12.5 g N m-2) and high N (25 g N m-2) -- measuring numerous aspects of crop growth, development, and final yield. The ultimate "bottom-line" finding of the eight Chinese scientists was that the 51% increase in atmospheric CO2 concentration employed in their study increased the final grain yield of the low N rice crop by 28% and that of the high N rice crop by 32%. As a result, and in light of the findings of two prior rice FACE experiments (Kim et al., 2003; Yang et al., 2006), they concluded that "hybrid rice appears to profit much more from CO2 enrichment than inbred rice cultivars (c. +13%)." Hence, it is little wonder that Yang et al. describe Liangyoupeijiu as "one of the most popular 'super' hybrid rice varieties in China (Peng et al., 2004)," and it appears that it will become ever more "super" as the air's CO2 content continues to rise, helping China to lead the way in future food production.

About the same time, Chavas et al. (2009) examined potential climate change impacts on the productivity of five major crops (canola, corn, potato, rice and winter wheat) of eastern China (30 to 42N, 108 to 123E) via full-domain simulations of the EPIC agro-ecosystem model for the baseline period AD 1961-1990 and the future period AD 2071-2100 under the IPCC's A2 scenario for projected atmospheric CO2 concentrations and accompanying climate change. This work revealed, as they describe it, that "without the enhanced CO2-fertilization effect, potential productivity declines in all cases ranging from 2.5 to 12%." However, they report that when the CO2-fertilization effect is included, as it must be in a CO2-enriched world, "aggregate potential productivity (i.e. if the crop is grown everywhere) increases 6.5% for rice, 8.3% for canola, 18.6% for corn, 22.9% for potato, and 24.9% for winter wheat." And they add that "similar results are reported at the national scale in the work of Lin et al. (2005) using alternative RCM output and the CERES crop simulation model." Thus, even in the face of the supposedly deleterious climate changes predicted to occur over the rest of the 21st century, when the aerial fertilization effect of the projected increase in the air's CO2 content is factored into the yield model employed by the seven scientists, the net productivities of all five crops -- when grown everywhere -- rise over the entire study region, which should be a tremendous blessing to the people of China. And if they use but a modicum of ingenuity and slightly adjust the areas where different crops are preferentially grown, the benefits can be expected to be even larger, which should add up to a big blessing for a big country.

Over in Japan, Shimono et al. (2007) report that lodging -- the environmental beating down of a crop -- "can occur under heavy rains and strong winds," and that this phenomenon "decreases canopy photosynthesis due to self-shading (Setter et al., 1997) and disturbs the translocation of carbon and nutrients to the rice grains (Hitaka and Kobayashi, 1961), resulting in lower yield and poor grain quality." In this regard, for example, they note that Setter et al. (1997) showed that a moderate degree of lodging, which reduced canopy height by 35%, decreased yield by about 20%, and that severe lodging, which reduced canopy height by 75%, decreased yield by up to 50%." Thus, they designed a free-Air CO2-enrichment experiment to determine what effect the ongoing rise in the air's CO2 content might have on lodging in rice plants, growing the cultivar Akitakomachi in paddy fields under three nitrogen (N) fertilization regimes -- low N (6 g N m-2), medium N (9 g N m-2) and high N (15 g N m-2) -- at two different season-long 24-hour mean CO2 concentrations -- 375 ppm (ambient) and 562 ppm (enriched) -- measuring the degree of naturally-occurring lodging at the time of grain maturity on a scale of 0-5, based on the bending angles of the stems at 18 intervals, where 0 = 0 from the vertical, 1 = 1-18, 2 = 19-36, 3 = 37-54, 4 = 55-72 and 5 = 73-90.

As expected, the six scientists found that lodging was significantly higher under high N than under medium and low N. However, they found that the lodging experienced in the high N treatment "was alleviated by elevated CO2," because the lowest internodes of the rice stems "became significantly shorter and thicker under elevated CO2," which likely "strengthened the rice culms against the increased lodging that occurred under high N." In addition, they found that the reduced lodging experienced under elevated CO2 in the high N treatment increased the grain ripening percentage of the rice by 4.5% per one-unit decrease in lodging score.

In discussing their findings, Shimono et al. state that some people have worried that in order "to increase rice yield under projected future CO2 levels, N fertilization must be increased to meet increased plant demand for this nutrient as a result of increased growth rates," but that greater N fertilization might enhance lodging, thereby defeating the purpose of the fertilization. However, they learned from their study that "elevated CO2 could significantly decrease lodging under high N fertilization, thereby increasing the ripening percentage and grain yield," in what amounts to another CO2-induced success story for what the researchers call "the most important crop for feeding the world's population."

Also working in Japan, and noting there is a pressing need to identify genotypes that would produce maximum grain yields under projected future atmospheric CO2 levels, Lou et al. (2008) grew four different rice cultivars -- Dular (a traditional indica variety), IR72 (an improved indica variety), Koshihikari (a temperate japonica variety), and IR65598 (a new variety not yet released to farmers) -- within growth chambers in submerged pots filled with a fertilized soil at two atmospheric CO2 concentrations: ambient (~370 ppm) and elevated (~570 ppm). This work revealed that the extra 200 ppm of CO2 actually reduced the ultimate grain yield of Dular (but by only 0.7%), while it increased the final grain yield of IR72 by 8.0%, that of Koshihikari by 13.4%, and that of IR65598 by 17.7%, indicating that the latter two cultivars would be much preferred over the first two in the fast-approaching CO2-enriched world of the future.

On the other side of the world, Moonen et al. (2002) studied agriculturally-important data collected from 1878 to 1999 on the outskirts of Pisa, Italy. Meteorological parameters routinely measured over this period were daily maximum, minimum and mean air temperature plus daily rainfall amount; while agrometeorological parameters included date of first autumn frost, date of last spring frost, length of growing season, number of frost days, lengths of dry spells, potential evapotranspiration, reference evapotranspiration, soil moisture surplus, theoretical irrigation requirement, number of days with soil moisture surplus, and number of days with soil moisture deficit.

With respect to temperature, they report that "extremely cold temperature events have decreased and extremely warm temperature events have remained unchanged." They suggest that both of these observations may be attributed to the increase in cloud cover that would be expected to occur in a warming world, since more clouds would reduce midday heating and thereby offset much -- if not all -- of the impetus for global warming during the hottest part of the day. At night, on the other hand, the increased cloud cover would enhance the atmosphere's greenhouse effect, thereby adding to the long-term warming trend. Consequently, Moonen et al. say that "no negative effects can be expected on crop production from this point of view." In fact, they found a real "silver lining" in the latter of these cloud feedback phenomena, reporting that "the number of frost days per year has decreased significantly resulting in a decrease in risk of crop damage." Hence, they say the time of planting spring crops could be safely advanced by many days, noting that the length of the growing season increased by fully 47 days over the period of their study.

With respect to rainfall, Moonen et al. found a somewhat analogous situation. On an annual basis, extremely high rainfall events did not appear to have changed; but there was an increase in very low rainfall events. The one exception to this rule on a seasonal basis was a decrease in high rainfall events in the spring, which might be expected to increase drought risk at that time of year. However, when the maximum length of dry spells was assessed on a seasonal basis, the only significant change observed was a lengthening of this parameter in the autumn. But autumn is the wettest season of the year in Pisa, Italy. Hence, the authors concluded that "no increased drought risk is to be expected."

The bottom line with respect to water in agriculture, however, is the balance that exists between what is received via rainfall and what is lost via evapotranspiration, as this difference is what determines the soil moisture balance. Hence, even though there was a downward trend in yearly rainfall at Pisa over the past 122 years (due to the decrease of high rainfall events in the spring), there was a nearly offsetting downward trend in evapotranspiration (possibly induced by enhanced daytime cloud cover), such that there were "no significant changes in soil water surplus or deficit on an annual basis." In the autumn, however, the scientists noted a significant decrease in the number of surplus soil moisture days; but because autumn is the wettest season of the year, the scientists say "this indicates a reduced flooding risk in autumn, which could have positive effects on workability of the soil and imply a reduction of erosion."

Considering their several observations in total, Moonen et al. concluded that concomitant with the warming of the Northern Hemisphere over the past 122 years, "extreme events in Pisa have not changed in a way that is likely to negatively affect crop production." More often than not, in fact, the changes that were demonstrated to have occurred seem to have had positive impacts on agriculture. And as the authors state in concluding their study, "there is no doubt regarding the reality of the observed changes."

Also working in Europe, Trnka et al. (2004) used the crop growth model CERES-Barley version 2.1 (Otter-Nacke et al., 1991) to assess the direct biological effect of a doubling of the air's CO2 concentration (from 350 to 700 ppm) on the growth and yield of spring barley in the Czech Republic, along with the indirect effect on growth and yield produced by the climate changes that are predicted to accompany such a CO2 increase, as simulated by several GCMs, including ECHAM4, HadCM2, NCAR-DOE and seven other GCMs available from the IPCC. In doing so they learned that the indirect effect on spring barley yield caused by changed weather conditions was mostly negative, ranging from -19% to +5% for the several climate scenarios applied to three different production regions of the Czech Republic. However, they report that "the magnitude of the direct [and positive] effect of doubled CO2 on the stressed yields for the three test sites is 35-55% in the present climate and 25-65% in the 2 x CO2 climates," and they note that "the stressed yields would increase in 2 x CO2 conditions by 13-52% when both direct [biological] and indirect [climatic] effects were considered." In addition, they report that "the decrease of the mean yields due to the indirect [climatic] effect of doubled CO2 may be reduced, and it might be even turned to increase, if the spring barley is planted 45-60 days sooner," leading them to conclude that "application of the earlier planting date would result thus in an additional 15-22% increase of the yields in 2 x CO2 conditions."

Clearly, in the words of Trnka et al., "the positive direct effect of doubled CO2 dominates over the negative effect of changed weather conditions." What is more, they note that the results they obtained "might be applied to vast regions of Central Europe with similar environmental characteristics," which should have been welcome news indeed for people who have long been told by many of their national leaders that the projected negative impacts of predicted CO2-induced global warming pose a far greater threat to the people of the world than either global terrorism or nuclear warfare.

Dropping down to equatorial East Africa, Nicholson and Yin (2001) analyzed climatic and hydrologic conditions from the late 1700s to close to the present, based on histories of the levels of ten major African lakes, while they used a water balance model to infer changes in rainfall associated with the different conditions, concentrating most heavily on Lake Victoria. These analyses revealed "two starkly contrasting climatic episodes." The first, which began sometime prior to 1800 during the Little Ice Age, was one of "drought and desiccation throughout Africa." This arid episode, which was most extreme during the 1820s and 30s, was accompanied by extremely low lake levels. As the two researchers describe it, "Lake Naivash was reduced to a puddle ... Lake Chad was desiccated ... Lake Malawi was so low that local inhabitants traversed dry land where a deep lake now resides ... Lake Rukwa [was] completely desiccated ... Lake Chilwa, at its southern end, was very low and nearby Lake Chiuta almost dried up." Throughout this unfortunate period, they say that "intense droughts were ubiquitous." Some, in fact, were "long and severe enough to force the migration of peoples and create warfare among various tribes."

As the Little Ice Age's grip on the world began to loosen in the mid to latter part of the 1800s, however, things began to improve for most of the continent. Nicholson and Yin report that "semi-arid regions of Mauritania and Mali experienced agricultural prosperity and abundant harvests; floods of the Niger and Senegal Rivers were continually high; and wheat was grown in and exported from the Niger Bend region." Across the east-west extent of the northern Sahel, in fact, maps and geographical reports described "forests." As the nineteenth century came to an end and the twentieth century began, there was a slight lowering of lake levels, but nothing like what had occurred a century earlier; and then, in the latter half of the twentieth century, things improved even more, with levels of some of the lakes actually rivaling high-stands characteristic of the years of transition to the Current Warm Period. Even in Africa, therefore, global warming has proven to be much better than global cooling for agriculture.

Taking a global view of things, Ortiz et al. (2008) write that "about 21% of the world's food depends on the wheat crop," that "81% of wheat consumed in the developing world is produced and utilized within the same country, if not the same community," and that "many poor households depend on increased wheat production on their own farms for improved household food security," which is becoming an ever greater concern as predictions of continued global warming grow ever more extreme. Hence, they pose for themselves the important question: Can wheat beat the heat?

The ten international researchers broach this important question via a review of some of the approaches for ameliorating the oft-predicted negative impacts that climate change may have on wheat production in some of the most important wheat growing areas of the world; and in doing so, they find that "to adapt and mitigate the climate change effects on wheat supplies for the poor, germplasm scientists and agronomists are developing heat-tolerant wheat germplasm, as well as cultivars better adapted to conservation agriculture," noting that these encouraging results include "identifying sources of alleles for heat tolerance and their introgression into breeding populations through conventional methods and biotechnology." In addition, they report that "wheat geneticists and physiologists are also assessing wild relatives of wheat as potential sources of genes with inhibitory effects on soil nitrification," which activity could lead to significantly reduced emissions of nitrous oxide from agricultural soils and thereby shrink the impetus for global warming provided by this powerful trace greenhouse gas, which molecule-for-molecule is about 300 times more radiatively active than CO2. And as a result of these several ongoing activities, Ortiz et al. conclude that important technology and knowledge will ultimately flow to farmers that will enable them "to face the risks associated with climate change," suggesting that it is indeed possible for wheat to "beat the heat" in the years and decades ahead.

In another important paper with global implications, Ainsworth et al. (2008) also make a case for (1) breeding varieties of the major crops upon which the world depends for food to best take advantage of the ongoing rise in the air's CO2 content -- which latter phenomenon is sure to continue for decades to come -- and (2) employing Free-Air CO2-Enrichment or FACE technology to accomplish it.

The international consortium of 32 scientists from twelve different countries begins by reminding us that "the growing world population, increasing demands for grains for animal feeds, land loss to urban expansion and demand for bioenergy production are exerting more and more pressure on global agricultural productivity." Therefore, they say that "a major challenge for plant biologists, agronomists and breeders will be to provide germplasm and seed material that maximize future crop production," particularly within the context of rising atmospheric CO2 concentrations that provide, in their words, "a unique opportunity to increase the productivity of C3 crops." However, they say that "only a fraction of available germplasm of crops has been tested for CO2 responsiveness," and that "further research is needed to elucidate the mechanisms of yield response to CO2, to assess the genetic diversity available for improving responsiveness and to devise efficient schemes for selection for adaptation to rising ambient CO2, whether based on conventional plant breeding or systems biology approaches for selecting and engineering improved genetics."

The first step in meeting these objectives, according to the researchers, "is to create facilities for field screening the yield response to elevated CO2 across a wide range of germplasm," while doing it under "conditions and management that reflect dominant agronomic practices and provide as natural an environment as possible." Hence, they suggest that FACE experimentation is the way to proceed, since it is felt to meet these criteria and present a minimally obtrusive interaction with the natural environment.

Although FACE systems are often considered expensive to construct and operate, Ainsworth et al. note that "the net cost is compensated for by economies of scale, and the cost per unit ground area is considerably less than alternative systems." This fact is very important, because, as they explain it, "the new research requires investigating large numbers of genotypes," and that "to investigate the association of CO2 responsiveness with a single quantitative trait locus mapping population, approximately 150 inbred lines would need to be investigated."

In concluding their treatise, the world-renowned group of scientists states that "because it may take 10-15 years to move from discovery of new advantaged genetics to commercial cultivars of annual grain crops, developing a robust strategy and supporting the planned work with the best possible facilities should be an urgent priority." We could not agree more. This work must be done, and as rapidly as possible, if we are to prevent massive food shortages and the taking of unconscionable amounts of land and water from what we could call "wild nature" - simply to produce the food needed to feed ourselves but a few short decades from now.

Last of all, we make mention of the intriguing paper of Cunniff et al. (2008), who note that "early agriculture was characterized by sets of primary domesticates or 'founder crops' that were adopted in several independent centers of origin," all at about the same time, of which they say that "this synchronicity suggests the involvement of a global trigger." Further noting that Sage (1995) saw a causal link between this development and the rise in atmospheric CO2 concentration that followed deglaciation (a jump from about 180 to 270 ppm), they hypothesized that the aerial fertilization effect caused by the rise in CO2 combined with its transpiration-reducing effect led to a large increase in the water use efficiencies of the world's major C4 founder crops, and that this development was the global trigger that launched the agricultural enterprise. Consequently, as a test of this hypothesis, they designed "a controlled environment experiment using five modern day representatives of wild C4 crop progenitors, all 'founder crops' from a variety of independent centers."

The five C4 crops employed in their study were Setaria viridis, Panicum miliaceum var. ruderale, Pennisetum violaceum, Sorghum arundinaceum, and Zea mays subsp. parviglumis. They were all grown individually in small pots filled with a 1:1 mix of washed sand and vermiculite for 40-50 days in growth chambers maintained at atmospheric CO2 concentrations of either 180, 280 or 380 ppm, characteristic of glacial, post-glacial and modern times, respectively. This work revealed that the "increase in CO2 from glacial to postglacial levels [180 to 280 ppm] caused a significant gain in vegetative biomass of up to 40%," together with "a reduction in the transpiration rate via decreases in stomatal conductance of ~35%," which led to "a 70% increase in water use efficiency, and a much greater productivity potential in water-limited conditions."

In discussing their results, the five researchers concluded that "these key physiological changes could have greatly enhanced the productivity of wild crop progenitors after deglaciation ... improving the productivity and survival of these wild C4 crop progenitors in early agricultural systems." And in this regard, they note that "the lowered water requirements of C4 crop progenitors under increased CO2 would have been particularly beneficial in the arid climatic regions where these plants were domesticated."

For comparative purposes, the researchers also included one C3 species in their study -- Hordeum spontaneum -- and they report that it "showed a near-doubling in biomass compared with [the] 40% increase in the C4 species under growth treatments equivalent to the postglacial CO2 rise."

In light of these several findings, it can be appreciated that the civilizations of the past, which could not have existed without agriculture, were largely made possible by the increase in the air's CO2 content that accompanied deglaciation, and that the peoples of the earth today are likewise indebted to this phenomenon, as well as the additional 100 ppm of CO2 the atmosphere has subsequently acquired.

With an eye to the future, we have long contended that the ongoing rise in the air's CO2 content will similarly play a pivotal role in enabling us to grow the food we will need to sustain our still-expanding global population in the year 2050 without usurping all of the planet's remaining freshwater resources and much of its untapped arable land, which latter actions would likely lead to our driving most of what yet remains of "wild nature" to extinction.

Clearly, rising atmospheric CO2 concentrations - and temperatures - have served both us and the rest of the biosphere well in the past; and the ongoing rise in the air's CO2 content will do the same in the future. Yet this latter phenomenon is claimed by radical climate alarmists to constitute the greatest threat currently facing the world. They could not be more wrong. In light of the material presented here, as well as in our Subject Index under the heading of Agriculture (Our Greatest Challenge), it is clear that we are going to need all of the extra carbon dioxide we can get in order to not have to usurp all of the planet's remaining land and freshwater resources just to produce the food that will be needed to sustain our growing numbers in the years and decades ahead.

References
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Chavas, D.R., Izaurralde, R.C., Thomson, A.M. and Gao, X. 2009. Long-term climate change impacts on agricultural productivity in eastern China. Agricultural and Forest Meteorology 149: 1118-1128.

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Last updated 3 February 2010