Carbon Cycle Part 3

“Redemption of the Beast”  (part 3)

One More Benefit: Carbon Dioxide and Ozone

There is another benefit to carbon dioxide enrichment that needs to be discussed. It relates to the effects of ozone pollution on plants. Ozone (O3) is a molecule composed of three oxygen atoms that normally makes up only about 0.6 parts-per-million (ppm) of the atmosphere. The greatest concentrations of ozone are found in the stratosphere between 6 and 30 miles above the Earth’s surface. Stratospheric concentrations of ozone range between 2 and 8 parts-per-million – about 10 to 50 times greater than at the bottom of the atmosphere. At this height above the Earth’s surface, ozone provides the crucially important service of intercepting ultraviolet rays which are very damaging to living things. However, at low atmospheric levels near the Earth’s surface, ozone can become highly phytotoxic. Ozone can interfere with photosynthesis and a considerable amount of evidence demonstrates reduced crop yields when exposed to ozone pollution.

The website of the Missouri Botanical Garden discusses the damaging effects to plant life from too much ozone exposure:

“Ozone is the most damaging air pollutant to plants. The action of sunlight (ultraviolet radiation) on molecular oxygen and oxides of nitrogen spontaneously generate ozone… Ozone can move across great distances to cause damage to plants far from its origin and is therefore classified as a non-pointsource pollutant. The extent of damage depends on the concentration of ozone, the duration of exposure, and plant sensitivity. Acute damage to deciduous trees causes marginal leaf burn and dot-like irregular-shaped lesions or spots that may be tan, white or dark brown. Symptoms may spread over entire leaves. Another common symptom is bleaching of the upper leaf surface… Acute damage to conifers causes browning at the same point on all needles in a bundle (needle cluster).”

Figure 6. Ozone damage on leaves of American linden or basswood tree (tilia).

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Figure 7. Muskmelon leaves showing damage from ozone pollution.

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Due to the known damaging effect of ozone on plants, and knowing that atmospheric levels of CO2 were rising, and would probably continue to rise, and, that many of the same industrial practices that added to the growing carbon pool also contributed ozone to the atmosphere, a number of scientists have looked at the interactive effects of carbon dioxide enrichment and high levels of ozone.

In one important, statistically rigorous study, the researchers sought to determine the interactive effect on plants in an environment of both elevated carbon dioxide and elevated ozone. [see: Volin, John C, Peter B. Reich & Thomas J Givnish (1998) Elevated carbon dioxide ameliorates the effects of ozone on photosynthesis and growth: species respond similarly regardless of photosynthetic pathway or plant functional group: New Phytology, Vol. 138, pp. 315 – 325]. To better understand this situation, the authors selected 6 perennial species consisting of two types of trees – quaking aspens and red oaks; two species of grass from the C3 group – western wheatgrass and prairie Junegrass; and two species from the C4 group – “sideoats grama” and little bluestem. (The number in subscript refers to the type of photosynthetic pathway.) C3 plants were discussed above. C4 plants have a different method of extracting carbon from the carbon dioxide molecule than C3 plants and are adapted generally to more arid environments. The idea in this study was to get a relatively diverse cross-section of plants. To perform the experiment, conducted at the University of Wisconsin, 64 seedlings of each species were planted in two controlled environment growth rooms with each room divided into four individual chambers for the purpose of testing the different treatment regimes.

The authors describe the situation: “In industrial regions, current ambient levels of O3 reduce photosynthesis in many, and probably most, plant species. Chronic O3 pollution commonly results in increased respiration rates, shifts in C allocation, decreased leaf retention, and shortened leaf longevity, and current levels are known to be high enough to reduce the growth and yield of agricultural crops and trees.”

After discussing their material and methods Volin and colleagues report on the results of their experiments, and the results proved quite remarkable. The first thing they noted was that “In all six species used in this experiment, plants grown at ambient CO2 were smaller and had a lower RGR (relative growth rate) when exposed to an elevated level of O3-induced reductions in in situ photosynthesis at ambient CO2.” In other words, under a concentration of CO2 equal to present atmospheric concentrations the presence of ozone caused stunted growth in the test plants. However, and this is where it gets interesting “Examination of the interactive effects of CO2 and O3 revealed that elevated CO2 reduced the deleterious effects of high O3 on both photosynthesis and growth.”

In conclusion they state: “An elevated CO2 environment seems to ameliorate the adverse effects of elevated O3 on both photosynthesis and growth, regardless of photosynthetic pathway or plant functional group.” And finally, “The amelioration of O3 by CO2 concentrations forecasted for the next century may have important consequences for both individual and interactive species responses.” Yes – important consequences indeed, potentially positive consequences – that again, are ignored or dismissed by proponents of AGW (anthropogenic global warming) without further consideration.

Here we have evidence that the presence of elevated levels of carbon dioxide counteracts the detrimental effects of elevated ozone. We can add that benefit of carbon dioxide to the list.

Given what we now know about the power of carbon dioxide to stimulate plant growth, it is time to address the question of what is happening on the global scale of terrestrial nature as a result of the enhancement of atmospheric carbon dioxide that is underway. To that end there is a considerable body of empirical evidence now available.

 The Terrestrial Biosphere and Carbon Dioxide

By the early 1980s, the first signs of what could potentially be a planetary-scale response to carbon fertilization were becoming apparent. In 1984 the work of Valmore C. LaMarche, Jr. and his colleagues with the Laboratory of Tree-Ring Research at the University of Arizona, on rates of tree ring growth in subalpine pine trees in New Mexico, Colorado and California, appeared in the journal Science. [See: LaMarche, Valmore C. et al. (1984) Increasing Atmospheric Carbon Dioxide: Tree Ring Evidence for Growth Enhancement in Natural Vegetation; Science, vol. 225, Sept. 7, pp. 1019-1021]

The two tree species studied for this research were specifically bristlecone pines that grew near the tree line at altitudes typically around 10 or 11 thousand feet above sea level. Earlier studies by LaMarche and others discovered that tree ring thickness, and hence tree growth rates, began accelerating after about 1840, coincident with the transition out of the Little Ice Age. It was assumed that this was due to the warming climate. However, later studies up to the 1980s showed continued accelerated growth rates in spite of the fact that climate began to cool during this period and continued to do so through the 1960s and 1970s.

In the abstract of their report, the authors write: “A response of plant growth to increased atmospheric carbon dioxide, which has been anticipated from laboratory data, may now have been detected in the annual rings of subalpine conifers growing in the western United States. Experimental evidence shows that carbon dioxide can be an important limiting factor in the growth of plants in this high-altitude environment. The greatly increased tree growth rates observed since the mid-19th century exceed those expected from climatic trends but are consistent in magnitude with global trends in carbon dioxide, especially in recent decades.”

The next two graphs depict this accelerated growth rate in high altitude bristlecone pines as documented by LaMarche, et al.

Figure 8. Tree width indices for limber pine, sampled at Mount Jefferson Nevada. Note rapid increase in growth rate since the 1960s. LaMarche, et al. p. 1019

Figure 9. These are the growth records for bristle cone pines sampled from the White Mountains, California. They are typical of all samples gathered and studied by this team. Growth rates at the Sheep Mountain site increased by 106 percent between 1850 and 1983 and at the Campito Mountain site they increased by 73 percent during the same time interval. LaMarche et al. p. 1020.

After careful consideration of all possible explanations the authors’ state: “We believe, from the evidence now available, that subalpine vegetation generally, and upper tree-line conifers in particular, could now be exhibiting enhanced growth as a direct response to increasing concentrations of atmospheric CO2.” They conclude by saying that: “Although high-altitude subalpine forests constitute only a small fraction of the earth’s standing biomass, increased CO2 uptake and storage could now be occurring in these habitats.”

Three years later a paper was published by the Royal Society of London anticipating the potential effects of enhanced carbon dioxide on forest growth. The author, Paul Gordon Jarvis (1935 – 2013) was a forester and ecologist with the Department of Forestry and Natural Resources at the University of Edinburgh. It was clear to Jarvis that plants and vegetation must be taking up increasing amounts of carbon dioxide:

“Growth and partitioning to the roots of seedlings and young trees generally increases in response to a doubling in atmospheric CO2 concentration. Experimental results are very variable, because of the differing length of the experiments, the artificial conditions and the artefactual constraints. At larger scales, direct measurements of responses to increase in atmospheric CO2 are impractical but models of canopy processes suggest that significant increases in assimilation will result from the rise in atmospheric CO2 concentrations.” [see: Jarvis, P. G. (1989) Atmospheric carbon dioxide and forests: Philosophical Transactions of the Royal Society of London, vol. B 324, pp. 369 – 392]

“Larger scales” in this case could be regional, continental, or even global. Jarvis comments on an important phenomenon: it is well known that there is a seasonal amplitude variation caused by the increased photosynthetic uptake of CO2 in the spring, causing atmospheric concentrations to go down and to rise during the winter when plants and leaves die-off. This oscillation is clearly shown in the Keeling Curve from Mauna Loa Observatory data, upon which average global concentrations are inferred. Jarvis’s comment is in reference to the fact that the amplitude of this oscillation has increased: “Inferences from the increase in amplitude of the seasonal oscillation in the global atmospheric CO2 concentration at different latitudes suggest that forest is having a significant impact on the global atmospheric concentration.” The amplitude of the seasonal oscillation is going to be a direct function of total biomass. In other words, if the amplitude increases it is because there is an increase in the amount of plants and forests taking up and releasing CO2.

In discussing a possible temperature increase caused by increasing carbon dioxide levels, Jarvis admits that:

“The detection of such an increase is difficult, not least because over the past 50 years the temperature in the temperate region of the Northern Hemisphere has been decreasing at a rate of about 0.15°C per year as a result of various superimposed climate cycles. There is not general agreement that an increase in temperature has so far been detected.”

Yes, you read that right. For the half-century prior to the publication of this paper in 1989, the global temperature had been cooling from its 20th century high during the 1930s. This fact alone casts doubt upon scenarios in which carbon dioxide is the principal driver of global warming, for exactly at the time humankind began to substantially add to the atmospheric carbon dioxide pool, global temperatures began to cool! Clearly there were other factors at work − the “various superimposed climate cycles” to which Jarvis refers − whatever those might be. In the late 1980s and early 1990s the global temperature began to rise, but with the onset of the 21st century the rise has been in a state of pause and global warming proponents have been attempting mightily to explain away the pause.

Jarvis conducted a number of first-hand experiments on the effects of carbon dioxide enrichment on young trees, one of which involved approximately 30 each of both conifers and broadleaves. The experiments ranged in duration from a few weeks up to 2 ½ years.  Jarvis comments on the results:

“In all cases, the rate of growth of dry matter was increased at the higher CO2 concentration, the increase being in the range of 20—120% with a median of about 40%. In most of the experiments there were increases in the mass of leaves as a result of increases in the number, area or thickness. Masses of both fine and coarse roots were also increased . . . To a considerable extent, an increase in ambient CO2 concentration was effective in compensating for lack of light, water or nutrients . . . Young trees growing in situations of low nitrogen or phosphorus, or on small volumes of nutrient-poor soils, none-the-less showed increased growth in response to a doubling in ambient CO2 concentrations. A scarcity of nutrients does not prevent a growth response to increase in CO2 concentration.”

Jarvis comments in regard to the carbon cycle that:

“Forests accumulate large amounts of carbon in woody branches, stems and litter. The standing crop of dry matter may typically vary from 100—500 t ha—1. (tons per hectare, a hectare being 10,000 sq. meters, or 2.471 acres) A stand of 320 t ha—1 of dry matter of typical composition will have taken up approximately twice that amount of CO2 during its period of growth, thus reducing the content of the atmosphere by that amount.”

The noteworthy lesson to be appreciated once more, is simply that as plants consume carbon dioxide in the process of photosynthesis, it is simultaneously being sequestered by becoming a part of the increasing plant matter and is therefore removed from the atmosphere.

Jarvis realizes that this fact has potentially far-reaching implications when considered on the planetary scale:

“If the atmospheric CO2 concentration is so sensitive to the physiological activities of vegetation, particularly forest, proper consideration must be given to the possible role of vegetation in ameliorating the rise in atmospheric CO2 concentration. A forest accumulating dry matter of average composition with respect to fats, proteins, carbohydrates and lignin at a rate of 5 tonne ha—1 per year, the approximate average for the U. K., would assimilate CO2 at a rate of ca. 10 tonne ha—1 per year, removing carbon from the atmosphere at 2.7 t ha—1 per year. Consequently, an area of such forest of 2 Gha would be able to assimilate the 5—6 Gt per year of carbon currently being added to the global atmosphere annually by the burning of fossil fuels . . . The approximate area of Europe is 1 Gha (10 x 106 km2). Thus a new, young, actively growing forest twice the area of Europe, could, in principle, assimilate all of the CO2 produced through combustion and oxidation at the present rate.”

Let’s try to make this easier to comprehend:

The area of Europe is about 3.931 million square miles. Twice this amount is 7.862 million sq. miles. The total land area of the Earth is about 57.308 sq. miles. So if an additional land area equal to about 1/15th the land area of Earth became forested, that forest would consume all of the carbon dioxide we humans are putting into it from the consumption of fossil fuels!

Consider that the total desert area of the Earth is about 19 million square miles and that the total area of land abandonment and degradation according to the estimates of the Global Assessment of Soil Degradation (GLASOD) commissioned by the United Nations Environment Program, is somewhere around 8 million square miles. Together the deserts of the world and the degraded land equal about 27 million square miles. If just a little over one-quarter of this land area were to revert to forest it would, again, yearly consume all the carbon dioxide we humans put into the atmosphere.

Obviously this affect could not go on forever. However, what it does mean is that as the density of Earth’s biomass increases, and as larger areas of Earth’s surface become green, the biospheric demand for carbon dioxide will increase as well. Jarvis estimates that it would take at least 80 years before such new, additional forest mass would cease to assimilate carbon. The key here would be well-managed forests, with regular harvesting and replacement planting of new trees, as well as full utilization of the timber in such a manner that oxidation is minimized.  What these observations    tell us is this: if the biomass of the Earth is, in fact, increasing due to stimulated photosynthesis and carbon uptake, we have at least a century to make the conversion to carbon neutral energy technologies.

The paper I referenced above by Sherwood Idso, describing in detail his experiments growing orange trees under conditions of CO2 enrichment, addresses the issue of biospheric feedbacks:

“Consider the fact that CO2 is the primary raw material used by plants in producing organic matter via the process of photosynthesis, and that the more CO2 there is in the air, the better plants can perform this vital function, even under conditions of limiting light, water and nutrients. This being the case, as literally hundreds of laboratory and field experiments have clearly demonstrated, the CO2 sequestering ability of the world’s plant life should rise right along with the CO2 content of the atmosphere. And at some future date it may be possible that it will have risen high enough to offset man’s perturbation of the global carbon cycle and yearly remove from the atmosphere all of the CO2 that we yearly put into it, which would stabilize the CO2 content of the air and prevent it from rising further.”

After discussing the dramatic results obtained from his orange tree experiments, Idso turns to the question of the effect on other trees comprising the total mix of Earth’s forests. To address that question he invokes the phenomenon of the fluctuating annual cycle of atmospheric CO2.

“When the terrestrial vegetation of the Northern Hemisphere awakens from winter dormancy each year, it withdraws great quantities of CO2 from the atmosphere as it begins a new season of growth, significantly lowering the CO2 content of the air. Likewise, when it senesces in the fall, great quantities of CO2 are liberated, raising the air’s CO2 content. The net result of these yearly recurring phenomena is a cyclic variation of the air’s CO2 concentration.”

But as Idso points out, something very interesting is going on with this process:

“The peaks and troughs of this cycle are becoming more enhanced each year, something that every group of scientists that has ever studied the subject has concluded is due to the aerial ‘fertilization effect’ of the rising CO2 content of earth’s atmosphere. That is, as the CO2 content of the air rises higher and higher each year, the plant life of the planet becomes more and more robust, so that each spring and summer it extracts more CO2 from the atmosphere than it did the year before, and each fall and winter it releases more of it back to the atmosphere.”

Recall that we learned that biospheric productivity increased at least 33% for a 300 parts per million increase of atmospheric CO2 in order to appreciate the significance of what Idso says next:

“What is particularly noteworthy about this observation is that the amplitude of the atmosphere’s seasonal CO2 cycle is increasing at a rate that is four times greater than what would be expected on the basis of what is known about the growth response of non-woody plants to atmospheric CO2 enrichment. This fact implies that total biospheric productivity would increase by about 4 x 33% for a 300-ppm increase in the air’s CO2 content.”

Based upon studies by Piers Sellers and James J. McCarthy in Planet Earth: Part III – Biosphere Interactions, Idso points out that land vegetation accounts for about 90% of the amplitude of the annual carbon dioxide cycle. [see: Sellers, Piers, and James J. McCarthy (1990) Planet Earth: Part III: Biosphere interactions. Eos, Transactions American Geophysical Union, vol. 71, no. 52 (Dec. 25) 1883-1884] As a percentage of the total planetary vegetation, trees account for about 75% of the land biospheric carbon exchange occurring in the process of photosynthesis. Therefore forests account for about 75% of 90% of the total global forest carbon uptake, or about two-thirds. The rest of Earth’s vegetation in the form of the non-woody plants account for about the remaining one-third of the response.

Based upon the rate of increase in the magnitude of the annual cyclic amplitude that is occurring four times greater than calculations would predict, Idso derives a very simple equation:

4(33%) = 1/3(33%) + 2/3GF

The term on the left represents the 4x net productivity enhancement of the entire biosphere as a consequence of a 300 ppm atmospheric enrichment. The first term on the right is the known response of non-woody plants and the second term is the mean response of the global forest (GF) to the same 300 ppm increase. Idso then solves the equation for GF:

132% = 11% + 2/3GF

132% − 11% = 2/3GF

3(121%) = 3(2/3GF)

362% = 2GF or GF = 181%

This number is consistent with Idso’s empirical studies on orange trees. Regarding the same experiments discussed above, Idso and his colleague Bruce Kimball provide additional details in the Journal of Agricultural and Forest Meteorology. In describing the increase in biomass both above ground and below ground, they note that: “although the fine root biomass density is enhanced by approximately 75% beneath the trees’ canopy, the fact that the roots of the CO2 enriched trees extend further out from their trunks than do the roots of the ambient trees results in a total biomass enhancement of 175%.” Admitting that such an increase seemed hard to believe Idso and Kimball point out that “A 175% enhancement of fine root biomass produced by a 300 (ppm) enrichment of the air may seem inordinately large, but other measurements we have made on the trees would appear to confirm its reality. Idso et al. (1991), for example, found the CO2 induced enhancement of total above-ground trunk plus branch volume to be 179%.”

Here we note something of great significance: Empirical studies in a microscale environment are consistent with the theoretical computations for the macro-scale global environment, implying that an increase of 180% in the mean productivity of the world’s forests is not far-fetched at all.

What does this imply with respect to climate change?

Simply this: Projections of future rise in carbon dioxide content would be limited as a result of accelerated consumption by increased global biomass.

Idso refers to the work of G. Marland from three years earlier (1988). In a paper prepared for the U.S. Department of Energy, Marland, who later became a contributing author for IPCC reports, calculated that the anthropogenic release of carbon dioxide into the global atmosphere could be balanced by a doubling of the growth rate of Earth’s forests. Based upon the idea that forests account for two-thirds of total global photosynthesis, Idso calculates the amount of additional carbon dioxide necessary to stimulate a doubling of global photosynthesis. What he discovers has provocative implications for, as he explains:

“the maximum increase in atmospheric CO2 predicted for the future is actually identical to the equivalent CO2 increase of the past hundred or so years. Hence, we have already lived through an equivalent atmospheric CO2 increase that is as large as the maximum additional CO2 rise that could yet occur in conjunction with current CO2 emission rates.”

And then Idso poses the $64,000 question: “If the past is prologue to the future, how much more CO2-induced warming is likely to occur?” His answer to that question is what has earned him the animosity of global warming promoters:

“Very little it would appear; for the most warming that is claimed for the globe over the course of the Industrial Revolution is about 0.5°C; and it can be effectively argued that only a portion of that warming may be attributed to CO2 and other trace gas increases. Thus, warming yet to be faced cannot be much more than what has already occurred, which may not even be sufficient to return the earth to the relative mildness of the climatic optimum that made possible the colonizing voyages of the Vikings.”

In regards to the question of the effect of a continued rise in the annual amount of CO2 released into the atmosphere by human activities, Idso points out that:

“higher rates of CO2 emissions would require relatively greater atmospheric CO2 increases to sequester the additional carbon. But as the greenhouse effect of a CO2 increase in this range is less than that of an equivalent CO2 increase in the 300- to 600-ppm range, a near linearity would still be maintained . . .”

Again, we have the fact that each incremental increase in atmospheric CO2 concentrations has a significantly diminished heat capturing capability than the equivalent increment that preceded it. Idso does stress the importance of preserving Earth’s forests since they function as such a powerful sink for atmospheric carbon dioxide, thereby significantly mitigating potential climatic consequences. In his closing remarks, he puts the carbon cycle phenomenon into perspective:

“In this regard, nature becomes our ally, as increases in atmospheric CO2 result in growth rate increases of trees five times greater than growth rate increases on nonwoody plants. Hence, as the CO2 content of the air continues to rise in the years ahead, woody species will begin to expand their ranges, as is already happening in many parts of the world. Also, as vegetative productivity increases simultaneously over the entire planet, man will harvest greater quantities of organic matter from each unit of land, thereby alleviating somewhat the pressures that currently lead to the felling of forests.”

Finally, Idso points out that:

“As the rising CO2 content of the atmosphere thus provides a strong impetus for forest expansion, it likewise provides a solution to any problems its continued upward trend might produce, as it intensifies the major mechanism responsible for its removal from the air, operating in true Gaian fashion.”

So we see that by 1991, Sherwood Idso is realizing that a small increase in atmospheric CO2 concentrations is beginning to stimulate a response from the biosphere and this stimulation could trigger a powerful negative feedback mechanism as far as greenhouse warming is concerned. We must now ask: What evidence has accrued of an increase of terrestrial biomass, in other words a greening of the Earth, in the interim since Idso published his work?

In an article published in the journal Nature in April of 1997, there appeared evidence portending things to come. The article was entitled: “Increased plant growth in the northern high latitudes from 1981 to 1991.” The lead author was Professor Ranga B. Myneni, with the Department of Earth and Environment at Boston University. Among the other four authors was the late Charles David Keeling (1928 – 2005), then with the Scripps Institute of Oceanography. Keeling is well-known in climate circles as the lead scientist responsible for establishing the carbon dioxide recording system at Mauna Loa Observatory that has documented the increase in atmospheric concentrations of CO2. The other authors included C. J. Tucker with NASA Goddard Space Flight Center; G. Asrar with the Office of Mission to Planet Earth, NASA; and R. R. Nemani with the School of Forestry, University of Montana.

In the Nature article, the authors present their analysis of data going back to 1981, collected by the Very High Resolution Radiometers (AVHRRs) carried on board National Oceanic and Atmospheric Administration (NOAA) meteorological satellites. These instruments can analyze the reflected wavelengths emanating from a variety of terrains, including desert, bare soil, inland water bodies, grasslands, forests and so on. Since each of these landscapes emits different wavelengths, it is possible to draw conclusions about the relative abundance of each type of land surface and the extent of vegetation. Study of the global land data so-produced led to the development of the “normalized difference vegetation index” or NDVI. The index is expressed as a scale from minus one to plus one and the greater the amount of vegetation the higher the number, with wavelengths in the range of 0.4 to 0.7 microns indicative of the photosynthetic activity of vegetation canopies. Studying 10 years’ worth of data that started in 1981, the authors discern a striking trend. In the abstract to their article they state: “Here we present evidence from satellite data that the photosynthetic activity of terrestrial vegetation increased from 1981 to 1991 in a manner suggestive of an increase in plant growth associated with a lengthening of the active growing season.” They further observe that the regions exhibiting the greatest increase occur between latitudes 45 and 70 degrees north.  [See: Myneni, R. B. et al. (1997) “Increased plant growth in the northern high latitudes from 1981 to 1991Nature, vol. 386 (April 17) pp. 698 – 702.]

In the same issue of Nature, an article introductory to the paper by Myneni et al., authored by Inez Fung with NASA Goddard Institute for Space Studies, puts their work into perspective.

“Sustained long-term observations of photosynthesis are rare. Furthermore, the biosphere is notoriously heterogeneous. It is very difficult to extrapolate from field measurements at a few sites to behavior over a large region. . . Myneni et al. present satellite evidence that, on average, the biosphere between 45° N and 70° N has been enjoying increased photosynthesis between 1981 and 1991 . . . The evidence presented by Myneni at al. is the first direct observation of the biosphere that photosynthesis has increased on such a broad scale for such a long time. The satellite observations are extremely provocative and, the authors argue, reveal specific areas where changes have occurred . . . It will be a challenge for ecologists to explain how photosynthesis could have increased by some 10% from 1981 to 1991.”  [See: Fung, Inez (1997) Climate change: a greener north. Nature, Vol. 386, April 17, pp. 659-660]

So here it is: By 1997 it had become apparent that because of the increased warmth since the late 19th century, coupled with increasing carbon dioxide amounts, the growing season had lengthened, as had the degree of photosynthetic activity of the biosphere. This was manifesting as amplified vegetation biomass, hence the phrase “a greener north” in the article’s title. The challenge to ecologists – to explain how photosynthesis could increase by 10% in a decade – is indeed provocative and implies the obligation to acknowledge a positive consequence to the increase in atmospheric carbon dioxide that is taking place, in contradistinction to the politically contrived view that seeks to demonize carbon dioxide as a pollutant. With this attitude regarding carbon dioxide now dominating the public discussion, an admission by workers in environmental and ecological fields of a positive effect would become a major liability, especially those seeking grant money from politically controlled or influenced sources.

The work of Myneni et al. examined forest response between the latitudes of 45 to 70 degrees north. What about tropical regions?

Tropical Response to CO2

A study appeared in Trends in Ecology & Evolution in the year 2000 that looked at the response of tropical forests to the increasing amounts of atmospheric carbon dioxide. The authors, Yadvinder Malhi and John Grace, were with the Institute of Ecology and Resource Management, University of Edinburgh, Scotland. Their report, appearing in the Perspectives section of the journal, began by discussing what they presumed to be the inexorable future rise of atmospheric CO2 concentrations due to fossil fuel burning and land clearing, and the implications of this increase to global climate change. They then qualify their statements by saying: “However, these changes are meshed within an immense natural global carbon cycle that is still poorly understood and that will almost certainly provide new surprises.” [See: Mahli, Yadvinder, and John Grace. “Tropical forests and atmospheric carbon dioxide.” Trends in Ecology & Evolution Vol 15, No. 8 (2000): 332-337.]

The two things these authors emphasize should be kept in mind before continuing: the immensity of the natural carbon cycle relative to the contributions of humans, and the fact that this immense natural phenomenon, which, in the authors’ words “is still poorly understood” is central to the question of climatic consequences.

If the authors are right, that the immense natural carbon cycle is “still poorly understood,” how is it possible to be so absolutely certain of outcomes that we can declare the debate over and the science settled with respect to the matter of climate change?

Mahli and Grace refer to a synopsis, published in the journal Tellus a year earlier, entitled Current perspectives on the terrestrial carbon cycle, by Jon Lloyd. They discuss some of the findings presented in Lloyds’ synopsis:

“A recent review of experimental studies growing trees in open-top chambers indicates that a 300 ppm increase in atmospheric CO2 concentration stimulates photosynthesis by 60%, the growth of young trees by 73% and wood growth per unit leaf area by 27%. It seems probable that there will be a similar response in natural forest ecosystems.”

In the context of the notable findings of Jon Lloyd, Mahli and Grace proceed to discuss the implications for the tropics: “Because of their intrinsic high productivity, tropical forests are a prime candidate for such a C fertilization response, the crucial question has been to what extent such a response might be limited by nutrient availability, in particular by low nitrogen or low phosphorus.” However, as they point out, studies referenced by Lloyd have shown that plants might “increase their nutrient acquisition process by investing in mycorrhizal colonization, and by mineralizing nutrient reserves in the soil by the production of surface enzyme systems and organic acid exudates.” In other words, it is entirely possible, if not likely, that plants in a carbon dioxide enriched environment will develop the means to more effectively utilize available nutrient supplies.

Mycorrhiza are actually two different entities, a plant and a fungus, existing in a symbiotic or mutually beneficial relationship. Various kinds of fungus associate themselves with a particular plant through the root system. It has been found that the mycelium of the fungus can perform a number of functions beneficial to the plant, for example, accessing sources of phosphorous unavailable to the plant alone. It has been found that plants in association with mycorrhizal fungus are more resistant to diseases and the effects of drought. Mycorrhizal fungi are important in the colonization of barren or desolate landscapes that have been devastated by catastrophic floods, fires, or volcanic eruptions, and provide greater protection for plants growing in soils with high metal or acid concentrations.

Mahli and Grace call attention to one of the important variables in the response of plants to rising CO2: If plants become more efficient in the process of nutrient uptake, it mitigates one of the limiting factors of plant response to increased carbon dioxide concentrations. In many of the hundreds of studies conducted on plant response to increased carbon dioxide, nutrient availability, along with availability of light, was most frequently the limiting factor in the plants’ exploitation of carbon dioxide conferred advantages. If this turns out to be true, that plants gain improved means of accessing nutrients in the soil, thereby increasing their bulk mass available for carbon uptake, then, as Mahli and Grace point out: “A small steady increase in forest productivity can produce a large net C sink.” In other words, the increase in biomass increases the ability of the forest to consume more carbon dioxide from the atmosphere transforming it into greater plant mass. The increased growth and plant mass, the forest in turn consumes even more carbon dioxide in a positive feedback loop, removing it from the atmosphere in the process.

Mahli and Grace presented a table displaying the net biotic carbon sink in tropical regions based on the results of the Large Scale Biosphere-Atmosphere Experiment (LBA) that not only looked at Amazonia, but Costa Rica and Southeast Asia as well. However, the implications of the results of the LBA were considered problematic by the authors who state that: “The total predicted tropical C sink is 4.5 Gt C year—1 (4.5 billion tons per year) . . . This seems implausible unless there are ‘missing sources’ in the global C budget that are currently neglected.”

Once again, we have the problem of the disappearing carbon. Let’s return to the question of carbon dioxide sources and sinks with which we began this essay.

Back to the Sink: Forests and Carbon Dioxide

4.5 Gt per year would amount to almost two-thirds of all the CO2 emitted annually through fossil fuel combustion. Is it possible that tropical forests are consuming this much carbon dioxide?

To understand this question better, the authors suggested that an alternative approach to detecting carbon uptake was to examine long-term forestry plots to see if there was evidence for increased biomass. To this end they turned to the work of O.L. Phillips et al., whose research report was published in the journal Science in 1998. Quoting from Phillips et al.:

“A recent study compiled data from forest inventories across 68 sites in apparently undisturbed tropical forests. It found large variability between plots, but reached a remarkable conclusion – most South American forests have increased in biomass in recent decades and have been accumulating C in biomass at a rate of 0.71 ± 0.39 t C ha-1 year-1.” [71 ± .39 tons of carbon per hectare per year]

Over the whole area of tropical forests, this translates into a total forest sink of some 2.0 gigatons of carbon per year of which at least half is in South America. So, according to these studies, tropical forests are taking up at about one-third of the amount of the carbon being released through fossil fuel consumption and they are responding with increased growth and biomass accumulation. This does not include the mid-latitude forests that are consuming a substantial amount of CO2 as well. In other words, Nature, with the help of Man, is initiating a rapid regeneration of tropical forests by exploiting the additional available carbon dioxide.

The Phillips et al. paper has some profound implications. They begin their paper by saying that: “Tropical forests contain as much as 40% of the C stored as terrestrial biomass and account for 30 to 50% of terrestrial productivity. Therefore, a small perturbation in this biome could result in a significant change in the global C cycle.” Their methodology involved compiling basal data on the cross-sectional area of trees per unit of ground area in mature tropical forest plots. The data was drawn from four tropical regions involving over 600,000 tree measurements. The results of Phillips et al. are consistent with the work of many other researchers and “are therefore indicative of a widespread increase in the biomass of surviving Neotropical forests over recent decades.” They come to no firm conclusions as to what factors, natural or anthropogenic, might be driving this increase in biomass but consider increasing carbon dioxide as a possibility saying: “The biomass increase could also be a response to recent anthropogenic global change . . . Candidate factors for nutrient fertilization include increasing atmospheric CO2. . .” Finally, in addressing the problem of the missing sink, the authors put forward the idea that is laden with implications: “Our results suggest that mature Neotropical forest biomass may account for ~40% of the so-called ‘missing’ terrestrial C sink. Hence, intact forests may be helping to buffer the rate of increase in atmospheric CO2, thereby reducing the impacts of global climate change.” [see: Philllips, O. L.  et al. (1998) Changes in the carbon balance of tropical forests: evidence from long term plots: Science, vol. 282 (Oct.18) pp. 439 – 442]

The same issue of Science contained a second article by a seven-member team describing a study of terrestrial carbon uptake in North America. The study utilized two atmospheric transport models incorporating data from 10 years’ worth of carbon dioxide samples collected from an array of atmospheric sampling stations. Using this data, spatial patterns indicative of the atmospheric distribution were developed and coupled with estimates of the ocean-atmosphere flux and the spatial distribution of fossil-fuel carbon dioxide emissions. From this information it became possible to determine that spatial distribution of carbon uptake, and ascertain an estimate of net annual terrestrial sources and sinks. Looking at variances in the pattern of carbon uptake, the authors report that: “A large North American terrestrial uptake was estimated consistently for a range of spatiotemporal patterns assumed for the terrestrial uptake.” This large-scale intake of carbon dioxide by North American vegetation is attributed to a number of factors, including regrowth of abandoned farmland and previously logged forests, with this process being enhanced by nitrogen deposition, CO2 fertilization, and a mild increase in temperature.  [see: Fan, S., M. Gloor, J. Mahlman, S. Pacala, J. Sarmiento, T Takahashi, P. Tans (1998) A Large Terrestrial Carbon Sink in North America Implied by Atmospheric and Oceanic Carbon Dioxide and Models: Science, vol. 282 (Oct. 16) pp. 442 – 446]

Both model simulations yielded more remarkable results. It was found that North America’s contribution to the annual uptake of carbon dioxide was about 1.7 billion tons. Given that the estimate of the annual North American emissions of CO2 by both the United States and Canada is about 1.6 billion tons, the implication is that North American vegetation is consuming each year more carbon dioxide than is being released through the burning of fossil fuel in North America!

A commentary on the findings of this team was included in the October 16 issue of Science to address this incredible and unexpected result:

“As greenhouse warming experts try to predict how much of the world’s climate may heat up in the next century, they keep bumping up against a mystery: Where does much of the carbon dioxide pumped into the air actually end up? . . . In what is shaping up as one of the most controversial findings yet to emerge in the greenhouse gas debate, a team of researchers . . . present evidence that North America sops up a whopping 1.7 petagrams (1.7 billion tons) of carbon a year – enough to suck up every ton of carbon discharged annually by fossil fuel burning in Canada and the United States.”

“The CMC  team acknowledges that its results strain credibility. ‘I have trouble quite believing’ the size of the sink, says Tans, adding that ‘We’re pushing the data pretty far.’ But, says Sarmiento, ‘we’ve really carefully analyzed the data in a lot of different ways.’ U.S. Geological Survey geochemist Eric Sundquist agrees: ‘The paper is a credible and rigorous interpretation of the available data.’ [see: Kaiser, Jocelyn (1998) Possibly Vast Greenhouse Gas Sponge Ignites Controversy: Science, vol. 282 (Oct. 16) pp. 386 – 387]

Obviously, these results have enormous implications relative to the whole global warming debate. And, just as obviously, “greenhouse warming experts” are not as omniscient as the mainstream press and varied promoters of propaganda would have us believe. It is time to recognize that the IPCC is NOT infallible, that the so-called “consensus” is a complete fiction, and, that an effort to impose a global regulatory scheme based upon uncertain science would be a certain blunder.

But let us proceed.

The Earth is Greening

In 2005, a study of the Sahel region of sub-Saharan Africa utilizing the NOAA AVHRR (Advanced Very High Resolution Radiometer) sensing system, employing the Normalized Difference Vegetation Index (NDVI), was published in the peer-reviewed Journal of Arid Environments. In their abstract the authors summarize the situation:

“For the last four decades there has been sustained scientific interest in contemporary environmental change in the Sahel (the southern fringe of the Sahara). It suffered several devastating droughts and famines between the late 1960s and early 1990s. Speculation about the climatology of these droughts is unresolved, as is speculation about the effects of land clearance on rainfall and about land degradation in this zone. However, recent findings suggest a consistent trend of increasing vegetation greenness in much of the region. Increasing rainfall over the last few years is certainly one reason, but does not fully explain the change.” [see: Olsson, L.; L. Eklundh & J. Ardo (2005) A recent greening of the Sahel—trends, patterns and potential causes: Journal of Arid Environments, vol. 63, pp. 556-566]

The figure below is reproduced from Olsson et al. It shows the results of trend analysis from 1982 to 1999 across the Sahel and southern Sahara region of North Africa. The data was derived from 40 climate observation stations and shows the percent change during that time frame. In regards to this figure the authors state: “The increase shown in Fig. 1 is remarkable. . .”

Reproduced below is Figure 1:

In the conclusion to their paper the authors state: “the strong secular trend of increasing vegetation greenness over the last two decades across the Sahel cannot be explained by a single factor such as climate. Increasing rainfall does explain some of the changes but not conclusively.”

So what other factors might remain to explain this greening of what has been desert through most of historical times?

As evidence continues to mount the answer to that question has become undeniable.

In 2005 the journal Global Change Biology carried a report on trends in the vegetation cover of Australia. The lead author Randall J. Donahue is a research scientist with CSIRO Land and Water, and the Research School of Biological Sciences at the Australian National University. The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is a 101 year old Australian scientific and research body, under whose auspices this work was conducted. The other two authors, Tim R. McVicar and Michael L. Roderick, are affiliated with the same institutions. The papers abstract describes their method:

“Using Advanced Very High Resolution Radiometer data spanning 1981-2006 . . . we examine whether vegetation cover has increased across Australia . . . Results from an Australia-wide analysis indicate that vegetation cover has increased, on average, by 0.0007 per year – an increase of ~8% over the 26 years . . . Over the same period, Australian average annual precipitation increased by 1.3 mm yr—2 (up 7%) . . . Interestingly, where vegetation cover increased at water-limited sites, precipitation trends were variable indicating that this is not the only factor driving vegetation response. As Australia is a generally highly water-limited environment, these findings indicate that the effective availability of water to plants has increased on average over the study period . . . Regardless of what has been driving these changes, the overall response of vegetation over the past 2 -3 decades has resulted in an observable greening of the driest inhabited continent on Earth.” [see: Donohue, Randall J.; Tim R. McVicar & Michael L. Roderick (2009) Climate-related trends in Australian vegetation cover as inferred from satellite observations, 1981-2006: Global Change Biology, vol. 15, pp. 1025-1039.]

By the year 2013, Randall Donahue and his colleagues had expanded the scope of their research from Australia to the globe. Their update was presented in Geophysical Research Letters. While they do not specifically name carbon dioxide as a culprit in their earlier work, by this time they had become convinced that it is playing a dominant role in the observed greening. They comment:

“Satellite observations reveal a greening of the globe over recent decades. The role in this greening of  the ‘CO2 fertilization’ effect—the enhancement of photosynthesis due to rising CO2 levels—is yet to be established. The direct CO2 effect on vegetation should be most clearly expressed in warm, arid environments where water is the dominant limit to vegetation growth. Using gas exchange theory, we predict that the 14% increase in atmospheric CO2 (1982-2010) led to a 5 to 10% increase in green foliage cover in warm, arid environments . . . Our results confirm that the anticipated CO2 fertilization effect is occurring alongside ongoing anthropogenic perturbations to the carbon cycle…”

“The increase in water use efficiency of photosynthesis with rising Ca [carbon dioxide] has long been anticipated to lead to increased foliage cover in warm, arid environments, and both satellite and ground observations from the world’s rangelands reveal widespread changes toward more densely vegetated and woodier landscapes. Our results suggest that Ca has played an important role in this greening trend and that, where water is the dominant limit to growth, cover has increased in direct proportion to the CO2-driven rise in Wp [water use efficiency of photosynthesis] . . . The CO2 fertilization cover effect warrants consideration as an important land surface process.” [See: Donohue, Randall J. et al. (2013) Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments: Geophysical Research Letters, vol. 40, pp. 3031 – 3035.]

The CO2 fertilization effect certainly does warrant consideration as an important land surface process – one that is clearly a net positive within the global terrestrial ecology. However, the reality is that among global warming promoters the subject of positive consequences is taboo – to even bring it up invites derision and condescension and charges of being a fossil fuel industry lackey. But such an attitude is, in reality, symptomatic of a combination of ignorance and arrogance, and an unwillingness to think outside the confines of one’s ideology.

Science Daily reported on the work of Donohue and his colleagues referenced above, after interviewing them about their work on the carbon fertilization effect. Among his comments, Donahue said this: “On the face of it, elevated CO2 boosting the foliage in dry country is good news and could assist forestry and agriculture in such areas; however there will be secondary effects that are likely to influence water availability, the carbon cycle, fire regimes and biodiversity, for example . . . Ongoing research is required if we are to fully comprehend the potential extent and severity of such secondary effects.” [see: CSIRO Australia. “Deserts ‘greening’ from rising carbon dioxide: Green foliage boosted across the world’s arid regions.Science Daily, July 8, 2013]

Absolutely we need more research, but it is also the case, based upon what we now know, that negative consequences of some of those secondary effects will be mitigated under a carbon dioxide enhanced atmosphere. For example, greater root mass means that the plant can reach deeper for water and nutrients; that it can consolidate and retain the soil against erosion more effectively; that it can survive the effects of fires more effectively, and would be less likely to uproot during an intense storm.

Evidence confirming a global biospheric recovery continues to accumulate. Another study was published in Nature, Climate Change in 2015 by a seven-member team that employed satellite-based passive microwave observation to estimate above ground biomass (ABC) whereas previous studies had utilized radar or optical observations. The authors make the point: “The intensity of natural microwave radiation from the Earth is a function of its temperature, soil moisture and the shielding effect of water in aboveground vegetation biomass.”  This new method supported earlier findings. From their investigations the team learned that:

“From 2003 onwards, forests in Russia and China expanded and tropical deforestation declined. Increased ABC associated with wetter conditions in the savannahs or northern Australia and southern Africa reversed global ABC loss, leading to an overall gain, consistent with trends in the global carbon sink reported in recent studies.” [see: Liu, Yi Y. et al. (2015) Recent reversal in loss of global terrestrial biomass: Nature Climate Change, vol. 5 (May) pp. 470 – 474]

A 2016 study on carbon exchange fluxes in the Sahel region concluded that: “A budget for the entire Sahel indicated a strong C sink mitigating the global anthropogenic C emissions.” [see: Tagesson, Torbern, et al. (2016) Spatiotemporal variability in carbon exchange fluxes across the Sahel: Agricultural and Forest Meteorology, vol. 226-227 (Oct.) pp. 108-118] It should be noted that the idea that the biosphere is acting as an important carbon dioxide sink, thereby reducing the amount in the atmosphere substantially over the long term, has generally been excluded from IPCC computerized projections of the future. But, here again, the evidence is mounting that as the density of the Earth’s vegetation increases so will the ongoing need for greater amounts of CO2 to stimulate photosynthesis, resulting in a positive feedback cycle.

Reinforcing this probable outcome is the work of Joseph M. Craine and Peter B. Reich, with the Department of Integrative Biology at the University of California, Berkelely, and the Department of Forest Resources at the University of Minnesota, respectively. Their work, published in 2001 in New Phytologist, looked at the longevity of leaves for ten grassland species under varying carbon dioxide concentrations and was able to demonstrate yet another positive effect. They write:

“Although many plant traits affect C and N cycles in an ecosystem, leaf longevity has a central role in determining litterfall, standing biomass, and net primary productivity (NPP). For example, increases in leaf longevity could increase the carbon gain of individual leaves . . . and therefore increase stand NPP.” [see: Craine, Joseph M. & Peter B. Reich (2001) Elevated CO2 and nitrogen supply alter leaf longevity of grassland species: New Phytologist, vol. 150, pp. 397 – 403)

In other words, by living longer the leaves of these plants would consume even more carbon dioxide. As the authors say in their concluding discussion: “All other things equal, the increase in leaf longevity due to elevated CO2 would lead to greater ecosystem carbon gain, assuming the leaves maintained positive net photosynthesis over the additional period.”

A 2014 study looked at long-term experimental forestry plots that were established in 1872 in Central Europe, the same year as the founding of the International Union of Forest Research Organizations. From then until the present day, now over 140 years, these plots were surveyed between 10 and 20 times. The authors of this new study, Hans Pretzsch and four others, used the data collected from these surveys to analyze growth trends. What they found was astounding:

“Based on the oldest existing experimental forest plots in Central Europe, we show that, currently, the dominant tree species Norway spruce and European beech exhibit significantly faster tree growth (+ 32 to 77%), stand volume growth (+ 10 to 30%) and standing stock accumulation (+ 6 to 7%) than in 1960 . . . Standing wood volume, mean diameter, dominant height and mean tree volume currently grow significantly faster than in the past . . . coinciding with an increase in resource supply (CO2, N), together with an extended growing season accompanied by changes in other climatic variables … present forest stands grow more rapidly, and accumulate a given standing volume earlier than comparable stands did a century ago.” [see: Pretzsch, Hans, et al. (2014) Forest stand growth dynamics in Central Europe have accelerated since 1870: NatureCommunications 5 : 4967 | DOI: 10.1038 / ncomms 5967 | /naturecommunications]

This study of forest plots that have been carefully surveyed and monitored for a period in excess of 140 years, revealed that the rate of forest growth itself has accelerated strikingly since 1960. Could this result be extrapolated to the global scale?

Recovery of the Biosphere and Popular Misconceptions

The authors of another 2016 study employ meta-analytic techniques to compare soil water content under both ambient and elevated CO2 concentrations with varying conditions of climate, vegetation, soil and so on. The research was based upon 1705 field measurements sampled from 21 separate sites widely dispersed across 8 countries and published in 45 independent studies. In the abstract to this report the authors concede the now unavoidable conclusion:

“While recent findings based on satellite records indicate a positive trend in vegetation greenness over global drylands, the reasons remain elusive. We hypothesize that enhanced levels of atmospheric CO2 play an important role in the observed greening through the CO2 effect on plant water savings and consequent available soil water increases.”

The authors begin their paper by defining and describing the phenomenon of drylands:

“Defined broadly as zones where mean annual precipitation is less than two-thirds of potential evaporation, drylands are critically important systems and represent the largest terrestrial biome on the planet. Climate change, increasing populations and resulting anthropogenic effects are all expected to impact dryland regions over the coming decades. Considering that approximately 90% of the more than 2 billion people living in drylands are geographically located within developing countries, improved understanding of these systems is an international imperative.” [see: Lu, Xuefei; Lixin Wang & Matthew F. McCabe (2016) Elevated CO2 as a driver of global dryland greening: reports (Feb. 12)]

Certainly the reoccurrences of drought and famine over the decades, especially in sub-Saharan Africa, have repeatedly underscored the importance of improved understanding as an international imperative.

But then the authors go on to describe the extraordinary developments beginning to manifest on planet Earth that could change the entire equation in profound ways:

“Recent regional scale analyses using satellite based vegetation indices such as the Normalized Difference Vegetation Index (NDVI), have found extensive areas of ‘greening’ in dryland areas of the Mediterranean, the Sahel, the Middle East and Northern China, as well as greening trends in Mongolia and South America. More recently, a global synthesis over the period 1982-2007 that used an integrated NDVI and annual rainfall, showed an overall ‘greening-up’ trend over the Sahel Belt, Mediterranean basin, China, Mongolia region and the drylands of South America.”

Pause for a minute and ponder what this research is saying. After years of a presumptive expansion of Earth’s deserts it is beginning to dawn upon researchers that something has changed – deserts are now contracting!

In various public forums and podcasts I have pointed out that the Earth’s deserts are actually contracting. In response to presenting this information various “critics” have typically said something to the effect that everybody “knows” that deserts are expanding around the world, and therefore I don’t know what I am talking about, and since I don’t know what I am talking about regarding that one thing, anything else I might have to say can be dismissed or ignored as well!

The idea of popular misconceptions regarding the status of Earth’s deserts was addressed recently in the Proceedings of the National Academy of Sciences in an article entitled “On regreening and degradation of Sahelian watersheds.” The study by Armel T. Kaptue and two colleagues at the Geospatial Sciences Center of Excellence, South Dakota State University, used satellite-derived vegetation indices in Senegal, Mali, and Niger from 1983 to 2012 to determine net primary production. As a preface to their work the authors explain that: “In the last 20 y, remote-sensing studies have documented an apparent increase in vegetation productivity in the Sahel using satellite measurements of vegetation greenness” (NDVI). But, while this has been going on, they further explain: “Over many decades our understanding of the impacts of intermittent drought in water-limited environments like the West African Sahel has been influenced by a narrative of overgrazing and human-induced desertification. The desertification narrative has persisted in both scientific and popular conception, such that regional-recovery (“regreening”) . . . following the severe droughts of the 1970s—1980s, are sometimes ignored.” And further “in the popular press and often in the environmental and development literature, the reports are sometimes forgotten, to the extent that popular opinion . . . holds fast to pessimistic images of overgrazing, degradation, sand storms, and sand-dunes “marching” south from the Sahara towards the sea.” [see: Kaptue, Armel; Lara Prihodka, and Niall P. Hanan (2015) On regreening and degradation in Sahelian watersheds: Proceedings of the National Academy of Science, vol. 112, no. 39 (Sept. 29) pp. 12133-12138]

As I am criticized by various individuals who find the information I bring to the table unpalatable because it goes against their assumptions and unexamined beliefs, it is persistently apparent that most of them are simply regurgitating something they have heard, or read in popular accounts and assume, therefore, that they have enough knowledge to express an opinion on the matter. The degree of ignorance, the amount of misinformation and lack of critical thinking skills manifest in many of the remarks directed towards me in some of these public forums is symptomatic, I believe, of the sorry state of modern liberal education in America today. But that is a discussion for another place.

Another report by a 19 member international scientific team was published in 2016 that utilized two 30-year remote-sensing-based estimates of the northern hemisphere leaf area index (LAI) coupled with simulations from 19 Earth system models (ESMs). There is no ambiguity about the findings of this team:

“Significant land greening in the northern extratropical latitudes (NEL) has been documented through satellite observations during the past three decades. This enhanced vegetation growth has broad implications for surface energy, water and carbon budgets and ecosystem services across multiple scales. . . Our findings reveal that the observed greening record is consistent with an assumption of anthropogenic forcings, where greenhouse gases play a dominant role . . .”

“Where greenhouse gases play a dominant role.” In the conclusion to their report the authors state that:

“This study adds to an increasing body of evidence that the NEL has experienced an enhancement of vegetation activity, as reflected by increased trends in vegetation indices, aboveground vegetation biomass, and terrestrial carbon fluxes during the satellite era. Our analysis goes beyond previous studies . . . to establish that the trend of strengthened northern vegetation greening is clearly distinguishable from both the IV (internal variability) and the response to natural forcings alone. It can be rigorously attributed, with high statistical confidence, to anthropogenic forcings, particularly to rising concentrations of greenhouse gases.” [see: Mao, Jiafu; et al. (2016) Human-induced greening of the northern extratropical land surface: Nature Climate Change, Vol. 6 (Oct.) pp. 959 – 963]

The results of yet another study, conducted by a multidisciplinary, international team of scientists were published in 2016 in the journal Nature, Climate Change. This research confirms what is becoming apparent to a growing number of researchers around the world concerning the terrestrial effects of carbon dioxide enrichment. NASA’s website featured an account of the work of this team under the heading “Carbon Dioxide Fertilization Greening Earth, Study Finds.” The account proceeds to describe the work of the team:

“From a quarter to half of Earth’s vegetated lands has shown significant greening over the last 35 years largely due to rising levels of atmospheric carbon dioxide, according to a new study published in the journal Nature, Climate Change on April 25. An international team of 32 authors from 24 institutions in eight countries led the effort, which involved using satellite data from NASA’s Moderate Resolution Imaging Spectrometer and the National Oceanic and Atmospheric Administration’s Advanced Very High Resolution Radiometer instruments to help determine the leaf area index, or amount of leaf cover, over the planet’s vegetated regions. See NASA’s website at

The study involved computer simulations of each variable in turn that could be stimulating the observed greening. The team looked at global temperature change, land cover change, precipitation, sunlight, nitrogen and carbon dioxide. The conclusion reached after extensive analysis was that nitrogen was responsible for 9% of the effect while carbon dioxide contributed a whopping 70%. One of the lead authors of this study was Ranga Myneni whose work was discussed above. Lead author Zaichun Zhu, from Peking University, China, is quoted as saying that the greening “has the ability to fundamentally change the cycling of water and carbon in the climate system.” Co-author Shilong Piao of the College of Urban and Environmental Sciences at Peking commented: “While our study did not address the connection between greening and carbon storage in plants, other studies have reported an increasing carbon sink on land since the 1980s, which is entirely consistent with the idea of a greening Earth.”

In any case the article concludes with a little perspective on the matter:

“The greening represents an increase in leaves on plants and trees equivalent in area to two times the continental United States.”

This incredible phenomenon of planetary greening is of such considerable interest and importance that it is worth referring to the original Nature, Climate Change paper upon which NASA based their report for additional insight. In the abstract of that paper the authors describe their procedure and results:

“Global environmental change is rapidly altering the dynamics of terrestrial vegetation, with consequences for the functioning of the Earth system . . . Yet how global vegetation is responding to the changing environment is not well established. Here we use three long-term satellite leaf area index (LAI) records and ten global ecosystem models to investigate 4 key drivers of LAI trends during 1982-2009. We show a persistent and widespread increase of the growing season integrated LAI (greening) over 25% to 50% of the global vegetated area . . . Factorial simulations with multiple global ecosystem models suggest that CO2 fertilization effects explain 70% of the observed greening trend, followed by nitrogen deposition (9%), climate change (8%) and land cover change (LCC) (4%). CO2 fertilization effects explain most of the greening trends in the tropics, whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau.” [See: Zhu, Zaichun, et al. (2016) Greening of the Earth and its drivers: Nature, Climate Change, Vol. 6, August, pp. 791 – 796]

By using the phrase “climate change,” the authors are referring to the global increase in average temperature of about one degree in the past 150 years. The authors conclude their milestone paper with this statement: “Overall, the described LAI (leaf area index) trends represent a significant alteration of the productive capacity of terrestrial vegetation through anthropogenic influences.”

Let’s consider what this statement is saying.

The alteration of the productive capacity of terrestrial vegetation is a positive alteration, meaning that it is leading to MORE productive capacity for Earth’s vegetation, and this, as they readily admit, is happening as the result of anthropogenic influences. In other words, by consuming fossil fuel and releasing carbon dioxide into the atmosphere, we humans are increasing the productive capacity of Earth’s vegetation.

Grand Finale – Part 4: Greening the Earth / Little Ice Age / Final Comments