The cumulative increase in mean global sea level (1904-2003) derived from nine high-quality tide gauge records from around the world. Adapted from Holgate (2007).

Another way of thinking about Holgate's century-long sea level history is suggested by the blue curve we have fit to it, which indicates that mean global sea level may have been rising ever more slowly with the passage of time throughout the entire last hundred years. In any event, and whichever way one looks at Holgate's findings - as either two linear trends or one longer continuous curve - the nine select tide gauge records indicate that the mean rate of global sea level rise has not accelerated over the recent past. In fact, it likely has done just the opposite - in clear contradiction of Hansen's adamant claim to the contrary.

Augmenting the findings of Holgate are those of Jevrejeva et al. (2006), who analyzed information contained in the Permanent Service for Mean Sea Level database using a method based on Monte Carlo Singular Spectrum Analysis. Removing 2- to 30-year quasi-periodic oscillations, they derived nonlinear long-term trends for 12 large ocean regions, which they combined to produce the mean global sea level (gsl) and mean global sea level rate-of-rise (gsl rate) curves depicted in the figure below.

Mean gsl (top), with its shaded 95% confidence interval, and mean gsl rate (bottom), with its shaded standard error interval. Adapted from Jevrejeva et al. (2006).

In discussing their results, Jevrejeva et al. say they show that "global sea level rise is irregular and varies greatly over time," and that "it is apparent that rates in the 1920-1945 period are likely to be as large as today's." In addition, they report that their "global sea level trend estimate of 2.4 ± 1.0 mm/year for the period from 1993 to 2000 matches the 2.6 ± 0.7 mm/year sea level rise found from TOPEX/Poseidon altimeter data."

With respect to what Jevrejeva et al. describe as "the discussion on whether sea level rise is accelerating," their results pretty much answer the question in the negative; and in further support of this conclusion, they note that "Church et al. (2004) pointed out that with decadal variability in the computed global mean sea level, it is not possible to detect a significant increase in the rate of sea level rise over the period 1950-2000," as is clearly evident from the bottom portion of the above figure.

These observations lead us to wonder why late 20th-century global warming - which climate alarmists describe as having been unprecedented over the past two millennia or more - barely makes a ripple in the global sea level data of the two preceding figures. We are even more intrigued about the matter in light of the fact that the warming that brought an end to the Little Ice Age is readily apparent in the first, and even the second, of the three upward-trending segments of Jevrejeva et al.'s gsl rate history. Likewise, we are perplexed by the fact that the rising atmospheric CO2 concentration - which climate alarmists contend was responsible for the "unprecedented" global warming of the late 20th century - experienced a dramatic increase in its rate of rise just after 1950 (shifting from a 1900-1950 mean rate-of-rise of 0.33 ppm/year to a 1950-2000 mean rate-of-rise of 1.17 ppm/year, which is a good three and a half times greater), yet the mean global sea level rate of rise did not trend upwards after 1950, nor has it subsequently exceeded its 1950 rate-of-rise, which means that something is very wrong with the climate-alarmist theory espoused by Hansen and his dozens of collaborators.

So what does a climate modeler do when the world of nature refuses to behave as his model suggests it should? One option is to claim that the response times of many of the modeled processes are so long that the major proportions of their manifestations are yet to be seen, which enables Hansen to contend that "we have not yet felt the full climate impact of the gases that have already been added to the atmosphere," and to affirm that the predicted phenomena are still, as he says, "in the pipeline." But this argument has its problems too.

Atmospheric Methane Concentrations

One of the major "slow" feedback processes that Hansen identifies is "the effect of warming on emissions of long-lived greenhouse gases," such as he claims is being caused by the "melting of tundra in North America and Eurasia," which he states "is observed to be causing increased ebullition of methane from methane hydrates." The real world of nature, however, seems little impressed by these contentions; for after rising rapidly since the start of the Industrial Revolution, the air's methane concentration has been rising ever more slowly, especially during the "unprecedented" warming of the last few decades. In fact, since the beginning of the 21st century, the atmosphere's methane concentration has actually stabilized - ceasing to rise any further - as indicated by the data provided by Dlugokencky et al. (2003), which we have plotted in the figure below, and to which we have fit two linear regressions and an intervening second-order polynomial.

Why are these observations so important? They are important because, as Dulgokencky et al. report, "atmospheric methane's contribution to anthropogenic climate forcing is about half that from CO2 [our italics] when direct and indirect components to its forcing are summed (Hansen and Sato, 2001)." In addition, they note that "all methane emission scenarios considered by the IPCC Special Report on Emission Scenarios (Nakicenovic et al., 2000) resulted in increasing [our italics] atmospheric methane for at least the next 3 decades, and many of the scenarios projected large increases through the 21st century (Prather et al., 2001)." In reality, however, it now appears that a large portion of the anticipated global warming problem may have simply disappeared, rather than gotten much worse, as Hansen claims.

Another - and slightly expanded - perspective of the atmosphere's methane history has been presented by Khalil et al. (2007), which we have reproduced in the figure below and to which we have added the smooth green line.

Global atmospheric methane concentration. Adapted from Khalil et al. (2007).

This graph suggests that the trend in atmospheric methane concentration, as Khalil et al. describe it, "has been decreasing for the last two decades until the present when it has reached near zero," and they say that "it is questionable whether human activities can cause methane concentrations to increase greatly in the future." In fact, there is reason to believe the global methane concentration may actually begin to decline ... and soon!

To explain the rational behind this surprising scenario, we turn to the study of Simpson et al. (2002), who presented annual global tropospheric methane growth rates for the period 1983-2000, based on measurements made by the Department of Chemistry at the University of California in Irvine, as depicted in the figure below.

Tropospheric methane growth rate vs. time. Adapted from Simpson et al. (2002).

With respect to the data of this figure, and particularly the data from the 1990s, Simpson et al. said they "caution against viewing each year of high methane growth as an anomaly against a trend of declining methane growth." Yet that is precisely what the data suggest, i.e., a declining baseline upon which are superimposed periodic anomalous increases; and in this interpretation, we are not alone. The first of the large methane spikes depicted in the above figure is widely recognized as having been caused by the sudden eruption of Mt. Pinatubo in June of 1991 (Bekki et al., 1994; Dlugokencky et al., 1996; Lowe et al., 1997); while the last and most dramatic of the spikes has been associated with the strong El Niño of 1997-98 (Dlugokencky et al., 2001). In addition, Dlugokencky et al. (1998), Francey et al. (1999) and Lassey et al. (2000) have all felt confident in concluding the data suggest that the annual rate-of-rise of the atmosphere's methane concentration has indeed declined and led to a cessation of methane concentration growth.

Projecting ahead, if anomalous methane spikes similar to those that occurred in the 1990s continue to occur at similar intervals in the future, the atmosphere's methane concentration should continue to rise - but only very slowly - for just a few more years, after which the declining background methane growth rate, which has already turned negative, will have dropped low enough to overwhelm any short-term impacts of periodic methane spikes. At that point in time we may thus be able to see an actual decline in the air's methane concentration, which should gradually accelerate if subsequent methane spikes fail to penetrate into positive territory. Consequently, if this scenario proves to be correct, the decreasing trend in atmospheric methane concentration may soon provide a negative-greenhouse force that could counter a good deal of the positive-greenhouse force created by the ongoing rise in the air's CO2 content.

Nevertheless, and in spite of all of the real-world observations supportive of either a flat or a soon-to-be-declining trend in atmospheric methane concentration, Hansen contends in his US House of Representatives testimony that "greenhouse gases" - of which methane stands next in importance to CO2 - "are skyrocketing." In making this claim, Hansen is totally out of touch with reality.

Climates of the Past

In an attempt to depict earth's current temperature as being extremely high and, therefore, extremely dangerous, Hansen focuses almost exclusively on a single point of the earth's surface in the Western Equatorial Pacific, for which he and others (Hansen et al., 2006) compared modern sea surface temperatures (SSTs) with paleo-SSTs that were derived by Medina-Elizade and Lea (2005) from the Mg/Ca ratios of shells of the surface-dwelling planktonic foraminifer Globigerinoides rubber that they obtained from an ocean sediment core. In doing so, they concluded that "this critical ocean region, and probably the planet as a whole [our italics], is approximately as warm now as at the Holocene maximum and within ~1°C of the maximum temperature of the past million years [our italics]."

Is there any compelling reason to believe these claims of Hansen et al. about the entire planet? In a word, no, because there are a multitude of other single-point measurements that suggest something vastly different.

Even in their own paper, Hansen et al. present data from the Indian Ocean that indicate, as best we can determine from their graph, that SSTs there were about 0.75°C warmer than they are currently some 125,000 years ago during the prior interglacial. Likewise, based on data obtained from the Vostok ice core in Antarctica, another of their graphs suggests that temperatures at that location some 125,000 years ago were about 1.8°C warmer than they are now; while data from two sites in the Eastern Equatorial Pacific indicate it was approximately 2.3 to 4.0°C warmer compared to the present at about that time. In fact, Petit et al.'s (1999) study of the Vostok ice core demonstrates that large periods of all four of the interglacials that preceded the Holocene were more than 2°C warmer than the peak warmth of the current interglacial.

But we don't have to go nearly so far back in time to demonstrate the non-uniqueness of current temperatures. Of the five SST records that Hansen et al. display, three of them indicate the mid-Holocene was also warmer than it is today. Indeed, it has been known for many years that the central portion of the current interglacial was much warmer than its latter stages have been. To cite just a few examples of pertinent work conducted in the 1970s and 80s - based on temperature reconstructions derived from studies of latitudinal displacements of terrestrial vegetation (Bernabo and Webb, 1977; Wijmstra, 1978; Davis et al., 1980; Ritchie et al., 1983; Overpeck, 1985) and vertical displacements of alpine plants (Kearney and Luckman, 1983) and mountain glaciers (Hope et al., 1976; Porter and Orombelli, 1985) - we note it was concluded by Webb et al. (1987) and the many COHMAP Members (1988) that mean annual temperatures in the Midwestern United States were about 2°C greater than those of the past few decades (Bartlein et al., 1984; Webb, 1985), that summer temperatures in Europe were 2°C warmer (Huntley and Prentice, 1988) - as they also were in New Guinea (Hope et al., 1976) - and that temperatures in the Alps were as much as 4°C warmer (Porter and Orombelli, 1985; Huntley and Prentice, 1988). Likewise, temperatures in the Russian Far East are reported to have been from 2°C (Velitchko and Klimanov, 1990) to as much as 4-6°C (Korotky et al., 1988) higher than they were in the 1970s and 80s; while the mean annual temperature of the Kuroshio Current between 22 and 35°N was 6°C warmer (Taira, 1975). Also, the southern boundary of the Pacific boreal region was positioned some 700 to 800 km north of its present location (Lutaenko, 1993).

But we needn't go back to even the mid-Holocene to encounter warmer-than-present temperatures, as the Medieval Warm Period, centered on about AD 1100, had lots of them. In fact, every single week since 1 Feb 2006, we have featured on our website (www.co2science.org) a different peer-reviewed scientific journal article that testifies to the existence of this several-centuries-long period of notable warmth, in a feature we call our Medieval Warm Period Record of the Week. Also, whenever it has been possible to make either a quantitative or qualitative comparison between the peak temperature of the Medieval Warm Period (MWP) and the peak temperature of the Current Warm Period (CWP), we have included those results in the appropriate quantitative or qualitative frequency distributions we have posted within this feature; and a quick perusal of these ever-growing databases (reproduced below as of 23 May 2007) indicates that, in the overwhelming majority of cases, the peak warmth of the Medieval Warm Period was significantly greater than the peak warmth of the Current Warm Period.

The distribution in 0.5°C increments of Level 1 Studies that allow one to identify the degree by which peak MWP temperatures either exceeded (positive values, red) or fell short of (negative values, blue) peak CWP temperatures.

The distribution of Level 2 Studies - not including Level 1 Studies - that allow one to determine whether peak MWP temperatures were warmer than (red), equivalent to (green), or cooler than (blue), peak CWP temperatures.

In concluding this portion of our critique of Hansen's testimony, we note that the mean surface air temperature of the earth is currently nowhere near as high as it was a million years ago. Neither are current temperatures as high as the peak temperatures of the prior four interglacials, nor are they as high as they were during the central portion of the current interglacial. In fact, it's not even as warm now as it was a paltry 900 years ago, when the atmosphere's CO2 concentration was 100 ppm less than it is today, which sure doesn't say much for the warming power of CO2 nor for the storyline promoted in Hansen's testimony.

Warming-Induced Extinctions of Terrestrial Plants and Animals

Hansen writes that "continued business-as-usual greenhouse gas emissions threaten many ecosystems," contending - even more ominously - that "very little additional [climate] forcing is needed ... to cause the extermination of a large fraction of plant and animal species." But where is the evidence for these claims? Hansen says that "animals and plants migrate as climate changes," and so they do, both upward in altitude and poleward in latitude; and he states that in response to global warming, "polar species can be pushed off the planet [i.e., driven to extinction], as they have no place else to go," and that "life in alpine regions ... is similarly in danger of being pushed off the planet." But again, where is the evidence to support these contentions?

In searching Hansen's testimony and his "accepted for publication" manuscript on the subject, we could find no real-world support for this aspect of his climate-alarmist thesis. What we did find was typically of the same nature as Hansen's own writings: claims, contentions and opinions, but no hard evidence. Such is also the case with many peer-reviewed science journal articles that promote the same philosophy, such as those of Root et al. (2003) and Parmesan and Yohe (2003). However, as we have indicated in a major study of the topic that is archived on our website (Idso et al., 2003), even these studies have failed to provide any hard data in support of their egregious extrapolations.

So what's the real situation with respect to rising air temperatures and atmospheric CO2 concentrations, as well as the life-and-death impacts they may - or may not - have on earth's plants and animals?

A good place to begin in answering this question is with the growth-enhancing effects of elevated atmospheric CO2, which typically increase with rising air and leaf temperatures. This phenomenon is illustrated by the data of Jurik et al. (1984), who exposed bigtooth aspen leaves to atmospheric CO2 concentrations of 325 and 1935 ppm and measured their photosynthetic rates at a number of different temperatures. In the figure below, we have reproduced their results and slightly extended the two relationships defined by their data to both warmer and cooler conditions.

In viewing this figure, it can be seen that at a leaf temperature of 10°C, elevated CO2 has essentially no effect on net photosynthesis in this particular species, as Idso and Idso (1994) have demonstrated is characteristic of plants in general. At 25°C, however, where the net photosynthetic rate of the leaves exposed to 325 ppm CO2 is maximal, the extra CO2 of this study boosted the net photosynthetic rate of the foliage by nearly 100%; and at 36°C, where the net photosynthetic rate of the leaves exposed to 1935 ppm CO2 is maximal, the extra CO2 boosted the net photosynthetic rate of the foliage by a whopping 450%. In addition, the extra CO2 increased the optimum temperature for net photosynthesis in this species by about 11°C: from 25°C in air of 325 ppm CO2 to 36°C in air of 1935 ppm CO2.

In viewing the warm-temperature projections of the two relationships at the right-hand side of the figure, it can additionally be seen that the transition from positive to negative net photosynthesis - which denotes a change from life-sustaining to life-sapping conditions - likely occurs somewhere in the vicinity of 39°C in air of 325 ppm CO2 but somewhere in the vicinity of 50°C in air of 1935 ppm CO2. Consequently, not only was the optimum temperature for photosynthesis of bigtooth aspen greatly increased by the extra CO2 of this experiment, so too was the lethal temperature (above which life cannot long be sustained) likewise increased, and by approximately the same amount, i.e., 11°C.

These observations, which are similar to what has been observed in many other plants, suggest that when the atmosphere's temperature and CO2 concentration rise together (Cowling, 1999), the vast majority of earth's plants would likely not feel a need (or only very little need) to migrate towards cooler regions of the globe. Any warming would obviously provide them an opportunity to move into places that were previously too cold for them, but it would not force them to move, even at the hottest extremes of their ranges; for as the planet warmed, the rising atmospheric CO2 concentration would work its biological wonders, significantly increasing the temperatures at which most of earth's C3 plants - which comprise about 95% of the planet's vegetation - function best, creating a situation where earth's plant life would actually "prefer" warmer conditions.

So what do we find at the tops of alpine mountains nowadays? Have any plants there been "pushed off the planet" in response to supposedly unprecedented 20th-century global warming?

Walther et al. (2005) investigated this climate-alarmist nightmare by resurveying (in July/August 2003) the floristic composition of the uppermost ten meters of ten mountain summits in the Swiss Alps, applying the same methodology used in earlier surveys of the same mountain tops by Rubel (1912), which was conducted in 1905, and Hofer (1992), which was conducted in 1985. Hence, their analysis covered the bulk of the Little Ice Age-to-Current Warm Period transition (1905-2003), the last portion of which (1985-2003) is claimed by climate alarmists such as Hansen to have experienced a warming that was unprecedented over the past two millennia (or more!) in terms of both the rate of temperature rise and the degree to which the temperature rose.

This work revealed that plants of many species marched up the mountainsides of the Swiss Alps as the earth warmed, but that none of them were "pushed off the planet." As a result, the species richness (i.e., biodiversity) of the ten mountaintops was dramatically increased over the past century of global warming. For the time interval 1905-1985, for example, the mean increase in species numbers recorded by Hofer (1992) was 86%; and Walther et al. report that "species numbers recorded in 2003 were generally more than double (138%) compared to the results by Rubel (1912) and 26% higher than those reported by Hofer (1992)." Put another way, they say that "the rate of change in species richness (3.7 species/decade) was significantly greater in the later period compared to the Hofer resurvey (1.3 species/decade)." Most important of all, they say that "the observed increase in species numbers does not entail the replacement of high alpine specialists by species from lower altitudes [our italics], but rather has led to an enrichment [our italics] of the overall summit plant diversity."

Another pertinent study of evolving mountaintop biodiversity was conducted by Kullman (2007), who analyzed the changing behavior of alpine and subalpine plants, together with shifts in their geographical patterns, during the past century, when air temperatures rose by about 1°C in the Scandes of west-central Sweden, which "methodical approach," in his words, "also included repeat photography, individual age determinations and analyses of permanent plots." This work revealed, according to Kullman, that "at all levels, from trees to tiny herbs, and from high to low altitudes, the results converge to indicate a causal association between temperature rise and biotic evolution." More specifically, he reports that "treeline advance since the early 20th century varies between 75 and 130 m, depending on species and site," and that "subalpine/alpine plant species have shifted upslope by [an] average [of] 200 m." In addition, he states that "present-day repetitions of floristic inventories on two alpine mountain summits reveal increases of plant species richness by 58 and 67%, respectively, since the early 1950s." And again, Kullman also reports that "no species have yet become extinct from the highest elevations [our italics]," adding that his results "converge with observations in other high-mountain regions worldwide," in support of which statement he cites the studies of Grabherr et al. (1994), Keller et al. (2000), Kullman (2002), Virtanen et al. (2003), Klanderud and Birks (2003), Walther et al. (2005) and Lacoul and Freedman (2006).

Switching from plants to animals, Parmesan et al. (1999) examined the distributional changes, broadly spread over the past century, of non-migratory species of butterflies whose northern boundaries were in northern Europe and whose southern boundaries were in southern Europe or northern Africa. Their analysis indicated that the northern boundaries of the ranges of 52 species shifted northward for 65% of them, remained stable for 34% of them, and shifted southward for 2% of them, while the southern boundaries of the ranges of 40 species shifted northward for 22% of them, remained stable for 72% of them, and shifted southward for 5% of them. Consequently, in the words of the thirteen researchers who conducted the work, "nearly all northward shifts involved extensions at the northern boundary with the southern boundary remaining stable."

Since this is precisely the type of behavior we would expect for plants in a CO2-enriched and warming world - i.e., an opportunity for significant poleward expansion at the cold edge of a species' range, but little to no impetus for poleward migration at the warm edge of its range - it is possible that the observed changes in European butterfly ranges over the past century of concomitant warming and rising atmospheric CO2 concentration are related to matching changes in the ranges of the plants upon which the butterflies depend for food. Or, the similarity could be due to some more complex phenomenon, possibly even a direct physiological effect of temperature and atmospheric CO2 concentration at work on the butterflies themselves.

In any event, in the face of the 0.8°C of warming experienced in Europe over the 20th century and the 75-ppm (25%) increase in atmospheric CO2 concentration experienced concurrently, the ultimate consequence for European butterflies has not been threatening at all, much less a portent of extinction. In fact, since "nearly all northward [range] shifts involved extensions at the northern boundary with the southern boundary remaining stable," according to Parmesan et al., "most species effectively expanded the size of their range when shifting northwards," which likely strengthened them against the possibility of extinction.

Although we have highlighted the findings of just a few real-world studies of the effects of concomitant increases in air temperature and atmospheric CO2 concentration on the "sustainability" of earth's plant and animal species, many additional studies that have yielded similar results have been described in detail by Idso et al. (2003), whose report on the subject can be found on our website and should be considered a vital appendage of our critique of Hansen's testimony. Consequently - and not wanting to "beat a dead horse" any further in this regard - we proceed to a consideration of a woefully under-reported aspect of the topic that is almost never discussed in the climate-alarmist literature that portrays anthropogenic CO2 emissions as leading to massive species extinctions. And why does it fail to appear there, as well as in Hansen's testimony? It fails to appear because this aspect of the subject totally undercuts climate-alarmist policy prescriptions for averting their contrived species extinction catastrophe, as well as the many other climate-related disasters described by Hansen.

The CO2-Induced Preservation of Terrestrial Species

How much land can ten billion people spare for nature? This provocative question was posed by Waggoner (1995) in an insightful essay wherein he explored the dynamic tension that exists between the need for land to support the agricultural enterprises that sustain mankind, and the need for land to support the natural ecosystems that sustain all other creatures. This challenge of meeting our future food needs - and not decimating the rest of the biosphere in the process - was stressed even more strongly by Huang et al. (2002), who wrote that humans "have encroached on almost all of the world's frontiers, leaving little new land that is cultivatable." And in consequence of humanity's usurpation of this most basic of natural resources, Raven (2002) stated in his Presidential Address to the American Association for the Advancement of Science that "species-area relationships, taken worldwide in relation to habitat destruction, lead to projections of the loss of fully two-thirds of all species on earth by the end of this century."

In a more detailed analysis of the nature and implications of this impending "global land-grab" - which moved it closer to the present by a full half-century - Tilman et al. (2001) concluded that the task of meeting the doubled world food demand, which they calculated would exist in the year 2050, would likely exact a toll that "may rival climate change in environmental and societal impacts." But how could something so catastrophic manifest itself so soon?

Tilman and his nine collaborators shed some light on this question by noting that at the end of the 20th century mankind was already appropriating "more than a third of the production of terrestrial ecosystems and about half of usable freshwaters." Now, think of doubling those figures, in order to meet the doubled global food demand that Tilman et al. predict for the year 2050. The results suggest that a mere 43 years from now mankind will be appropriating more than two thirds of terrestrial ecosystem production plus all of earth's remaining usable freshwater, as has also been discussed by Wallace (2000).

In terms of land devoted to agriculture, Tilman et al. calculate a much less ominous 18% increase by the year 2050. However, because most developed countries are projected to withdraw large areas of land from farming over the next fifty years, the loss of natural ecosystems to crops and pastures in developing countries will amount to about half of their remaining suitable land, which would, in the words of the Tilman team, "represent the worldwide loss of natural ecosystems larger than the United States." What is more, they say that these land usurpations "could lead to the loss of about a third of remaining tropical and temperate forests, savannas, and grasslands." And in a worrisome reflection upon the consequences of these land-use changes, they remind us that "species extinction is an irreversible impact of habitat destruction."

What can be done to avoid this horrific situation? In a subsequent analysis, Tilman et al. (2002) introduced a few more facts before suggesting some solutions. First of all, they noted that by 2050 the human population of the globe is projected to be 50% larger than it was just prior to the writing of their paper, and that global grain demand by 2050 could well double, due to expected increases in per capita real income and dietary shifts toward a higher proportion of meat. Hence, they but stated the obvious when they concluded that "raising yields on existing farmland is essential for 'saving land for nature'."

So how can this readily-defined but Herculean task be accomplished? Tilman et al. proposed a strategy that focuses on three essential efforts: (1) increasing crop yield per unit of land area, (2) increasing crop yield per unit of nutrients applied, and (3) increasing crop yield per unit of water used.

With respect to the first of these efforts - increasing crop yield per unit of land area - the researchers note that in many parts of the world the historical rate-of-increase in crop yield is declining, as the genetic ceiling for maximal yield potential is being approached. This observation, in their estimation, "highlights the need for efforts to steadily increase the yield potential ceiling." With respect to the second effort - increasing crop yield per unit of nutrients applied - they note that "without the use of synthetic fertilizers, world food production could not have increased at the rate [that it did in the past] and more natural ecosystems would have been converted to agriculture." Hence, they say that the ultimate solution "will require significant increases in nutrient use efficiency, that is, in cereal production per unit of added nitrogen." Finally, with respect to the third effort - increasing crop yield per unit of water used - Tilman et al. note that "water is regionally scarce," and that "many countries in a band from China through India and Pakistan, and the Middle East to North Africa either currently or will soon fail to have adequate water to maintain per capita food production from irrigated land." Increasing crop water use efficiency, therefore, is also a must.

Although the impending man vs. nature crisis and several important elements of its potential solution are thus well defined, Tilman and his first set of collaborators concluded that "even the best available technologies, fully deployed, cannot prevent many of the forecasted problems." This was also the finding of Idso and Idso (2000), who concluded that although "expected advances in agricultural technology and expertise will significantly increase the food production potential of many countries and regions," these advances "will not increase production fast enough to meet the demands of the even faster-growing human population of the planet."

How can we prevent this unthinkable catastrophe from occurring, especially when it has been concluded by highly-credentialed researchers that earth possesses insufficient land and freshwater resources to forestall it, while simultaneously retaining any semblance of the natural world and its myriad animate creations? Although the task may appear next to impossible to accomplish, it can be done; for we have a powerful ally in the ongoing rise in the atmosphere's CO2 concentration that can provide what we can't.

Since atmospheric CO2 is the basic "food" of nearly all plants, the more of it there is in the air, the better they function and the more productive they become. For a 300-ppm increase in the atmosphere's CO2 concentration above the planet's current base level of slightly less than 400 ppm, for example, the productivity of earth's herbaceous plants rises by something on the order of 30% (Kimball, 1983; Idso and Idso, 1994), while the productivity of its woody plants rises by something on the order of 50% (Saxe et al., 1998; Idso and Kimball, 2001). Thus, as the air's CO2 content continues to rise, so too will the productive capacity or land-use efficiency of the planet continue to rise, as the aerial fertilization effect of the upward-trending atmospheric CO2 concentration boosts the growth rates and biomass production of nearly all plants in nearly all places. In addition, elevated atmospheric CO2 concentrations typically increase plant nutrient-use efficiency in general - and nitrogen-use efficiency in particular - as well as plant water-use efficiency, as may be verified by perusing the many reviews of scientific journal articles we have produced on these topics and archived in the Subject Index of our website (www.co2science.org). Consequently, with respect to fostering all three of the plant physiological phenomena that Tilman et al. (2002) contend are needed to prevent the catastrophic consequences they foresee for the planet just a few short decades from now, a continuation of the current upward trend in the atmosphere's CO2 concentration would appear to be essential.

In the case we are considering here, for example, the degree of crop yield enhancement likely to be provided by the increase in atmospheric CO2 concentration expected to occur between 2000 and 2050 has been calculated by Idso and Idso (2000) to be sufficient - but only by the slightest of margins - to compensate for the huge differential that is expected to otherwise prevail between the supply and demand for food earmarked for human consumption just 43 years from now. Consequently, letting the evolution of technology take its natural course, with respect to anthropogenic CO2 emissions, would appear to be the only way we will ever be able to produce sufficient agricultural commodities to support ourselves in the year 2050 without the taking of unconscionable amounts of land and freshwater resources from nature and decimating the biosphere in the process.

But what about life in the oceans?

CO2-Induced Extinctions of Calcifying Marine Organisms

For some time now the ongoing rise in the atmosphere's CO2 concentration has been predicted by climate alarmists to raise havoc with earth's coral reefs and other calcifying marine organisms by acidifying the world's oceans and thus lowering the calcium carbonate saturation state of seawater, making it ever more difficult for these creatures to produce their calcium carbonate skeletons; and in this regard, Hansen claims "we will be able to avoid acidification of the ocean with its destruction of coral reefs and other ocean life" if we follow his policy prescriptions. However, there is no compelling reason to believe that "coral reefs and other ocean life" will be significantly harmed - much less "destroyed" - by continuing to let technology take its natural course in terms of transitioning from fossil fuel-burning to other forms of energy production; for just like the CO2-induced global warming concept itself, the CO2-induced acidification of the world's oceans - and especially its deadly consequences concept - is an unproven theoretical construct that ignores many important biological phenomena. Nevertheless, the degree to which this catastrophic concept of CO2-induced death-in-the-oceans has been embraced, even by scientists, is nothing short of astounding, as is indicated by a paper authored by 27 researchers from eight countries that was published in the 29 September 2005 issue of Nature (Orr et al., 2005), in which the group wrote that under a "business-as-usual" scenario of future anthropogenic CO2 emissions, "key marine organisms - such as corals and some plankton - will have difficulty maintaining their external calcium carbonate skeletons," and where they suggested that these dire conditions "could develop within decades, not centuries as suggested previously."

So what's the story here? Is there any real-world evidence that can be cited in support of these strident claims? Hansen and Orr et al. certainly make it appear that such exists, but a little scientific sleuthing reveals nothing of substance that supports their claim. In fact, it actually suggests just the opposite of what they predict.

We begin by noting the 27 scientists contend that (1) in response to the ongoing rise in the air's CO2 content, "aqueous CO2 concentrations will increase and carbonate ion concentrations will decrease, making it more difficult for marine calcifying organisms to form biogenic calcium carbonate," and that (2) "substantial experimental evidence indicates that calcification rates will decrease in low-latitude corals (Millero, 1995; Dickson, 1990; Dickson and Riley, 1979), which form reefs out of aragonite [a metastable form of calcium carbonate (CaCO3)], and in phytoplankton that form their tests (shells) out of calcite (Mucci, 1983; Bischoff et al., 1987), the stable form of CaCO3)." In reviewing the five papers they cite in support of these contentions, however, we find that none of them deal with living organisms, and, therefore, that none of them deal with the calcification process as it is conducted in nature by living entities.

We have previously written extensively about the importance of not excluding life from such important considerations, noting that calcification is much more than a physical-chemical process that can be accurately described by a set of equations. Rather, we have emphasized, time and again, that coral calcification is a biologically-driven physical-chemical process that may not yet be amenable to explicit mathematical description. In fact, we reported several years ago (Idso et al., 2000) - based on proper citations of the scientific literature - that "the photosynthetic activity of zooxanthellae is the chief source of energy for the energetically-expensive process of calcification," and that considerable evidence shows that "long-term reef calcification rates generally rise in direct proportion to increases in rates of reef primary production," which suggests that if anthropogenic-induced increases in the transfer of CO2 from the air to the world's oceans were to lead to increases in coral symbiont photosynthesis - as atmospheric CO2 enrichment generally does for nearly all land plants - it is likely that increases in coral calcification rates would occur as well.

We have also noted that the calcium carbonate saturation state of seawater actually rises with an increase in temperature, countering the adverse oceanic chemistry consequences of an increase in aqueous CO2 concentration, which is a matter that is also considered by Orr et al., but which they dismiss as having a rather small effect, "typically counteracting less than 10% of the decrease due to the geochemical effect." With this little problem thus handily dispatched - and ignoring the many ways in which the forces of life might enter the picture - they calculate that "relative to preindustrial conditions, invasion of anthropogenic CO2 has already reduced modern surface carbonate ion concentrations by more than 10%," and they further calculate - "in agreement with previous predictions (Kleypas et al., 1999)" - that a 45% reduction relative to preindustrial levels may be reached by the end of the century, and that ultimately, "rates of calcification could decline even further, to zero." We, however, suggest these contentions are grossly in error.

So what do real-world studies of living and fossil corals and phytoplankton reveal about the various claims and counterclaims swirling about this issue? Have the increases in air temperature and atmospheric CO2 concentration that have occurred since the beginning of the Industrial Revolution seriously hampered coral and phytoplankton calcification rates? Let's review what some actual observations have to say about the matter.

In a study of calcification rates of massive Porites coral colonies on Australia's Great Barrier Reef (GBR), Lough and Barnes (1997) found that "the 20th century has witnessed the second highest period [our italics] of above average calcification in the past 237 years." Intrigued by this observation, the two researchers analyzed the calcification characteristics of 245 similar-sized massive colonies of Porites corals obtained from 29 sites located along the length, and across the breadth, of the GBR, which data spanned a latitudinal range of approximately 9° and an annual average sea surface temperature (SST) range of 25-27°C. To these data they then added other published data from the Hawaiian Archipelago (Grigg, 1981, 1997) and Phuket, Thailand (Scoffin et al., 1992), thereby extending the latitudinal range of their expanded data set to 20° and the annual average SST range to 23-29°C.

Lough and Barnes' analysis indicated that GBR calcification rates were linearly related to average annual SST, such that "a 1°C rise in average annual SST increased average annual calcification by 0.39 g cm^-2 year^-1." Results were much the same for the extended data set they developed; and they report that "the regression equation explained 83.6% of the variance in average annual calcification," while noting that "this equation provides for a change [increase] in calcification rate of 0.33 g cm^-2 year^-1 for each 1°C change [increase] in average annual SST," in spite of unprecedented concurrent increases in atmospheric CO2 concentration.

Noting that their results "allow assessment of possible impacts of global climate change on coral reef ecosystems," Lough and Barnes determined that between the two 50-year periods 1780-1829 and 1930-1979, there was a mean calcification increase of 0.06 g cm^-2 year^-1; and they note that "this increase [our italics] of ~4% in calcification rate conflicts with the estimated decrease [our italics] in coral calcification rate of 6-14% over the same time period suggested by Kleypas et al. (1999) as a response to changes in ocean chemistry." Even more stunning was their observation that between the two 20-year periods 1903-1922 and 1979-1998, the warming-induced increase in calcification was about 12% in the central GBR, about 20% in the southern GBR and as much as 50% to the south of the GBR. In light of these real-world observations, therefore, and in stark contrast to the predictions of Kleypas et al. (1999), Orr et al. (2005) and the testimony of Hansen, the two researchers concluded that coral calcification rates "may have already significantly increased [our italics] along the GBR in response to global climate change."

Two other scientists that investigated the subject by means of real-world data were Bessat and Buigues (2001), who worked with a core retrieved from a massive Porites coral on the French Polynesian island of Moorea that covered the period 1801-1990, and who said they undertook the study because they thought it "may provide information about long-term variability in the performance of coral reefs, allowing unnatural changes to be distinguished from natural variability." This effort revealed that a 1°C increase in water temperature increased coral calcification rate by 4.5%, and that "instead of a 6-14% decline in calcification over the past 100 years computed by the Kleypas group, the calcification has increased." And to further emphasize this point, they reiterated that their results "do not confirm those predicted by the Kleypas et al. (1999) model," which is merely an earlier version of the Orr et al. model.

Nevertheless, and in spite of these real-world observations that refute the "lifeless" worldview of Kleypas et al. and Orr et al., certain researchers such as Buddemeier et al. (2004) have continued to claim that the ongoing rise in the air's CO2 content, and its predicted ability to lower surface ocean water pH, could dramatically decrease coral calcification rates, which they claim could lead to "a slow-down or reversal of reef-building and the potential loss of reef structures in the future." However, they were forced to admit - and in the very same publication - that "temperature and calcification rates are correlated," and that the corals of the real-world "have so far responded more to increases in water temperature (growing faster through increased metabolism and the increased photosynthetic rates of their zooxanthellae) than to decreases in carbonate ion concentration."

At about the same time, and following in the footsteps of Lough and Barnes who had worked in the Indo-Pacific, Carricart-Ganivet (2004) developed relationships between coral calcification rates and annual average SSTs based on data collected from colonies of the reef-building coral Montastraea annularis at twelve locations in the Gulf of Mexico and the Caribbean Sea. This work revealed, in his words, that "calcification rate in the Gulf of Mexico increased 0.55 g cm^-2 year^-1 for each 1°C increase, while, in the Caribbean Sea, it increased 0.58 g cm^-2 year^-1 for each 1°C increase," a result that was nearly twice as great as that obtained by Lough and Barnes for Porites corals. Further pooling these data "with those of M. annularis and M. faveolata, growing up to 10 m depth in Carrie Bow Cay, Belize, reported by Graus and Macintyre (1982), those of Dodge and Brass (1982) from all the reefs they studied at St. Croix, US Virgin Islands, and those of M. faveolata, growing up to 10 m depth in Curacao, Netherlands, Antilles, reported by Bosscher (1993)," Carricart-Ganivet obtained a relationship of ~0.5 g cm^-2 year^-1 for each 1°C increase in annual average SST.

To these papers can be added many others that also depict increasing coral calcification rates in the face of rising temperatures and/or atmospheric CO2 concentrations, including those of Clausen and Roth (1975), Coles and Coles (1977), Kajiwara et al. (1995), Nie et al. (1997), Reynaud-Vaganay et al. (1999) and Reyanud et al. (2004). As for why this is the way earth's corals respond, McNeil et al. (2004) say that "observed increases in coral reef calcification with ocean warming are most likely due to an enhancement in coral metabolism and/or increases in photosynthetic rates of their symbiotic algae," as we have consistently said when noting over and over that coral calcification is a biologically-driven process that can overcome physical-chemical limitations that in the absence of life would appear to be insurmountable.

Another reason for not believing that the ongoing rise in the atmosphere's CO2 content will lead to reduced oceanic pH and, therefore, lower calcification rates in the world's coral reefs and other calcifying organisms, is that the same phenomenon that powers the twin processes of coral calcification and phytoplanktonic growth (i.e., photosynthesis) tends to increase the pH of marine waters (Gnaiger et al., 1978; Santhanam et al., 1994; Brussaard et al., 1996; Lindholm and Nummelin, 1999; Macedo et al., 2001; Hansen, 2002); and this phenomenon has been shown to have the ability to dramatically increase the pH of marine bays, lagoons and tidal pools (Gnaiger et al., 1978; Santhanam, 1994; Macedo et al., 2001 Hansen, 2002), as well as significantly enhance the surface water pH of areas as large as the North Sea (Brussaard et al., 1996).

Before concluding our discussion of this important subject, however, we briefly switch our focus from corals to phytoplankton, beginning with a review of the work of Riebesell (2004), who notes that "doubling present-day atmospheric CO2 concentrations is predicted to cause a 20-40% reduction in biogenic calcification of the predominant calcifying organisms, the corals, coccolithophorids, and foraminifera." In a significant challenge to this climate-alarmist dogma, Riebesell notes that a moderate increase in CO2 actually facilitates photosynthetic carbon fixation of certain phytoplankton, such as the coccolithophorids, as represented by Emiliania huxleyi and Gephyrocapsa oceanica. In fact, Riebesell writes that "CO2-sensitive taxa, such as the calcifying coccolithophorids, should therefore benefit more [our italics] from the present increase in atmospheric CO2 compared to the non-calcifying diatoms."

More recently, Crabbe et al. (2006) used digital photography, image analysis and measurements in the field to determine the original growth rates of long-dead Quaternary corals found in exposed onshore limestone deposits near the margins of Hoga and Kaledupa Islands in the Wakatobi Marine National Park of Indonesia, after which they compared them to the growth rates of present-day corals of the same genera (Porites and Favites) living in the same area. This work revealed that the Quaternary corals appeared to have grown "in a comparable environment to modern reefs at Kaledupa and Hoga," except, of course, for the air's CO2 concentration, which is currently higher than it has been at any other time throughout the entire Quaternary, i.e., the past 1.8 million years. In addition, their measurements indicated that the radial growth rates of the modern corals were 31% greater than those of their more ancient Quaternary cousins in the case of Porites species, and 34% greater in the case of Favites species. Clearly, therefore, the impact of the historical increase in the atmosphere's CO2 concentration on the corals in question has not been as catastrophically negative as Hansen suggests it should have been. In fact, the increase in the CO2 content of the modern atmosphere appears to have not been negative at all. In fact, it appears to have been positive.

Most interesting of all, perhaps, Fine and Tchernov (2007) grew 30 coral fragments from five colonies of the scleractinian Mediterranean species Oculina patagonica and Madracis pharencis within indoor flow-through systems under ambient Mediterranean seawater temperatures and photoperiod in water maintained at pH values of 7.3-7.6 (acidified) and 8.0-8.3 (ambient) for a period of 12 months. After one month in the acidic conditions, they report there was an elongation of the coral polyps that was "followed by dissociation of the colony form and complete skeleton dissolution." However, they observed that "the polyps remained attached to the undissolved hard rocky substrate." In fact, they found that "the biomass of the solitary polyps under acidic conditions was three times as high [our italics] as the biomass of the polyps in the control colonies that continued to calcify." In addition, they say that both "control and treatment fragments maintained their algal symbionts during the entire experiment, except for six fragments (10%) of O. patagonica that partially lost their symbionts (bleached) during July but recovered within 2 months." And they report that "after 12 months, when transferred back to ambient pH conditions, the experimental soft-bodied polyps calcified and reformed colonies [our italics]." Thus, after restating their major finding that "in the absence of conditions supporting skeleton building, both species maintained basic life functions as skeleton-less ecophenotypes," Fine and Tchernov concluded that "corals might survive large-scale environmental change, such as that expected for the following century." And why not? If they've done it before - as some have theorized (Stanley and Fautin, 2001; Stanley, 2003; Medina et al., 2006), and as Fine and Tchernov have actually demonstrated can in truth be done - they likely have the capacity do it again ... and again ... and again.

Miscellaneous Misstatements of Hansen

In addition to the major misconceptions he promulgates with respect to the several subjects we discus above, Hansen makes a number of brief but serious misstatements throughout his testimony, the most serious of which we identify and discuss in what follows.

(1)