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Grendel
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pt 2
Most of these important negative feedbacks are not adequately represented in state-of-the-art climate models. What is more, many related (and totally ignored!) phenomena are set in motion when the land surfaces of the globe warm. In response to the increase in temperature between 25°N latitude and the equator, for example, the soil-to-air flux of various sulfur gases rises by a factor of 25, as a consequence of warmth-induced increases in soil microbial activity; and this phenomenon can lead to the production of more cloud condensation nuclei just as biological processes over the sea do. Clearly, therefore, any number of combinations of these several negative feedbacks could easily thwart the impetus for warming provided by future increases in the air's CO2 content.
Growth-enhancing effects of CO2 create an impetus for cooling. Carbon dioxide is a powerful aerial fertilizer, directly enhancing the growth of almost all terrestrial plants and many aquatic plants as its atmospheric concentration rises. And just as increased algal productivity at sea increases the emission of sulfur gases to the atmosphere, ultimately leading to more and brighter clouds over the world's oceans, so too do CO2-induced increases in terrestrial plant productivity lead to enhanced emissions of various sulfur gases over land, where they likewise ultimately cool the planet. In addition, many non-sulfur-based biogenic materials of the terrestrial environment play major roles as water- and ice-nucleating aerosols; and the airborne presence of these materials should also be enhanced by rising levels of atmospheric CO2. Hence, it is possible that incorporation of this multifaceted CO2-induced cooling effect into the suite of equations that comprise the current generation of global climate models might actually tip the climatic scales in favor of global cooling in the face of continued growth of anthropogenic CO2 emissions.
There is no evidence for warming-induced increases in extreme weather. Proponents of the CO2-induced global warming hypothesis often predict that extreme weather events such as droughts, floods, and hurricanes will become more numerous and/or extreme in a warmer world; however, there is no evidence to support this claim. In fact, many studies have revealed that the numbers and intensities of extreme weather events have remained relatively constant over the last century of modest global warming or have actually declined. Costs of damages from these phenomena, however, have risen dramatically; but this phenomenon has been demonstrated to be the result of evolving societal, demographic and economic factors.
Elevated levels of atmospheric CO2 are a boon to the biosphere. In lieu of global warming, a little of which would in all probability be good for the planet, where do the above considerations leave us? Simply with the biospheric benefits that come from the aerial fertilization effect of atmospheric CO2 enrichment: enhanced plant growth, increased plant water use efficiency, greater food production for both people and animals, plus a host of other biological benefits too numerous to describe in this short statement.
And these benefits are not mere predictions. They are real. Already, in fact, they are evident in long-term tree-ring records, which reveal a history of increasing forest growth rates that have closely paralleled the progression of the Industrial Revolution. They can also be seen in the slow but inexorable spreading of woody plants into areas where only grasses grew before. In fact, the atmosphere itself bears witness to the increasing prowess of the entire biosphere in the yearly expanding amplitude of the its seasonal CO2 cycle. This oscillatory "breath of the biosphere" - its inhalation of CO2, produced by spring and summer terrestrial plant growth, and its exhalation of CO2, produced by fall and winter biomass decomposition - has been documented to be growing greater and greater each year in response to the ever-increasing growth stimulation provided by the ongoing rise in the air's CO2 content.
Atmospheric CO2 enrichment brings growth and prosperity to man and nature alike. This, then, is what we truly believe will be the result of the ongoing rise in the air's CO2 content: a reinvigorated biosphere characteristic of those prior periods of earth's history when the air's CO2 concentration was much higher than it is today, coupled with a climate not much different from that of the present. Are we right? Only time will tell. But one thing is certain now: there is much more real-world evidence for the encouraging scenario we paint here than for the doom-and-gloom predictions of apocalypse that are preached by those who blindly follow the manifestly less-than-adequate prognostications of imperfect climate models.
Our policy prescription relative to anthropogenic CO2 emissions is thus to leave well enough alone and let nature and humanity take their inextricably intertwined course. All indications are that both will be well served by the ongoing rise in atmospheric CO2.
Supporting references. This brief was written in 1998. References to the voluminous scientific literature that supports the many factual statements of this position paper may be found on our website - www.co2science.org - which we update weekly.
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