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U.S.Foresb Havelncreased 40•/. iA SA Years 1"' >1N rR M .o aU a ,,,, o 3 7~ E AO 19N lf'M 11tN 1~ 2~p0 Year Figure 22: Inventories of standing hardwood and softwood timber in the United States compiled in Forest Resources of the United States, 2002, U.S. Depaztrnent of Agriculture Forest Service (111,112). The linear trend cited in 1998 (1) with an increase of 30% has continued. The increase is now 40%. The amount of U.S. timber is rising almost 1% per yeaz. taken place since 1950. Much of this increase is due to the increase in atmospheric CO2 that has already occurred. In addition, it has been reported that Amazonian rain forests are increasing their vegetation by about 900 pounds of carbon per acre per year (113), or approximately 2 tons of biomass per acre per year. Trees respond to CO2 fertilization more strongly than do most other plants, but all plants respond to some extent. Since plant response to CO2 fertilization is nearly linear with re- spect to CO2 concentration over the range from 300 to 600 ppm, as seen in Figure 23, experimental measurements at different levels of CO2 enrichment can be extrapolated. This has been done in Figure 24 in order to illustrate CO2 growth enhancements calculated for the atmospheric increase of about 88 ppm that has already taken place and those expected from a projected total increase of 305 ppm. Wheat growth is accelerated by increased atmospheric CO2, espe- cially under dry conditions. Figure 24 shows the response of wheat grown under wet conditions versus that of wheat stressed by lack of water. The underlying data is from open-field experiments. Wheat was grown in the usual way, but the atmospheric CO2 concentrations of circular sections of the fields were increased by arrays of com- d 6 d u C as s C W r 3 L V 0 u L d a teo~ O Resource-limited and Stressed • Not Resource-limited or Stressed t40 rpp 48 300 tip0 X00 1200 1 S00 Atmospheric COz Enrichment ppm Figure 23: Summary data from 279 published experiments in which plants of all types were grown under paired stressed (open red circles) and un- stressed (closed blue circles) conditions (114). There were 208, 50, and 21 sets at 300, 600, and an average of about 1350 ppm CO2, respectively. The plant mixture in the 279 studies was slightly biased toward plant types that respond less to COZ fertilization than does the actual global mixture. There- fore, the figure underestimates the expected global response. COZ enrich- ment also allows plants to grow in drier regrons, further increasing the response. puter-controlled equipment that released CO2 into the air to hold the levels as specified (115,116). Orange and young pine tree growth en- hancement (117-119) with two atmospheric CO2 increases -that which has already occurred since 1885 and that projected for the next two centuries - is also shown. The relative growth enhancement of trees by CO2 diminishes with age. Figure 24 shows young trees. Figure 23 summarizes 279 experiments in which plants of various types were raised under CO2-enhanced conditions. Plants under stress from less-than-ideal conditions - a common occurrence in na- ture -respond more to COz fertilization. The selections of species in Figure 23 were biased toward plants that respond less to CO2 fertil- ization than does the mixture actually covering the Earth, so Figure 23 underestimates the effects of global CO2 enhancement. Clearly, the green revolution in agriculture has already benefitted from CO2 fertilization, and benefits in the future will be even greater. Animal life is increasing proportionally, as shown by studies of 51 terrestrial (120) and 22 aquatic ecosystems (121). Moreover, as shown by a study of 94 terrestrial ecosystems on all continents ex- B a a N O 0 z 4a0 asp a ~ 295 ppm CO= t 3>e3 ppm C02 3~ 250 2a0 72`/• lsp 37% 3z'/• 11•/. 4•/. lip so 0 Dry Wheat Wet Wheat Oraa~es taraa~e Trees Yeaae rtae Trees 4~0 a 33p h ~ 29S ppm C02 248Y• a t 60, ppln C02 N 3~ zso 13N/. 111% ~ z~0 Z 1~ ~% o c 15 /• ~ la0 Ow 0 Dry Wbeat Wet Wheat Oraaxes Oraa~e Tress Yom Mae Trees Figure 24: Calculated (1,2) growth rate enhancement of wheat, young or- ange trees, and very young pine h~ees already taking place as a result of at- mospheric enrichment by COZ from 1885 to 2007 (a), and expected as a result of atmospheric enrichment by COZ to a level of 600 ppm (b). cept Antazctica (122), species richness - biodiversity - is more posi- tivelycorrelated with productivity -the total quantity of plant life per acre -than with anything else. Atmospheric C02 is required for life by both plants and animals. It is the sole source of carbon in all of the protein, carbohydrate, fat, and other organic molecules of which living things are constructed. Plants extract carbon from atmospheric CO2 and are thereby fer- tilized. Animals obtain their carbon from plants. Without atmo- spheric COz, none of the life we see on Earth would exist. Water, oxygen, and carbon dioxide aze the three most important substances that make life possible. They are surely not environmental pollutants. -9-