Global returns

Equation (23.9) can then be easily extended to all the original factors in the model. Assuming now that purely local returns are uncorrelated across markets and uncorrelated with global returns, the covariance matrix can be written as ... 

The synthesis of 1 kg of dry plant biomass requires the evapotranspiration of about 300 L of water, although smaller amounts of water are needed by some plants such as desert cacti. Approximately one-third of the annual continental rainfall (100 cm/yr) is returned to the atmosphere by evapotranspiration. Although it accounts for only about 10-15% of global evaporation, plant evapotranspiration can play a major role in local climates. For example, a molecule of water falling on the upper Amazon Basin is recycled on average five times during its eventual return to the Atlantic Ocean. 

Water returns to the atmosphere via evaporation from the oceans and evapotranspiration from the land surface. Like precipitation, evaporation is largest over the oceans (88% of total) and is distributed non-uniformly around the globe. Evaporation requires a large input of energy to overcome the latent heat of vaporization, so global patterns are similar to radiation balance and temperature distributions, though anomalous local maxima and minima occur due to the effects of wind and water availability. 

Hansen, J., Ruedy, R., Sato, M. and Reynolds, R. (1996). Global surface air temperature in 1995 Return to pre-Pinatubo level, Geophys. Res. Lett. 23, 1665-1668. 

Lerman et al. (1975) considered several cases in which mankind s activities perturbed the natural cycle. If we assume that all mined P is supplied to the land as fertilizer and that all of this P is incorporated into land biota, the mass of the land biota will increase by 20%. This amount is small relative to the P stored in the land reservoir. Since P incorporated into land biota must first decompose and be returned to the land reservoir before being transported further, there is essentially no change in the other reservoirs. Thus, although such inputs would significantly alter the freshwater-terrestrial ecosystem locally where the P release is concentrated, the global cycle would be essentially unaffected. 

Observe that the new statement first stores all global values which are not actual parameters Cy, ...,ym) on the pushdown store, then puts label Lq on top of the pushdown store, and finally lets the values of the actual parameters of the call, v, ...,vn, specify the formal parameters of procedure F, x,, ...,x the x. will be used as variables in the execution of F. Then con-trol passes to the start of the procedure body of F. When F is completed, label Lq r will be retrieved from the top of the store and a GOTO will pass control to the statement labeled by Lq. Then each actual parameter of the call, v, will be respecified by the final value of the corresponding formal parameter, x, of F, the other global variables will have their proper values restored from the pushdown store and control will return to , the statement originally following . ... 

ABSTRACT The locations, magnitudes, variations and mechanisms responsible for the atmospheric C02 sink are uncertain and under debate. Previous studies concentrated mainly on oceans, and soil and terrestrial vegetation as sinks. Here, we show that there is an important C02 sink in carbonate dissolution, the global water cycle and photosynthetic uptake of DIC by aquatic ecosystems. The sink constitutes up to 0.82 Pg C/a 0.24 Pg C/a is delivered to oceans via rivers and 0.22 Pg C/a by meteoric precipitation, 0.12 Pg C/a is returned to the atmosphere, and 0.23 Pg C/a is stored in the continental aquatic ecosystem. The net sink could be as much as 0.70 Pg C/a, may increase with intensification of the global water cycle, increase in C02 and carbonate dust in atmosphere, reforestation/afforestation, and with fertilization of aquatic ecosystems. Under the projection of global warming for the year 2100, it is estimated that this C02 sink may increase by 22%, or about 0.18 Pg c/a. 

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