Terrestrial global carbon sink

Randerson, J. T., Thompson, M. V., Conway, T. J., Fung, I. Y. and Field, C. B. (1997). The contribution of terrestrial sources and sinks to trends in the seasonal cycle of atmospheric carbon dioxide. Global Biogeochem. Cycles 11,535-560. 

Hudson R. J. M. et al. (1994). Modeling the global carbon cycle Nitrogen fertilization of the terrestrial biosphere and the "missing" CO2 sink. Global Bio-geochem. Cycles 8, 307-333. 

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. 

Potter C. Klooster S. Tan P. Steinbach M. Kumar V. and Genovese V. (2005). Variability in terrestrial carbon sinks over two decades Part 2—Eurasia. Global and Planetary Change, 49(3-4), 177-186. 

Houghton, R. A., E. A. Davidson, and G. M. Woodwell. 1998. Missing sinks, feedbacks, and understanding the role of terrestrial ecosystems in the global carbon balance. Global Biogeochemical Cycles 12 25-34. 

It is obvious, therefore, that ignoring Dl would result with over-estimating C-derived estimate of terrestrial carbon sink (or under-estimate a source). The error can be significant, in the order of 0.6PgCyr globally, and proportionally larger in regions such as the tropics (Ciais et al., 1999). 

White A., Cannell M. G. R., and Friend A. D. (1999) Chmate change impacts on ecosystems and the terrestrial carbon sink a new assessment. Global Environ. Change 9, S21-S30. 

In the past few years, application of improved measurements and models suggests a robust partitioning of CO, emissions from fossil fuel consumption and land use about one-third remains in the atmosphere, one-third is reassimilated by land surfaces, and one-third is absorbed by the oceans (Keeling el ah, 1996). The terrestrial component of the sink has special political interest, because it is that part of the global carbon which can most directly be managed. If we were able to change the large fluxes of assimilation and respiration, as they were summarized by Schimel... 

Inspection of the global carbon cycle provides a useful backdrop for considering the natural fate of wood. Terrestrial ecosystems accumulate an extremely small fraction of the organic matter photosynthesized within them. Almost all (>99%) of the organic material produced on land is remineralized back to carbon dioxide and water within an average half-life of 10-100 years 11). The small fraction that escapes is exported by rivers to lakes and coastal marine zones, where a portion of the plant debris becomes waterlogged, sinks, and is incorporated in bottom deposits (12). 

FIGURE 7 Interannual variations in the fossil fuel emission and atmospheric increase in CO2. The difference between the two is the carbon sink. The varying rate of CO2 increase in the atmosphere reflects the response of the terrestrial biosphere and ocean to interannual climate variations. After 1988, global sink strength increased, while the atmosphere CO2 increase slowed down. 

Assuming the current emissions and sinks remain about the same, estimate the global atmospheric CO2 mixing ratio in the year 2050. Now repeat this calculation, but this time assume that the terrestrial biosphere no longer continues to sequester some of this anthropogenic carbon. 

Previous studies addressed oceans and terrestrial vegetation as C02 sinks. Here, we describe an important C02 sink in carbonate dissolution, the global water cycle (GWC), and uptake of dissolved inorganic carbon (DIC) by aquatic. The sink is larger than previous estimates (Meybeck 1993 Gombert 2002). 

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