Carbon dioxide global change

A. H. C. M. Schapendonk, P. Dijkstra, J. Groenwold, C. S. Pot, and S. C. Van De Geijn, Carbon balance and water use efficiency of frequently cut Loliuni perenne L. swards at elevated carbon dioxide. Global Change Biol. 5 207 (1997). 

Concerns about global climate change have led to extensive research and high-level international debates about the need for targets and timetables to reduce carbon dioxide emissions. Some policymakers believe that current uncertainties in how to approach the issue do notjustify an all-out effort to reduce carbon dioxide emission, while others feel that this is a crisis needing immediate attention. 

Fig. 11-18 A four-box model of the global carbon cycle. Reservoir inventories are given in moles and fluxes in mol/yr. The turnover time of CO2 in each reservoir with respect to the outgoing flux is shown in brackets. (Reprinted with permission from L. Machta, The role of the oceans and biosphere in the carbon dioxide cycle, in D. Dryssen and D. Jagner (1972). "The Changing Chemistry of the Oceans," pp. 121-146, John Wiley.)...

C. J. and Schloss, A. L. (1997). Equilibrium responses of global net primary production and carbon storage to doubled atmospheric carbon dioxide Sensitivity to changes in vegetation nitrogen concentration, Global Biogeochem. Cycles 11,173-189. 

Among the components of our atmosphere, the concentration of carbon dioxide is a mere 325 parts per million (ppm). In other words, 999,675 of every million molecules in the air are not CO2. (Almost all the molecules are N2 or O2.) At such a low concentration, how could CO2 possibly cause a measurable change in the Earth s surface temperature The answer lies in the role that minor atmospheric species play in the global energy balance. 

What has changed in the last few hundred years is the additional release of carbon dioxide by human activities. Fossil fuels burned to run cars and trucks, heat homes and businesses, and power factories are responsible for about 98% of carbon dioxide emissions, 24% of methane emissions, and 18% of nitrous oxide emissions. Increased agriculture, deforestation, landfills, industrial production, and mining also contribute a significant share of emissions (5). For example, in 1997, the United States emitted about one-fifth of total global greenhouse gases. 

Biomass resources are a major component of strategies to mitigate global climate change. Plant growth recycles C02 from the atmosphere, and the use of biomass resources for energy and chemicals results in low net emissions of carbon dioxide. Since the emissions of NOx and SOx from biomass facilities are also typically low, it is a technology that helps to reduce acid rain. 

It is notable that the (future) actions are for economic growth and prosperity, and not to protect the global environment of our planet And how little attitudes have changed (for a more detailed and eloquent suite of arguments, see Ref. 2). The United States, with 5% of the world s population, emits nearly one-third of the world s carbon dioxide. It promised to cut emissions by 7% over 1990 levels by 2012 at the latest, but its emissions in fact rose by more than 10% between 1990 and 2000 (see Figure 5.2). While the Kyoto Protocol" is a deeply flawed document (and do read it, not the distorted accounts in the press), it was the best that we had. 

---