The Effect Of Co2 And Greenhouse Gas Emissions On Climate And Global Warming

The CO2 content of the atmosphere has been essentially constant throughout the past centuries (Fig. 14), but measurable change can be detected from 1950 and today the characteristic concentration is about 380400 ppm (Arscott, 2003; IPCC, 1995; Falkowski, 2002). According to a reliable forecast the CO2 content in the atmosphere might be as high as 750 ppm by the end of the 21st century. Since CO2 directly influences the average temperature of the earth its accumulation in the atmosphere results in global warming, as is well demonstrated by the fact that temperatures have been rising since 1970 (Fig. 15).

Responsible organizations (IPCC, 1995; Falkowski, 2002; Glick et al., 2004) have painted global warming in the darkest colour: oceans warm, glaciers melt, sea levels rise, permafrost thaws, lakes shrink, etc. All these unfavourable and accelerating processes may have serious and detrimental impact on flora, fauna and human life. Although the essence of the problem is not questioned, there is no consensus concerning the role of anthropogenic factors. Opponents of the anthropogenic factors usually refer to the distribution of CO2 on earth. It is a fact that only 2% of the total amount of CO2 is found in the atmosphere, while the majority (93%) is absorbed in the hydrosphere (particularly in the deep ocean water) (Onodi, 2003). Hence, the anthropogenic influence may have a negligible effect on CO2 equilibrium, or in other words, any positive or negative man-made interference in water, CO2 and other gases might have only limited impact on natural processes and climate.

Figure 14. Concentration of carbon dioxide in the atmosphere.

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Figure 14. Concentration of carbon dioxide in the atmosphere.

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Figure 15. Deviation from average temperature on earth (basis: 1950-1970).

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Some sceptic remarks can also be traced back to the cosmic and geological evolution of the earth (Petit, 1999; Gerhard et al., 2001). It is well know that the global climate is fundamentally influenced by long-term factors. In geoscience the following two factors are often mentioned:

1. Extraterrestrial (astronomical) phenomena, like decreasing solar radiation, irregular emission and distribution of cosmic dust and

2. Terrestrial phenomena, like continental drift, polar wandering and changes in the rotation axis of the planet.

These factors may result in a rhythmic fluctuation of glacial (cooling) and interglacial (warming) periods in each cosmic (190-200 million terrestrial) year, which means 15-20 global climate cycles (ice age or global warming) during the past 3 billion years. It is certain that the climate drastically changed in each cycle, but the crucial question today is how fast did these changes proceed in the past. Today it is increasingly apparent that the present rate of global warming is unusual and that the anthropogenic factor is probably decisive in the unfavourable processes.

The net CO2 production always depends on the rates of emission and absorption. Some countries are net emitters, others absorbers. A detailed study carried out in Hungary (Fig. 16) has definitely shown that the CO2 balance is negative and that the net CO2 emission is estimated to be 40 TgC/y. Obviously, all countries must strive for zero CO2 release or positive absorbance.

Despite different arguments it seems evident that anthropogenic CO2 emissions are relatively small, but that their decrease may beneficially influence the global warming.

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Figure 16. Emission/absorption equilibrium of CO2 in Hungary.

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