Climate possible natural causes

Here we should refer to the opinion of some other authors who have argued that increased CO2 levels in the atmosphere may be a consequence of atmospheric warming, rather than the cause. The statistical analysis led Kuo et al (1990) and recently A. Kapitsa (2000) to the conclusion that, although there is a correlation between p(C02) and global temperatures, the changes in p(C02) appear to lag behind the temperature change by ca. 5 months. A possible explanation, if this trend is proved correct, would be that natural climatic variability alters the temperature of the global Ocean, which contains about 90% of total CO2 mass. In turn, this leads to increase of CO2 flux from the warmer oceanic water to atmosphere in accordance with the Henry law (see Box 1 for explanation). 

Coca leaves (Erythroxylum coca) have been used in South America since the time of the Incas, if not longer. Although the habit of coca chewing is usually attributed to the extremes of altitude and climate, other causes, such as malnutrition and adverse social, educational, and economic factors, are probably of more importance (278). As with opium, use of the crude plant material does not produce so dramatic a syndrome as does the use of the pure alkaloid (279). Nevertheless, in spite of the often-repeated statement that the use of coca increases resistance to fatigue and is harmless and possibly beneficial in its natural environment, the fact remains that it undermines the physical and mental health of the population and thus leads to a deterioration of the very living conditions that caused it (280). 

Damage to crops caused by gaseous pollutants like that of trees can be acute or have chronic/growth effects. However unlike trees/ there is little evidence for any acute damage. Identification of yield effects by their very nature must rely upon constructed experiments otherwise other factors such as climate soil or agricultural management mask any possible effects. 

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