Since the beginning of the last century the world is experiencing an important demographic transition, which will probably impact on economic growth. Many demographers and social scientists are trying to understand the key drivers of such transition as well as its profound implications. A correct understanding will help to predict other important trends of the world primary energy demand and the carbon emission to the atmosphere, which may be leading to an important climate change. This paper proposes a set of coupled differential equations to describe the changes of population, gross domestic product, primary energy consumption and carbon emissions, modeled as competing-species as in Lokta-Volterra prey-predator relations. The predator-prey model is well known in the biological, ecological and environmental literature and has also been applied successfully in other fields. This model proposes a new and simple conceptual explanation of the interactions and feedbacks among the principal driving forces leading to the present transition. The estimated results for the temporal evolution of world population, gross domestic product, primary energy consumption and carbon emissions are calculated from year 1850 to year 2150. The calculated scenarios are in good agreement with common world data and projections for the next 100 years.
A series of continuous ambient tropospheric ozone measurements were taken in Mendoza, Argentina, for a period of one year starting in November 1995. The data obtained were analyzed in terms of diurnal and annual variation. Indications were found of the strong impact of the mountain-valley circulation system, which ventilates and considerably cleans the air in Mendoza. The data are discussed in comparison with air pollution in the German city of Leipzig. In Mendoza, the high concentration of precursors and the strong solar radiation contribute to high levels of ozone. In fact, monitoring reveals considerably lower concentrations than in Leipzig, owing to the diluting effect of local meteorology. The low-level jet is mainly active during the summer. It lowers the peak mid-day ozone concentration and produces a temporary concentration increase at night. The Environmental Protection Agency standard of a maximum one-hour mean concentration of 0.250 mg ozone/m3 (125 ppb) is never reached, and the World Health Organization standard of 0.113 mg ozone/m3 (56.5 ppb) is only rarely exceeded during winter.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.