The government's current plans also represent a threat to the Amazon climate system, thereby threatening the region's ecosystems and agricultural production systems. Extensive cattle ranching, slash and burn agriculture and forest fires inhibit rainfall because they substitute primary forests with pastures, crop fields, and secondary forests, which release less water to the atmosphere and absorb less solar radiation. The smoke that is released from fires also contributes to this effect by saturating the atmosphere with an excessive number of condensation nuclei, thus inhibiting the formation of droplets that are heavy enough to fall to the ground as rain. The resulting drought contributes to an increase in the probability of forest fires. The vicious feedback cycle between land-use change, smoke emissions and rainfall inhibition.
Smoke released by forest and management fires inhibit rainfall.
The transformation of forests into pastures, and forests impoverished through logging or fire, may also inhibit rainfall by reducing evapotranspiration and the absorption of solar radiation by vegetation. These three vicious feedback cycles could transform almost half of the Amazon forest into a landscape of impoverished scrub vegetation and cattle pastures because of the interaction between road paving, uncontrolled deforestation in the frontier, predatory logging, and changes in the region's climate. This transformation would lead to the deterioration in the quality of life in Amazonia due to the increase in air pollution during the three to four months of the dry season, exacerbating respiratory problems affecting the population. Rural exodus and the swelling of urban centers would tend to increase as a result of this inability to extend basic services to rural dwellers. 19 C. A. Nobre et al. 1991, op. cit.