Insolation-driven changes in atmospheric circulation over the past 116,000 years in subtropical Brazil.

During the last glacial period, large millennial-scale temperature oscillations--the 'Dansgaard/Oeschger' cycles--were the primary climate signal in Northern Hemisphere climate archives from the high latitudes to the tropics. But whether the influence of these abrupt climate changes extended to the tropical and subtropical Southern Hemisphere, where changes in insolation are thought to be the main direct forcing of climate, has remained unclear. Here we present a high-resolution oxygen isotope record of a U/Th-dated stalagmite from subtropical southern Brazil, covering the past 116,200 years. The oxygen isotope signature varies with shifts in the source region and amount of rainfall in the area, and hence records changes in atmospheric circulation and convective intensity over South America. We find that these variations in rainfall source and amount are primarily driven by summer solar radiation, which is controlled by the Earth's precessional cycle. The Dansgaard/Oeschger cycles can be detected in our record and therefore we confirm that they also affect the tropical hydrological cycle, but that in southern subtropical Brazil, millennial-scale climate changes are not as dominant as they are in the Northern Hemisphere.

Influences of the weather and air pollutants on cardiovascular disease in the metropolitan area of São Paulo.

OBJECTIVE: Cardiovascular disease (CVD) has been associated with meteorological variables and pollutant levels. However, these relationships have rarely been studied in São Paulo, Brazil. METHODS: From 1996 to 2000, biometeorological indices including meteorological variables such as temperature, relative humidity, and wind were used to measure thermal comfort in elderly people mortality (>65 years old), and CVD was quantified. RESULTS: Statistical analysis showed a significant negative loading between CVD and meteorological variables as well as thermal comfort indices. The CVD curve was a U-shaped, showing higher value for cold stress than for heat stress. The results clearly show seasonal variations in CVD mortality rates, which were higher in winter. Meteorological variables were found to play an important role as well as through the thermal comfort indices. The air pollutants, PM(10) and SO(2), except ozone, presented positive loadings with CVD, albeit less than statistically significant.