Extreme Temperature Events Throughout South America
Rusticucci, M. 2012. Observed and simulated variability of extreme temperature events over South America. Atmospheric Research 106: 1-17.
The Buenos Aires researcher reports finding the most significant trends in the evolution of the daily minimum air temperature, with "positive trends in almost all studies on the occurrence of warm nights (or hot extremes of minimum temperature)," as well as negative trends in the cold extremes of the minimum temperature, which is indeed what one would expect to find with rising mean air temperatures. And she says that this was the case "in almost all studies." On the other hand, she writes that "on the maximum temperature behavior there is little agreement, but generally the maximum temperature in South America has decreased," which is just the opposite of what would be expected in a warming world.
It is interesting to note that, in general, over most of South America there has been a decrease in the extremeness of both daily maximum and minimum air temperatures, with the maximums declining and the minimums rising. This finding is very encouraging for that continent's inhabitants, for Rusticucci notes that cold waves and frost are especially harmful to agriculture, which she says is one of the main economic activities in South America. And cold waves and frost days have been on the decline nearly everywhere throughout the continent during the period of 20th-century global warming.
Sura, P. 2011. A general perspective of extreme events in weather and climate. Atmospheric Research 101: 1-21.