Rusticucci, M. 2012. Observed and simulated variability of extreme temperature events over South America. Atmospheric Research 106: 1-17.
Climate alarmists typically claim that one of the negative consequences of global warming is a concomitant increase in climatic variability, including more extreme values of meteorological variables, such as air temperature. And the author, who has taken upon herself the goal of exploring this phenomenon as it pertains to South America, writes that what she calls the "overarching goal" of studying extremes is to "understand and then manage the risks of extreme events and related disasters to advance strategies for efficient climate change adaptation," citing Sura (2011).
What was done
Rusticucci reviews the many studies that have explored this subject - throughout the length and breadth of South America - particularly as it applies to daily maximum and minimum air temperatures, the former of which would be expected to become more extreme in both degree and frequency in a warming world, while the latter of which would be expected to become less extreme.
What was learned
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.
What it means
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.