A Century of Drought in Southern South America
Minetti, J.L., Vargas, W.M., Poblete, A.G., de la Zerda, L.R. and Acuņa, L.R. 2010. Regional droughts in southern South America. Theoretical and Applied Climatology 102: 403-415.
Results indicated, in the words of the authors, "the presence of long favorable tendencies [1901-2000] regarding precipitations or the inverse of droughts occurrence are confirmed for the eastern Andes Mountains in Argentina with its five sub-regions (Northwest Argentina, Northeast Argentina, Humid Pampa, West-Centre Provinces and Patagonia) and the inverse over the central region of Chile." From the middle of 2003 to 2009, however, they report "an upward trend in the occurrence of droughts with a slight moderation over the year 2006." Last of all, they note that the driest single year periods were 1910-11, 1915-16, 1916-17, 1924-25 and 1933-34.
All things considered, it would appear that 20th-century global warming has not promoted an increase in droughts over the southern third of South America.