Droughts in South America have become more frequent and destructive since the second half of the XX century: the natural frequency of their occurrence were 16-34 years, but now they occur approximately every five years. To such conclusions scientists have come, having analysed the data of annual rings of trees since 1400, and comparing it with instrumental measurements of soil moisture. Article published in the journal Proceedings of the National Academy of Sciences.
Since the second half of the XX century in South America occurred a series of devastating droughts in 1968-1969, 1976-1977, 1996-1997 and the years 2010-2019. The last drought lasted for almost a decade, and scientists link this with global warming, leading to a shortage of snow in the Andes. Unfortunately, to understand the causes of droughts increase and match the observation with the conventional climate models is quite difficult because global climate models are poorly applicable to mountain regions, and the climate of the whole of South America largely is determined by the longest mountain system the Andes.
Scientists under the leadership of Mariano Morales (Mariano S. Morales) of the Argentine Institute of glaciology and nivology created the South American drought Atlas (SADA), which covers the territory of the continent between 12 and 56 degrees South latitude. They were able to obtain data on the drought from the 1400s to today, from rings 286 trees. Samples were collected in Chile, Argentina and Bolivia, they covered the territory on both sides of the Andes and the Patagonian woods. To this, the study authors added instrumental observations of soil moisture on the territory of the continent.