That's a good question, and I don't have an immediate answer. The frequent La Ninas in recent years may be contributing to the dryness in the region, but there are other possible contributing factors like soil moisture variations, chaotic weather variability, and climate change, as you mention. I am now working with an undergraduate intern who is investigating projected changes in atmospheric rivers over South America, so I hope to gain a better understanding of the possible role of climate change in the near future.