Potential impacts of climate change in the Plata basin

Significant climate change effects on river discharges of the Plata basin cannot be discounted, as the regional precipitation has already had a substantial positive trend in the past. Besides, rivers discharges, when expressed as percentages, considerably amplify the precipitation variability. Trends during the last 40 years were principally caused by the intensification of the El Nino signal on precipitation, leading to an increased frequency of large floods in the middle and lower Parana River, where four out of the five largest floods of the 20th century occurred during the last 20 years of that century. In addition, episodes of heavy rainfall are also becoming more frequent, contributing to increased vulnerability to climate change. There is currently too much uncertainty in future precipitation and hydrological scenarios for the next 50 years over most of the Plata basin, because outputs of global climate models underestimate considerably the present mean precipitation, and also differ among themselves.