A Dry and Warm Future Projected by Regional Climate Models in the Subtropical Andes Mountains, Southwestern South America

Abstract

The population and the ecosystems along the foothills of the Andes Mountains depend heavily on the snowmelt, glacier melt, and precipitation in the high elevations. However, this region has experienced a warming and dying trend, making these sectors particularly vulnerable to climate change. Climate projections based on Regional Climate Models (RCMs) can support decision-making processes related to adaptive measures. This study quantifies the changes in future climate over the portion of the Andes located between 21°S and 47°S in South America. First, we compared temperature and precipitation historical simulations of 25 RCMs using several statistical metrics against the CRU TS 4.07 dataset over three regions, defined according to their geographic and climatic characteristics. Then, we selected the best RCMs to quantify future climate changes relative to a baseline period (1981–2010), forced under the RCP4.5 (5 models) and RCP8.5 (7 models) scenarios. Projections indicate a decline in regional precipitation, ranging from 5% to 30%, depending on the selected scenario and time horizon. Additionally, temperature is projected to increase under all scenarios and time horizons, with the largest magnitude of warming -up to 5 °C- observed under RCP8.5 during the period 2081–2100, particularly in the northern portion of the study area. There is a clear signal of an elevation-dependent warming, specifically in the Central Andes, with a warming rate up to 0.6 °C/km. The combination of drier and warmer conditions is expected to generate profound changes in the cryosphere, posing significant challenges for regional water management and conservation of biodiversity.