Long-term Temperature, Relative Humidity and Vapor Pressure Deficit Trends in Bolivia

Mountainous and highland regions are among the most sensitive and vulnerable areas to climate change and to its impacts since these ecosystems support a remarkable level of biodiversity. Small changes in temperature and precipitation with altitude could have major habitat implications for animal and plant species living in upper mountain environments leading to important social and economic consequences. However, although some authors pointed out a faster warming at highland elevation than the global average it is still unclear whether the trend of different climatic variables has an altitude dependence or not. We present a long-term assessment of temperature, relative humidity and vapor pressure deficit data over the whole Bolivia for the period 1961–2021 using in-situ observationsat different elevation ranges over a gradient of more than 4000 meters. The analysis shows statistically significant increments of the mean (0.17ºC decade-1), the maximum (0.16ºC decade-1) and the minimum temperature (0.17ºC decade-1) records over the whole study period. The relative humidity trend reflects a slightly decrease (-0.08% decade-1) although it was not statistically significant. Besides, the vapor pressure deficit data display an increment of 0.01 hPa decade-1 (p < 0.05). Contrary to previous studies based on shorter records, we detected by using long-term and quality controlled series no statistically significant relationship among the trend in the climatic variables analyzed and the altitude. Just an inverse and statistically significant relationship for the minimum temperatures and altitude was found for the dataset during the warm season but the opposite is found when considering the maximum temperatures during the cold season. This study contributes to understand climate processes in complex topographic areas of South America, which are poorly studied up to date. Keywords:climatic variables, altitude dependence, in-situ observations, trends, South America.