Extreme temperature projections for Buenos Aires, Argentina, under different warming levels

Buenos Aires is one of the largest cities in the world in terms of population and the second in South America, housing more than 14 million people, which represents around 30% of Argentina's total population. A comprehensive analysis of extreme temperatures from 1959 to the present shows that the annual mean maximum and minimum temperatures have significant positive trends. Specifically, the maximum temperature has been increasing at a rate of 0.17°C per decade, while the minimum temperature has risen at a rate of 0.21°C per decade. This rise in urban temperatures poses risks to human health, increases energy demand, and makes the city population, assets, and economy more vulnerable. Therefore, assessing future projections of mean and extreme temperatures at the urban scale is a priority to contribute to developing appropriate adaptation and mitigation strategies.

In this study we provide estimates of local temperature changes at different levels of global warming (1,5°C, 2°C and 3°C) considering a subset of CMIP6 simulations from those models that better represent the regional temperature at annual and seasonal scale. Four climate models out of 16 were selected according to different metrics (bias of annual, summer and winter temperatures, correlations in the annual cycle and standard deviation ratio) and their maximum and minimum temperature daily outputs were downscaled and bias corrected using the delta, eqm and qdm methods. This information was used to analyze changes in extreme temperature indices, such as summer days, tropical nights, and daily maximum and minimum temperature values. Results indicate that the intensity of maximum and minimum temperatures, as well as the frequency of hot extremes, will continue to rise in Buenos Aires due to increasing levels of global warming. However, the rate of this increase will vary depending on the emissions scenario adopted to achieve the different global warming levels analyzed.