Detection of increase in air temperature in Barrow, AK, USA, through the use of extreme value indices and its impact on the permafrost active layer thickness

The current conditions of climatic variability make it necessary to analyse in detail the parameters that determine it to clearly understand the consequences on the environment, especially in highly strategic sites in terms of geographic location, such as Barrow, AK, USA, which is a global observatory on the impact of current climate change. Through the study of current air and ground temperature data, and through the calculation of extreme temperature and precipitation indices (ETCCDI), it was obtained as a result that the air freezing indices, FD and ID, decrease at a rate of 0.56 and 0.51 days/year respectively, while TNX, TXn and TNn have increased at a rate of 0.03, 0.118 and 0.068 degrees C/year respectively. At least 3 out of 4 extreme temperature indices indicate that the minimum temperature has been clearly higher in the last 70 years. As consequence of the above, it has caused an average annual air temperature to increase at a rate of 0.06 degrees C/year during 1950-2019. This leads to reconsider a new climatological normal with an annual value of - 10.17 degrees C. The effect of this continuous increase in temperature has forced the thickness of the active layer at the site to increment over time at a rate between 0.25 and 0.37 cm/year. The close correlation found between air temperature and the thickness of the active layer suggests that the gradual impact in both variables could continue in a linear and almost parallel increase as it has been happening in recent decades.