Recent changes in climate extremes in Guinea-Bissau
Orlando Mendes, Marcelo Fragoso
Abstract
Guinea-Bissau has experienced the tangible effects of climate change in recent years. An examination of the annual and monthly precipitation patterns from 1960-2020 indicates an overall decreasing trend in climatological series. In contrast, the monthly average maximum and minimum temperatures exhibit significant increasing trends during the same period. Analysing daily rainfall and maximum and minimum temperature leads us to conclude that rainfall and temperature patterns have evolved in different ways. The non-parametric Mann–Kendall test was used to assess trends in climate indices, and Sen’s slope estimator was used to detect the magnitude of trends. Despite the significant decrease in wet days, there has been an upward trend in rainfall over the 1981-2020 climatological series. Days with maximum temperatures of at least 30 and 35ºC have increased in all seasons with a very significant upward trend for 30ºC. On the other hand, absolute annual maximum temperatures have tended to decrease in Bolama and Bafatá by -0.25 and -0.17ºC per decade respectively. There has also been a decrease of 0.30ºC and 0.39ºC per decade in the minimum temperatures in Bolama and Bafata, i.e. the nights have been getting cooler, which somewhat contradicts the global trends generally reported for this same parameter.