Future changes in precipitation over Guinea-Bissau under the Shared Socioeconomic Pathways (SSPs)

ABSTRACT Guinea-Bissau, like many countries in sub-Saharan Africa, faces persistent food insecurity due to its reliance on rainfed agriculture. Climate change is expected to heighten this vulnerability. This study evaluates projected changes in precipitation extremes in Guinea-Bissau throughout the 21st century using the NEX-GDDP-CMIP6 dataset. Two Shared Socioeconomic Pathways were considered: a medium (SSP2-4.5) and a high forcing scenario (SSP5-8.5). Precipitation indices were calculated following the guidelines of the World Meteorological Organization Expert Team on Climate Change Detection and Indices (ETCCDI). Climate models were first assessed for their ability to reproduce historical precipitation extremes (1981–2010), and then future changes were examined for the near term (2031–2060) and long term (2071–2100). Results reveal contrasting future trends, including a decline in the number of wet days (R1mm) and shorter wet spells (CWD), alongside increases in consecutive dry days (CDD), maximum 1-day rainfall (RX1DAY), and precipitation from extremely wet days (R99P). Together, these projections suggest an intensification of alternating droughts and rainstorms. Such shifts threaten agricultural stability by disrupting planting calendars, damaging crops and soils, and aggravating food insecurity. The findings provide essential evidence to support water management, disaster risk reduction, and adaptive agricultural strategies in Guinea-Bissau.