Vol.:(0123456789) 1 3 Climate Dynamics https://doi.org/10.1007/s00382-020-05212-7 Downscaling projections of climate change in Sao Tome and Principe Islands, Africa Sin Chan Chou 1  · André de Arruda Lyra 1  · Jorge Luís Gomes 1  · Daniel Andrés Rodriguez 2  · Minella Alves Martins 1  · Nicole Costa Resende 1  · Priscila da Silva Tavares 1  · Claudine Pereira Dereczynski 2  · Isabel Lopes Pilotto 1  · Alessandro Marques Martins 1  · Luís Felipe Alves de Carvalho 1  · José Luiz Lima Onofre 3  · Idalécio Major 3  · Manuel Penhor 3  · Adérito Santana 3 Received: 18 June 2019 / Accepted: 13 March 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Sao Tome and Principe is a small insular African country extremely vulnerable to rising sea levels and impacts such as inun- dation, shore line change, and salt water intrusion into underground aquifers. Projections of climate change have considered coarse model resolutions. The objective of this work is to dynamically downscale the global model projections to 4-km resolution and to assess the climate change in the Sao Tome and Principe islands. The global climate projections are provided by the Canadian Earth System Model under two Representative Concentration Pathways greenhouse gas scenarios, RCP4.5 and RCP8.5. The downscaling is produced by the Eta regional climate model. The baseline period is taken between 1971 and 2000, and the future climate period is taken between 2041 and 2070. The 2-m temperature simulations show good agree- ment with station data. The model simulates temperature more accurately than precipitation. The precipitation simulations systematically show underestimation and delay of the rainy and the dry seasons by about 1 month, a feature inherited from the global climate model. In the middle of the 21st century, projections show the strongest warming in the elevated parts of the Sao Tome Island, especially in February under RCP8.5. Warmer nights and warmer days become more frequent in the islands when compared with those in the present. While under RCP4.5, precipitation increases in the islands; under RCP8.5, it decreases everywhere in both islands. Heavy precipitation rates should increase, especially in the south-southwestern parts of the Sao Tome islands. Detailed spatial variability of the temperature and precipitation changes in the islands can only be revealed at very high spatial model resolution. Implications for the potential energy production from two major river basins are assessed in this work. Keywords Central Africa · Gulf of Guinea · Small Islands developing states · Downscaling · Eta model · Regional climate model 1 Introduction The Democratic Republic of Sao Tome and Principe (STP), one of the smallest island nations in the world, with an area near 1000 km 2 , is located in the Gulf of Guinea of the western equatorial coast of Central Africa (CAF). Sao Tome and Principe are the two major islands of the country and they are about 140 km apart from each other. Sao Tome and Principe is located about 250 km of the northwestern coast of Gabon, the closest continental country. As many other Small Islands Developing States (SIDS), due to its low-lying coastal zones, Sao Tome and Principe is particu- larly vulnerable to the efects of climate change, including sea level rise and the occurrence of extreme events such as heavy rainfalls, droughts, heat waves etc. According to Mur- ray et al. (2012), SIDS share similar development challenges including small but growing populations, economic depend- ence on international funders, and the lack of resources (e.g., freshwater, land). Furthermore, projections show that Africa, the second largest continent on Earth and with the fastest Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05212-7) contains supplementary material, which is available to authorized users. * Sin Chan Chou chou.chan@inpe.br Extended author information available on the last page of the article