These will affect cereal production, which would fall by almost 40% by 2050 according to the RCP8.517 scenario. The drop in yields that will affect olive production could reach 32%. The share of agricultural production in the national GDP would decrease by 5% to 10% in 2030, depending on the scenarios of economic openness of the agricultural sector. The impacts will be reflected in a drop in yields and a reduction in the area of tree and cereal crops, a loss of soil fertility and the area of arable land. The highest level of vulnerability is observed in central and southern Tunisia, and the level of vulnerability is particularly critical in the south (east and west). 2.1.3. Natural Ecosystems.