Climate change may threaten the food security because of the reduced recharge of aquifers and increased plant water use. The majority of vegetables in Turkey are grown in the coastal plains along the Mediterranean Sea where the groundwater is the main source of irrigation water. The sustainability of long-term food production in such plains depends on groundwater availability under changing climate conditions. This study focuses on the Demre coastal aquifer of southwestern Turkey, where 15 million cubic meters of groundwater has been abstracted annually for irrigation. A numerical groundwater flow model is used to simulate the aquifer's behavior until 2050, under the climate change scenarios named Representative Concentration Pathway (RCP) 4.5 and 8.5. Results show that the present groundwater use pattern would reach its limit of sustainable use until 2050 if the agricultural production pattern is not changed and lateral recharge from the mountainous karst aquifer continues. However, discrepancies between RCP-anticipated and observed precipitation and temperature values raise doubts on the results of the groundwater flow model used to estimate the future aquifer conditions. It is understood that the accuracy of the RCP-anticipated parameters should be increased before attempting to establish reliable groundwater management policies based on the outputs of the predictive groundwater flow models. Future work should concentrate also on using more accurate input data and assessing the effect of uncertainties on the results of predictive groundwater flow models.