section_path: Oceanography/Climate change
section_name: Climate change
paragraph_text: Climate change
  
  Because of the short residence time of waters, the Mediterranean Sea is considered a hot spot for climate change effects. Deep water temperatures have increased by 0.12 °C (0.22 °F) between 1959 and 1989. According to climate projections, the Mediterranean Sea could become warmer. The decrease in precipitation over the region could lead to more evaporation ultimately increasing the Mediterranean Sea salinity. Because of the changes in temperature and salinity, the Mediterranean Sea may become more stratified by the end of the 21st century, with notable consequences on water circulation and biogeochemistry. The stratification and warming have already led to the eastern Mediterranean to become a net source of CO to the atmosphere notably during summer. This strong summer degassing, combined with the prolonged and pronounced stratification results in the formation of aragonite crystals abiotically in the water column. The cumulative warming at the surface of the Mediterranean has a significant impact on the ecological system. Extreme warming has led to biodiversity loss and presents an existential threat to some habitats while making conditions more hospitable to invasive tropical species.