The Earth“s climate has always changed, but due to the anthropogenic impact it is changing faster. Global warming is an aspect of climate change and it is caused by increased concentrations of greenhouse gases. Adriatic Sea during the last few decades has been influenced by climate change. It has been observed an increasing of water temperature, especially expressed in the surface layer up to 20 m. Another change is an acidification of water due to the increase of atmospheric carbon, nitrogen and sulfur oxides. This, together with the increase of temperature, has an effect on sessile organisms. Coral reefs are especially vulnerable to climate change and they are affected by bleaching. The increasing seawater temperature facilitated the spreading of thermophilic species such fish, algae, bacteria and gelatinous organisms. There is also the change in the migration patterns of species that are native to the Adriatic Sea. A marked decrease of the freshwater outflow that caused a rise of surface salinity was observed during the last few decades. Phytoplankton blooms have been occurring more and more frequently. The sea level and the circulation of the Adriatic Sea is also changing. There are many other consequences that will be magnified in the coming years if temperatures continue to rise at the same rate.