The well-established climate models state that the increasing temperature, the different dynamics of rainfalls and the increasing concentration of atmospheric CO2 will lead to significant changes in both natural ecosystems and, above all, in the urban ecosystem. Given that over 50% of the world population lives in the urban areas and that this percentage is already higher than 70% in Europe, in the present work we will focus on the potential direct and indirect impacts of climate change on trees with specific references to the urban environment, in relation to their role as providers of ecosystem services to the society. These are services that justify the investment of resources such as labor, energy and water, and represent the direct and indirect contributions of ecosystems to human well-being directly or indirectly supporting our survival and quality of life. While knowledge of tree response to changes in individual variables, such as CO2 or temperature, continue to increase, only recently research has investigated the impact that might result in the simultaneous variation of these parameters on the life cycle of trees.
Keywords: drought, temperature, stress, physiology, photosynthesis