The crucial role of plant photosynthesis has been emphasized in relation to the atmospheric CO2 concentration and climate change. Because of the irreplaceable role of plants in ecosystem services, potential changes of both crop and wild plants could impact sustainability of human societies. The dependence of the rate of photosynthesis of the C3 and C4 plants on irradiance, CO2 concentration and temperature has been illustrated. Potential consequences of the atmospheric CO2 concentration rise and climate change on ecosystem composition and functions are briefly described.(In Czech, English summary only)