Natural exergy losses connected with the absorption of solar radiation by the Earth have been calculated. The exergy income caused by the radiation exchange between the Earth and the cosmic space has also been considered. The exergy losses occurring near the Earth's surface have been distinguished because they represent the most accessible natural resources of exergy. The term 'natural losses of utilizable exergy' has been proposed. These losses have been compared with the anthropogenic ones caused by the activity of humankind. The positive impact of the natural exergy losses has been pointed out: they were a main cause of the formation of the terrestrial natural environment, of the non-renewable natural resources of fuels, and of the generation of stable dissipative structures in form of living beings. (C) 2003 Elsevier Science Ltd. All rights reserved.