Based on a 63-station radiosonde network, annual and annual temperature change have been estimated by means of linear regression for the earth’s surface, troposphere (1.5–9 km), tropopause layer (9–16 km) and low stratosphere (16–20 km) in polar, temperate, subtopical and equatorial zones, as well as the tropics, both hemisphere and the word, for intervals 1960–85, 1965–85, 1970–85 and 1975–85. During the last quarter century, the surface and the troposphere have warned and the tropopause layer and the low stratosphere have cooled in almost all climatic zones, i.e., there ha been an increase in lapse rate. The low-level warming and higher-level cooling have been more pronounced in the Southern Hemisphere than in the Northern Hemisphere. There is little evidence on the hemispheric scale for an increase in the rate of warming or cooling, but there is evidence in individual climatic zones. For example, there has been an increase in rate of cooling in the low stratosphere of the south polar zone, especially in the spring presumably associated with the low (and decreasing) springtime total-ozone in this region. In the Northern Hemisphere, surface temperatures have warmed the most in winter, whereas in the Southern Hemisphere the warming has been greatest in autumn or winter. For the world as a whole, surface and tropospheric temperatures have warmed the least in September-October-November. In the tropopause layer of both hemispheres the cooling has been greatest in September-October-November and December-January-February. The influence of the El Chichón eruption on the temperature decrease determined for the low stratosphere has been evaluated, and limited evidence is presented that the cooling in the low stratosphere has been increasing with height. The pattern of observed temperature change is considered in the context of temperature changes to be expected from an increase in C02 and certain trace gases.