Resumen
Surface air temperature changes during the last century is one of the most disputable topics among researchers concerned with the problem. Nevertheless, the basic question - whether the temperature growth has been connected with human activities or it has been the result of natural climatic variability - has not been solved yet. Over-simplification of processes driving the climate system leads to misundertanding the nature of climatic change. Results of analysis of statistical properties of two independent time series are considered. Changes in statistical structure of air surface temperature with the growth of the scale of spatial averaging from local to the global one are marked. Similarity between global air temperature changes and a random walk is discussed.