The paper is devoted to brief analysis of climate change issue, connected international activities and monitoring system. About 3000 reliable meteorological stations can be used for monitoring of long-term climatic changes on the whole Earth since 1951. Besides these also many aerologic, hydrologic, phenologic and other observing station networks can be utilized. Prior to 1951 the number of regular observing stations is still lower and only paleoclimatic reconstructions are possible before 1850. Satellite observation system is a new tool developed also for climatic changes monitoring in the 60th and 70th of the 20th century. There exist a number of satellites with sensors for measurements of the Earth and sea surface temperature, snow cover extent and depth, sea ice extent and concentration, soil moisture, atmospheric water content, cloudiness etc.