The subject of the present thesis fits within the scope of global climate change analysis. It focuses on two main areas of interest, namely the study of recent past climate over the last few decades and the development of tools for modeling future climate. Study of past climate.The first part of this thesis deals with the interpretation of NOAA-AVHRR (National Oceanic and Atmospheric Administration - Advanced Very High Resolution Radiometer) time series at the continental spatial scale.The data constitute an archive of decadal or weekly composite spanning over two decades which was developed for studying and monitoring boreal ecosystem activity in Canada. This study uses classical parameters derived from remote sensing in the visible and th...