Data captured from remote sensing systems in space yield evidence of global climate changes. In this book international experts consider the potential value of such data. In particular they address the problem of calibration to ensure that detected changes do not arise from drift in the calibration of the instrument. Consideration is given to large international projects on cloud climatology, archived meteorological satellite data, and to vegetation indices derived from the global sets. This book concludes with a discussion on the future role of satellite data.