Global warming is expected to increase the frequency and severity of droughts and heatwaves. Yet, the recent IPCC report remains inconclusive on this matter and reveals surprisingly large discrepancies among studies of past trends. These discrepancies result from (a) the limited availability of global-scale observations, and (b) the imperfect knowledge of the large-scale processes and land-atmospheric feedbacks that drive these climate extremes. Both the limited observational evidence and lack of physical understanding hamper our ability to evaluate the skill of climate models at representing droughts and heatwaves. However, recent advances in satellite Earth observation, with the development of consistent global historical records of critical environmental and climatic variables, now provide the means to unravel the processes driving these climate extremes and uncover the spatiotemporal scales at which they operate. I propose to use new global satellite-derived datasets of soil moisture, temperature, vegetation water content and evaporation to study the major droughts and heatwaves that have occurred over the past three decades, and to test the hypothesis that dry soils are a crucial factor in the development and intensification of these events. These satellite observations will be combined with meteorological and balloon sounding measurements, mechanistic modelling of the lower atmosphere, and outputs from climate models. Results will reveal: (a) if dry soils are a necessary condition to generate a mega-heatwave, (b) how soil desiccation affects meteorological drought persistency and over which spatial scales, (c) where droughts and heatwaves have become more severe in the past three decades, uncovering the role of soil dryness in this intensification, and (d) the skill of current IPCC climate models at representing the critical soil-atmosphere feedbacks that dominate these climate extremes. Findings will advance towards the timely forecasting of droughts and heatwaves, and the improvement of their long-term predictions for the future.