Abstract: Ecosystems use solar energy for self-organisation and cool themselves by exporting entropy to the atmosphere as heat. These energy transformations are achieved through evapotranspiration, with plants as ‘heat valves’. In this study, the dissipative process is demonstrated at sites in the Czech Republic and Belgium, using landscape temperature data from thermovision and satellite images. While global warming is commonly attributed to atmospheric CO2, the research shows water vapour has a concentration two orders of magnitude higher than other greenhouse gases. It is critical that landscape management protects the hydrological cycle with its capacity for dissipation of incoming solar energy.