Abstract Climate data are usefully applied to many economic and societal sectors. Sustained, high quality and uninterrupted climate observations are vital for the development of all countries, because climate variability and change impact significantly on economies and societies. The sectors treated in this paper include the key areas of human health, energy and water. The special needs for research and for the development of strategies to mitigate and adapt to climate change are also considered. All countries should be encouraged to give high priority to national needs for observations in their national adaptation planning. The full implementation of the Global Climate Observing System is required to ensure that countries are able to understand and manage climate variability and change over the twenty-first century.