The past few years saw the completion of NASA's Earth Observing System and the creation of new data sets for climate studies, with data volumes measured in the many peta-bytes. As the need for accurate climate forecasts grows in order to understand regional impacts and consequences, data access and use for model validation, verification and improvement is an everyday challenge for the research community. The next decade will see the deployment of the first of the missions recommended to NASA and NOAA in the National Academies' "Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond", NPOESS, and several international environmental satellites, potentially dwarfing the previous satellite data collections. This talk will set forth challenges to be met if these new enterprises are to realise benefits beyond knowledge gained through fundamental research, but in applications requiring the coupling of data from many disparate sources such as the census, health, energy consumption, utilities, and economic information.