Developing large-scale environmental data bases

There are inherent challenges in working with datasets on a global scale. Given that in general only data with the same definition, standards and date of measurement can be safely aggregated to a regional or global level, even small discrepancies or gaps can make datasets incomplete or otherwise deficient. On the other hand, even with good quality data, aggregation and averaging may mask important spatial or temporal diversity. In large-scale aggregations, issues unique to smaller regions disappear. Therefore the scale of aggregation and reporting of averages should be carefully matched with the scale of environmental issues or policies and the purpose of assessment.