The document discusses methods for optimally designing climate observing networks. It notes that some networks grow organically while others are designed before implementation. The authors describe using objective network design which involves finding sites that maximize a performance measure given constraints. They apply this approach to the Climate Reference Network and find that five stations explain 95% of the variance in monthly precipitation for a region, with stations located in mountains. The summary provides the key details about network design methods and findings in a concise manner.