Finding innovative solutions to complex problems is often about finding people who have access to novel information and alternative viewpoints. Research has found that most people are connected to each other through just a few degrees of separation, but successful social search is often difficult because it depends on people using their weak ties to make connections to distant social networks. Recursive incentive schemes have shown promise for social search by motivating people to use their weak ties to find distant targets, such as specific people or even weather balloons placed at undisclosed locations. Here, we report on a case study of a similar recursive incentive scheme for finding innovative ideas. Specifically, we implemented a competition to reward individual(s) who helped refer Grand Prize winner(s) in MIT's Climate CoLab, an open innovation platform for addressing global climate change. Using data on over 78,000 CoLab members and over 36,000 people from over 100 countries who engaged with the referral contest, we find that people who are referred using this method are more likely than others both to submit proposals and to submit high quality proposals. Furthermore, we find suggestive evidence that among the contributors referred via the contest, those who had more than one degree of separation from a pre-existing CoLab member were more likely to submit high quality proposals. Thus, the results from this case study are consistent with the theory that people from distant networks are more likely to provide innovative solutions to complex problems. More broadly, the results suggest that rewarding indirect intermediaries in addition to final finders may promote effective social network recruitment.