White, T., S. Brantley, S. Banwart, J. Chorover, W. Dietrich, L. Derry, K. Lohse, S. Anderson, A. Aufdenkampe, R. Bales, P. Kumar, D. Richter, and B. McDowell. 2015. Pages 15–17 in J.R. Giardino and C. Houser (editors). Developments in earth surface processes, volume 19: principles and dynamics of the Critical Zone. Elsevier, Cambridge, Massachusetts.
The US National Science Foundation (NSF) has pioneered an integrated approach to the study of Earth’s Critical Zone by supporting a network of Critical Zone Observatories (CZOs). The CZOs are intensively studied and monitored sites with a focus on a range of Critical Zone processes that are well represented at the various sites. The initial network (beginning in 2007) consisted of 3 CZOs, expanded to 6 in 2009, and is currently expanding to a total of 10 in 2014. The investment in financial and human resources into the CZOs has enabled a range of new scientific investigations that were not accessible under traditional funding mechanisms, and this is leading to novel and exciting advances in scientific understanding of a fundamentally important part of the Earth system.