Earth's critical zone

History

The term "critical zone" was first used in chemistry by Dimitrios Tsakalotos in 1909 to describe a mixture of two fluids. In 1998, Gail Ashley repurposed it to describe the link between vegetation, soil, and weathered rock. In October 2003, the first Weathering System Science Workshop took place. Attendees agreed to boost outreach to involve more Earth scientists and developed key questions to advance the field, which was defined as covering the chemistry, biology, physics, and geology of the critical zone.

The Weathering System Science Consortium formed in early 2004 and was renamed the Critical Zone Exploration Network (CZEN) in 2006. In October 2005, the consortium asked for proposals to fund seed sites for a critical zone network; ten sites received grants, and nine got continued funding. That same year, an NSF-sponsored workshop at the University of Delaware led scientists to call for an international critical zone initiative, emphasizing a systematic study across geology, soil science, biology, ecology, chemistry, geochemistry, geomorphology, and hydrology.

A booklet called Frontiers in Exploration of the Critical Zone resulted from this meeting. On July 24, 2006, the NSF issued a call for proposals for Critical Zone Observatories through its Division of Earth Sciences. The Delaware Environmental Institute (DENIN), launched in 2009, is a multidisciplinary effort uniting scientists, engineers, and policy experts to address environmental challenges through research and partnerships.