Free-air concentration enrichment

Experiments using FACE are required because most studies looking at the effect of elevated CO2 concentrations have been conducted in labs and where there are many missing factors including plant competition.

For example, FACE circles have been used to measure the response of soybean plants to increased levels of ozone and carbon dioxide at research facilities at the University of Illinois at Urbana–Champaign.

The National Wheat FACE array is presently being established in Horsham, Victoria, Australia as a joint project of the Victorian Department of Primary Industries and the University of Melbourne.

[3] EucFACE is Australia's only forest FACE experiment, and was established by the University of Western Sydney in Cumberland Plain Woodland dominated by Eucalyptus tereticornis near Richmond, New South Wales in 2012.

Increased atmospheric carbon dioxide has been found to reduce plant water use, and consequently, the uptake of nitrogen, so particularly benefiting crop yields in arid regions.