FACE means Free Air Carbon Enrichment and is a technique used to increase CO2 concentrations in open plots (as compared to enclosures like green houses). Several projects all over the world use this technique. 

http://globalecology.stanford.edu/DGE/Dukes/JRGCE
Jasper Ridge global change experiment

http://cdiac.esd.ornl.gov/programs/FACE/whereisface.html
Where are all the FACE experiments in the world ?

http://www.face.bnl.gov/
Brookhaven National Laboratory FACE experiment

http://www.fb.ipw.agrl.ethz.ch/FACE.html
Swiss FACE experiment

http://aspenface.mtu.edu/
Aspen FACE experiment

http://www.env.duke.edu/forest/FACTSI.htm
Duke Forest FACE experiment

http://www.unitus.it/euroface/
EUROFACE FACE experiment in Italy

http://www.utas.edu.au/docs
/plant_science/Ecophys/TasFACE.html
FACE experiment on Tasmania