SPRUCE, one of the world’s largest peatland warming experiments, is located in a forested bog at the southern boundary of the boreal region . Ten large open-top enclosures, 12.8-m wide and reaching to 7 m in height, were used to explore the effects of whole ecosystem warming (above- and belowground) on peatland ecological and biogeochemical processes. Five enclosures spanned a range of warming from +0, +2.25, +4.5, +6.75, to +9°C, while another five enclosures spanned the same range of warming and were also exposed to elevated [CO₂] (+500 ppm above ambient). Belowground peat warming began in 2014, aboveground air-warming began in 2015, and elevated [CO₂] treatments began in 2016.