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Figure 2. Global warming potential (GWP) of fresh lettuce cultivated in the sunlight greenhouse (G) and plant factory with artificial light (P). (A) The 100(20)-year GWP. Greenhouse: Baseline G₀ excludes the N₂O emission of nitrogen fertilizer uses, and G_1-3 consider N₂O with three separately measured emission coefficients^[20-22]. Plant factory: P₀ represents baseline power sources from China Southern Power Grid and others from coal (P₁), oil (P₂), natural gas (P₃), solar (P₄), wind (P₅), nuclear (P₆), and hydro (P₇). (B) Material contributions to the 100-year GWP.