( Methane ( ( is ( ( ( a ( renewable ( energy source ) ) ) and ) ( ( a ( greenhouse gas ) ) ( that ( contributes ( to ( global warming ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Methane)) (VP (VBZ is) (NP (NP (DT a) (JJ renewable) (NN energy) (NN source)) (CC and) (NP (NP (DT a) (NN greenhouse) (NN gas)) (SBAR (WHNP (WDT that)) (S (VP (VBZ contributes) (PP (TO to) (NP (JJ global) (NN warming))))))))) (. .)))
Methane is a renewable energy source and a greenhouse gas that contributes to global warming.
(ROOT (S (NP (JJ Renewable) (NN energy) (NNS sources)) (VP (VBP emit) (NP (NP (JJR fewer)) (CC or) (NP (DT no) (NN greenhouse) (NNS gases)))) (. .)))