( ( Human activities ) ( ( have ( resulted ( in ( ( increasing concentrations ) ( of ( ( ( some ( greenhouse gases ) ) , ) ( which ( is ( intensifying ( the ( greenhouse effect ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Human) (NNS activities)) (VP (VBP have) (VP (VBN resulted) (PP (IN in) (NP (NP (VBG increasing) (NNS concentrations)) (PP (IN of) (NP (NP (DT some) (NN greenhouse) (NNS gases)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (VP (VBG intensifying) (NP (DT the) (NN greenhouse) (NN effect)))))))))))) (. .)))
Human activities have resulted in increasing concentrations of some greenhouse gases, which is intensifying the greenhouse effect.
(ROOT (S (NP (NNP Human) (NNS actions)) (VP (VBZ has) (VP (VBN increased) (NP (DT the) (NN greenhouse) (NN effect)))) (. .)))