( ( ( These ( human-caused emissions ) ) ( of ( greenhouse gases ) ) ) ( ( ( ( enhance ( the ( greenhouse effect ) ) ) and ) ( may ( be ( responsible ( for ( ( the ( recent increase ) ) ( in ( global warming ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT These) (JJ human-caused) (NNS emissions)) (PP (IN of) (NP (NN greenhouse) (NNS gases)))) (VP (VP (VB enhance) (NP (DT the) (NN greenhouse) (NN effect))) (CC and) (VP (MD may) (VP (VB be) (ADJP (JJ responsible) (PP (IN for) (NP (NP (DT the) (JJ recent) (NN increase)) (PP (IN in) (NP (JJ global) (NN warming))))))))) (. .)))
These human-caused emissions of greenhouse gases enhance the greenhouse effect and may be responsible for the recent increase in global warming.
(ROOT (S (NP (NNP Human) (NNS actions)) (VP (VBZ has) (VP (VBN increased) (NP (DT the) (NN greenhouse) (NN effect)))) (. .)))