( Humans ( ( ( are not ) ( causing ( global warming ) ) ) . ) )
(ROOT (S (NP (NNS Humans)) (VP (VBP are) (RB not) (VP (VBG causing) (NP (JJ global) (NN warming)))) (. .)))
Humans are not causing global warming.
(ROOT (S (NP (NNP Human) (NNS beings)) (VP (VBP is/are) (NP (NP (DT the) (JJ main) (NN cause)) (PP (IN of) (NP (JJ recent) (JJ global) (NN warming))))) (. .)))
Human beings is/are the main cause of recent global warming.