( ( ( ( ( Humans ( didnt ( cause ( global warming ) ) ) ) , ) and ) ( humans ( ( can t ) ( stop it ) ) ) ) . )
(ROOT (S (S (NP (NNS Humans)) (VP (VBP didnt) (VP (VB cause) (NP (JJ global) (NN warming))))) (, ,) (CC and) (S (NP (NNS humans)) (VP (MD can) (ADVP (RB t)) (VP (VB stop) (NP (PRP it))))) (. .)))
Humans didnt cause global warming, and humans can t stop it.
(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.