( Taylor ( , ( however ( , ( ( says ( it ( is ( likely ( humans ( have ( caused ( ( only ( a ( small percentage ) ) ) ( of ( ( the ( global warming ) ) ( that ( has ( taken ( place ( in ( recent decades ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (NP (NNP Taylor)) (, ,) (ADVP (RB however)) (, ,) (VP (VBZ says) (SBAR (S (NP (PRP it)) (VP (VBZ is) (ADJP (JJ likely) (SBAR (S (NP (NNS humans)) (VP (VBP have) (VP (VBN caused) (NP (NP (RB only) (DT a) (JJ small) (NN percentage)) (PP (IN of) (NP (NP (DT the) (JJ global) (NN warming)) (SBAR (WHNP (WDT that)) (S (VP (VBZ has) (VP (VBN taken) (NP (NP (NN place)) (PP (IN in) (NP (JJ recent) (NNS decades)))))))))))))))))))) (. .)))
Taylor, however, says it is likely humans have caused only a small percentage of the global warming that has taken place in recent decades.
(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.