( ( ( ( ( ( Carbon dioxide ) ( is ( implicated ( in ( global warming ) ) ) ) ) ( , ( ( ( sulfur dioxide ) ( causes ( acid rain ) ) ) , ) ) ) and ) ( ( oil spills ) ( have ( polluted ( ( ( ( ( ( our oceans ) , ) rivers ) , ) and ) lakes ) ) ) ) ) . )
(ROOT (S (S (NP (NNP Carbon) (NN dioxide)) (VP (VBZ is) (VP (VBN implicated) (PP (IN in) (NP (JJ global) (NN warming)))))) (PRN (, ,) (S (NP (NN sulfur) (NN dioxide)) (VP (VBZ causes) (NP (JJ acid) (NN rain)))) (, ,)) (CC and) (S (NP (NN oil) (NNS spills)) (VP (VBP have) (VP (VBN polluted) (NP (NP (PRP$ our) (NNS oceans)) (, ,) (NP (NNS rivers)) (, ,) (CC and) (NP (NNS lakes)))))) (. .)))
Carbon dioxide is implicated in global warming, sulfur dioxide causes acid rain, and oil spills have polluted our oceans, rivers, and lakes.
(ROOT (S (NP (NNP Ocean) (NNP acidification)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NP (JJ excess) (NN carbon) (NN dioxide)) (PP (IN in) (NP (DT the) (NN atmosphere)))) (VP (VBZ causes) (S (NP (DT the) (NNS oceans)) (VP (TO to) (VP (VB become) (NP (NNS acidic))))))))) (. .)))
Ocean acidification occurs when excess carbon dioxide in the atmosphere causes the oceans to become acidic.