( ( Modeling ( the ( global ( ocean-atmosphere ( carbon ( dioxide system ) ) ) ) ) ) ( ( is ( becoming ( increasingly ( important ( to ( greenhouse ( gas policy ) ) ) ) ) ) ) . ) )
(ROOT (S (S (VP (VBG Modeling) (NP (DT the) (JJ global) (JJ ocean-atmosphere) (NN carbon) (NN dioxide) (NN system)))) (VP (VBZ is) (VP (VBG becoming) (ADJP (RB increasingly) (JJ important) (PP (TO to) (NP (NN greenhouse) (NN gas) (NN policy)))))) (. .)))
Modeling the global ocean-atmosphere carbon dioxide system is becoming increasingly important to greenhouse gas policy.
(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.