( ( When ( ( cleared and ) burned ) ) ( , ( ( much ( of ( this carbon ) ) ) ( ( ( ends up ) ( in ( ( the atmosphere ) ( as ( carbon dioxide ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (VP (VP (VBN cleared)) (CC and) (VP (JJ burned))))) (, ,) (NP (NP (RB much)) (PP (IN of) (NP (DT this) (NN carbon)))) (VP (VBZ ends) (PRT (RP up)) (PP (IN in) (NP (NP (DT the) (NN atmosphere)) (PP (IN as) (NP (NN carbon) (NN dioxide)))))) (. .)))
When cleared and burned, much of this carbon ends up in the atmosphere as carbon dioxide.
(ROOT (S (PP (IN During) (NP (DT the) (JJ early) (NN paleozoic))) (, ,) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN carbon) (NN dioxide)) (PP (IN in) (NP (DT the) (NN atmosphere)))))) (VP (VBD was) (ADJP (RB much) (JJR greater)) (PP (VBN compared) (PP (TO to) (NP (NN today))))) (. .)))