( ( Understand ( that ( ( the CO2 ) ( was ( ( created ( by ( ( the release ) ( of energy ) ) ) ) ( from ( burning ( the ( fossil fuel ) ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VB Understand) (SBAR (IN that) (S (NP (DT the) (NN CO2)) (VP (VBD was) (VP (VBN created) (PP (IN by) (NP (NP (DT the) (NN release)) (PP (IN of) (NP (NN energy))))) (PP (IN from) (S (VP (VBG burning) (NP (DT the) (JJ fossil) (NN fuel)))))))))) (. .)))
Understand that the CO2 was created by the release of energy from burning the fossil fuel.
(ROOT (S (NP (JJ Co2) (NN gas)) (VP (VBZ is) (VP (VBN released) (PP (IN into) (NP (NP (DT the) (NN atmosphere)) (SBAR (WHADVP (WRB when)) (S (NP (JJ fossil) (NNS fuels)) (VP (VBP are) (VP (VBN burned))))))))) (. .)))