( ( At ( the ( global level ) ) ) ( , ( ( ( ( ( ( the burning ) ( of ( ( ( fossil fuels ) and ) ( ( the release ) ( of ( CO2 ( into ( the atmosphere ) ) ) ) ) ) ) ) , ) ( free ( at ( ( the point ) ( of use ) ) ) ) ) , ) ( ( is ( ( a ( major cause ) ) ( of ( global warming ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (DT the) (JJ global) (NN level))) (, ,) (NP (NP (DT the) (NN burning)) (PP (IN of) (NP (NP (JJ fossil) (NNS fuels)) (CC and) (NP (NP (DT the) (NN release)) (PP (IN of) (NP (NP (NNP CO2)) (PP (IN into) (NP (DT the) (NN atmosphere)))))))) (, ,) (ADJP (JJ free) (PP (IN at) (NP (NP (DT the) (NN point)) (PP (IN of) (NP (NN use)))))) (, ,)) (VP (VBZ is) (NP (NP (DT a) (JJ major) (NN cause)) (PP (IN of) (NP (JJ global) (NN warming))))) (. .)))
At the global level, the burning of fossil fuels and the release of CO2 into the atmosphere, free at the point of use, is a major cause of global warming.
(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))))))))) (. .)))