( They ( begin ( with ( ( ( a problem ) : ) ( How ( ( ( will ( ( the CO2 ) ( released ( from ( burning ( fossil fuels ) ) ) ) ) ) ( ( affect ( future ( atmospheric ( CO2 levels ) ) ) ) ( in ( the ( next century ) ) ) ) ) ? ) ) ) ) ) )
(ROOT (S (NP (PRP They)) (VP (VBP begin) (PP (IN with) (NP (NP (DT a) (NN problem)) (: :) (SBARQ (WHADVP (WRB How)) (SQ (MD will) (NP (NP (DT the) (NN CO2)) (VP (VBN released) (PP (IN from) (NP (VBG burning) (JJ fossil) (NNS fuels))))) (VP (VB affect) (NP (JJ future) (JJ atmospheric) (NN CO2) (NNS levels)) (PP (IN in) (NP (DT the) (JJ next) (NN century))))) (. ?)))))))
They begin with a problem: How will the CO2 released from burning fossil fuels affect future atmospheric CO2 levels in the next century?
(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))))))))) (. .)))