( ( ( ( ( ( Natural ( gas companies ) ) ( ( ( claim ( that ( fracking ( is safe ) ) ) ) and ) ( has ( ( gone on ) ( for decades ) ) ) ) ) , ) but ) ( there ( are ( ( a lot ) ( of ( people ( who ( ( ( ( ( disagree ( with ( ( the safety ) ( of ( fracking operations ) ) ) ) ) , ) and ) worry ) ( ( about ( the ( recent proliferation ) ) ) ( of fracking ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (JJ Natural) (NN gas) (NNS companies)) (VP (VP (VBP claim) (SBAR (IN that) (S (NP (NN fracking)) (VP (VBZ is) (ADJP (JJ safe)))))) (CC and) (VP (VBZ has) (VP (VBN gone) (PRT (RP on)) (PP (IN for) (NP (NNS decades))))))) (, ,) (CC but) (S (NP (EX there)) (VP (VBP are) (NP (NP (DT a) (NN lot)) (PP (IN of) (NP (NP (NNS people)) (SBAR (WHNP (WP who)) (S (VP (VBP disagree) (PP (IN with) (NP (NP (DT the) (NN safety)) (PP (IN of) (NP (VBG fracking) (NNS operations))))) (, ,) (CC and) (VBP worry) (NP (NP (RB about) (DT the) (JJ recent) (NN proliferation)) (PP (IN of) (NP (VBG fracking)))))))))))) (. .)))
Natural gas companies claim that fracking is safe and has gone on for decades, but there are a lot of people who disagree with the safety of fracking operations, and worry about the recent proliferation of fracking.
(ROOT (S (NP (NNP Fracking)) (VP (VBZ delivers) (NP (JJ natural) (NN gas)) (PP (IN from) (NP (NP (NN rock)) (SBAR (WHNP (WDT that)) (S (VP (MD might) (RB not) (ADVP (RB otherwise)) (VP (VB be) (ADJP (JJ obtainable))))))))) (. .)))
Fracking delivers natural gas from rock that might not otherwise be obtainable.