(S (S (BASENP (NNP EPA) (NN administrator) (NNP Lisa) (NNP Jackson)) (VP (VBZ has) (VP (ADVP (RB previously)) (VP (VBN suggested) (UCP (S (VP (VBG declaring) (S (BASENP (JJ global) (NN warming)) (BASENP (DT a) (NN health) (NN threat))))) (CONJP (COMMA ,) (CC and)) (SBAR (IN that) (S (BASENP (DT the) (NN agency)) (VP (MD could) (VP (VP (VB use) (BASENP (DT the) (NN 1970) (JJ Clean) (NN Air) (NN Act))) (S (VP (TO to) (VP (VB use) (S (VP (TO to) (VP (VB combat) (BASENP (PRP it))))))))))))))))) (PERIOD .))