(S (S (BASENP (PRP He)) (VP (VBD warned) (SBAR (IN that) (S (BASENP (JJ severe) (NN climate) (NN change)) (VP (MD will) (VP (VB trigger) (SBAR (WHNP (WP what)) (S (BASENP (PRP he)) (VP (VBD called) (S (NP (QT (DQL ``) (QTC (BASENP (JJ dramatic) (NN population) (NN migration)) (COMMA ,)) (DQR '')) (NP (CONJP (ADVP (RB as) (RB well)) (IN as)) (NP (BASENP (NN war)) (PP (IN over) (NP (BASENP (NN water)) (CC and) (BASENP (JJ other) (NNS resources))))))))))))))))) (PERIOD .))