( ( ( The records ) ( from ( the ( GISP2 ( and ( GRIP cores ) ) ) ) ) ) ( ( ( have already ) ( been ( proven ( to ( ( ( contain ( evidence ( of ( ( ( unexpectedly ( ( rapid and ) dramatic ) ) shifts ) ( of climate ) ) ) ) ) , ) ( with ( ( ( changes ( in ( ( ( ( ( the composition ) ( of ( the ( ice signaling ) ) ) ) , ) or ) ( ( at least ) accompanying ) ) ) ) , ) ( ( most such ) ( climate shifts ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNS records)) (PP (IN from) (NP (DT the) (NNP GISP2) (CC and) (NNP GRIP) (NNS cores)))) (VP (VBP have) (ADVP (RB already)) (VP (VBN been) (VP (VBN proven) (S (VP (TO to) (VP (VB contain) (NP (NP (NN evidence)) (PP (IN of) (NP (NP (ADJP (RB unexpectedly) (JJ rapid) (CC and) (JJ dramatic)) (NNS shifts)) (PP (IN of) (NP (NN climate)))))) (, ,) (PP (IN with) (NP (NP (NP (NNS changes)) (PP (IN in) (NP (NP (NP (DT the) (NN composition)) (PP (IN of) (NP (DT the) (NN ice) (NN signaling)))) (, ,) (CC or) (NP (QP (IN at) (JJS least) (CD accompanying)))))) (, ,) (NP (ADJP (RBS most) (JJ such)) (NN climate) (NNS shifts)))))))))) (. .)))
The records from the GISP2 and GRIP cores have already been proven to contain evidence of  unexpectedly rapid and dramatic shifts of climate, with changes in the composition of the ice signaling, or at least accompanying, most such climate shifts.
(ROOT (S (SBAR (WHADVP (WRB How)) (S (NP (NN ice) (NNS cores)) (VP (VBP are) (ADJP (JJ important) (PP (TO to) (NP (NP (DT the) (NN study)) (PP (IN of) (NP (JJ geologic) (NN history))))))))) (VP (VBZ is) (ADVP (RBS best)) (VP (VBN described) (SBAR (IN as) (S (NP (PRP they)) (VP (VBP contain) (NP (NN evidence) (NN showing) (NNS changes)) (PP (IN in) (NP (NP (DT the) (JJ atmospheric) (NN composition)) (PP (IN over) (NP (NN time)))))))))) (. .)))