( ( ( A number ) ( of ( ( ( ( factors ( such ( as ( ( the expansion ) ( of ( ( the oceans ) ( in ( response ( to ( higher temperatures ) ) ) ) ) ) ) ) ) ) ( -LRB- ( ( called ( thermal expansion ) ) -RRB- ) ) ) and ) ( changes ( in ( ( the ( mass balance ) ) ( of ( glaciers ( and ( the ( Antarctic ( and ( Greenland ( ice sheets ) ) ) ) ) ) ) ) ) ) ) ) ) ) ( ( are ( thought ( to ( have ( contributed ( to ( ( a ( ( ( greater or ) lesser ) extent ) ) ( to ( this change ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (NN number)) (PP (IN of) (NP (NP (NP (NNS factors)) (PP (JJ such) (IN as) (NP (NP (DT the) (NN expansion)) (PP (IN of) (NP (NP (DT the) (NNS oceans)) (PP (IN in) (NP (NP (NN response)) (PP (TO to) (NP (JJR higher) (NNS temperatures)))))))))) (PRN (-LRB- -LRB-) (VP (VBN called) (NP (JJ thermal) (NN expansion))) (-RRB- -RRB-)) (CC and) (NP (NP (NNS changes)) (PP (IN in) (NP (NP (DT the) (JJ mass) (NN balance)) (PP (IN of) (NP (NN glaciers) (CC and) (DT the) (NNP Antarctic) (CC and) (NNP Greenland) (NN ice) (NNS sheets))))))))) (VP (VBP are) (VP (VBN thought) (S (VP (TO to) (VP (VB have) (VP (VBN contributed) (PP (TO to) (NP (NP (DT a) (ADJP (JJR greater) (CC or) (JJR lesser)) (NN extent)) (PP (TO to) (NP (DT this) (NN change))))))))))) (. .)))
A number of factors such as the expansion of the oceans in response to higher temperatures (called thermal expansion) and changes in the mass balance of glaciers and the Antarctic and Greenland ice sheets are thought to have contributed to a greater or lesser extent to this change.
(ROOT (S (NP (DT The) (NN term) (JJ thermal) (NN expansion)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB describe) (NP (NP (DT the) (NN change)) (PP (IN in) (NP (NN size) (CC or) (NN volume))) (PP (IN of) (NP (NP (DT a) (VBN given) (NN mass)) (PP (IN with) (NP (NN temperature))))))))))) (. .)))