The sea level is predicted to rise by 50 centimeters by the end of next century.

Literal

Next-century [possessive-の] end [by-までに] sea [topic-は] 50-cm [by-で] rise [quotative-と] is-predicted.

予想される is the passive of 予想する ('to predict'), used here impersonally — 'it is predicted.' と marks the content of the prediction. センチ is a shortened katakana loanword from センチメートル. ~までに marks the future deadline.