Catalyzes the reversible hydration of carbon dioxide (PubMed:10550681, PubMed:16506782, PubMed:16686544, PubMed:16807956, PubMed:17127057, PubMed:17314045, PubMed:17407288, PubMed:18618712, PubMed:19186056, PubMed:19206230). Can hydrate cyanamide to urea (PubMed:10550681).