Complex sentence: Kamchatka is much wetter and milder than eastern Siberia, and is essentially transitional from the hypercontinental climate of Siberia and northeast China to the rain-drenched subpolar oceanic climate of the Aleutian Islands.
Split into simpler sentences: Kamchatka is much wetter and milder than eastern Siberia. It is essentially transitional from the hypercontinental climate of Siberia and northeast China to the rain-drenched subpolar oceanic climate of the Aleutian Islands.