With no explanation, label text_A→text_B with either "not-entailed" or "entailed".
text_A: The Alaskan tundra , for instance , has switched from being a net sink of carbon dioxide -- absorbing and storing more carbon from the atmosphere than it releases -- to `` being a net source of CO2 ( releasing more carbon than is stored ) because warmer winters have allowed dead plant matter previously stored in the soil to decompose and release CO2 . ``
text_B: The switching happened
entailed.