骤变 (zhòu biàn) literally combines 骤 (zhòu), meaning 'sudden' or 'abrupt', and 变 (biàn), meaning 'change' or 'to change'. Together, they form a noun meaning 'abrupt change' — emphasizing speed, unexpectedness, and often intensity. It describes a rapid, dramatic shift in conditions, state, or situation, usually within a short time frame.

This word is commonly used in formal or literary contexts — such as news reports, scientific descriptions, or discussions of ecology and climate — to highlight how swiftly things can shift. While it can apply broadly (e.g., weather, politics, health), it appears frequently when describing sudden environmental shifts affecting wildlife, like habitat loss or temperature spikes that disrupt animal behavior or migration patterns. It carries a slightly serious or even alarming tone, implying consequences or instability resulting from the change.