去掉一個2，改問CO。 AI當秘書不是蓋的。

The majority of carbon monoxide (CO) emissions are from natural sources, but human activities significantly contribute as well. Here's a breakdown:

1. Natural Sources: About 70-90% of CO emissions come from natural sources, primarily from wildfires, vegetation decay, volcanic activity, and the oceans.

2. Human-made Sources: The remaining 10-30% of CO emissions come from anthropogenic (human-caused) sources, mainly from the burning of fossil fuels, including transportation (vehicles), industrial processes, and residential heating and cooking.

While natural sources dominate, human activity is responsible for a considerable portion of CO emissions, contributing to air pollution and impacting air quality, especially in urban areas.