To provide a method for expressing a time axis for allowing easy realization and understanding about a time interval in the past and future so as to solve a problem that a human knows, but hardly recognizes and understands that a human activity is a cause for global environmental problems because the human living along a time axis recognizes time closer to oneself more than time farther from oneself.

A timeline includes the time axis for indicating years centered on the present and extended from the past to the future having index numbers X each provided in an equal interval, wherein X denotes an exponent of Xth power of 2. With the present being at the center, both present and future events are similarly expressed except that events closer to the present are placed near, and events farther from the present are placed far from the center. The time axis for the past and future places successive years at the same interval such that an interval between the present year and a year before, and an interval between the present year and the year 00 of 10 billion years ago have the same length.