Global Warming Distorts the Twenty-Four Solar Terms

摘要

Two thousand years ago, ancient China created a system of twenty-four solar terms through the observation of the Sun's annual motionand position along the ecliptic, where every 15° segment is a solar termencompassing a period of 15 days. Thefirst term “Start of Spring”begins from the Sun’s position at 315° on the day of 4 February in theGregorian calendar. This solar term means the start of a new year cyclethat the coldest weather ends and the planet is going to warm up. Eachof the twenty-four solar terms was named to reflect the evolution ofnatural phenomena, phenological seasons and climates (see theIllustration Figure 1) and has guided agricultural and living activities across China since their creation. For instance, the third term“Awakening of Insects”, which commences on 6 March, the day of Sun’sposition at 345°, signals a rise in temperature and rainfall, alluding tothe fact that animals and insects are awakened from winter hibernationby spring thunder and it is the time to start spring plough in thecentral plan, the origin of the solar term system. The twenty-four solarterms were crucial for agrarian societies in ancient China and spread toKorea, Vietnam, Japan, and countries in the East Asian cultural sphere.The solar term system was inscribed on the UNESCO’s representativelist of intangible cultural heritage on 30 November 2016.