With industrial pollution entering the world's atmosphere, researchers have to get an understanding of past changes that have occurred in the earth's climate. The study of the yearly growth circles in old trees to reveal past climatic changes has become an important scientific discipline.
當工業汙染影響到地球氣候，研究人員須要瞭解過去地球氣候變遷，由老樹年輪來看過去氣候變化的年輪學，也成了今天重要的一門科學。