"We are doing violence towards the earth, towards nature. We have become butchers of nature," Sunderlal Bahuguna once told an interviewer. Bahuguna, who died with Covid-19 on Thursday aged 94, was known the world over as the man who taught Indians to hug trees to protect the environment. He was one of the main leaders of the Chipko movement in northern India in the 1970s. In Hindi, chipko literally means "hugging".