At the beginning of the 20th century, there were about 500,000 rhinos across Africa and Asia. By 1970, the number was down to 70,000. Today, there are less than 30,000 rhinos in the wild. The number of black rhinos dropped to as low as 2,300 in 1993. Aggressive conservation efforts have brought their numbers up to over 5,000 today.
Much of the public discourse about pollution is focused on the long-term consequences of greenhouse gases in the atmosphere. There are still some who doubt that such consequences are really in the offing or that our actions are responsible in any case.