The Rio Declaration of the United Nations Framework Convention on Climate Change emphasises that human beings are at the centre of concerns for sustainable development and are entitled to a healthy and productive life in harmony with nature. This principle affirms that considerations of human well-being should guide policymaking for sustainable development and that conservation of natural entities must be reckoned as part of such well-being. This paper suggests an equity approach for all candidate ethical principles to be subject to identical tests of invalidation, either by means of the present methodology or some other agreed methodology. Those that survive may then form the bases of climate change policymaking. The point of this paper is to start a debate.