Ethically Relevant Facts
To study the ethics of climate change, we need to understand how climate change will affect people around the world, now and in the future. That understanding requires knowledge of scientific predictions about the effects of greenhouse gases in various regions of the world and over time, of how people will be affected by these changes, and the extent to which they will adapt. For example, scientific predictions may tell us that a certain region is expected to suffer from a decline in rainfall over the next one hundred years. We need to understand how this change might affect activities in the region, such as agriculture, and the extent to which the people living there will be able to find other sources of food.
It is an understatement to say that there is a vast literature on these issues.1 Our goal here is to distill this literature into its basic elements so that we have a set of facts and predictions to use in thinking about our ethical obligations with respect to climate change. We rely heavily on the Intergovernmental Panel on Climate Change (the IPCC), the Nobel Prize-winning international agency that was set up to report the scientific consensus on climate-related issues in periodic reports.2 While there is agreement that climate change is occurring and that it is caused by humans, it is extremely difficult to predict the impact of carbon emissions on people living one hundred or two hundred years in the future. Predictions combine substantial uncertainty on the science of climate change with guesses of how society will evolve over the next several hundred years. Imagine someone living in 1909 or 1809 predicting what life would be like today. We will