ABSTRACT: Environmental politics, especially regarding sustainable use of the planet, must be based on a shared set of ethical values. Although there is a fundamental conflict between ecological doctrine and human cultures, naturalistic assemblages of plants and animals can co-exist with human society in a mutualistic relationship. Numerous environmental practices of human society have ethical implications and are serious obstacles to the quest for sustainability. Continuing them will probably result in crossing one or more important ecological thresholds, which may result in new ecological conditions less favorable to human society than those that presently exist. Some of the probable conditions (e.g., global climate change) could be characterized as paradigm-shifting catastrophes. Motivational ethics may triumph initially, but consequential ethics may eventually emerge in environmental politics, which would then produce some interesting conditions in a sustainability context. Since humans have only one planet on which to experiment, speculation about possible future scenarios seems prudent, as does precautionary action to avoid undesirable outcomes.