The change he talked about was the change in the environment as a result of the human actions which are adversely affecting the environment.
Step-by-step explanation:
Bill McKibben talked about the adverse effects on the environment as a result of the human actions. One of the changes he talks about is air pollution because of the burning of the fossil fuels for the own use of the humans as a source of energy.
Because of these actions of the human, the quality of air has been deteriorated a lot and has reached the hazardous level which is not even safe for the humans to inhale. In some cities, it has been recommended to use oxygen masks throughout by the humans. This makes sure that the prediction made by him about the human survival endangered is seeming to be possible in sometime in the future. Because the air quality is not nice, water has been polluted, land has been damaged, making the survival of humans tough and not safe.