Before the Industrial Revolution we felt powerless in the face of nature. Actually some of our worst human environmental disasters had already happened: the destruction of the megafauna outside Africa; deforestation of Britain and many other places. With fossil fuels the potential for destruction became so great that we invented the National Park. With nuclear power we need to aim even higher: the restoration of most of the Earth to its natural condition (plus intervention to compensate for the lack of megafauna). Let's let the rivers flood as they are meant to, and the oceans and rivers be free of industrial fishing. Let's use our biological skills to get rid of introduced species in many places.
Of course it is a bit premature to worry about a world with too much energy.