Reflecting on time and its nature has a long tradition e.g. in philosophy, economies andsocial science. In contrast to that, environmental science did not focus on time up to now.The importance of time is known sufficiently by many ecologists. Time is of big importancefor mankind and its relation to itself and its association with nature, the world around. To manand environment time is like water to the fish: always present, absolutely necessary, butrarely noticed in its meaning, because time is such an important part of our lives that it israrely thought about. Therefore it is outlined how the inclusion of time is possible and wouldlead to new insights in environmental science. The meaning of "balanced" or "sound"ecosystems or consequences of our acting like the depletion of the ozone layer, thegreenhouse effect or floods are concerned. Reflecting on time is basically for ourunderstanding of environmental science, its tools and our environmental and political acting.The consideration of time in environmental science among others means to think of and toact in accordance with time scales and the rhythms of man and nature