Human beings perceive environmental change mainly as change in the state (qualitative character or structure) or condition (quantitative composition or amount) of nearby communities of living organisms, or of the weather. For example, a change of state for living communities might be gains or losses in the diversity of plants or animals represented; a change in condition might be an increase or decrease in the numbers of plants and animals. For the weather, a switch fromwinter rains to predominantly summer rains in mid-latitudes would constitute a change in state, whereas a marked decrease in precipitation over a month or more would be a change in condition. We notice such changes, because they violate our expectations that things vary little from year to year. Our experience and observations of the environment are at the local scale and are mediated by language and opportunity, so that each of us has a slightly different idea of things. Because of thewaysweperceive environmental change, our “commonsense” leads us to seek the causes of change wherewe perceive it – among living communities and in the weather systems. Recent research in geophysics and climatology has demonstrated that this approach is oversimplified and misleading.