If you had to pick the human influences most responsible for altering the earth, what would they be? Half a century ago, this question was (dispassionately) addressed in a landmark symposium called, "Man's Role in Changing the Face of the Earth." A 2005 retrospective review of the volume of interdiscplinary scholarship that emerged in 1956 notes that the syposium was "terrestrially oriented" and that
some omissions seem glaring from our perspective in the twenty-first century. Except for a chapter about ocean fisheries and coastlines, there is no discussion of the oceans. There is a section on the atmosphere, but the chapters mostly examine changes in rural and metropolitan climates. There is no sense that people are capable of altering the planet's climate as a whole.
In this month's issue of National Geographic magazine, Elizabeth Kolbert takes stock of the various dominant forces shaping the planet today (from agriculture to urbanization) and concludes:
Probably the most significant change, from a geologic perspective, is one that's invisible to us"”the change in the composition of the atmosphere. Carbon dioxide emissions are colorless, odorless, and in an immediate sense, harmless. But their warming effects could easily push global temperatures to levels that have not been seen for millions of years. Some plants and animals are already shifting their ranges toward the Poles, and those shifts will leave traces in the fossil record. Some species will not survive the warming at all. Meanwhile rising temperatures could eventually raise sea levels 20 feet or more. Long after our cars, cities, and factories have turned to dust, the consequences of burning billions of tons' worth of coal and oil are likely to be clearly discernible. As carbon dioxide warms the planet, it also seeps into the oceans and acidifies them.
Anybody want to speculate what kinds of National Geographic stories will be appearing in 2050?