We welcome Earth Day on Sunday, a time to consider our obligation to the environment as the dominant race on the planet.

In Genesis, humans receive dominion over the fish of the sea, and presumably the sea in which the fish live; over the fowl of the air and the atmosphere in which the fowl live; and over every living thing that moves upon the Earth that humans must replenish.

We have the means to carry out this obligation. Our bodies, while not the strongest of all creatures, are by far the most flexible, and our brains are without peer. Earth Day is an appropriate time for Americans to consider their record as keepers of our nation’s lands and waters, a country blessed with bountiful natural resources.

This also is election season, and some candidates are suggesting that President Barack Obama’s worldview placed care of the Earth and natural resources above human needs. … Others in public life suggest that mere humans do not affect the large forces that control the Earth’s environment.

Long before humans appeared they note, the Earth’s temperature varied through the ages from tropical to very cold. Atmospheric greenhouse gases such as carbon dioxide were often at several times the levels of today without us. More recent temperature variations – such as the medieval warm period when the Vikings colonized Greenland, and the following Little Ice Age – occurred before the Industrial Revolution and substantial human greenhouse gas emissions.

Canadian scholar Vaclav Smil has quantified the difference through history of the energy used by the average human. Muscles aided by simple tools were the prime movers for all of human existence until the early modern era. The farmer working his field could maintain output at the equivalent of 70-80 watts. A big advance was the taming of large animals, and behind a pair of properly yoked draft horses he controlled at least 800 watts. Now, his great grandson operates tractors and combines with the power of 100,000 watts.

As William Catton put it in his pioneering work, “Overshoot,” we are no longer mere homo sapiens, with little impact on the Earth’s environment. We are now homo colossus, each of us having the energy impact of the hundreds of slaves once controlled only by lords and kings. …

Today, as we look east, we see Appalachian mountain forests, clear cut so our tractors can push mountain tops off into the valleys, retrieving small seams of coal while blocking miles of streams in the ruined valleys below. In the Midwest, our machines allowed us to plow vast dry area grasslands that once supported countless birds and buffalo. …

Before the Europeans, Minnesota was a natural resource treasure, with forests of virgin White Pine, and some of the world’s largest deposits of rich iron ore. … Now those forests are clear cut, their lumber exported to the world. Most of the iron ore also has gone everywhere, leaving behind empty pits.

All over the Earth, this drawing down of nature’s resources continues. … The vengeance for these acts of desecration will not be sudden, as in the great flood of biblical history. Instead, rivers will gradually silt up the dams, overtop and remove them, and resume their destined routes to the sea. Soils, impoverished and eroded from single cropping and excessive fertilizers, will no longer nourish our billions. A warming atmosphere, polluted by overuse of carbon fuels, will wreak its own havoc.

We need to protect our remaining soil and the waters that nourish it. There is still time, but not much time, to take seriously the responsibility for the Earth that dominion gives us.

This is the opinion of Rolf Westgard, a St. Paul resident who recently taught the class “Peak Oil or Peak Water” for the University of Minnesota Lifelong Learning program.