Bruce E. Dale in the WSJ

A basic fact about agricultural products such as grains and oilseeds is that the carbon in them, called biogenic carbon, came from the atmosphere. Biogenic carbon will return to the atmosphere when these products are consumed, such as when human beings eat bread and then breathe out the carbon dioxide resulting from the breakdown of bread in the body. Biogenic carbon therefore cannot contribute to climate change.

Why is the Environmental Protection Agency denying this basic fact of climate science? The EPA is counting biogenic-carbon emissions as if they were the same as fossil-carbon emissions. They are not the same. Carbon atoms emitted by burning fossil fuels are, in effect, on a one-way trip from the ground to the atmosphere, where they will stay for hundreds of millions of years. In contrast, carbon atoms taken from the atmosphere to make agricultural products are on a round trip from the atmosphere to farms then back to the atmosphere.

The EPA intends to penalize American farmers and those who make modern energy and bioproducts such as plastics from agricultural feedstocks by treating biogenic carbon like fossil carbon. As part of its approach, the EPA is now attempting to regulate “sustainability” in the farm field.

The agency’s new Clean Power Plan proposes to penalize biogenic carbon emissions unless food processors (bakeries, brewers, grain processors) or energy producers (like utilities using seed hulls to produce electricity) can prove that they used “sustainably-derived” agricultural feedstocks. The definition of “sustainably-derived” and the proposed penalties go on for many pages in the proposed regulations. They defy easy summary. But the proposed regulation on biogenic carbon is simply and clearly an unjustified carbon tax on American farmers.

The EPA is trying to put itself in charge of regulating farms—an outstanding example of “mission creep” and bureaucratic overreach. Regulating agriculture is not the EPA’s job—we already have an Agriculture Department. The EPA’s approach would demand proof of exactly which farm produced every pound of corn, wheat, soy or cottonseed used by customers of those farms—a practical impossibility in the U.S. agricultural system.

There is a growing world-wide effort to establish the “bioeconomy,” an economy based on use of renewable raw materials to make the products that humans need, and to reduce and eventually eliminate dependence on fossil carbon. The aim is essential—the world will eventually run out of fossil carbon. Yet sound policy must be informed by sound science. The EPA’s treatment of biogenic carbon and fossil carbon as if they were identical is wrong at the most basic scientific level. America’s farmers and the consumers of what they produce would be collateral damage of the EPA’s misguided plans.

Mr. Dale, a professor of chemical engineering and materials science at Michigan State University, is a fellow of the American Institute of Chemical Engineers and of the American Institute of Medical and Biological Engineers