In my environmental chemistry classes, I ask my students to think about the methane emissions of livestock such as cattle and sheep (C&EN, June 17, page 31). Then I ask them to think about the enormous herds of bison and musk oxen before we figured out how to obliterate them. I wonder what the mass balance comparison would be like if one were to calculate the methane emissions of all ruminants before, for example, 1000 B.C. and the present day. Let’s look to reducing methane emissions from oil rigs, hydraulic fracturing, and sources of carbon dioxide emissions by adding new solar energy capacity.
On a molecule-to-molecule comparison with CO2, methane may have close to 25 times the impact on emitted infrared radiation trapping. Using fruit products to reduce methane emissions from ruminants may work, but will it lead to diversion of human food supplies the way corn for ethanol has?
J. William (Bill) Louda
Boca Raton, Fla.