Many thanks to The Post and Courier for keeping the focus on climate change. The editorial “Welcome climate focus on soot” identifies the really promising opportunities to slow the rate of climate change by controlling short-lived climate-forcing agents such as soot and methane (natural gas). These pollutants come from myriad and diverse sources throughout the world, requiring many different local solutions.

Soot, or black carbon, contributes significantly to global warming. The main sources of soot are burning of forests and grasslands; use of solid fuels (charcoal, coal, wood, dung) for cooking and heating in the developing nations; and diesel engine emissions.

The U.S. has reduced total soot emissions by 60 percent since 1990 by regulation of diesel engine emissions, and the rest of the world is following rapidly, as much to improve air quality and public health as to address climate change. Soot emissions that affect arctic climate come largely from use of solid fuels in Eurasia.

Two of the largest sources of methane are cattle and rice cultivation, which are difficult sources to control. Global methane emissions can be reduced by about 30 percent at an affordable cost by controlling emissions at coal mines, landfills, and from the oil and gas industries.

Soot remains in the atmosphere for weeks, and methane for about 12 years, so reducing these emissions will provide rapid benefit in reducing the rate of global warming.

Carbon dioxide, largely from fossil fuel combustion, remains in the atmosphere for over 1,000 years. As a result, the atmospheric concentration is always increasing — from 290 parts per million in 19th century to 400 ppm this year. At 450 ppm, rapid climate destabilization is likely, and 450 is coming fast. Because carbon dioxide accumulates, it poses the biggest threat to our climate.

Slowing the build-up of carbon dioxide is even more urgent than reducing soot and methane emissions, even if the benefits are not as immediate.

A tax on the carbon content of fuels will encourage substituting natural gas for coal, more efficient use of energy, and renewable energy development.

Mark Gould

Ashley Avenue