coal

Efforts to limit climate change generally focus on reducing carbon dioxide emissions caused by burning fossil fuels. However, another byproduct of fossil fuel combustion is black carbon, a major component of soot. Sources include diesel truck and car engines as well as wood fires, kilns, and stoves. Particles of black carbon in the atmosphere absorb sunlight and can have significant effects on the temperature, as do ozone, methane and other chemicals.

According to a 2012 report from the Congressional Research Service, “U.S. Energy: Overview and Key Statistics,” energy consumption in the U.S. nearly tripled from 1950 to 2011. Over the same period, however, electricity consumption grew even faster, rising from 334 billion to 4,120 billion kilowatt hours — an increase of 1,134%.

Energy plays a central role in the U.S. economy, from transportation and manufacturing to agriculture, housing and beyond. The mix of power sources and uses are in constant flux, however, as indicated by a 2012 report from the Congressional Research Service, “U.S. Energy: Overview and Key Statistics.”