The widespread adoption of cleaner-burning technologies and declines in fire activity over the past two decades has drawn down global levels of the pollutant.
For more than two decades, NASA’s Terra satellite has measured atmospheric concentrations of carbon monoxide (CO). The good news is that average levels of the toxic air pollutant have dropped by about 15 percent since 2000. However, the rate of decline has slowed, falling from about 1 percent per year in the earlier part of the record to about 0.5 percent per year in the later years.
“We’ve seen carbon monoxide levels drop because cleaner-burning technologies are much more common now in the United States, Western Europe, and Eastern China due to stricter air quality standards,” explained Rebecca Buchholz, an atmospheric scientist at the U.S. National Center for Atmospheric Research (NCAR). “We’ve also seen a reduction in fires and burned area in the tropics.” The research findings were published in Remote Sensing of the Environment.
Deciphering the reasons for declining carbon monoxide levels was complicated for Buchholz and colleagues because there are several sources of the pollutant. The burning of carbon-based fuel of any type—including coal, gasoline, oil, natural gas, and wood—can emit CO. As a result, many common technologies (combustion engines, blast furnaces, and fireplaces) are all potential sources of it. Outdoor fires—both wildfires and agricultural fires—are also major sources of the pollutant. Finally, there are natural sources, such as emissions from certain plants that react with the atmosphere to produce the gas. Volcanoes and decomposing organic matter in rivers and oceans are also minor sources.
Continue reading at NASA Earth Observatory
Image via NASA Earth Observatory
