Carbon dioxide in the atmosphere is increasing. What is its concentration now?
Jamie Confrist, Chicago
Carbon dioxide is a heavy, colorless, odorless gas and it is the fourth most abundant constituent of dry air. By volume it occupies only about 0.04 percent of dry air. Though only a minor constituent of the atmosphere, its presence is meteorologically important because it strongly absorbs and emits long-wave infrared radiation that greatly influences the temperature of the atmosphere. Because of that property, it is one of the so-called “greenhouse” gases. It is released into the atmosphere as one of the by-products of combustion. In 1860 atmospheric carbon dioxide concentration was 288 parts per million (ppm), 332 ppm in 1980 and about 414 ppm now.