Fire & Carbon Monoxide
On Earth, something is always burning: wildfires started by lightning or people, controlled agricultural fires, or fossil fuels. When anything made out of carbon — whether it's vegetation, gasoline, or coal — burns completely, the only end products are carbon dioxide and water vapor. But in most situations, burning is not complete, and fires or burning fossil fuels produce a mixture of gases, including carbon dioxide, methane, and carbon monoxide.
The fire maps show the locations of actively burning fires around the world on a monthly basis, based on observations from the MODIS sensors on NASA's Terra satellite. The colors are based on a count of the number (not size) of fires observed within a 1,000-square-kilometer area. White pixels show the high end of the count — as many as 30 fires in a 1,000-square-kilometer area per day. Orange pixels show as many as 10 fires, while red areas show as few as 1 fire per day.
The carbon monoxide maps show the monthly averages of carbon monoxide at an altitude of about 12,000 feet, based on data from the MOPITT sensor on NASA’s Terra satellite. Concentrations of carbon monoxide are expressed in parts per billion by volume (ppbv). A concentration of 1 ppbv means that for every billion molecules of gas in the measured volume, one of them is a carbon monoxide molecule. Yellow areas have little or no carbon monoxide, while progressively higher concentrations are shown in orange and red.
The comparison shows that fires and atmospheric carbon monoxide levels are very closely related for some regions and some times of year, but are less closely related in other places and times. For example, carbon monoxide concentrations across Africa and South America go hand in hand with fire counts there. When fire counts are high, carbon monoxide is high; when fire counts are low, carbon monoxide is low. These increases and decreases follow an obvious seasonal pattern, linked to human cultural patterns of agricultural burning and land clearing.
In other parts of the world, however, carbon monoxide levels are elevated even during months when fire counts are low. About half way up the eastern coast of Asia, for example, a pocket of high carbon monoxide appears virtually year round, even when fires are not occurring nearby. Here, the carbon monoxide is part of the urban and industrial pollution generated in and around rapidly industrializing Beijing, China. A similar pattern exists over the United States, the North Atlantic, and western Europe, which have relatively high (yellow) carbon monoxide concentrations even in December, January, and February, when fire activity throughout the middle and high latitudes of the Northern Hemisphere is very low. That pattern suggests that the carbon monoxide is coming from the burning of fossil fuels (and also perhaps from wood-burning stoves or fireplaces).