NASA imaging of fires around the world over 12 years compiled by Andy Revkin
Here is where he got the images to stitch together - and an explanation of the imaging:
News reports portray wildfires as terrifying, accidental episodes in which people and animals flee as roiling flames consume houses and trees, and send massive plumes of thick smoke billowing into the sky. While wildfires can bring death and destruction, not all wildfires are bad and some can even be good for forest ecosystems. High-latitude forests regularly experience wildfires, triggered mostly by lightning strikes hitting the surface. Some coniferous trees are resistant to fire, and evolved to use the flames as a means for spreading their seeds. When seen from above, the high-latitude forests of Alaska, Canada, Northern Europe, and Asia look like a patchwork mosaic of areas in different stages of re-growth after a wildfire. Scientists have come to see wildfire as a natural part of the boreal ecosystem. Fire clears away dead and dying underbrush, which can help restore an ecosystem to good health. Thus, humans use fire as tool in what are sometimes called "prescribed burns." Humans also use fire in slash-and-burn agriculture to expedite the process of returning unwanted vegetation back to the soil. Humans also use fire to clear away old-growth forests and grasslands to make room for living spaces, roads, and fields for raising crops and cattle. Scientists estimate humans burn an average of 175 million acres of forest and grassland every year. So, by far, humans are leading cause of fire around the world. Some fires are not good. Because humanity's biomass burning is so widespread around the world, it significantly impacts Earth's carbon cycle. Not only does burning biomass release the carbon that was fixed in plants into the atmosphere (in the form of various gaseous and particle pollutants), but it also destroys plants and trees that would otherwise be removing carbon dioxide from the atmosphere during photosynthesis. Scientists need better measurements of how much area burns every year so they can better understand the roles fire plays in Earth's environment — how it changes the land surface, how it impacts life and the health of ecosystems, and how it changes the chemistry of the atmosphere. Using fire data collected globally every day by NASA's Terra and Aqua satellites, scientists produce maps like these to show the number and extent of fire around the world. The fire maps are helping scientists to better understand Earth's environment and climate system.
The red, orange, and yellow splotches on these maps show the locations where the MODIS instrument aboard NASA's Terra satellite detects actively burning fires. Don't be fooled by sizes of some of the bright splotches on these maps. The colors represent a count of the number of fires observed within a 1,000-square-kilometer area. White pixels show the high end of the count — as many as 100 fires in a 1,000-square-kilometer area per day. Yellow pixels show as many as 10 fires, orange shows as many as 5 fires, and red areas as few as 1 fire in a 1,000-square-kilometer area per day.