Thousands of fires (outlined in red) dot this image of the Atlantic coast of Africa. The timing and pattern of these fires indicate that these are set by humans. First, the fire season in this part of the globe begins in early November and ends in early April. Second, the individual fires are numerous and small, suggesting that they are of relatively low intensity. Fire is used for agriculture by clearing the land of its natural ground cover and crop reside from the previous growing season. Burning also enriches the soil, albeit temporarily. Satellite images are used to closely monitor the extent of fires for several important reasons. The burning of vegetation releases carbon dioxide, a greenhouse gas, into the atmosphere; accurate measurements of the amount of area affected by fires aids in accurate monitoring of climate change. Equatorial rainforests as well as mountain forests are generally protected from intentionally-set forests; images provide an early warning system to these places, as well as for population centers—protecting biological diversity as well as humans. Also, the smoke and accompanying gases and particles create a public health hazard; during an area’s burning season, the amounts of ground-level ozone and other air pollutants can become hazardous to human health.