Ecology: The vertical lift of a severe thunderstorm or pyrocumulonimbus can be enhanced in the area of a large wildfire, which can propel smoke, soot, and other particulate matter as high as the lowerstratosphere. Previously, prevailing scientific theory held that most particles in the stratosphere came from volcanoes, but smoke and other wildfire emissions have been detected from the lower stratosphere. Pyrocumulus clouds can reach 6,100 meters (20,000 ft) over wildfires. Increased fire byproducts in the stratosphere can increase ozone concentration beyond safe levels. Satellite observation of smoke plumes from wildfires revealed that the plumes could be traced intact for distances exceeding 1,600 kilometers (1,000 mi). Computer-aided models such as CALPUFF may help predict the size and direction of wildfire-generated smoke plumes by using atmospheric dispersion modeling. Wildfires can affect climate and weather and have major impacts on atmospheric pollution. Wildfire emissionscontain fine particulate matter which can cause cardiovascular and respiratory problems. Forest fires in Indonesia in 1997 were estimated to have released between 0. 81 and 2. 57 gigatonnes (0. 89 and 2. 83 billion short tons) of CO2 into the atmosphere, which is between 13%-40% of the annual carbon dioxide emissions from burning fossil fuels. Atmospheric models suggest that these concentrations of sooty particles could increase absorption of incoming solar radiation during winter months by as much as 15%