NASA satellites have detected from space that the number of fires across tropical forests in South America, the Eurasian Steppe, and the savannas of Africa are increasingly declining due to settled lifestyle than previous nomadic lifestyle in the regions.
The transition is leading intensified agriculture and steep drop in the use of fire leading to decline of forest fires, said researchers from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The total acreage burned by fires declined annually by 24% from 1998 to 2015, said a research paper based on NASA satellite data and ground-based socioeconomic information. The beneficiaries are mainly the savannas and grasslands, which witnessed fires burning out half the size of the US every year, said Niels Andela, a research scientist at Goddard and lead author.
In traditional savanna cultures, people often set fires to keep grazing lands productive and free of shrubs. Since many of these communities have shifted to cultivate more permanent fields and to build more houses, roads and villages, the use of fire declines.eading organisaed governance that controls fires. By 2015, savanna fires in Africa had declined by 270,000 square miles (700,000 square km), almost equivalent to an area the size of Texas.
“When land use intensifies on savannas, fire is used less and less as a tool. As soon as people invest in houses, crops and livestock, they don’t want these fires close by anymore. The way of doing agriculture changes, the practices change, and fire slowly disappears from the grassland landscape,” said Andela.
Fires in the savanna, like this one in South Africa, burn quickly through grasses, and help prevent trees and larger shrubs from taking root. CREDIT: Guido van der Werf / Vrije Universiteit Amsterdam, the Netherlands
For their study, researchers used data derived from the Moderate Resolution Imaging Spectrometer (MODIS) instruments on NASA’s Terra and Aqua satellites, as well as other sources and compared it with trends in population, agriculture, livestock density and gross domestic product.
The scientists found a different pattern emerging in the rainforests close to the equator. Natural fires are rare in tropical forests, but as people settle an area they often burn to clear land for cropland and pastures. Once settled, they set fewer fires and the burned area declines.
The impact of a warming and drying climate is seen at higher latitudes in Canada and the American west, where fire has increased. Even in parts of China, India, Brazil and southern Africa, an increase in burned area is coming to light, said Doug Morton, a research scientist at Goddard and a co-author of the study.
“Climate change has increased fire risk in many regions, but satellite burned area data show that human activity has effectively counterbalanced that climate risk, especially across the global tropics,” Morton said.
The 24% decline in burned area may have contributed about 7% to the ability of global vegetation to absorb the increase in carbon dioxide emissions from burning fossil fuels and land use change.
