In the savannas of Australia’s Northern Territory, the wet season draws to a close around April. In the early months of the dry season, while conditions are still relatively cool, and the vegetation is still moist from the recent rains, land managers set strategic fires in a patchwork of landscapes to prevent larger, more devastating fires later in the dry season. This image of the Northern Territory on June 10, 2007, was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. Places where MODIS detected active fires, probably planned strategic burns, are marked in red. Southeasterly winds are pushing the smoke out toward the Timor Sea.
Traditional Aboriginal landholders (Arnhem Land is an Aboriginal land holding) have been strategically using fire in this way for thousands of years, but in the century following European settlement of Australia, settlement and land ownership patterns have dramatically changed. A decline in strategic, early-season burning across much of the area has lead to an increase in huge, intense, late dry-season fires.
This shift in the regional fire patterns has important implications not only for the ecosystem's ability to recover from fire, but also for greenhouse gas emissions. When fires occur early in the season, when the vegetation is still moist, they are less intense and they produce fewer greenhouse gas emissions. The carbon dioxide released by the burning grass and smaller shrubs is roughly in balance with the amount taken in when vegetation re-grows in the burned area during the following wet season.
However, the same cannot be said for the larger, more intense fires of the late dry season; these fires consume not only grasses and leaves, but also trees. Too frequent, intense burns do not allow the ecosystem to recover an equal amount of carbon in the next growing season. The carbon dioxide equilibrium between burning and re-growth is tipped in favor of emissions. Over time, late dry-season fires have become a major source of greenhouse gas emissions in the Northern Territory.
Awareness of these ecological and atmospheric connections is at the heart of a partnership between energy producers, territory government, and Aboriginal land holders in the area. Through the partnership, a re-establishment of strategic early-season burning across larger areas of Arnhem Land will reduce greenhouse gas emissions from late-season fires, offsetting some of the greenhouse gas emissions produced by the operation of a liquefied natural gas plant in Darwin. To read more about fire in the tropical savannas of Northern Territory, please visit the Website of the Tropical Savannas Cooperative Research Centre.
The large image provided above has a spatial resolution (level of detail) of 250 meters per pixel. The MODIS Rapid Response Team provides twice-daily images of the region in additional resolutions.
NASA image courtesy the MODIS Rapid Response Team, Goddard Space Flight Center
- Aqua - MODIS