MODIS Witnesses Deforestation in Borneo: Agricultural fires rage

The skies over Indonesian Borneo is filled with the smoke from hundreds of fires set deliberately to clear indigenous forest areas for subsistence farmland and illegal logging. 

A shroud of thick, gray smoke hangs over the area when the Aqua satellite captured this image on Sept. 25, 2014. 

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua satellite detected dozens of fires (locations outlined in red) across the entire region from Central Borneo to South Borneo and even on East Laut Island. 

Credit: Jeff Schmaltz, MODIS Rapid Response Team.

The skies over Indonesian Borneo are filled with the smoke from hundreds of fires set deliberately to clear indigenous forest areas for subsistence farmland and illegal logging.

A shroud of thick, gray smoke hung over the area when the Aqua satellite captured this image on September 25, 2014.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the Aqua satellite detected dozens of fires (locations outlined in red) across the entire region from Central Borneo to South Borneo and even on East Laut Island.

Widespread burning in lowland forests on Borneo is an annual, man-made occurrence.

People use fires to manage and create agricultural lands, including large palm tree plantations that supply palm oil for biodiesel fuel; others are set accidentally during illegal exploitation and logging.

Lowland tropical forests are underlain by a swampy layer of peat that can be up to 20 meters (66 feet) thick.

During the rainy season, when the peat is waterlogged, leaves and other organic matter in the soil don't decay; when the peat dries out, it becomes flammable.

Burning peat generates huge amounts of smoke as is evident in this satellite image. These fires contribute significantly to annual greenhouse gas emissions.

In addition, the smoke released by any type of fire (forest, brush, crop, structure, tires, waste or wood burning) is a mixture of particles and chemicals produced by incomplete burning of carbon-containing materials.

All smoke contains carbon monoxide, carbon dioxide and particulate matter (PM or soot).

Smoke can contain many different chemicals, including aldehydes, acid gases, sulphur dioxide, nitrogen oxides, polycyclic aromatic hydrocarbons (PAHs), benzene, toluene, styrene, metals and dioxins.

Human's exposure to adverse air quality and smoke should be limited as it can cause severe respiratory ailments.

NASA MODIS: Agricultural fires across Sierra Leone

Credit: NASA image courtesy Jeff Schmaltz, MODIS Rapid Response Team.

Marked in red, hundreds of land use fires burn in the fields across Sierra Leone.

Most fires in this region are deliberately set for a variety of reasons, including slash and burn agriculture.

When a plot of land becomes exhausted, farmers shift cultivation to another plot where they cut the trees and brush at the beginning of the dry season in January and February.

Once the dead plant material has dried, they set fire to it. Such fires peak in March and April right before farming season begins.

From space, MODIS detects thermal anomalies, including fires, flares, and volcanoes.

Each MODIS "fire pixel" or fire detection covers one square kilometer, which means that one or more fire is burning in the corresponding one-square kilometer area on the ground.

There are hundreds of fire pixels evident in this image, so there are at least that many distinct fires burning in this scene.

MODIS tends to undercount fires because it can't detect fires through smoke or clouds, nor does it see small cool fires, a fire type common to land use fires.

Where there is fire, there is also smoke, affecting air quality. Smoke contains soot and other particulates that pose a threat to human health and affect regional climate. Burning also releases greenhouse gases.

This natural-colour satellite image was collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite on March 24, 2014.