Peat fires in Indonesia are threatening rare wildlife such as orangutans and causing severe air pollution and carbon emissions, environmentalists have warned.
Drone footage filmed by Greenpeace shows smoke from numerous fires where peat soils and forests are burning, which the environmental group says is the result of decades of illegal logging and deforestation for palm oil and paper pulp plantations.
Waterlogged peat soils under rainforest rarely burn but if forests are cleared and the land drained for plantations they can dry out, becoming a tinderbox which, if it catches fire, can smoulder below the surface where it is hard to put out, Greenpeace said.
Fires are burning around the edge of Gunung Palung National Park in Borneo, which is home to the world's largest surviving population of orangutans.
Other fires were widespread across Tesso Nilo National Park in Riau, Sumatra, an area of vital tiger habitat, in July and August, and have been reported around Tanjung Puting National Park, central Kalimantan, also home to orangutans and other wildlife.
The environmental group also warned that the burning peat and forests causes air pollution, with such fires causing an estimated 110,000 deaths each year across South East Asia.
The landscape has also become a "carbon bomb" which could release huge amounts of carbon dioxide emissions that drive climate change.
This year's fire season coincides with a strong El Nino, a weather phenomenon in the Pacific, which causes drought in Indonesia that worsens the situation, Greenpeace said.
The El Nino is expected to be the strongest since 1997, when experts estimated that carbon dioxide equivalent to between 13% and 40% of the global average emissions from fossil fuels was spewed into the atmosphere.
The fires that year helped cause the largest annual increase in the levels of carbon dioxide in the atmosphere since records began.
Ahead of crucial United Nations climate talks in Paris, Greenpeace is calling for efforts to restore the rainforests and protect the peatland, starting with blocking drainage channels to re-wet the peat and reduce fire risk, to preserve wildlife and prevent carbon emissions.
Greenpeace's Indonesian forest project leader Bustar Maitar said: "As governments prepare to meet in Paris to save the world for catastrophic warming, the earth in Indonesia is already on fire.
"Companies destroying forests and draining peatland have made Indonesia's landscape into a huge carbon bomb, and the drought has given it a thousand fuses.
"The Indonesian government can no longer turn a blind eye to this destruction when half of Asia is living with the consequences," he added.
He also called on pulp and palm oil companies to work together to break the link between producing their products and destruction of the forests.