"1997 will be remembered as the year the world caught fire," said Jean- Paul Jeanrenaud, head of the World Wide Fund for Nature (WWF) International's forest programme.
In Indonesia and Brazil alone, more than 5 million hectares of species- rich woodland habitat have been consumed by fire - an area about as large as Switzerland, says a report from the organisation. But there have been serious fires on every continent apart from Antarctica, with the latest striking the east coast of Australia at the beginning of this month.
Many of these fires are started deliberately, and often illegally, to clear land for agriculture and plantations. In some countries they have become massive and uncontrollable because of drought attributed to this year's El Nino, a global weather event which occurs every few years and this time appears extreme.
The fires have caused air pollution levels much higher and more dangerous than those for which traffic, industry and power stations are responsible. They are also adding significantly to the emissions of global-warming carbon dioxide gas which come from burning fossil fuels.
"We are creating a vicious cycle of destruction, where increased fires are both a result of changes in weather and a contributory factor to these changes," said Mr Jeanrenaud.
WWF says the fires in Indonesia may have set light to thick peat deposits which could smoulder underground for years and start new surface fires during the next dry season.
Hundreds of infant orang-utan in Indonesia have been found in the hands of villagers, available for the pet trade. It is believed their mothers fled from the burning forests with their babies and were then killed by local people. Meanwhile, the government has reinstated 45 or the 146 timber exploitation permits it revoked in the wake of the catastrophic forest fires this year.
The WWF report says that in the Amazon jungles of Brazil says there has been a 50 per cent increase in the number of fires in this year's burning season, which begins in August, compared with that of 1996.
The Brazilian government says the great bulk of these fires are taking place on cleared land or in secondary forest which had already been burnt. But WWF does not accept that the big increase is not destroying more virgin forest areas.
Other countries cited in the report as having had severe forest fires are Papua New Guinea, Colombia, Kenya, Tanzania and Rwanda.