The 1997 group of forest fires in Indonesia that lasted well into 1998 were probably among the two or three, if not the largest forest fires group in the last two centuries of recorded history.
In the middle of 1997 forest fires burning in Indonesia began to affect neighbouring countries, spreading thick clouds of smoke and haze to Malaysia and Singapore. Then Malaysian Prime Minister Mahathir bin Mohamad searched desperately for a solution, and based on a plan by the head of the Malaysian fire and rescue department sent a team of Malaysian firefighters across to Indonesia under code name Operation Haze. This is to mitigate the effect of the Haze to Malaysia economy. The value of the Haze damage to Malaysian GDP is estimated to be 0.30 per cent. Seasonal rains in early December brought a brief respite but soon after the dry conditions and fires returned. By 1998 Brunei and to a lesser extent Thailand, Vietnam and the Philippines had also felt the haze from the smoke of the forest fires. By the time the 1997-98 forest fires were finally over some 8 million hectares of land had burned while countless millions of people suffered from air pollution.
The 1997 Indonesian forest fires were caused mainly by slash and burn techniques adopted by farmers in Indonesia. Slash and burn has been extensively used for many years as the cheapest and easiest means to clear the lands for traditional agriculture. Fire is also used during the long fallow rotation of the so-called jungle rubber in Sumatra and Kalimantan to remove most of the biomass, including the woody parts before new plantations are re-established.
Fire may also be deliberately used as a weapon to claim property on the islands and provinces where land ownership is not clear, an action taken by both smallholders and large operators alike. After burning out its previous owner, the smallholder or large operator plants their own crops there, gaining de facto control over the disputed land.
During the fire season, dry fuels readily ignite and lead to large wild fires. In cases like this, fire suppression can be very difficult and costly especially when they reach the highly flammable peat-swamp areas. NASA has linked El Niño to then that causes drier conditions in much of Indonesia. Historically its arrival has been welcomed as time of bounty when mass fruiting of Dipterocarp trees spawn a boom in wildlife activity and bring prosperity to indigenous seed collectors. However, in recent years, large-scale land use change in Indonesia, especially on the islands of Borneo and Sumatra, mean that El Niño is increasingly associated with massive forests fires that spread a choking haze and economic concerns across Southeast Asia.