The ENSO phenomenon is associated ultimately with sea-surface temperature anomalies in the central and eastern Pacific Ocean and correlated atmospheric responses. It usually last 6-18 months and occur cyclically at intervals of from 2 to 10 years, averaging about once every 4 years.
These fluctuations have been linked to changes across the entire tropical Pacific, and indirectly to exceptional weather patterns throughout the atmosphere and oceans of the world. The 1982-83 ENSO was perhaps the strongest this century. In the Indo-Pacific region, severe droughts occurred in places as distant as Australia, the Philippines, South India and southern Africa.
Two or three times each decade, the dry season in Borneo is more severe and prolonged than normal. Large-scale droughts occurred in the years 1965, 1972, 1976, 1982-83, 1987, 1991, 1994 and 1997-98, with the last five being particularly severe and the final one the most intense in recorded history.
The fires of 1982-83
The ENSO phenomenon of 1982-83 resulted in one of the most extreme droughts this century in Sabah. At the height of the drought in February-April, rainfall was only 15 % of normal. Fires caused by man began in January and were most widespread throughout the state from March to May. One million or more hectares of forest were burnt, of which 85% was logged-over forest. Economic and ecological losses in natural forests were enormous, and extensive areas of plantation forests and agricultural crops also burnt.
According to Beaman et al (1985):
The total forested area burned was approximately 950,000 ha or 15 % of Sabah.
Logged-over forest is 6 times more likely to be burnt during a drought than primary forest.
Royalty losses to the state was estimated to be in the tens of millions of ringgit.
See map of the extent of the 1983 fires.
The fires of 1997/98
The total area burnt is not as severe as that of 1983. It was estimated to cover about 130,000 to 150,000 ha. However, if the fires of 1983 were widespread, 1997/98 saw the fires mainly occurring in southwest and the northern part of the state. In the southwest, fires occurred in the peat swamps of the Klias Peninsula (see also Binsuluk FR and Klias FR), in the Sabah Forest Industries Sdn Bhd concession area and in the areas east of Tenom and Keningau towns. Areas in the north included the Crocker Plains and the northern Crocker Foothills, parts of the Bandau Plains and large areas in the Sugut Delta
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