Kalimantan's fires: El Nino is the multiplier, the drained peat is the base rate

Start with the arithmetic the pixel totals hide. Add the five provincial VIIRS counts and you get 159,278 detections over 18 days ^[16], an average of about 8,850 a day ^[19], with West Kalimantan alone supplying 52% of them ^[17]. One VIIRS pixel at 375 metres a side covers 14.06 hectares, which is how those detections turn into the 2.24 million hectare figure ^[14]. The authors say plainly it is not burned area ^[8], and the size of that caveat deserves stating in local terms: 2.24 million hectares is close to half of all the peatland in Kalimantan ^[15]. Sensor choice moves the number as much as fire does. A MODIS pixel covers 100 hectares, about seven times a VIIRS pixel ^[20], which is why one day of MODIS detections converts to 520,600 hectares of observation area ^[6].

What the detections do locate is where the water stopped being held. Peat forms under waterlogged conditions and resists burning as long as the water table stays high ^[9]. Canals cut to clear peat for plantations removed that condition ^[1]. Soil holds moisture through its structure, organic matter, porosity and groundwater level, and once those are disturbed a short dry spell behaves like a long one ^[2]. According to the analysis, pulpwood and oil palm expansion is what cost Borneo that retention capacity, and the loss has been nearly irreversible for decades ^[3].

That reading is what makes the 2.7 figure from the npj Natural Hazards study a multiplier and not a cause ^[10]. A multiplier needs something to act on. The same study notes severe fires continue across all ENSO phases, La Nina included ^[10], so the quantity being amplified is not zero when the Pacific is neutral or cool. El Nino sets the year. Drainage sets the level.

The cost record points the same way. The World Bank put 2015 losses at US$16.1 billion, about 1.9% of Indonesian GDP ^[11], and 2019 at US$5.2 billion, about 0.5% ^[12]. In dollars, 2015 was 3.1 times 2019; as a share of the economy, 3.8 times ^[18]. Both bills were presented to the same degraded landscape, and the recurring pattern across 1997-98, 2015 and 2019 was drought arriving on ground already prepared for it ^[13]. The variable that swung between those two years was rainfall, which no ministry controls. The variable that persisted was the water table, and the canals that lowered it were dug on purpose ^[1].

That is the practical asymmetry in this data. Smoke is now choking residential areas and drifting across borders ^[4], and the near-real-time counts will fall when the rains come, because thermal anomalies track flame rather than the condition underneath it. Storage capacity in 4.5 million hectares of peat ^[9] will not recover on the same schedule.