Indonesia scales cloud seeding against a fire season it cannot yet count

Indonesia is putting dozens of helicopters and fixed-wing aircraft on standby to seed clouds over burning Borneo, a technique that is rarely used against wildfires anywhere in the world ^[1][2]. The scale-up is arriving before either the method's effectiveness or the size of the fire season has been pinned down: the government reports more than 100,000 hectares burned in the first half of the year, while the deforestation monitoring site Nusantara Atlas puts the figure through July at more than 285,000 hectares ^[3][4].

The two counts do not cover identical periods, so the gap is not a clean discrepancy. It is still large. Nusantara Atlas is reporting roughly 2.9 times the government's number, a difference of about 185,000 hectares, an area Agence France-Presse notes is more than four times the size of Jakarta ^[5][6][4]. For anyone judging whether an intervention works, that is the denominator problem in plain sight. Hotspot suppression claims are measured against a baseline that two credible counters cannot agree on.

The operational tempo is real. The BMKG weather agency says Indonesia carried out 252 cloud-seeding operations between 2021 and August this year, against 85 in the preceding decade, roughly three times as many sorties in a shorter window ^[7][8]. Most of those flights were not about fire: they aimed to pull rain away from flooded areas, though many targeted wildfires or the wetting of flammable peatland ^[9]. The technique itself is not new in the country, having first been used in 1977 to fill a dam ^[10].

The physical constraint is acknowledged by the people flying the missions. "Weather modification does not create clouds: we optimize clouds that have the potential to produce rain," meteorologist Safillah Anggie Wahyuni told AFP after a flight over Palangkaraya in Central Kalimantan, adding that it works "only if the conditions are right" ^[11][12]. That is a problem in the dry season, when fires peak. I Putu Santikayasa, a hydroclimatology lecturer at IPB University, told AFP effectiveness "will be very low because of the lack of clouds" ^[13].

The supporting evidence is thin and comes from inside the program. Research authored by BMKG weather modification director Budi Harsoyo found a 12-day operation in 2023 doubled likely rainfall and eliminated fire hotspots ^[14]. Harsoyo also calls cloud seeding "a mitigation effort, not a permanent solution" and says there is no evidence of harm from it ^[15]. Independent research, according to AFP's summary, suggests cloud seeding efficacy is hard to assess at all, with open questions about the cost and about widespread silver iodide use ^[16][17].

Meanwhile the actual suppression work is manual: nearly 50,000 firefighters are currently deployed ^[18]. Peat fires smolder underground and reignite, which is why wetting is the strategy at all ^[19]. WALHI campaign coordinator Uli Arta Siagian argues the state's job is upstream, "by not issuing permits in areas that are vulnerable to fire" ^[20]. Large plantations are barred from burning to clear land; smallholders are exempt, and the practice is blamed for most of the country's fires ^[21].

Watch whether the government's burned-area figure converges with Nusantara Atlas as the season closes, whether BMKG publishes outcomes per sortie rather than per campaign, and whether the environment minister's threatened fines and criminal penalties for illegal burning produce cases ^[22]. Haze has already spiked pollution in Malaysian Borneo and closed schools ^[23].