The farm fires paradox
From The Times of India on November 18, 2024:
A curious claim by all means. The scientist, a Hiren Jethva at NASA Goddard, compared data from the Aqua, Suomi-NPP, and GEO-KOMPSAT 2A satellites and reported that the number of farm fires over North India and Pakistan had dropped whereas the aerosol optical depth — a proxy measure of the aerosol load in the atmosphere — has remained what it's been over the last half decade or so. He interpreted this to suggest farmers could be burning paddy stubble after the Aqua and Suomi-NPP satellites had completed their overpass. GEO-KOMPSAT 2A is in a geostationary orbit so there's no evading its gaze.
The idea that farmers across the many paddy-growing states in North India collectively decided to postpone their fires to keep them out of the satellites' sight seems preposterous. The The Times of India article has some experts towards the end saying this…
The farmers aren't particularly keen on burning the stubble — they're doing it because it's what's cheapest and quickest. It also matters that there is no surer path to national headlines than being one of the causes of air pollution in New Delhi, much more than dirtying the air in any other city in the country, and that both national and states' governments have thus far failed to institute sustainable alternatives to burning the stubble. Taken together, if any farmers are looking for better alternatives, more farm fires seem to be the best way to put pressure on governments to do better.
All this said, there may be a fallacy lurking in Jethva's decision to interpret the timing change solely with respect to the overpass times of the two US satellites and not with any other factor. It's amusing with a tinge of disappointment that the possibility of someone somewhere "educating" farmers to change their behaviour — and then them following suit en masse — was more within reach than the possibility of satellite data being flawed. If a fire burns in a farm and no satellite is around to see it, does it still produce smoke?
As The Hindu reported:
The data on fire counts are from a heat-sensing instrument on two American satellites — Suomi-NPP and NOAA-20 polar-orbiting satellites. Instruments on polar-orbiting satellites typically observe a wildfire at a given location a few times a day as they orbit the Earth, pole to pole. They pass over India from 1 p.m. to 2 p.m. …
Other researchers also suggest that merely relying on fire counts from the polar satellites may be inadequate and newer satellite data parameters, such as estimating the actual extent of fields burned, may be a more accurate indicator of the true measure of stubble burning.
