Delhi's Toxic Air: The Green Revolution Connection
The green revolution led to stubble burning practises, which are a small but important source of the hazardous pollution.
It is that time of the year again when the air pollution in Delhi – and large parts of north India, Pakistan and Nepal – reaches hazardous levels, severely impacting the health of millions of people across the region.
It is also the time when we witness the failure of the media to cover the issue, evidenced by headlines such as this one.
What this headline is trying to say is that Delhi’s air quality index (AQI) went from being between 401 and 500, characterised as “severe”, to being between 301 and 400, characterised as “very poor” by the Central Pollution Control Board (CPCB) of India.
There are considerable issues with how AQI is calculated in India. An AQI of 100 in India means a higher concentration of pollutants than the World Health Organisation’s (WHO) guidelines.
The AQI scale is capped at 500, so even if the AQI is actually 1,000, it will still be shown as 500. There are other non CPCP scales that show higher numbers, such as this one below.
Then, the categories themselves – “poor”, “very poor”, “severe”, etc – have also been Indianised. An AQI of 200 in most countries would mean unhealthy levels of air pollution, but in India it means “moderate”.
Be that as it may. That is not what I promised to tell you in the headline.
What I did promise to tell you was how the Green Revolution contributes to the problem. It contributes through what is described as stubble burning or crop residue burning.
I will break that down, but first it's important to understand that crop burning is not the only or the most significant source of the problem in the subcontinent during winter. The biggest source of air pollution is, by far, pollution from vehicles.
But, crop residue burning also plays an important role and can contribute upto 35% of Delhi’s air pollution during peak burning season, as Siddharth Singh has detailed in his book The Great Smog of India.
The paddy (rice) crop in north India and Pakistan is harvested in early winter using combine harvesters. That leaves behind about a foot of stubble (parali in hindi) on the ground. That stubble has to be cleared in time for the next wheat crop to be sowed. The fastest and cheapest way to clear it is to burn it. That is what many farmers do and that burning contributes to making the air pollution in the subcontinent worse.
What does this have to do with the Green Revolution? Before the green revolution, crop residue burning was not a common practise, primarily because not a lot of rice was grown in north India and Pakistan.
The Green Revolution of the 1960s brought in high-yielding varieties of first wheat and then rice to increase production of both the staples, with the aim of addressing the massive problem of food deficit that the regions faced at the time.
But, as this newsletter has said before, that had unintended consequences and the contribution to air pollution is one of them.
The Green Revolution regions grew a great variety of crops, particularly in the kharif, or the autumn harvest season (The word kharif originates from Arabic, where it translates to "autumn.").
India’s Punjab, for example, grew a whole range of crops like maize, cotton, groundnut, pulses. It wasn’t only wheat and rice like today. In fact, in 1966, just before the Green Revolution obtained wings, wheat and rice combined accounted for 45% of the area under cultivation in Punjab, and wheat was 85% of that.
Now, wheat and rice are grown on more than 90% of the grown area, with rice almost as prominent as wheat. That is the rice-wheat monocropping system that the green revolution has led to in north-western India and parts of Pakistan.
Rice is now grown in summer to coincide with the monsoon, as the crop needs enormous amounts of water. And wheat is grown in the drier winter season, following the rice harvest, requiring the field to be cleared.
And this is where crop reside burning comes in because it’s not as if rice can be sown at any time during the monsoon or wheat at any time during the winter. There are specific windows.
For rice, the government sets a timeline in the north-western states of Punjab, Haryana and parts of Uttar Pradesh before which the crop cannot be grown. They do this to ensure that the sowing coincides as much as possible with the onset of the monsoon, because otherwise all of the crop’s intensive water needs would have to be fulfilled with water extracted from the ground.
Groundwater depletion in these regions is also a major problem, and an unintended consequence of the green revolution – something I have written about here.
So, usually, the government mandates that rice cannot be grown before the first or second week of June. That is where things get tricky because the rice crop can take upto 160 days to be ready for harvest.
That then sets the clock ticking because wheat has to be sown starting mid-October but latest by mid-November. Beyond that, farmers face the prospect of yield loss due to lower temperatures.
So, the turnaround window between the rice harvest and wheat sowing becomes precariously short. That is why crop residue burning remains the cheapest and the fastest way of getting rid of the residue from the fields.
There are newer crop residue management tools like the happy seeder, for example, which drills the wheat into the field without the need to clear the left over stubble. But, these have had varying degrees of success and are expensive.
The turnaround window is getting even shorter due to climate change because the monsoon has started getting delayed. That means that rice sowing gets delayed.
Monsoon withdrawal is also getting pushed further into what used to be autumn, which means that rice harvest also gets delayed. This has happened this year, as this report from the Indian Express shows.
What does this mean for Delhi and the Indo Gangetic plain’s early winter air pollution?
It means that crop diversification in north India and Pakistan away from rice, in particular, will improve Delhi’s air quality, but by a very small margin.
The chief contributor to the pollution is vehicular emission, which is, of course, a much more difficult problem to solve. On crop burning, there has been some progress in the last few years, but there has been no progress in curbing vehicular emissions. In fact, the trend is in the opposite direction with the heavy polluting SUVs now forming 50% of the India’s car market, up from 25% just 5 years ago.
So, all in all, this is not a rosy picture because there is no rosy picture to paint. Some have left Delhi to escape the pollution, but that is not a choice that everyone can afford to make.
Also, leaving Delhi is easier said than done, as the poet Ibrahim Zauq (the great Mirza Ghalib’s most significant rival) said 2 centuries ago.
इन दिनों गरचे दकन में है बड़ी क़द्र-ए-सुख़न
कौन जाए 'ज़ौक़' पर दिल्ली की गलियाँ छोड़ कर
in dinon garche dakan mein hai badi qadr-e-sukhan
kaun jaye 'zauq' par dilli ki galiyan chhod kar
Translation
We hear that poetry is greatly valued in Deccan these days,
But, Zauq, who can bear to leave behind the alleyways of Delhi