Weather just isn’t what it used to be. Calcutta winters aren’t as sharp; Kashmir’s snowfall not as regular; Delhi’s monsoon not as much of a relief as it once was. Some of all that is true; there are hard numbers for confirmation. And here’s something else that is true: we care less about the weather. And: we might well be responsible, and not because of greenhouse gases, either.

Delhi, for example, is supposed to be semi-desert, with “dry scrub” — as the survey of India maps used to put it — as vegetation, and life clustered around the life-giving river. Drive through Delhi today. Or take a lift to the top floor of one of the few buildings that pierce the city centre’s canopy of trees — one of the hotels, perhaps — and look around. You don’t see semi-desert. You see green. Humans, seeking refuge from the blazing sun, have changed what this city looks like. Further out, in the farms that you can’t see through the dust haze, pumps run for hours in the day, pushing water out for paddy. Humans, seeking refuge from the parched summer, have changed what cultivation looks like. And, invisible beyond the curved green horizon, far, far to the south, are the endless farms of the centre of India, farms that exist where once, not so long ago, there was uninterrupted jungle.

But what does this defence against the heat have to do with this apparently endless, pavement-melting, hair-curling, energy-sapping, quarrel-causing, teeth-clenchingly awful summer? The answer lies in how the monsoon works: as a front of humid air moving up in response to the build-up of dry, hot air over the northern plains. As we planted trees and irrigated our plains, we reduced how dry that air was; the increased humidity meant the pressure on humid air from the south-east to move north-west wasn’t as strong. And, as we cut down our forests, we reduced the amount of humidity that air would pick up on the way. So we have a weak monsoon that doesn’t rush in arriving — and coolers that don’t work like they used to because the entire north-west is more humid than it used to be. Unsurprisingly, if ironically, it’s the north-west, the home of the green revolution, that has gone thirstiest in recent bad monsoons; it looks like it will be the same this time. At around 80 per cent of normal, the irrigation miracle itself might be in danger if the groundwater isn’t replenished, and if low water levels in the big dams endanger power production.

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