A thermometer at a weather station in Delhi records the temperature every day. Over forty years, such records accumulate enough to reveal that all of India is slowly warming, while also gently "breathing": the temperature nudges up and down every few years.
Scientists took records from 1970 to 2009 at hundreds of locations nationwide. They computed the average temperature for each year and found that over forty years it warmed by 0.4 °C. That is modest but noticeable. On top of this slow rise lie rapid oscillations. Roughly every three to five years, temperature jumps or dips by the same 0.4 °C. These oscillations are consistent from north to south, so their cause is common to all of India.
It turns out that these oscillations are linked to cosmic rays, charged particles from deep space, and also to El Niño, but with a one-year lag: if an El Niño occurs in the Pacific, then a year later India's temperature shifts. Now it is clear that warming in India proceeds not smoothly but in waves, and this matters for those planning harvests and water reserves.
The standard deviation of daily temperatures over India increases with latitude: near the equator it is small, but above 20–25°N it rises sharply due to the contrast between winter and summer. This means that the "average temperature for the whole country" hides very different climatic realities.
In Kim Stanley Robinson's novel 'The Ministry for the Future', a heat wave in India becomes a turning point after which the world begins to seriously combat warming. This article provides the factual basis for such scenarios: not only a slow trend but also rapid oscillations that can amplify extreme episodes.