Climate crisis: Wet-bulb heat is a threat we cannot afford to ignore

livemint.com:

maximum temperature of 52.9° Celsius. This is the highest ever—not just for the capital, but for all of India. As anything above 50° is rare even during intense heat waves, the reading left observers agape.

And since it was an outlier among other mercury readings across Delhi, a central minister said that the weather department has been asked to check if the thermometer was okay. Whether or not it has its notches correct, the scorching heat this year makes anything around the 50° mark seem believable. The oven-like conditions that have gripped large parts of our landmass are all too real, with people groaning that this summer is the hottest they have ever experienced.

The tragic irony of such groans is that unlike a ‘once in a century’ event like the covid pandemic, it’s likely that the same attestation of misery will be made year after year as we go along. After all, the blazing sun is only the most visible cause. Air pollution that traps heat on the planet has put us on a path whose perils are only just starting to show.

An analysis of data from India Meteorological Department by the Centre for Science and Environment (CSE) reveals that it’s not just regular heat, the hot season has gradually become more muggy too. In Delhi, the average relative humidity in summer months was 52.5% in the first decade of the millennium, but recent years have seen it go above 60%, pushing us into a sweltering zone. Perspiration cools our bodies down as sweat evaporates, but if the ambient air is too humid—with high moisture, i.e.—then we take longer to dry and this cooling effect weakens.