PARIS: One of the annoying things about global warming — besides the likelihood it will ravage life on Earth — is all the new words we are expected to learn in order to track our descent into climate chaos.

Rising temperatures have not only boosted the intensity or frequency of major storms and heatwaves, they have spawned rare or novel weather phenomena, accompanied by new more-or-less scientific names.

“Firenados”, for example, occur when searing heat and turbulent winds rise above out-of-control forest fires in tornado-like columns.

California and Australia have seen plenty of these vertical flame-throwers, and will likely see a lot more, scientists say.

So-called “dry thunderstorms” in drought-stricken regions such as the southwestern United States are a big tease, producing thunder and lightning, but no rain.

The air below these high-altitude light-shows is so parched that any moisture produced evaporates on the way down.

Then there are the fire-induced, smoke-infused “pyrocumulonimbus” clouds that darkened Australian skies during the Black Summer of 2019-2020; or “urban heat islands” in big cities everywhere that run a couple degrees Celsius hotter than surrounding areas.

But nothing is more terrifying, perhaps, than the potentially deadly combination of heat and relative humidity.

A healthy human adult in the shade with unlimited drinking water will die if so-called “wet-bulb” temperatures (TW) exceed 35C for six hours, scientists have calculated.

It was long assumed this theoretical threshold would never be crossed, but US researchers reported last year on two locations — one in Pakistan, another in the United Arab Emirates — where the 35C TW barrier was breached more than once, if only fleetingly.

An increase in algae blooms — sometimes known as “sea snot” — is one thing, at least, that can’t be blamed on climate change, according to a recent study.

A critical UN assessment of climate science currently under review by 196 nations, meanwhile, will highlight the rising threat of “tipping points” in Earth’s climate system, according to sources who have seen drafts of the report.

Anyone who has tried to balance in a chair leaning back on two legs knows there is a point-of-no-return beyond which things crash to the floor.

And so it is with kilometres-thick ice sheets atop Greenland and West Antarctica holding enough frozen water to lift oceans more than a dozen metres (40 feet).

Published in Dawn, July 29th , 2021