Within certain bounds. Climate scientists likely don't agree on the ideal CO2 PPM level, while agreeing that the current level is not it.

Anyone who wishes to claim pollution is always a subjective concept is welcome to drink a few gallons of water from Lake Karachay.

> Lake Karachay

From https://en.wikipedia.org/wiki/Lake_Karachay

> Today the lake is completely infilled, acting as "a near-surface permanent and dry nuclear waste storage facility."

Doesn’t really matter here, I’m talking about the pollution the article is referring to. I am simply discussing the concept of reaching a peak in pollution vs. a peak in emission of the same pollutants.

Putting the above aside though, I would disagree. Everything is subjective except math (and even there, I think there’s a debate), but I would definitely not classify pollution as _highly_ subjective, that makes it sound it belongs to the category of things that particularly lack consensus, which is definitely not the case amongst the scientific community. Not to say there’s 100% agreement on all things, but I think there’s a broad consensus.

It's really not, for most things. What exactly would you call an oil spill or leaded gas fumes if not pollution?

Certain substances are certainly clear cut.

But consider, I dunno, salt? A little built of salt in the environment is normal. But a whole lot of it is pollution.

I’m no climate scientist but I would think it’s similar to toxicity/poisoning. You can die from water intoxication but certainly you need it to live as well. So no, I don’t think it’s subjective. It seems to me that if something is capable of causing harm in a certain amount, it’s poisonous/pollution/toxic.

Yes, the dangers of Dihydrogen monoxide are well known yet underestimated

Dihydrogen monoxide levels have also peaked.

That's more a quibble over dosage, though, than any subjective disagreement on "can too much salt be a pollutant?"

I think that it is primarily grounded in objective measurements and scientific understanding

Sure, but interpretation of measurements is a largely individual endeavor, one way or another.

And comparison of different, potentially codependent variables, is notably relevant.