> right now we don't really understand what may happen to the planet if the US or Russia unleash their full nuclear arsenal
Nothing will happen. Planetary nuclear arsenal yield is dwarfed by a single large vulcanic eruption, and those happen regularly. In fact, modern nuclear arsenal is barely enough to destroy military targets and major cities of both parties. Direct casualties will be in millions, but probably in single digits of them.
In other words, it will be a major humanitarian catastrophe, but nothing humanity (or even a major world power like US) can't survive. Probably the biggest change would be due to large areas rendered uninhabitable for decades, but then again, plenty will be left and "uninhabitability" is a matter of life quality standards. People live in Hiroshima and Chernobyl just fine.
You're free to believe what you want, but the peer reviewed studies that have been conducted with current climactic models predict significant global cooling that would lead to at least global famine. The crux is not the power of the explosion, but the amount of soot generated by detonating high - yield weapons in huge cities.
And people do not live in Chernobyl at all. However, it's not really relevant to a discussion of nuclear weapons, as nuclear plant meltdowns are a completely different problem. For sure if the Chernobyl core had melted down and exploded nothing would be living in Ukraine at all, and possibly a much larger area. Hopefully though, that is one area though where technological progress has actually significantly reduced the chance that it would ever happen, in a systematic manner.
Not matter the opinion, "nuclear winter" concept is a belief, you are totally right here. It has never been a scientific question in the first place, the idea was largely accepted for political reasons. Wikipedia [1] has a short overview of the discussion on the topic, but in reality there is no debate on that for a long time: one can't really argue in favor of milder consequences because he'd be labeled as a militarist and all. And I agree that this is one of the few discussions that we probably shouldn't have.
But in general: all the articles greatly exaggerate the volume of nuclear arsenal (tenfold), the number of actual nuclear detonations, the territory of fire and ash yield of the fires. And even then, the planet has tolerated all those at larger scale in volcanic eruptions and forest fires.
Napkin math: US/Russia arsenal is about 1500 warheads on 500-1000 carriers each, which is about 500MT combined. Out of those optimistically maybe a half will detonate on each side (they will be destroyed in preventive strikes/intercepted/etc.), which leaves you with about 125MT total yield - about the yield of a couple of Tsar Bombs that was detonated in 1961 without any consequences whatsoever. The majority of the strikes will be on military targets in the middle of nowhere, where there won't be any fire at all. The rest will fall on modern concrete cities that don't have much fuel either.
> And people do not live in Chernobyl at all
They do, there are about 3000 people working there at any given time and even more living there illegally. Also, animals have no problems living there whatsoever and in fact the ecosystem is in a better shape due to low human activity. Also, you are aware, that Chernobyl power plant itself was operational until year 2000, right?
> nuclear plant meltdowns are a completely different problem
I absolutely is, and in terms of ecological consequence Chernobyl is far more severe than thermonuclear warhead detonation. The core HAS melted down and exploded, pieces of graphite rods were found as far as hundreds of meters away from the building.
I'm not saying nuclear war is nothing to think about - this would be a major catastrophe. But it's very unlikely to end the civilization.
The Chernobyl facts you bring up are very interesting. I had no idea that the plant kept operating for so long. I knew that there were people who stayed behind, and that there are workers around the exclusion area, though I admit that I would have imagined significantly lower numbers.
Nothing will happen. Planetary nuclear arsenal yield is dwarfed by a single large vulcanic eruption, and those happen regularly. In fact, modern nuclear arsenal is barely enough to destroy military targets and major cities of both parties. Direct casualties will be in millions, but probably in single digits of them.
In other words, it will be a major humanitarian catastrophe, but nothing humanity (or even a major world power like US) can't survive. Probably the biggest change would be due to large areas rendered uninhabitable for decades, but then again, plenty will be left and "uninhabitability" is a matter of life quality standards. People live in Hiroshima and Chernobyl just fine.