How would a nuclear winter play out?

It is theorized that a nuclear war can have a cooling effect on Earth because of the dust and smoke a catastrophic event of this magnitude would create. Could humanity survive such an ordeal?
Interesting Engineering

When Little Boy and Fat Man were dropped – the two nuclear bombs that fell on Hiroshima and Nagasaki during WWII – nearly 200,000 people died. Then, the aftereffects plagued thousands of inhabitants long after the bombs were dropped. It was hard to imagine a worse disaster caused by humanity.

Yet, today, nearly 12,705 reported nuclear warheads across 20 countries exist. That’s not even counting the 100 or so nuclear weapons that are rumored to be missing, many of which are small enough to fit into a backpack.

Moreover, nowadays nuclear warheads are much more powerful than those from 1945. The most powerful nuclear weapon ever tested, the Tsar Bomb, yields a power of 50 megatons. We’re talking 3,333 times stronger than Little Boy, which was dropped on Hiroshima.

A prototype of the Tsar Bomb is said to have a blast yield of 100 megatons. If a bomb of this magnitude were dropped on a major city like London, there would be absolutely nothing left. The effects from the blast would be felt in cities as far as Cambridge, Oxford, and Brighton.

To say the potential for an even bigger disaster than Hiroshima or Nagasaki is considerably higher today would be an understatement.

Up until recently, the focus on such nuclear weapons was limited to their blast and radioactive fallout. Through new research, it is now believed that the long-term effects of nuclear war may be even more far-reaching that we could ever imagine.

If a 5000-megaton nuclear war were to break out, the smoke coming from fires in bombed cities could cause long-term changes in our earth’s atmosphere. The massive amounts of dust and smoke could encircle the earth, limiting the sun’s reach down to the earth’s surface. This would cause our planet’s temperatures to drop between 15 to 25 degrees Celcius, creating a nuclear winter.

Without sun, plants, livestock, and ultimately us humans cannot survive.

There would be an over arcing scarcity of food as the balance of our world’s ecosystem would be utterly disrupted. Wild animals would suffer from the lack of food and the drastic change in weather would dip our oceans’ temperatures to a point where fish populations would wipe out.

If a nuclear winter were to occur, it is theorized it would last up to 25 years. At this stage, it’s still unknown whether humans could survive that long in such conditions.

The hope is that we never have to find out.