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  • Nuclear war would forever split  human history. Into anything that  

  • happened before and the post-war apocalypse.

  • In the worst case, mass fires consume everything  within tens of thousands of square kilometers,  

  • killing hundreds of millions within  hours. But the worst part comes  

  • after that - nuclear war could triggernuclear winter that might kill billions,  

  • maybe even completely collapsing our civilizationHow does it work and what would it look like?

  • Fire Causes Winter

  • When a nuclear weapon is detonated, a bubble of  gas hotter than the sun is forced into existence,  

  • so hot that everything within kilometers  immediately begins to burn. The terror bubble  

  • expands rapidly, filling the sky over its targetcreating a devastating shockwave that causes most  

  • of the immediate destruction. Basically you  break a lot of stuff and set it on fireand  

  • in the worst case this turns into a firestorm that  consumes everything and everyone on the ground.

  • Right after the explosion a gigantic mushroom  cloud rises over the destruction like a demon  

  • throning over its perverse work, but in  the following hours a far more deadly  

  • cloud forms. The fire burning citiesforests or fields, heats up so much air  

  • that it creates its own micro climate and  wind system. Hot air and hot smoke rise,  

  • pulling in fresh air from the surroundingsand fresh oxygen stoking the flames even more.  

  • This creates an updraft and forms  a colossal pyrocumulonimbus cloud  

  • that carries the soot and aerosols from  the flames high into the stratosphere.

  • Under normal conditions, the soot rising  from a big fire is quickly washed out by rain.

  • But a pyrocumulonimbus cloud can  reach altitudes well above the height  

  • where rain clouds form. Once above the tropopause,  

  • there is simply no weather to remove soot from  the atmosphere, so it can stay aloft for years.

  • If this happens to a single city, it's a tragedybut a fairly local one. But in a full scale  

  • nuclear war, warring nations following the cold  logic of mutually assured destruction, could use  

  • hundreds or even thousands of nuclear weapons all  at once, creating hundreds of fire storms, sending  

  • up to 150 million tons of soot, a cube the size  of a skyscraper, directly into the stratosphere.

  • In the next few days and weeks the soot  begins to blanket the earth at high altitudes,  

  • absorbing light high above the ground  and preventing sunlight from reaching  

  • the surface . This is not like science fiction  where the sky turns dark and the sun disappears.  

  • Winter is what happens when just a little less  sunlight hits the groundand now suddenly a  

  • lot less sunlight gets through. Yesterday the  world was normal. Today nuclear winter begins.

  • Winter Causes Hunger

  • How bad nuclear winter would be is still an active  area of research. It all hinges on one thing:  

  • How much stuff will burn really hot? How many  firestorms would be caused by the heat of the  

  • explosions? This depends on many factors, from  the materials a city is made of, to the time of  

  • the year, if a forest is nearby and so on. So just  keep in mind we are working with some assumptions.

  • Here is the good news: Nuclear winter is  not permanent, and definitely no new ice age.

  • The effects on the climate only last as  long as the soot remains in the atmosphere,  

  • which is at most a decade or so until it  clears out and temperatures normalize.

  • The bad news is that this causes almost  immediate climate change within a few  

  • weeksit disrupts our climate system  faster than any living being can adapt to.

  • In this new climate our seasons are suddenly  all wrong. Winters are much longer, summers  

  • shorter and colderor gone altogether. This  also means less evaporation over the oceans,  

  • which means less rain and maybe large scale  droughts. This is bad because our food eats the sun.

  • Without good summers and enough raingrowing seasons shrink or even collapse.

  • The majority of humanity lives in  an area called the midlatitudes,  

  • a strip of land that has the ideal temperature  for our speciesnot just because it's not  

  • too hot or cold, it's also where the plants  we eat grow best. The vast majority of the food  

  • we eat stems from a few highly efficient  crops, that are mostly produced in a few  

  • very agriculturally productive regions, like  the US Great Plains or Ukraine. From these  

  • bread and rice baskets of the world, they  get traded and shipped around the world.

  • In the worst case of a full scale nuclear  war the temperatures in the midlatitudes  

  • will probably stay below freezing for  several years. Nothing at all can grow  

  • under these conditions and the world's  breadbaskets would suddenly turn empty

  • If food production crashes, the world's food  producers would very likely ramp up prices or  

  • even stop selling food to other countriesif  they're still able to farm their fields at all.

  • It's easy to calculate how many people can be  alive on earthyou take all the calories we  

  • can produce and divide them by what the  average person needs to survive. If you  

  • have more people than calories, then within a few  weeks you don't anymore. Humanity has only a few  

  • weeks' supply of crops and food, not enough  to survive this drastic drop in production.

  • But the climate is not the only issue: modern  industrialized agriculture is a complex affair  

  • that relies on functioning supply chains to  provide unthinkable amounts of industrially  

  • produced fertilizer and chemicals to kill weeds  and vermin. Massive numbers of specialized modern  

  • machinery is plowing, sowing, harvesting  and distributing. After a nuclear war,  

  • especially if the countries that produce the  food were part of the nuclear exchange, there  

  • may simply be no more fuel, fertilizer or machine  parts, because there are no more oil refineries,  

  • ports and other essential infrastructure leftdamaging global food production even more.

  • Ok, so now that we set the stage, let's look  

  • at what science says about the  actual wars that could happen.

  • Actual Nuclear War

  • Today there are two main conflicts that scientists  think about when making calculations of nuclear  

  • winter: a nuclear war between India and  Pakistan and one between the US and Russia.

  • The most likely smallish nuclear exchange would  be fought today between India and Pakistan,  

  • with relatively low yield weapons. Even  in a pretty mild nuclear war like this,  

  • the immediate explosions would  kill around 27 million people,  

  • which is horrible enough. In just a few  hours, more people would die than in all  

  • of World War 1. The ensuing fires would not cause a nuclear winter,

  • but a mild 'nuclear autumn'. But even this would disrupt the climate,  

  • and thereby global agriculture, enough to  starve up to 250 million people worldwide.

  • Unfortunately India and Pakistan are in an  arms race and have been increasing the number  

  • and power of warheads in their arsenal. The next  stage of escalation would be war with hundreds of  

  • nuclear weapons, the bombs and fires destroying  many major population centers and killing over  

  • 100 million people. A war on this scale would  cause a nuclear winter that would damage global  

  • agriculture enough to cut the available calories  for humanity in half. The number of people

  • that starve to death would be as high as 2 billion.

  • One in four humans alive today.

  • The worst-case scenario is a full scale global  war between NATO nations and Russiaor China,  

  • which also continues to build its nuclear  arsenal. In a war between a former,  

  • future and current superpower, thousands  of nuclear weapons could be detonated.

  • In a scenario with around 4400 nuclear weapons,  360 million people would perish right away. We  

  • have no other event to even compare the death  and destruction to. It's like humanity dropping  

  • an asteroid on itself. The nuclear winter  that follows such an apocalyptic war would  

  • tank human calorie production by as much  as 90%. Not only would almost all of our  

  • agriculture take an immediate and deadly  hit, the climate would take at least a  

  • decade to recover. Because a war like this would  specifically hit the world regions that produce  

  • most of the food for humanityrecovery will  be much, much harder than with other conflicts.

  • Within two years the global death toll from  starvation could rise to about 5 billion.  

  • In mid latitude countries like Russia, ChinaCanada, the U.S. and much of Europe only a few  

  • percent of the population might surviveHumanity will never be the same again.

  • While nowhere is truly safe, some nations in  the southern hemisphere may fare well enough  

  • to endure, while the rest of the world collapsesAll the nuclear weapon states are in the northern  

  • hemisphere. So a few countries like Australia, New  Zealand, and Argentina may be able to endure for  

  • a bunch of different reasons. Their nuclear winter  would be milder, they have a lot of livestock that  

  • would not be as affected as crops. So they would  probably stop exporting food and focus on keeping  

  • their own people aliveassuming they aren't  invaded for their food by other starving nations.

  • It's safe to say that the world would become  extremely unpleasant for a long time and it's

  • impossible to know how many people will have  died when the nuclear winter ends. In the worst  

  • case human civilization could collapse  and the survivors would be thrown back  

  • thousands of years, slowly trying to recover  a world full of scars and graves. Eventually,  

  • when they've rebuilt civilization, would  they ever build nuclear weapons again?

  • We know for sure that we need to do  anything we can to make sure nuclear  

  • war never happens. This video was supported  by Open Philanthropyif you want to know  

  • what YOU can do to reduce the risk for  nuclear war you can either support expert  

  • organizations or become a citizen expert  yourself and learn more. We've compiled a list  

  • of further reading and expert recommendations  in the infobox and our sources doc for you.

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Nuclear war would forever split  human history. Into anything that  

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