It has been 500 years after a large nuclear war between America and the USSR. Almost 3,000 nukes hit cities across the globe, like Los Angeles, Washington DC, New York, Moscow, Paris, London and more. My question is what would be the long-term effects on the climate and environment 500 years after the war?

  • The bombs used varied in size from smaller warheads to larger ones.
  • About 85% of the world population was killed off almost immediately, mostly from the initial blast and the lingering radiation
  • The Southern hemisphere was left mostly untouched by the bombs, but there was large famine from nuclear winter.

What would be the most likely long-term effects on the environment?

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    $\begingroup$ Voted "too broad" because there are entire books on the topic, and even that was not a full answer, with room left for future work. $\endgroup$
    – Mołot
    Jan 15, 2018 at 7:16
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    $\begingroup$ "The Southern hemisphere was left mostly untouched by the bombs, but there was large famine from nuclear winter": so you already took a leap of faith and assumed a global nuclear winter. You could as well continue following whatever reference book you have which gave you this global nuclear winter. By the way, there is no scientific consensus about the climatological effects of a large scale nuclear war. $\endgroup$
    – AlexP
    Jan 15, 2018 at 8:06

2 Answers 2


Climate Impacts

There probably won't be any significant long-term effects on climate. A nuclear war will release a huge amount of soot into the atmosphere, which would block out the sun and cooling down the Earth and reducing rainfall. However aerosols do not stay in the atmosphere for long, so pretty soon, the Earth will begin to warm up again. The ozone layer would also be destroyed. However, this is also a short-term effect because without human influence for 500 years, ozone can be naturally reformed.

A possible long-term effect would be the reversal of global warming. Since there would be a lot less greenhouse gas emissions over the next 500 years, as long as plants could grow back fast enough, global warming might be reversed.

Environment Impacts

3,000 nukes would probably cause a mass extinction. In the years following the nuclear war, huge ash clouds would block sunlight1 causing plants to die off because they cannot photosynthesize. As plants begin to die off, so will animals. The largest organisms would suffer the most because they require the most energy to function. However, some organisms might be able to adapt to the new environment and they will be the ones who repopulate Earth over the next 500 years.

You really can't predict what the environment will be like in 500 years. Most organisms will probability need adaptations for a harsher and more radioactive environment. 500 years isn't enough time fore Earth's environment to recover, since the nukes would have created patches of lifeless rock, and succession takes hundreds of years.

p.s. This is my first time answering, and I would really appreciate any comments.

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    $\begingroup$ Welcome to Worldbuilding SE. Your answer is well formed and referenced so ironically enough you're unlikely to get a lot of comments. :) That said, I'd like to ask how long you think the ash clouds would last, and whether there are some plant species that would still be viable when they dissipate. That could be the best indication of what animals are likely to survive or adapt going forward. $\endgroup$
    – Tim B II
    Jan 15, 2018 at 5:09
  • $\begingroup$ "A possible long-term effect would be the reversal of global warming." or maybe not, at least for short term en.wikipedia.org/wiki/Nuclear_winter#Nuclear_summer $\endgroup$
    – Vashu
    Jan 16, 2018 at 1:45
  • $\begingroup$ "3,000 nukes would probably cause a mass extinction" recent modelling is much more conservative about scale of nuclear winter. $\endgroup$
    – Vashu
    Jan 16, 2018 at 1:46
  • $\begingroup$ On reversing climate warming, we should consider that without human-caused greenhouse gas emissions, we would be now heading into an Ice Age. All the natural causes of climate change are trending towards cooling down. $\endgroup$ Mar 11 at 7:29

Global cooling.

Look at what happened in the New World after Columbus. The Old World diseases devastated the New World, the population crashed, forests reclaimed previously cleared land. This took carbon out of the atmosphere and you can see the effect on the world temperature.

You're going to get the same effect except worldwide, thus more cooling.


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