I feel like Veeky Forums is the most appropriate board to ask this question...

There may be extremophiles that could survive, but most life on earth would be eliminated.

It wouldn't be that bad compared to historical extinctions. Humans would e fine as a species.

Not necessarily all world would be destroyed in a nuclear war.

Europe, USA, East Asia, Israel, Pakistan & India would be destroyed

However Large parts of World would be Spared from Nukes
Such as New Zealand, Latin America, Southeast Asia, Africa & perhaps also Australia & Canada.
Although probably they will be in Social Chaos after that.
Any species already brought there would survive the extinction.

Most of Species in World dwell in Tropical Areas (mostly spared from devastation).
Many species living in Ocean will be spared.
Most Species of Microorganisms will be spared too.

People are way overestimating the damage caused as far as the environment is concerned here given that a nuclear war is not the same thing as a nuclear holocaust. If you are imagining some doomsday scenario where everyone that has them starts firing all of them off every which way, yeah shits going to be fucked. But the most likely scenario is a random rogue state says fuck this and blasts a western nation maybe a city or 2 get trashed and then said state just gets erased. Meanwhile rest of the world is like man maybe we should have disarmed sooner.

Depends on where the nuclear war took place and the severity of it.

The fallout would be only part of the problem as the sheer displacement (loss of food and habitat for local species and negative influence by invasive species) could be a bigger threat. There is also the fact that surviving human population migrations from nuclear war to new/already occupied areas will overburden and exhaust the land of resources. Along with inability to utilize "nuked land" will add more burden to other surrounding areas. However the percentage of biodiversity affected would wildly differ by location.

Conservatively 0.1% loss in biodiversity for every nuke dropped (and it's nuclear fallout) in a non-repeated terrestrial base area that is not taking place on a land mass smaller than Madagascar.

However land masses with endemic hotspots like Madagascar getting nuked could affect up to 1-2% of total known biodiversity. Nuclear fallout on land masses and forests near the equator in South America, Africa and South Asia would do the most damage in reduction of biodiversity.

The damage from invading species, loss of habitat, higher exhaustion in land support by human migrations and increase density from the fallout potentially would do more damage than the nuke itself.

The numbers aren't as high as one would assume mostly because of location. It can easily be argued that deforestation has done more damage to life than all nukes that have been used. But a nuke near the equator would be extremely devastating. That's where the real danger lies.

0%

>However Large parts of World would be Spared from Nukes
>Such as New Zealand, Latin America, Southeast Asia, Africa & perhaps also Australia & Canada.

You don't understand MAD do you?
It's not just nuclear nations that will get nuked friendo

>the most likely scenario
Is between Pakistan and India, once Indus starts drying out

youtu.be/Mc_4Z1oiXhY?t=39m15s

Why does everyone assume the nukes will all hit the earth within an equal distribution? Wouldn't only the nation's that are in conflict bomb each other why would any shit hole third world countries get nuked? Sure they'll suffer radiation and other issues but why

en.wikipedia.org/wiki/Indus_Waters_Treaty

>why would any shit hole third world countries get nuked?

Because if a person behind the button didn't give a fuck about spoils of war nuking third world countries with high oil/ minerals could economically handicap 1st world nations.

Seems unlikely given some countries are allied to second and third world countries who have if or no army

With the current armaments, it's rather small. Smaller than your typical apocalypse tier entertainment content. I suggest you /k/ where this subject has been discussed to death with people knowing their stuff about this stuff and so on. People telling you extinction level damage and nuclear winter don't know much, such occurrence would be incredibly unlikely even in the remote case every armed nation decides to strike most populated areas completely ignoring targets of military interest, such as enemy C&C chain and available launch sites. That's quite simplified.