By lifewipe I mean wipe out all life on earth, including Extremophiles.
No way. I doubt if the entire US nuclear arsenal could even wipe out all people, let alone tougher organisms.
IIRC the US owns ~30k nuclear weapons. Split evenly across the planet that's roughly 1 weapon per 20k square km (a square ~150km on its side). I'm not sure what the destructive power of the average weapon is but as far as I am aware it is nowhere near powerful enough for one weapon to destroy 20k square km.
If this was attempted there would be a devestating affect on the biosphere; radiation, nuclear winter and habitat destruction would probably result in many land species going extinct but I highly doubt all of them would (there are most likely simple organisms like moss, algae, soil fungi, insects etc that would survive and adapt). In addition I can't see marine life being that badly affected. You might cause the extinction of larger species due to disruption of the food web but especially in deeper waters there would be little difference. Extremophiles living deep in the ocean and crust wouldnt even notice what you have done.
Life is extremely resilient. Habitats and ecologists are easy to destabilise do as to cause extinctions (sometimes on a mass scale) but some life somewhere always remains and thanks to a lack of competition will proliferate and adapt to til the depopulated niches.
Nice answer. Thanks.
No problem, to expand on the statement about the destructive power of nuclear weapons this is a cool/morbid website that allows you to select a location and see how much devastation a nuclear bomb can cause. Using the scale you can see that the at the maximum the B53 nuclear bomb (the largest built by the US the last of which was decommissioned last year) has a radius of about 20km. That's not even the area that will get annihilated that's just the area where some effect will be felt. Even the Russian Tsa Bomba, the largest ever built doesn't get much bigger.
Lastly it's worth bearing in mind that the meteorite impact that created the Chicxulub crater which was many many many times greater than a nuclear explosion didn't even cause the biggest mass extinction on Earth.
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