Climate 300 years after nuclear apocalypse?

[ToBoldlyKnow]

So, I'm writing something taking place a few centuries after a global nuclear war, but I'm unsure what the climate would be like, both in general and in the story's specific setting - the western coast of Canada. Would the average temperature or amount of yearly rainfall change? Would areas that were directly hit still be dangerous to go near for prolonged periods of time? Could food be grown and water be safe enough to drink? And besides climate, how many survivors could there be? I'm also curious as to what the world would have looked liked fifty and one hundred years after the aforementioned apocalypse as well, since I'm planning on having my characters discuss the history of their world. Any input?

 

[Baluncore]

Don't expect local survivors in North America, Europe or Japan. I suspect that west coast Canada would be repopulated by primative South American people moving north through Mexico.

“Apocalypse” usually means the final end of the world, by definition, there can be no survivors. I assume you mean a catastrophic nuclear war that ends the world as it was known.

Much will depend on the magnitude of the event. Where are the targets? How many bombs? Of what type are detonated? First you need to model that political scenario or “play that game” in order to evaluate the inputs to the system.

There will initially be a cooling due to dust in the atmosphere. I think the biggest recent volcanic eruptions have resulted in 10 years of cooling, do some research on historical climate records. I would expect it to take between 10 and 50 years for the dust to settle.

The survivors will probably be from the tropical southern hemisphere. I see no reason why they will need to move towards the poles quickly. Without technology and a political structure it will be tribal warfare that drives families towards the poles as the dust settles. Look back at the stone-age aboriginal tribes to see how they survived, if there is a future it will follow that same evolutionary path.

 

[stefan r]

Don't expect local survivors in North America, Europe or Japan. I suspect that west coast Canada would be repopulated by primative South American people moving north through Mexico.

Unlikely to have "no survivors". There were detailed studies conducted during the cold war. The primary causes of death is starvation and disease. A lot of early disease will lower the starvation rate. Increasing the number of people killed by nuclear blast and radiation poisoning will increase the number of survivors because the blasted people do not eat and they are not running around spreading microbes. A 5 to 20% survival rate in North America is likely for any scenario.

A climate collapse would effect tropical regions and regions that were not targeted. Those countries will have a full population of hungry people and will get exposed to the lethal epidemics after the food is already severely depleted and social order has collapsed.

...I'm unsure what the climate would be like, both in general and in the story's specific setting - the western coast of Canada. Would the average temperature or amount of yearly rainfall change?

The climate and environment might be better off than it will be if civilization continues with business as usual. The first year will get hit by a nuclear winter. That is caused by dust in the upper atmosphere adsorbing sunlight. The Hadley cells break down which allows arctic wind to blow south (blows north down under). That will kill a lot of plants and cause havoc. The percent of sunlight blocked would be rather small. The sky would look the same. The dust would have settled out in much less than 300 years. A lot of it in year 1.
Year 2 the Hadley cells would be back and western Canada would get rain not far from normal. 300 years would depend on overall climate change. You have CO2 from dead plants and a disrupted ozone layer. You can find lots of debates about the seriousness of climate change.

The survivors are likely to attempt to return to business as usual so the climate is likely to get hit with damage both the war and civilization.

Would areas that were directly hit still be dangerous to go near for prolonged periods of time? Could food be grown and water be safe enough to drink?

Nuclear bombs can be salted so that they contaminate an area for long periods. If I was driving through Nevada and passed the nuclear test sites from the 60s I would stop and look around. No rational reason to be afraid. If there is a choice between feeding children food grown in high fallout areas or feeding them food from low fallout areas most parents will select the low-fallout grown food. It is a good idea to drink anti-oxidant tea, eat berries and not worry too much. Worrying can cause life shortening stress. Vegetarians who survive the first decade after the nuclear war will have lower cancer rates than meat eaters do now.