We’ve all seen those nuclear bunker apocalypse movies, but is it really possible to survive an all-out nuclear war?  Scientists have been trying to answer that question for decades, and the topic gets a bit of renewed attention everytime global tensions rise.  There are a number of competing theories about the effects of a nuclear winter, and depending on the specifics, it just might be possible to ride out a nuclear apocalypse with the right preparation.

Even as a child of the cold war, nuclear war never seemed that scary.  The movies taught me that anyone could survive a direct hit in an underground bunker with 30 years worth of food.  We lived in a rural area, far from potential targets and I obviously didn’t have a realistic vision of what the aftermath would entail.  I assumed “nuclear winter” meant one year without a summer growing season, which seemed easy enough survive with a little planning.  That special naivety of a child carried through for a long time, until a recent conversation with my father.

I made some joke about surviving a nuclear apocalypse, and he looked at me dumbfounded and asked, “Why on earth would you want to survive that?  If a nuke is coming, I want it to land square on top of me and end it.”  I laughed, assuming I’d inherited my survival instinct from my mother, but then I started wondering if there might be more to it.  What exactly would a nuclear aftermath look like?  How long would a nuclear winter really last?

In reality, it’s hard to imagine and just as hard to model scientifically.  Smithsonian Magazine summed it up pretty well, “Both nuclear winter and global climate change are fairly abstract phenomena that occur on a scale beyond our immediate sensory experience.  We’re asking people to accept a result and imagine a change that is just beyond the realm of any of us, what we’ve experienced in our lives.” 

But it’s more than just hard to fathom.  It turns out, no one really knows.

What is a Nuclear Winter?

Nuclear winter is a theory that the impact of nuclear weapons would throw huge volumes of soot into the atmosphere.  The extra particles would effectively blot out the sun and create catastrophic cooling all over the globe.  Scientists have tried to model the effects of a nuclear winter by looking at modern wildfires and volcanic eruptions and then scaling them to various nuclear scenarios.

The problem is, none of the models seem to agree about the true effects of a nuclear winter.

Originally scientists assumed that an all-out nuclear war would release vast amounts of NOx that would obliterate the atmosphere, ending all life on the planet.  By the 1980’s newer science discredited this theory and in 1983 the first “nuclear twilight” model predicted a winter lasting roughly 4 years.

In 1991, fires in the Kuwait oil fields allowed climate scientists to test out models on a real-life atmospheric soot injection.  All of them completely failed to predict the outcome.  While local temperatures around the fires fell dramatically, as much as 10 degrees C, the impacts were only regional.  Since then, scientists have put out widely conflicting models trying to predict the effects of a nuclear winter, and there are even some minority opinions that believe additional CO2 in the atmosphere would actually create a nuclear summer instead.

A single volcanic eruption in 1815 created a year without a summer the following year, with snow storms in July in the US.  Another eruption in 1883 caused global temperatures to drop more than 1 degree for a full year.  There is the precedent for a single incident on one side of the world to create global disruption for an extended period, but it’s hard to predict the exact effects of nuclear war.  Will the conditions be just right to send particles into the upper levels of the atmosphere, or will it fizzle out relatively quickly?

How Many Nukes Does it Take to Create a Nuclear Winter?

More recent models suggest that a small nuclear conflict, with only 50 to 100 missiles exchanged would create a mini nuclear winter that could impact the entire globe.  This is intended to model a small power conflict, say for example in a conflict between India and Pakistan.  The theory suggests that the soot would reduce global temperatures around 1 degree C for 2-3 years, with more catastrophic effects in the immediate area of the conflict.

Though average temperatures would only be impacted by 1 degree, the total “frost free” days in any particular growing region could be completely disrupted.  Unpredictable frosts mid summer could destroy crops on a large scale, even if on average the temperature only dropped modestly.  This would mimic the volcanic eruptions that created a year without a summer, but potentially lasting for several years with the added “perk” of radiation.

How Long Would a Nuclear Winter Last?

While small-scale conflicts are predicted to create worldwide impacts lasting 1 to 4 years, large conflicts would obviously have longer lasting more severe impacts.

Larger scale conflicts, like those feared during the cold war between the US and Russia, would potentially detonate thousands of nuclear weapons.  These models predict that global temperatures would drop to an average of just above freezing year-round, lasting for around 10 years.  Limited effects would linger on for many decades past the initial nuclear winter, potentially disrupting food production for a whole generation.

It’s really unclear how likely this catastrophic nuclear winter is in practice.  Models run on large wildfires suggest much shorter times and show that even large amounts of soot are cleared from the atmosphere in as little as 2 months.  While there could be a tipping point where so much soot is injected into the atmosphere that it disrupts natural cycles, it’s unclear if or when that would happen.

Still, other theories suggest that the real worry is the catastrophic fires that result in cities from the nuclear strikes, rather than the strikes themselves.  That means that it may really depend on where the strikes happen, how fast fires go out and what the current wind patterns look like during detonation.  There’s a theory that modern cities, complete with fire retardant buildings wouldn’t create the intense firestorm that’s required to send particles high into the atmosphere.  Not all cities are “modern” though, and the fire retardant capabilities haven’t exactly been tested by a modern nuke.

In short, the answer is…it depends.  Somewhere between localized effects for one year for a small conflict, all the way up to full-on frozen winter apocalypse for at least 10 years.  This, of course, says nothing about the radiation, and only addresses climate and temperature.  Even if the nuclear winter were shorter than expected, the detonations are predicted to damage the ozone layer causing intense UV rays to reach the earth’s surface once the sky’s clear, which will come with its own unique health consequences.

Can You Survive a Nuclear Winter?

Again, it depends.  A small-scale nuclear winter is much easier to survive than a larger scale disaster.  Assuming the nuclear winter is caused by a small scale conflict that’s far from your location, survival would largely depend on the political stability of your country and your own personal food storage preparedness.  There would be the potential for widespread crop failures, potentially leading to worldwide food shortages.  A good long-term emergency food supply would be vital in this case.

Given the information available, it seems like this period would last at least 3-4 years, during which time law and order may be at risk and food may be scarce.

For a larger scale conflict between major superpowers, all bets are off.  I can’t imagine realistically storing enough food for 10 plus years of near freezing temperatures.  While you can pretend that eating grasshoppers and bark is an option, the grasshoppers will be long gone in just a few months, and bark flour only contains nutrients while the trees are alive.  They won’t make it long without sunlight.

That said, there is a book out called Feeding Everyone No Matter What that tries to address the possibility of keeping civilization alive in the event of an extended solar blackout, be it from nuclear war or mass volcanic eruption.  The author contends that it is possible, given some pretty extreme scientific intervention.  Things like bacteria that digest cellulose being fed to small mammals to produce meat, and mass cultivation of mushrooms that yield without sunlight.  I’ll admit the author is thinking outside the box, but all of these options would require some pretty intense preparation long before the event of nuclear war.

How To Prepare for a Nuclear Winter

The first step in surviving a nuclear winter is avoiding the initial impact zone.  Move away from potential targets, and get away from cities.  Some suggest moving to remote locations in the Southern Hemisphere, such as Australia because they’re furthest away from the most likely locations for nuclear detonations.  For most of us, that’s not really practical.

Beyond that, a good plan for long-term security coupled with heavy food stores to get you through the period where food cultivation is not possible.  After that, supply lines will still be limited, and a working knowledge of food cultivation coupled with a supply of survival seeds will hopefully carry you through until things return to a new post-nuclear normal.