Nuclear war would be catastrophic – but maybe not just for the reasons you think. Hi, I'm Cameron, and this is MinuteEarth. Yes, it’s true that immediately following the detonation of a nuclear weapon, everything – and everyone – inside the blast zone is incinerated.
And yes, over the following days, weeks, and years, radiation poisoning causes death and debilitating disease in those just a little farther afield. But that’s just the first domino of devastation: radioactive fallout, refugees, looting, and large-scale damage to infrastructure will all be bad, but the smoke is what has the farthest-reaching – and deadliest – effects. When lots of smoke goes into the atmosphere at one time, it absorbs sunlight, which means it can affect the climate.
After Mount Pinatubo erupted in 1991, the resulting ash cloud temporarily dropped global temperatures by an average of a degree Celcius. Smoke from mega-wildfires can have similar local effects. The smoke from a burning city is even more of a problem, though.
As cities, with all of their buildings, plastics, asphalt, etc – as all of this stuff burns. . .
It creates smoke with tons of free-floating groups of carbon atoms known as “black carbon,” which is the special sauce of our nuclear doom. These dark particles soak up sunlight and warm the surrounding air, making it buoyant and lofting the smoke into the stratosphere. Smoke from wildfires and volcanoes also make it high in the air, but these sources don’t produce much black carbon.
As a result, their lighter-colored smoke doesn’t absorb as much sunlight, and therefore won’t float very long. But smoke made mostly of black carbon can stay aloft for as long as a decade, riding air currents, and cooling the planet by absorbing the sun's rays in the upper atmosphere so that they (and their heat) never make it to the surface below. Scientists have recently calculated that just 15 nuclear bombs could create as much as five million tons of black carbon – that’s enough to cool the planet by an average of 2 degrees Celsius.
But wait a minute – we have detonated more than 2,000 nuclear bombs – why haven’t we experienced this cooling already? Well, the vast majority of nuclear detonations have happened either high in the atmosphere, in remote places, or deep underground. That’s all in order to minimize the potential for damage – including the damage that would be caused by megatons of black carbon soot.
Two nuclear bombs have been used to their full – and devastating – potential. But, somewhat frighteningly, those were small bombs compared to what we have now. Today, not only are nuclear weapons way bigger, we also have way more of them than we did then, albeit not nearly as much as existed during the Cold War.
Still, a war between nuclear powerhouses could create as much as 150 million tons of black carbon, enough to drop global temperatures by an average of 16 degrees. For reference, during the most recent ice age – you know, when glaciers covered half the earth – global temperatures were just 7 degrees colder than they are now. And if a nuclear-triggered mini ice age were to occur, it would freeze food production in most of the world, many of those who manage to survive the bombs and radiation and freezing conditions would suffer from inevitable global food shortages; as many as 5 billion people worldwide might starve in the first year – that’s nearly two-thirds of the global population.
At northern latitudes, it gets even worse – up to 99% of people there may starve to death. A war that heats up to the point of going nuclear could leave everyone in the cold. This video was brought to you by the Future of Life Institute to celebrate recipients of the Future of Life Award.
This award is given annually to individuals who have steered the course of history away from disaster without having received much public recognition at the time. The 2022 Award went to John Birks, Paul Crutzen, Jeannie Peterson, Alan Robock, Carl Sagan, Georgiy Stenchikov, Brian Toon and Richard Turco for their roles in discovering and popularizing the science of nuclear winter.
