NUCLEAR WINTERNuclear War Would Be More Devastating for Earth’s Climate Than Cold War Predictions – Even with Fewer Weapons

By Mark Maslin

Published 1 August 2023

A limited nuclear war between India and Pakistan could kill 130 million people and deprive a further 2.5 billion of food for at least two years. A global nuclear war including the US, Europe, and China could result in 360 million people dead and condemn nearly 5.3 billion people to starvation in the two years following the exchange.

Christopher Nolan’s biopic of J. Robert Oppenheimer has revived morbid curiosity in the destructive power of nuclear weapons. There are now an estimated 12,512 nuclear warheads.

A war in which even a fraction of these bombs were detonated would create blast waves and fires capable of killing millions of people almost instantly. The radiation-induced cancers and genetic damage would affect the remaining population for generations.

But what sort of world would remain amid the radioactive fallout? For the last four decades, scientists modelling the Earth system have run computer simulations to find out.

Using their knowledge of chemistry and climate modelling, atmospheric scientists Paul Crutzen and John Birks wrote a short paper in 1982 which suggested a nuclear war would produce a smoke cloud so massive that it would cause what became known as a nuclear winter. This, they claimed, would devastate agriculture and with it, civilization.

A year later, scientists from the US and Soviet Union confirmed first that cities and industrial complexes hit by nuclear weapons would indeed produce much more smoke and dust than burning the equivalent area of forest. And second, this global layer of smog would block out sunlight, causing conditions at Earth’s surface to become rapidly colder, dryer and darker.

Climate modelling shows the reduced sunlight would plunge global temperatures by up to 10˚C for nearly a decade. These freezing conditions, combined with less sunlight for plants to photosynthesize, would have catastrophic consequences for global food production and lead to mass starvation worldwide.

Modern climate models are much more sophisticated than those used in the 1980s. And while there are fewer nukes in working order today, more recent results from computer simulations suggest that the grim prophecy delivered by scientists 40 years ago may actually have been an underestimate.

Clear and Present Danger
Environmental scientists led by Alan Robock at Rutgers University in the US argued in a recent paper that the nuclear winter theory helped end the proliferation of nuclear weapons during the cold war. In 1986, President Ronald Reagan and General Secretary Mikhail Gorbachev took the first steps in history to reduce the number of nuclear weapons while citing the predicted consequences of a nuclear winter for all life on Earth.