Millions rallied all across the world in the past few weeks to raise awareness for the climate, urging politicians, policymakers, big business, and everyone else, no matter how small, to urgently act so we might preserve the planet for future generations.

The climate emergency is one of the biggest challenges that humanity has ever faced, and if nothing is done soon global temperatures could rise by as much as 5°C by the end of the century. This abrupt shift in the planet’s climate is likely to lead to unprecedented heatwaves, severe drought, and major floods in many regions, with serious impacts on human systems, ecosystems, and associated services. To see the most recent climatic lookalike, we have to turn the geological clock back between 144m and 65m years, to the Cretaceous, which ended with the extinction of the dinosaurs.

Yet climate change isn’t the most immediate nor the most menacing threat to life on Earth.

Imagine having a gun pointed at the back of your head every moment of your life. The gun is loaded, a looming threat that would prevent anyone from living a normal life. Luckily (perhaps), the vast majority of us are unaware of the gun and the silent terrorist behind it — but it is there, cocked, and ready to fire at all times.

We can’t see this gun because it is carefully hidden away in nuclear silos, submarines, stealth bombers, and moveable ICBM launchers.

Although the exact number of nukes in each country’s arsenal is a closely guarded secret, officially there are nine nations who operate a total of 14,500 nuclear weapons. The vast majority are owned by the US and Russia.

Considering that the world’s nuclear arsenal has shrunk by over three-fourths since its peak in the mid-1980s, this sounds like we’ve made some progress. But the nuclear stockpile is still large and powerful enough to destroy the world several times over.

For instance, a 2019 simulation performed by researchers at Rutgers University, the University of Colorado Boulder, and the National Center for Atmospheric Research found that an all-out nuclear war between the U.S. and Russia would inject nearly 150 million tons of soot into the atmosphere.

Within weeks of the first detonations, the soot would have spread around the whole stratosphere, blocking sunlight. As a result, during the first year following the soot injection, global temperatures would plunge by more than 7°C. Later, the planet could cool by as much as 9°C.

The knock-off effects of such a dramatic cooling would be devastating. Food crops would be severely affected, rainfall would be reduced by around 30% globally, extreme weather events would become more variable — and that’s without taking into account the effects of nuclear fallout on human health and wildlife.

Anxiety over nuclear war is nowhere near what it was during the height of the Cold War. However, a 2018 World Economic Forum survey of over 1,000 leaders from government, business, and other industries identified nuclear war as a top threat.

So, what’s the risk of a nuclear war happening? Martin Hellman, a Stanford Professor Emeritus in Engineering, has some disquieting news.

Hellman is best known for inventing public-key cryptography, along with Whitfield Diffie and Ralph Merkle — the technology that, among other uses, enables secure internet transactions. In 2015, Hellman was awarded the 2015 ACM Turing Award, often called “the Nobel Prize of Computer Science.” 

However, since the 1980s, Professor Hellman has been heavily involved in creating nuclear awareness.

During his keynote at the recent 2019 Heidelberg Laureate Forum (HLF) in Germany, a yearly event that gathers the foremost luminaries in mathematics and computer science, Hellman spoke at length about the risks of nuclear annihilation and “the technological imperative for ethical evolution.”

“Climate change has been put forth as the greatest existential threat to humanity. I think that’s wrong. I think climate change is a major threat but nuclear weapons are the only thing that can wipe us out at this very instant. So, I think we need to work on both,” he told a packed audience at HLF19.

Some argue that nuclear weapons have made war obsolete — something that is commonly known as nuclear deterrence. Simply put, the prospect of mutual annihilation keeps each player in check.

However, history has taught us that this is merely wishful thinking. In 1962, during the infamous Cuban missile crisis, President John F. Kennedy estimated the odds of nuclear war as somewhere between “one-in-three and even.”

Even in relatively recent times, there have been quite a few post-Cold War tensions looming with nuclear war. For instance, in 1995, Norway launched a meteorological rocket that Russia mistook for a US submarine-launched ballistic missile. The situation was so tense that then-Russian President Boris Yeltsin was presented with the device that contains the codes for launching a nuclear attack. Fortunately, Yeltsin, famous for his heavy drinking and ludicrous antics, was sober enough not to doom us all.

During the harrowing 9/11 terrorist attack, coincidence had it that the Russian Air Force had scheduled an exercise on the same day in which strategic bombers were to be flown toward the United States. Some US Air Force officers thought that the World Trade Center attack was part of a grand Russian surprise attack that included targeting US cities with nuclear weapons. Russia, however, learned of the New York City events in due time and grounded its planes.

These are just a couple of examples of highly tense situations. There are many others that the public will probably never become aware of during our lifetimes. Add terrorists to the mix and you end up with what looks like a ticking time bomb.

“I’m an activist for human survival,” Hellman told journalists during a press conference at HLF19, explaining his involvement in nuclear awareness despite his seemingly unconnected computer science background.

How ethical is society’s current approach to nuclear weapons? Is it ethical to threaten with the destruction of the human species to preserve peace, Hellman asked the audience in Heidelberg, Germany.

In a 2016 study published in the Bulletin of Atomic Scientists, Hellman performed a risk analysis in order to determine whether nuclear optimism is justified. He used a method called quantitative risk analysis which breaks down a catastrophic event into a sequence of smaller failures.

Los Alamos and Lawrence Livermore National Laboratories have employed quantitative risk analysis for various aspects of the country’s nuclear programs, but Hellman was the first to use this approach to estimate the risk of deterrence failure.

Hellman’s research and discussions with some of the world’s foremost security experts suggest that the likelihood of a nuclear war happening in the next 10 years is extremely low. However, the odds of all-out nuclear war happening sometime in the next 1,000 years shoots through the roof, becoming almost inevitable. In between the two extremes is a sweet spot in the next 100 years when nuclear war could become highly likely.

“We are either going to grow up really fast or we’re going to destroy ourselves”

According to Hellman, even if nuclear deterrence could be expected to work for 1,000 years—a time frame that seems overly optimistic to most people—a child born today with an average life expectancy of 80-90 years “would have almost a 10 percent chance of not living out his or her natural life due to our reliance on nuclear weapons—a highly unacceptable level of risk.”

“We’ll probably have between 10-20 crises comparable to the Cuban Missile Crisis in that time (1,000 years). If we look at Georgian wars and Ukranian wars, which happened in 2008 and 2014 — maybe every 10 years and we’d have a 100 of those. And a lot of other things that you don’t know about,” Hellman said.

“If the time horizon for nuclear war is 100 years, that’s equivalent to 1% per year risk; 10% per decade,” he continued, adding that:

“This shows that the risk is far greater than society gives it credit for.”

This risk — that each of us may die as a result of failed nuclear deterrence — is up to thousands of times greater than the risk posed to your life by a nuclear power plant built right next to your home. Would any of us walk into an airplane if we knew there was a 1% chance of it crashing? That’s something to think about.

All this might sound depressing, but there are reasons to be hopeful. Although the notion of nuclear disarmament sounds naïve in today’s geopolitical context, it is not impossible to accomplish in the future. Many parts of the world have abolished slavery, introduced universal suffrage, improved human rights, and started to tackle human environmental degradation. These are now common sense policies but until not too long ago people would have laughed at entertaining such ideas.

“Ethics is an evolutionary process. We tend to think of ethical decision making as static, but if you think about it just a little bit you’ll see that it changes dynamically over time,” Hellman said.

Hellman says that world peace starts at home because, ultimately, how we treat others reflects how we treat other nations. What’s more, he proposes the radical idea that national security, as it has historically been applied, has become obsolete in an age of nuclear weapons, terrorism, and global environmental crisis.

Instead, national security should be seen as a piece of global security — including that of our adversaries.

“To be more practical, which recent wars of the United States have had their intended results? Which backfired? All of them,” Hellman said.

So far, Hellman has personally spoken to dozens of US Congressmen, educating them on the real risk of nuclear annihilation. This is something we can all do, not just with our representatives, but with our friends, colleagues, and families as well. And if you happen to live in a non-nuclear country, your nation should play a leading role in nuclear disarmament because it is less invested in the myth of the power of these weapons.

“Talking is much more effective than most people realize, it’s how we create societal interest and societal motivation to solve these problems,” Hellman said at HLF19.

Hellman argues that our current biggest societal problems — whether it’s climate change, nuclear weapons, poverty, killer AI, and so on — are merely symptoms that have the same root cause. And in order to survive an uncertain future rife with so many existential threats, humanity simply has to grow up.

“Technology has offered human beings physical power that historically has been thought of as god-like in nature. To use the Judaio-Christian heritage as an example, in the bible only god had the ability to destroy Sodom and Gomora with thunderbolts. What do we call them today? Nuclear weapons. In the bible, only god was capable to create a flood that would necessitate Noah building an arc. Climate change threatens similar consequences today. In Genesis, only god could create lifeforms. We do it routinely in laboratories,” Hellman said.

“In contrast to our technology, our maturity-level as a species will never be godlike. At best, as a society, we behave as irresponsible adolescents who are having a great party and anyone who says ‘hey, maybe we should stop drinking because there’s gonna be a hangover in the morning’, people call him a party pooper,” he added.

In this case, the hangover might be much worse than a bad headache — it could genuinely mean the end of civilization as we know it. Yet there is still much we can do. Be that ‘party pooper’ and talk about this important issue with friends, family, colleagues, and, especially, your political representatives.

“There are two hypotheses. The nobler hypothesis, the better hypothesis is that human beings are capable of radical changes needed for survival in the age of nuclear weapons and other technological powers. The less noble hypothesis is that we’re doomed.”

“If we accept the less noble hypothesis, we’re doomed even if we were capable of the change. If we accept the nobler hypothesis, the worst that happens is we go down fighting and the best that happens is we succeed. So why not assume the nobler hypothesis?”

Watch Martin Hellman’s entire lecture at the 7th Heidelberg Laureate Forum below. He and his wife Dorothy also wrote a book together called “A New Map for Relationships: Creating True Love at Home & Peace on the Planet,” which you can download for free.