At its height, the Roman Empire was home to about  30% of the world’s population, and in many ways it was the pinnacle of human advancement. Its  citizens enjoyed the benefits of central heating, concrete, double glazing,  banking, international trade, and upward social mobility. Rome became the first city in history with one million inhabitants  and was a center of technological, legal, and economic progress. An empire impossible  to topple, stable and rich and powerful.

Until it wasn’t anymore. First slowly then  suddenly, the most powerful civilization on earth collapsed. By civilization, we mean a complex  society where labor is specialized and social classes emerge and which is ruled by institutions.  Civilisations share a dominant mutual language and culture and domesticate plants and  animals to feed and sustain large cities, where they often construct impressive monuments.

Civilization lets us become efficient on large  scales, collect vast amounts of knowledge, and put human ingenuity and the natural resources  of the world to work. Without civilization, most people would never have been born. Which  makes it a bit concerning that collapse is the rule, not the exception. Virtually all  civilizations end, on average after 340 years.

Collapse is rarely nice for individuals.  Their shared cultural identity is shattered as institutions lose the power to organize people.  Knowledge is lost, living standards fall, violence increases and often the population declines.  The civilization either completely disappears, is absorbed by stronger neighbors  or something new emerges, sometimes with more primitive  technology than before.

If this is how it has been over  the ages, what about us today?

Just as Europeans forgot how to build  indoor plumbing and make cement, will we lose our industrial technology,  and with that our greatest achievements, from one dollar pizza to smartphones or  laser eye surgery? Will all this go away too?

Today our cities stretch for thousands of  square kilometers, we travel the skies, our communication is instant. Industrial  agriculture with engineered high yield plants, efficient machinery and high potency fertilizer  feeds billions of people. Modern medicine gives us the longest lifespan we’ve ever had, while  Industrial technology gives us an unprecedented level of comfort and abundance – even though  we haven’t yet learned to attain them without destroying our ecosphere. There are arguably  still different civilizations around today that compete and coexist with each other, but together  they also form a singular, global civilization.

But this modern, globalized civilization is even  more vulnerable in some ways than past empires, because we are much more deeply interconnected.

A collapse of the industrialized world literally  means that the majority of people alive today would perish since without industrial agriculture  we would no longer be able to feed them.

And there is an even greater  risk: What if a collapse were so deeply destructive that we were  unable to re-industrialize again?

What if it ruined our chances of enjoying a  flourishing future as a multiplanetary species?

A global civilizational collapse  could be an existential catastrophe: something that ruins not just the  lives of everyone alive today, but all the future generations that could have  come into being. All the knowledge we might have discovered, the art we might have created, the  joys we might have experienced, would be lost.

So, how likely is all of this?

Let’s start with some good news. While  civilization collapses have happened regularly, none have ever derailed the course of  global civilization. Rome collapsed, but the Aksumite Empire or the Teotihuacans  and of course the Byzantine Empire, carried on.

What about sudden population crashes?

So far we have not seen a catastrophe  that has killed much more than 10% of the global population. No pandemic,  no natural disaster, no war.

The last clear example of a rapid global  population decrease was the Black Death, a pandemic of the bubonic plague in the fourteenth  century that spread across the Middle East and Europe and killed a third of all Europeans  and about 1/10th of the global population.

If any event was going to cause the  collapse of civilization, that should have been it. But even the Black Death demonstrates  humanity's resilience more than its fragility.

While the old societies were  massively disrupted in the short term, the intense loss of human lives and suffering  did little to negatively impact European economic and technological development in the long run.  Population size recovered within 2 centuries, and just 2 centuries later, the  Industrial Revolution began.

History is full of incredible recoveries from  horrible tragedies. Take the atomic bombing of Hiroshima during World War 2. 140,000 people were  killed and 90% of the city was at least partially incinerated or reduced to rubble. But against all  odds, they made a remarkable recovery! Hiroshima’s population recovered within a decade, and today  it is a thriving city of 1.2 million people.

None of this made these horrible events any  less horrible for those who lived through them.

But for us as a species, these  signs of resilience are good news.

Why Recovery is Likely Even in the Worst Case One thing that’s different from historic collapses  is that humanity now has unprecedented destructive power: Today’s nuclear arsenals are so powerful  that an all-out global war could cause a nuclear winter and billions of deaths. Our knowledge  of our own biology and how to manipulate it is getting so advanced that it is becoming  possible to engineer viruses as contagious as the coronavirus and as deadly  as ebola. Increasingly the risk of global pandemics is much higher than in the past. So we may cause a collapse ourselves and it might be much worse than the things nature has thrown  at us, so far. But if, say 99% of the population died, would global civilization collapse  forever? Could we recover from such a tragedy?

We have some reasons to be optimistic.  Let’s start with food. There are 1 billion agricultural workers today so, even if the  global population fell to just 80 million, it is virtually guaranteed that many  survivors would know how to produce food.

And we don’t need to start at square one because  we could still use modern high-yield crops.

Maize is 10 times bigger than its wild ancestor;  ancient tomatoes were the size of today’s peas.

After agriculture, the next step towards recovery would be rebuilding industrial capacity,  like power grids and automated manufacturing.

A huge problem is that our economies of scale make  it impossible to just pick up where we left off.

Many of our high tech industries are  only functional because of huge demand and intensely interconnected supply  chains across different continents.

Even if our infrastructure were left unharmed, we  would make huge steps backwards technologically.

But then again, we are thinking in larger time  frames. Industrialization originally happened 12,000 years after the agricultural revolution. So  if we need to start over after a massive collapse, it shouldn’t be that hard to re-industrialize,  at least on evolutionary timescales.

There’s a hitch, though. The Industrial  Revolution was fuelled, literally, by burning easily-accessible coal and we are still very  much reliant on it. If we use it all up today, aside from making rapid climate change  much worse, we could hinder our ability to recover from a huge crisis. So we  should stop using easy-to-access coal, so it can serve as a civilization  insurance in case something bad happens.

Another thing that makes recovery likely is that  we’d probably have most of the information we need to rebuild civilization. We would certainly  lose a lot of crucial institutional knowledge, especially on hard drives that nobody could  read or operate anymore. But a lot of the technological, scientific, and cultural knowledge  stored in the world's 2.6 million libraries, would survive the catastrophe. The post-collapse  survivors would know what used to be possible, and they could reverse engineer some  of the tools and machines they’d find.

In conclusion, despite the bleak  prospect of catastrophic threats, natural or created by ourselves,  there is reason for optimism: humankind is remarkably resilient, and even in  the case of a global civilizational collapse, it seems likely that we would be able to recover  – Even if many people were to perish or suffer immense hardship. Even if we lost cultural  and technological achievements in the process.

But given the stakes, the risks are still  unnervingly high. Nuclear war and dangerous pandemics threaten the amazing global civilization  we have built. Humanity is like a teenager, speeding around blind corners, drunk, without  a seat belt. The good news is that it is still early enough to prepare for and to mitigate  these risks. We just need to actually do it.