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Could climate change really end civilisation?

Global warming will cause massive social and political upheaval. But despite wild claims of apocalypse, our civilisation – and our species – are not under threat.

 Australia has an abundance of think-tank reports. Some are even useful. But few attract the attention given to a 2019 report from the little-known Breakthrough group which claimed there was an “existential risk to civilisation”.

It was reported world-wide.

Other claims go further. “Will global warming cause extinction?” asked one green activist website, before answering its own question with: “Eventually, yes. Global warming will invariably result in the mass extinction of millions of different species, humankind included.”

These claims make good headlines. Whether they’re true, or responsible, are different questions seldom asked by journalists.

A young woman asked me recently whether it was ethical for her to have children because she was so deeply worried about climate change. It was a shocking thing to hear. The world will continue, I replied. Civilisation and humanity will continue. We will get through this.

There’s a lively debate about whether fear is the best tool for promoting behaviour change. There’s less debate about whether any message, however well-intended, should be based on anything but solid science. The truth, in other words.

Those who deny that anthropogenic climate change is happening at all, and those who claim it will end the world, are equally dishonest and equally wrong.


The most authoritative guide to climate change comes from the most recent report from the UN’s Intergovernmental Panel on Climate Change. It’s scary enough.

The report models four main scenarios: global warming at 1.5, 2, 3 and 4 degrees above pre-industrial levels.

The point at which global warming can be kept to 1.5 degrees has probably been passed. If all the pledges made in the Paris Agreement in 2015 actually happened, warming would reach 2.1 degrees by 2100. And pledges are easier than action: according to the independent Climate Action Tracker, actual policies would deliver warming of 2.7 degrees.

On the other hand, policies are unlikely to remain where they are now. Big emitters – the US, Europe and China – are making more serious attempts to limit emissions, though India remains a laggard. Smaller emitters, including Australia, are also taking serious action. None of this is yet enough, but there’s more reason for hope than there was a few years ago. So the most likely outcome is a global increase at around two degrees: maybe a bit more, possibly a bit less.

At two degrees, peak summer temperatures are likely to increase by between two and three degrees across Australia, with the worst impacts in the already-arid zone. Globally, increases in maximum land temperatures of around three degrees can be expected across most continents: the Mediterranean basin, the Middle East, South America, the Sahara and southern Africa.

Australia will become drier, though not dramatically so. The worst drying effects, measured by soil moisture – a key measure for food production – will be around the Mediterranean, Central and South America, and inland China. Equatorial Africa and central Asia will become wetter.

Rainfall (measured by wettest-day change) isn’t expected to vary much in Australia. Across the globe, equatorial Africa is the standout, with maximum rainfall increasing by 30% to 40%.

If this sounds benign, it isn’t. We are already experiencing the effects of climate change, though global average temperatures are now only about 1.1 degrees above pre-industrial levels. The fires, floods, cyclones and droughts we have been living through will continue to increase in frequency and severity. The number of heat-related deaths will increase, particularly in tropical areas. Fish stocks will be further depleted. Crops will be harder to grow and food crises will become even more severe and more frequent. More and more species and habitats will be lost.

Sea level rise is perhaps the greatest near-term threat to human populations, given that so many millions live in low-lying regions, such as river deltas.

But there’s hope in the IPCC report too: “Deep, rapid and sustained greenhouse gas emission reductions would limit further sea level rise acceleration and projected long-term sea level rise commitment.”

And the report says that the critically important Atlantic Meridional Overturning Circulation [AMOC] current “will not collapse abruptly before 2100.”

“The AMOC circulates water from north to south and back in a long cycle within the Atlantic Ocean,” explains the US National Ocean Service. “This circulation brings warmth to various parts of the globe and also carries nutrients necessary to sustain ocean life.”

If this system remains in place, as seems likely under a two-degree scenario, it is probable other critical ocean systems will survive too. The world will be spared some of the worst effects of climate change.

America’s National Aeronautics and Space Administration (NASA) has produced this chart using IPCC data to show what would happen if global temperatures rose by two degrees above pre-industrial levels. The line shows the most likely outcome; the shaded areas show the range of statistical probabilities.

According to the base-case scenario, average sea levels would increase by 20 centimetres by 2050, 51 centimetres by the end of the century and 71 centimetres by 2150.


None of this, though, justifies the overwrought imaginings of climate apocalypse. It does not imply the destruction of civilisation and of the human race itself.

Those who push these glib notions often draw on what they claim to be the lessons of history, where environmental pressure has caused ancient societies to collapse. They point to four examples:

  • The Mayan culture in central America between the third and seventh centuries;

Today, the ruins of some of these cities remain – the Angkor Wat complex in Cambodia, Mayan ruins in Guatemala and eroded remains in the Iraqi desert.

Climate changes did occur, including a 300-year dry period in Mesopotamia. But over-population, war, conquest and cultural decline had an equal and, often, greater influence. And the people did not just die: they moved, just as the Mayans did. Climate change is only one of several conflicting theories about the cause of the protracted Mayan decline. Most archaeologists reject the term “collapse”.

A bigger point is that these were local events. However disastrous they may have been to the people involved, they did not constitute a collapse of global civilisation. Even the fall of the western Roman empire did not end world civilisation. Western Europe declined into a Dark Age but the eastern empire, based on Constantinople, flourished and even reconquered Italy. In Persia, dynasties succeeded each other but its rich culture survived wars and the Mongol invasions. The Arab culture of the Middle-East reached its height after the fall of Rome.

There are other lessons in the history of humanity’s resilience.

Around 6000 years ago, probably in central Asia, a bacterium lost some of its genetic code and acquired new genes from another passing bacterium.

It happens all the time. Usually it doesn’t mean much but this time it did. We now know the reconstituted microbe as Yersinia pestis, the plague bacillus.

Then, as now, Y. pestis infected rats and was transmitted to humans through flea bites. In the ancient world of scattered neolithic settlements, outbreaks remained local and small. By the early sixth century AD, trade routes expanded its range – first to Egypt and then, accompanying grain shipments, to Constantinople, the heart of the Byzantine empire.

The Plague of Justinian began in 542. The historian Procopius, who was there, estimated that at its peak, 10,000 people in Constantinople were dying daily. By the time the main wave was over, in 549, it had spread throughout Europe and the Mediterranean.

It was only the first stage of what is now called the First Plague Pandemic. Major outbreaks recurred periodically over the next two centuries, killing somewhere between 20 million and 100 million people – 20% to 60% of the entire population of Europe.

It spread to Rome, the Arabian peninsula, Mesopotamia, Syria, Africa and China. There are no reliable estimates but the global death toll could be as high as half of the earth’s population.

It did not, though, end civilisation. Humanity continued. The Byzantine empire was weakened and the balance of power in the Mediterranean changed but the eastern Roman Empire persisted until 1453, when the Ottoman Turks captured Constantinople. By then, Europe was on the brink of the renaissance and the birth of the modern era.

Eight hundred years after the first outbreak in Constantinople, the Mongol Golden Horde of the khan Jani Beg besieged the Genoese trading port of Kaffa in the Crimea. The Mongols threw the bodies of dead plague victims into the walled city. From there, refugees carried the bacillus to other Genoese centres; rats on trading ships took the disease across the Mediterranean Basin. It caused massive loss of life throughout north Africa, western Asia, and reached the rest of Europe through Constantinople, Sicily, and the Italian peninsula.

“There was no one who wept for any death,” wrote Agnolo di Tura in Siena, “for all awaited death. And so many died that all believed it was the end of the world.”

The Black Death is believed to have killed between 30% and 60% of the European population between 1346 and 1353 – between 75 million and 200 million. But it was only the first stage of the Second Plague Pandemic, which continued in waves for the next several centuries across Europe as far north as Scandinavia, and throughout the Mediterranean, Russia, India, Mongolia and China.

Once again, though, civilisation and humanity continued.


Humans are ill-equipped to deal with new threats until they become so close as to be undeniable. We seem to have evolved to react when we see the sabre-toothed tiger, not when we hear a distant roar.

So our tardiness in dealing with climate change is unsurprising. For at least 30 years, the science of global warming has been clear. But it was still in the distance, so we kept going as we always had. And those who said it wasn’t happening at all were listened to.

Now, though, the sabre-toothed tiger has entered the compound. We can smell its breath.

Over the past couple of years, the entire world has experienced patterns of climatic destruction that just do not comply with normal weather. There have been record-breaking wildfires in Australia, the Arctic, in South Africa, in both North and South America; storms and savage cyclones in the Pacific; floods in Australia, south Asia and China; heatwaves in east Asia and Europe; droughts in the Middle-East and Africa.

It is as if the climate has reached a tipping-point; and it has supplied a second tipping-point. The pendulum has finally swung, far too late for comfort, from inertia to action. At last, the demand from peoples around the world is to do something. Now!

The painful and dilatory response of human institutions to climate change has followed a familiar, classic pattern. It is clearly recognisable in the famous seven stages of grief conceived by Elisabeth K├╝bler-Ross:

  • Shock: Initial paralysis at hearing the bad news.

  • Denial: Trying to avoid the inevitable.

  • Anger: Frustrated outpouring of bottled-up emotion.

  • Bargaining: Seeking in vain for a way out.

  • Depression: Final realisation of the inevitable.

  • Testing: Seeking realistic solutions.

  • Acceptance: Finally finding the way forward.

After being grievously bludgeoned by reality, we have finally reached Number Five: depression, the final realisation of the inevitable. Some governments, but not enough, are seeking realistic solutions. But the world is still too far away from finally finding the way forward.

As the climate crisis continues to make itself obvious, and the tiger’s breath becomes ever more fetid, the fight back is ramping up. If that continues, as seems likely, we have sound reason to hope.


As climate policies strengthen and become more effective, they will initiate and then accelerate a downward trend in greenhouse gas emissions. The worst damage will be avoided and some may even be reversed.

The 2023 IPCC report gives some highly qualified hope. “Some future changes are unavoidable and/or irreversible but can be limited by deep, rapid and sustained global greenhouse gas emissions reduction,” it says.

“Limiting global surface temperature does not prevent continued climate system components that have multi-decadal or longer timescales of response. Sea level rise is unavoidable for centuries to millennia due to continuing deep ocean warming and ice sheet melt, and sea levels will remain elevated for thousands of years.”

But we have a decent chance of reversing or at least halting some changes. These may include the frequency and intensity of storms and the depth of droughts. They also include limiting or avoiding changes to ocean and atmospheric chemistry that would have the theoretical potential of disrupting the earth’s complex mechanisms of adjustment upon which everything relies.

Climate change is happening at the first time in history that humans have the science to detect it and the technology to do something about it. Just a few decades ago, the capacity of measuring and interpreting atmospheric changes would have been unable to give us the essential information upon which climate action depends. Alternatives to fossil fuels for driving the machinery of modern life were limited or absent. There were no solar panels and no lithium ion batteries. The wind turbines of the past would not have been able to do the job now demanded of them. Pumped hydro, large-scale solar farms and hydrogen power were seldom discussed and would not have been thought viable.

Now, renewables are cheaper than fossil fuels. Human ingenuity created the industrial world and got us into this mess. But that same ingenuity provides the way out.

By the skin of our teeth, we will get through this.


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