By Laura Watson

 Event summary by Luke Hatton

“Climate Emergency” was declared as the word of the year in 2019 by Oxford Dictionaries, as the phrase’s popularity soared from relative obscurity into one of the most prominent terms of the year. Scientists have known for decades that climate change poses a significant threat to the world and society, but 2019 seemed to represent a shift in awareness of the urgency of the situation in the mind of the wider world. 
 
There’s no doubt about it—the situation is dire, and action must be taken swiftly if we are to limit climate change to the ‘safe’ level of 1.5 degrees Celsius. But does climate change really represent a ‘major threat to civilisation’, in the words of the 2020 Doomsday Clock Statement? Does it merit moving the minute hand of the Doomsday Clock (a measure of threats to humanity and the planet, founded in 1945 by scientists who helped develop the first atomic weapons) closer to the midnight apocalypse than ever? 
 
We invited three expert panellists, David Wallace-Wells, Zeke Hausfather and Luke Kemp, to shed some light on whether climate change truly poses an existential risk to human life as we know it. 
 
David Wallace-Wells
David is the Deputy Editor of New York magazine, where he writes frequently about climate change and the near future of technology. His cover story from July 2017, surveying the landscape of worst-case scenarios for global warming, became the most-read story the magazine has ever published, and his book on this topic, The Uninhabitable Earth, is a Sunday and New York Times Bestseller. 
 
Primarily, David said he viewed the question of whether climate change poses an existential risk as more of a semantic question; it really does depend on what you mean by the word existential. Practically speaking, he doesn’t think that the threats some climate activists warn of, such as civilisational collapse over the course of the century, are likely. 
 
In some regions, there will be—and indeed there already is—a literal threat to existence due to climate change, with many people dying from climate-related catastrophes. He warns that we have already reached a level of warming today—estimated at over 1℃ above pre industrial levels—where our lives and our society are being shaped by these forces, with increased risk of droughts, hurricanes and mass migration already being seen as a result of climate change. Practically speaking, a 2℃ rise from pre-industrial levels is the best possible outcome we can hope for, but even this could result in hundreds of millions of climate refugees, an additional 150m deaths from air pollution, and summer temperatures that cause heat death or stroke in some regions.
 
Political institutions will be challenged in ways that require us to renovate, reform or rebuild them to cope with this 2℃ world, David added, with the shape of life in a time of intense climate change depending not only on the physical warming, but the institutions we build and the protections we put in place to support human flourishing. To some degree, the nature of our existence will be preserved, but the lives of our children and grandchildren may well be unrecognizable. 
 
We are very far from the curtains coming down and all life on Earth ending from climate change, but we are fooling ourselves by thinking about this in binary terms. We live in a world transformed by global warming and have the opportunity to shape the future of all human life on the planet by choosing to adapt and respond today. Our existence is already being shaped by the climate—the question we must act to answer is how far along that spectrum we will fall. 
 
Zeke Hausfather
Zeke is a climate scientist and energy systems analyst whose research focuses on observational temperature records, climate models and mitigation technologies. He has spent 10 years working in the cleantech sector, and currently is the Director of Climate and Energy at the Breakthrough Institute and the US analyst for Carbon Brief.
 
Zeke began by suggesting that we can all agree that climate change isn’t going to cause the extinction of the human race. Humanity is a remarkably adaptable species, and has spread to the most extreme environments on the planet. However, climate change can and will have a huge impact on society, and could act as an existential risk multiplier, amplifying the impact of other shocks to society, he warned. 
 
The work being done in the lead up to the next report from the International Panel on Climate Change (IPCC) is dividing the ability to adapt to climate change and the magnitude of climate change itself into separate scenarios so the two can be compared. As it turns out, Zeke explained, the worst case for climate change is not necessarily the one with the most warming. The worst case will be a world that is relatively poor and unequal, rife with nationalism, isolationism and conflict, coupled with a high degree of warming. This is a world where institutions and governments are weak, and where climate change could tip civilisations into collapse. Echoing David’s point, he explained that the strength of society and institutions will play a strong role in whether climate change can pose an existential risk. 
 
However, Zeke warned of the risk of framing climate change in terms of extinction, as this can be reductive and lead to doom-ism with regard to climate action. Scientists now argue more with doom-ists than climate sceptics, and defeatism around climate change is dangerous.
 
From a scientific perspective, there is certainly a lot that is unknown about climate systems, but the best models do not tend to indicate a strong significance for tipping points (that is, the risk of reaching a level of warming that sets off a domino effect of positive feedback, significantly raising the warming past the initial level), at least on a global scale. Global warming is largely a function of cumulative emissions, a pretty linear relationship—certainly not containing a strong tipping point that could turn the climate crisis into a climate catastrophe.  
 
Overall, the world certainly isn’t moving in the direction we need fast enough, Zeke said, but it has come far in the last two decades. 20 years ago it looked quite possible that emissions would double or even triple by the end of the century, while ten years ago China was building a coal-fired power station every two days. Ten years later, in 2013, global coal peaked, and has fallen ever since, while renewables are increasingly becoming the cheapest form of energy in many places. We’re moving towards a ‘muddling through’ world right now, where we’re avoiding 4-5℃ but are very far from the best case outcome of 1-2℃. This will be catastrophic for some human and natural systems but it is less likely to pose an existential threat to society than the unconstrained world we were on track for. 
 
Luke Kemp
Luke is a Research Associate with the Cambridge Centre for the Study of Existential Risk, where he looks at past civilisation collapses to guide present policy. He is also an honorary lecturer in environmental policy at the Australian National University (ANU), holds a PhD in international relations and was previously a senior economist at Vivid Economics.
 
The blunt answer, Luke began, is that climate change does pose an existential threat. Above three degrees of warming we are running in the dark, and have to rely on geological records to work out what could happen. There is a lack of interest amongst scientists in looking at the outcomes for large temperature increases and worst case scenarios, as people tend to err on the side of the least drama. Unfortunately, there is not enough information to base conclusions on.
 
It's useful to define what an existential risk is when examining it with regard to climate change, Luke explained. Professor Nick Bostrom defines it as the annihilation of earth-originating intelligent life and/or permanent drastic curtailment of human potential. The easy way to think about this is to think of a global civilisation collapse, with the destruction of most critical systems, the failure of many states and drastic loss of social complexity. With a 2℃ rise, already most atoll and small islands nations are likely to become uninhabitable. 
 
Luke set out four reasons why we can consider climate change as an existential risk;

1. Precedence - all five of the last great extinction events have involved some form of climate change over the last 540m years. The Great Permian Die Off was probably in the region of 8℃, with roughly 90% of the biosphere becoming extinct. However, this event took place over 200,000 years; anthropogenic climate change is happening at a much faster rate. Climactic change has also contributed to the collapse of historical human civilisations, including the Hittites, the lowland Maya, and the Western Roman Empire. However, it was very rare for the climate to be the only stressing factor, echoing the multiplier effect first brought to the discussion by Zeke.
2. Humans are adapted to a very particular climate niche. A recent paper from the National Academy of Sciences estimated this niche to be one with a mean average temperature of 13 degrees, which was also determined to be the optimum level for economic growth.
3. The second order effects of climate change will be much worse in a world rife with inequality, conflict and weak institutions. Conflict already happens in areas with existing ethnic divisions, and climate will act as a stressor. There are good reasons to think that climate change will have knock on effects that make the world a worse place.
4. The occurrence of another event which shocks civilisation, such as nuclear winters or super-volcano eruptions, could combine with climate change to create the ‘perfect storm’ that could lead to civilisational collapse. 

 
Given the unknowns and uncertainties with regard to climate change - it would be bad risk management to not think about the worst case scenario, Luke concluded.
 
To hear a more in-depth examination of the question of whether climate change poses an existential risk, and to hear the answers to the questions posed by the audience, head to our YouTube channel, where a copy of the panel discussion has been uploaded: https://www.youtube.com/watch?v=ah1pLU10o_U. 

By Laura Watson

​Across the world, many stories are being told about climate change. Below are some you may or may not have heard. The complex interactions in these stories between people and the planet mean that they offer us learning opportunities: about the importance of a balance with nature, about the centrality of climate mitigation to human rights, and about the need for action now.
 
Stories of too little water
The Aral Sea was once the 4th largest lake in the world, but 60 years ago Soviet premier Nikita Khrushchev decided to industrialise agriculture across central Asia with dramatic consequences for the lake. To achieve Khruschev’s lofty agricultural goals, the Amu Darya and Syr Darya rivers, which are part of the Aral Sea drainage basin, were diverted into irrigation for cotton fields, and the lake slowly started to dry up. Over 25 years ago, an international fund for saving the Aral Sea was set up, but due to a lack of cooperation between the 5 Asian countries involved on key issues surrounding water, the fund has however had little success; the Aral Sea has now all but disappeared.
 
The disappearance of the inland sea is an issue in and of itself, but its implications go further. Silt from what used to be the lake-bed can now be subjected to wind erosion, with resulting dust storms in 2018 blotting out the sky, turning rain brackish and causing issues for crops. The industrial production of cotton, often using forced labour, in the surrounding region has led to the salinisation of the soil and serious accretion of persistent, toxic pesticide residues, leading to significant health problems. The loss of the moderating influence of this large body of water has made winters colder and summers hotter and drier.

It’s not just the people in the surrounding area who have been impacted by this disaster. As the lake became smaller and the salinity of the water increased, fewer and fewer fish species were able to survive. The lake ecosystem has now collapsed, contributing to the decimation of the once thriving fishing industry in the towns surrounding the lake, and the loss of a number of land animals whose life-cycles depended on the health of the lake.
 
Water issues are amplified by climate change, and the ecological crisis. The Amu Darya and Syr Darya rivers, for example, are fed by glaciers in the distant Pamir mountains which are now rapidly shrinking. But what is even more important is to realise that it didn’t have to go this way. The lesson to learn from the Aral Sea is one which should be applied to the rest of the planet, especially as the climate changes and water becomes more of an issue. This story shows the need to find a balance between extracting water from nature and leaving it where it is, to support the complex ecosystem dynamics which depend on it.
 
The Aral Sea is a worst-case outcome, but one which could soon become true for the rest of the world, including for large rivers like the Colorado River, USA, in the face of both climate change and human exploitation. Water management issues are playing out across the world, and we could soon have conflict breaking out over access to water. For example, an Ethiopian hydro-electric dam project which will affect water levels downstream for countries such as Sudan who already experience water issues will soon begin construction. Some experts claim this could cause a war over water in as little as a few years. We must learn from the mistakes of the Aral Sea before it is too late.
 
Stories of snow
The upper reaches of Finnish Lapland are a largely pristine landscape of forests, marshes, deep clean lakes and scree-covered fells. They are also the homeland of the Sami (Saami, or Sámi) people, as well as lynxes, brown bears, wolves and golden eagles. This important region acts as a buffer against climate change: the peat-rich soils of the area trap significant amounts of carbon, acting as a massive carbon sink. Unfortunately, the area is under direct threat from climate change, as well as the proposed construction of a railroad across the region. 
 
The Sami culture is highly adapted to their home in Finnish Lapland. They use hides for clothing, bones and reindeer antlers for tools and handicrafts. Around 1,000 words in the Sami language exist to describe the appearance and behaviour of reindeer, and 360 relating to snow.
 
But conditions for snow and the reindeer are now no longer predictable; the snow now arrives later, there is less of it, and its structure is different. These changes to snow conditions are threatening the Sami way of life, and in particular their herding practices. Some have now turned to modern technologies to ensure that their reindeer survive in longer snow-free periods. It is likely that as the Sami people lose what was unique to their way of life, the Sami culture and language may begin to disappear too. 
 
Sadly, issues relating to snow are not limited to Finland. Across the world, retreating snowlines have “beached” places like ski resorts. Taking the example of the French mountains, climate change is a threat to the winter ski industry there, as they are receiving declining amounts of natural snow, and the snow they do get falls over shorter periods. The elevation where snow can reliably be expected to fall is predicted to rise, by up to 600m in the Pyrenees, and up to 300m across the Alps.
 
We can move and repurpose hotels, but the ecosystems that these places had as their foundation are changing and even disappearing. While the depopulation of mountain regions may be a feasible response strategy for humans, it is not necessarily one available to the animals and plants left behind. Further concerns for the non-human population arise in relation to potential conflict between humans and animals. Skiing activities will respond to the retreating snow line by moving further up mountain slopes. At the same time, suitable ranges for high elevation bird species may significantly contract (by up to 67% in the Alps). As bird habitats and skiing areas increasingly overlap, conflict between species may ensue, a pattern that may be seen for many animals and ecosystems as climate change progresses.
 
What can we learn from these stories?

• We should seek approaches to human development which allow us to be in balance with nature.
• Both humans and non-human nature need to be considered when taking action to mitigate climate change 
• Climate change mitigation can be a question of human rights for many people, including indigenous inhabitants of vulnerable places
• The impacts of climate change on ecosystems need to be discussed
• We need to act now