Understanding the Potential Impact of Climate Change on Humanity
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Chapter 1: The Existential Risk of Climate Change
Is climate change likely to lead to human extinction? The short answer is probably not. However, the long answer reveals more complexity.
Existential risk refers to the possibility that humanity could face complete extinction, akin to the fate of the dinosaurs. This concept is distinct from severe global conflicts, pandemics, or civilizational declines; it signifies the total eradication of human life or a future devoid of hope.
In his recent book The Precipice, Toby Ord discusses the existential threats facing humanity in the 21st century, suggesting a 1 in 6 chance of total extinction—similar to the odds of rolling a six on a die.
A breakdown of extinction probabilities from various causes is as follows: - Natural disasters (like asteroids and supervolcanoes): 1 in 10,000 - Naturally occurring pandemics: 1 in 10,000 - Nuclear conflict: 1 in 1,000 - Climate change: 1 in 1,000 - Engineered pandemics: 1 in 30 - Unaligned artificial intelligence: 1 in 10 - Unforeseen human-induced risks: 1 in 30
Overall, the aggregate risk is 1 in 6. For a thorough exploration, Toby Ord's book is an excellent resource, based on approximately 15 years of research. The findings indicate that climate change is not our primary concern. If existential extinction is your primary worry, it is far more urgent to focus on preventing unaligned AI (100 times more critical) or engineered pandemics (30 times more critical).
What makes climate change seem less of a threat? While it is indeed one of the pressing challenges of our time, there are layers to this issue that warrant exploration.
Why Climate Change May Not Be an Existential Threat
Toby Ord acknowledges a 1 in 1,000 chance that climate change could pose an existential threat, albeit a low one. Although Ord's analysis is broad, John Halstead provides a detailed examination of how climate change can pose risks and estimates its likelihood. By evaluating factors like equilibrium climate sensitivity and Earth system sensitivity, Halstead looks into critical tipping points such as the permafrost carbon release and the melting of methane clathrates.
In numerous scenarios concerning climate feedback loops and tipping points—especially those that could take millennia to reverse—temperature increases appear minimal compared to human-induced factors. For instance, even if permafrost thaws, it would only contribute an increase of 0.42 degrees Celsius by 2300 at the current rate. Additionally, while methane clathrate could release significant carbon, the timeline for such events spans centuries to millennia, allowing humanity ample opportunity to adapt and mitigate the effects.
Consideration of Other Indirect Risks
Halstead also assesses other indirect threats, concluding they are unlikely to lead to extinction. Species have historically adapted to much larger temperature changes. Research indicates that mass extinctions were often driven by volcanic activity rather than CO2 increases alone. While sea levels may rise by 1 meter by the century's end, this is manageable. Moreover, although heat stress may become more frequent, adaptation strategies like air conditioning are already in place. Crop yields, modeled under a 5-degree increase, might vary between -20% and +10% with adaptation strategies. Advances in technology such as gene editing and improved logistics could further bolster food security.
It’s Not a Clear-Cut Situation
This is not to downplay the seriousness of climate change. It could potentially be five times deadlier than COVID-19 by 2100, due to heatwaves, droughts, and flooding, leading to massive displacement of populations.
According to Bill Gates, "By 2060, climate change could be as deadly as COVID-19, and by 2100, it could be five times as lethal." There remains substantial uncertainty within climate models, particularly concerning extreme scenarios, such as a 6-degree temperature rise. While this may seem remote, reaching 700 ppm CO2—our current trajectory under existing policies—could present a 1 in 10 chance of a 6-degree increase.
Furthermore, even if climate change does not pose a direct existential threat, it can create significant indirect risks, including mass migrations and political unrest. Thus, while climate change might not directly lead to human extinction, it could foster conditions ripe for nuclear conflict or hinder cooperation on other critical risks, like engineered pandemics or unaligned AI.
Thus, climate change should be viewed as a contributing factor to existential risks: it may not directly threaten human extinction, but it heightens the risk of it occurring. This is a sobering consideration.
What Actions Can Be Taken?
In addition to advocating for rapid decarbonization and electrification, as well as developing carbon capture technologies, further research is essential. There is a notable gap in understanding the tail risks of climate sensitivity, as well as uncertainties regarding key feedback loops. Toby Ord has identified several research areas worth pursuing: - The possibility of a runaway greenhouse effect - Understanding feedback loops from permafrost and methane clathrates - Investigating cloud feedback mechanisms - Characterizing the right-hand tail of climate sensitivity - Enhancing our understanding of extreme warming events - Investing in food substitutes to mitigate potential long-term reductions in global food supply
The recent pandemic has highlighted the fragility of our systems and our dependence on natural forces. For humanity to thrive within natural ecosystems, we must learn from and collaborate with them. Failure to do so could jeopardize our very existence.
For further insights on this topic, consider exploring Climate Shock and the referenced document.
Chapter 2: Exploring the Risks of Climate Change
The first video, Can climate change cause human extinction?, delves into the relationship between climate change and the potential for human extinction.
The second video, Human Extinction in 2050? Stop Dreaming!, discusses the myths and realities surrounding the timeline and risks of human extinction due to climate change.