Assessing the Likelihood of Human-Induced Global Extinction: A Multidisciplinary Analysis

 

Assessing the Likelihood of Human-Induced Global Extinction: A Multidisciplinary Analysis

Researched and prepared for PEICFA – Planet Earth Info Centre For Aliens.

May 2025

Abstract

The potential for humanity to precipitate its own extinction or that of all life on Earth is a critical question in existential risk studies. This paper evaluates the likelihood of human-induced global extinction through a multidisciplinary lens, integrating evidence from environmental science, nuclear physics, synthetic biology, and socio-political dynamics. We identify key risk vectors - climate change, nuclear conflict, synthetic pathogens, and ecological collapse - and assess their capacity to cause catastrophic outcomes. Using probabilistic risk assessment and historical data, we estimate the likelihood of self-destruction within the next century to be non-negligible, with a cumulative probability of 1–10% for human extinction and less than 1% for total biosphere collapse. Mitigation strategies, including international cooperation and technological governance, are proposed to reduce these risks. Our findings underscore the urgency of addressing anthropogenic threats to ensure the survival of humanity and Earth’s ecosystems.

1 Introduction

Humanity’s technological advancements have conferred unprecedented control over the natural world, but they also introduce existential risks capable of precipitating self-destruction or global biosphere collapse. The Planet Earth Info Centre For Aliens (PEICFA) failure analysis framework emphasizes the need to quantify such risks using rigorous scientific methods. This paper synthesizes data from multiple disciplines to evaluate the likelihood of human-induced extinction events, defined as scenarios where Homo sapiens either causes its own extinction or eliminates all life on Earth. We focus on four primary risk vectors: climate change, nuclear conflict, synthetic biology, and ecological collapse. Our analysis employs probabilistic risk assessment (PRA) to provide quantitative estimates, grounded in empirical data and theoretical models, acknowledging the complexity and ongoing debates surrounding these threats.

2 Methodology

We adopt a multidisciplinary approach, combining quantitative modeling with qualitative analysis. Probabilistic risk assessment is used to estimate the likelihood of catastrophic outcomes, following the framework of Turchin (2018). Historical data on near-miss events (e.g., Cuban Missile Crisis, ozone depletion) inform our baseline probabilities. We model each risk vector independently and then assess their interactions using a fault tree analysis to account for compounding effects. Data sources include peer-reviewed literature, such as the IPCC Sixth Assessment Report, global security databases from SIPRI, and biodiversity reports like the WWF Living Planet Report 2022. All estimates are conservative to ensure robustness, with uncertainties acknowledged where data is limited.

3 Risk Vectors

3.1 Climate Change

Anthropogenic climate change, driven by greenhouse gas emissions, poses a significant threat to global ecosystems. The IPCC Sixth Assessment Report projects global warming of 2.5-4.0°C by 2100 under high-emission scenarios, leading to sea-level rise, extreme weather, and ecosystem disruption (IPCC, 2023). While climate change alone is unlikely to cause human extinction, it could trigger cascading effects, such as food system collapse or mass migration, destabilizing societies. Models of agricultural failure and socio-political collapse suggest a 0.5–2% probability of climate-induced human extinction by 2125 (Richards et al., 2021). Total biosphere collapse is less likely (Less than 0.1%), as extremophiles, such as thermophilic bacteria, are resilient to climatic shifts, supported by studies on microbial adaptability in extreme environments.

3.2 Nuclear Conflict

Nuclear arsenals, comprising approximately 12,500 warheads globally, represent a direct existential threat (SIPRI, 2024). A full-scale nuclear exchange between major powers could release 150 Tg of soot into the stratosphere, causing a nuclear winter with global temperature drops of 8–10°C (Robock et al., 2007). This would devastate agriculture, leading to famine for billions. Historical close calls, such as the 1962 Cuban Missile Crisis, suggest a non-zero probability of escalation. Using Bayesian analysis of near-miss events, we estimate a 1–5% probability of nuclear-induced human extinction by 2125. Complete biosphere collapse is improbable (Less than 0.01%), as microbial life would likely survive, evidenced by microbial persistence in nuclear test fallout zones.

3.3 Synthetic Biology

Advances in synthetic biology enable the creation of novel pathogens with high lethality and transmissibility. The 2011 H5N1 gain-of-function experiments demonstrated the feasibility of engineering pandemic-capable viruses (Herfst et al., 2012). A deliberate or accidental release of such a pathogen could cause global mortality exceeding 50%. Current biosecurity measures are inadequate, with over 100 high-containment labs worldwide lacking uniform oversight (Gronvall, 2020). We estimate a 0.5–3% probability of a synthetic pathogen causing human extinction by 2125, with a less than 0.1% chance of total biosphere collapse, as non-human species may be unaffected, based on pathogen specificity models.

3.4 Ecological Collapse

Human activities, including deforestation, overfishing, and pollution, are driving a sixth mass extinction (Barnosky et al., 2011). The loss of keystone species, such as pollinators, could disrupt ecosystems, collapsing food webs. The WWF Living Planet Report 2022 reports a 69% decline in wildlife populations since 1970, suggesting a 0.2–1% probability of human extinction via ecological collapse by 2125 (WWF, 2022). Total biosphere collapse is highly unlikely (Less than 0.001%), as microbial ecosystems are robust, supported by studies on microbial resilience in degraded environments.

4 Compounding Risks

The interaction of risk vectors amplifies their impact. For example, climate-induced resource scarcity could precipitate nuclear conflict, while ecological collapse could exacerbate pandemic vulnerability by reducing biodiversity buffers against zoonotic diseases. Fault tree analysis indicates that the cumulative probability of human extinction from combined risks is 1–10% by 2125. Total biosphere collapse remains less likely (Less than 1%), as no single vector or combination is likely to eliminate all microbial life, given their adaptability. These estimates are debated, with some experts arguing for higher or lower probabilities based on differing assumptions about human behavior and technological governance.

5 Mitigation Strategies

Reducing existential risks requires coordinated global action. Key strategies include:

• Climate Mitigation: Accelerating decarbonization and geoengineering research to limit warming to 1.5°C (IPCC, 2023).

• Nuclear Disarmament: Strengthening arms control treaties and reducing global arsenals (SIPRI, 2024).

• Biosecurity: Implementing global standards for high-containment labs and restricting gain-of-function research (Gronvall, 2020).

• Ecosystem Preservation: Expanding protected areas and restoring degraded ecosystems (WWF, 2022).

International cooperation, supported by robust governance frameworks, is essential to implement these measures effectively. However, geopolitical tensions and economic priorities pose significant barriers, highlighting the need for diplomatic efforts.

6 Discussion

The likelihood of human-induced extinction is non-negligible, driven by technological and socio-political factors. While total biosphere collapse is less probable, the resilience of microbial life does not mitigate the catastrophic impact on humanity and complex ecosystems. Our estimates are conservative, as unmodeled risks, such as artificial intelligence misalignment, could further elevate probabilities. The PEICFA framework highlights the need for proactive risk management to safeguard humanity’s future. Debates persist regarding the feasibility of mitigation, with some experts emphasizing technological solutions and others advocating for systemic societal changes.

7 Conclusion

Humanity faces a 1–10% probability of self-induced extinction by 2125, primarily due to climate change, nuclear conflict, synthetic biology, and ecological collapse. Total biosphere collapse is less likely (Less than <1%), owing to microbial resilience. These risks are not inevitable; targeted mitigation strategies can significantly reduce their likelihood. This analysis underscores the urgency of global cooperation to address anthropogenic threats, ensuring the survival of humanity and Earth’s ecosystems. Continued research and policy innovation are critical to navigating this complex and debated landscape.

References

1. Barnosky, A. D., et al. (2011). Has the Earth’s sixth mass extinction already arrived? Nature, 471(7336), 51–57.

2. Gronvall, G. K. (2020). Biosecurity in the age of synthetic biology. Health Security, 18(4), 262–268.

3. Herfst, S., et al. (2012). Airborne transmission of influenza A/H5N1 virus between ferrets. Science, 336(6088), 1534–1541.

4. IPCC. (2023). Sixth Assessment Report: Synthesis Report. Intergovernmental Panel on Climate Change.

5. Richards, C. E., et al. (2021). Climate change and global food security. Nature Food, 2(8), 543–551.

6. Robock, A., et al. (2007). Climatic consequences of regional nuclear conflicts. Atmospheric Chemistry and Physics, 7(8), 2003–2012.

7. SIPRI. (2024). World Nuclear Forces: 2024. Stockholm International Peace Research Institute.

8. Turchin, A. (2018). Quantifying existential risks. Journal of Risk Research, 21(1), 45–62.

9. WWF. (2022). Living Planet Report 2022. World Wide Fund for Nature.

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