Quantifying Global Greenhouse Gas Emissions in Human Deaths to Guide Energy Policy

The paper addresses how to quantify the human cost of greenhouse gas emissions in terms of premature deaths, arguing that deaths are a clearer and more morally salient metric than economic measures or DALYs for guiding energy policy. It outlines the diverse pathways by which climate change causes mortality (direct heat, crop failures, droughts, floods, extreme weather, sea level rise, disease, conflict, and forced migration) and emphasizes that vulnerable populations, especially in the Global South and coastal and equatorial regions, will bear the brunt. The purpose is to synthesize existing approaches to estimating climate-related mortality and to translate emissions into a simple, policy-relevant human-death metric to inform aggressive decarbonization policies.

The review synthesizes multiple strands of literature: (1) Carbon budget and temperature response studies indicating roughly 1 trillion tons of fossil carbon burned leads to ~2 °C warming (Allen et al., Tokarska et al.). (2) Mortality estimations linked to emissions, including Nolt’s philosophical analysis attributing roughly one to two future casualties to an average American’s lifetime emissions (~1840 t CO2e), and Bressler’s "mortality cost of carbon" estimating one premature death per 4434 t CO2 above 2020 emissions rates from heat alone. (3) Human climate niche literature (Xu et al.; Lenton et al.) connecting degrees of warming with billions of people outside the historical temperature niche, implying large mortality absent migration/adaptation. (4) WHO and other public health sources documenting current and projected climate-related mortality burdens (e.g., heat stress, malnutrition, disease) and air pollution mortality from fossil fuels independent of climate effects. (5) Broader risk, conflict, migration, and systems-collapse literatures positing elevated indirect death risks via food insecurity, displacement, and conflict. Together, these sources converge on order-of-magnitude estimates supporting the "1000-ton rule" and highlight large uncertainties and potential non-linearities at higher warming levels.

This is a narrative review and synthesis. The authors: (1) Summarize published approaches that relate cumulative carbon emissions to global temperature increase and then to mortality, using order-of-magnitude reasoning. (2) Derive and apply a heuristic—the "1000-ton rule"—linking 1000 tons of fossil carbon burned to one future premature death, based on a carbon budget of ~1 trillion tons C for ~2 °C warming and a corresponding central estimate of ~1 billion deaths. (3) Cross-check the heuristic with convergent evidence (e.g., Nolt’s per-capita emissions, Bressler’s mortality cost of carbon, human climate niche projections). (4) Introduce the "millilife" unit to translate carbon footprints into fractional human lives lost for communication and policy. (5) Demonstrate applications to policy and corporate accountability by pro-rating responsibility by emissions, proposing decision criteria (e.g., industry kills fewer people than it employs), and exploring legal-economic instruments (e.g., liability, asset forfeiture, bans, taxation). The analysis is explicitly approximate and intended to guide policy prioritization rather than provide precise forecasts.

• 1000-ton rule: Burning approximately 1000 tons of fossil carbon (~3700 tons CO2) causes one future premature death (order-of-magnitude estimate). If ~1 trillion tons of carbon are burned, ~2 °C warming and roughly 1 billion premature deaths are expected over about a century.
• Mortality bounds for ~2 °C: Likely between ~300 million (best case) and ~3 billion (worst case) premature deaths, with central estimate ~1 billion; far higher mortality possible at >2 °C due to non-linear impacts and feedbacks.
• Marginal framing: Every 0.1 °C of additional warming corresponds to roughly 100 million deaths; every 0.001 °C ~1 million deaths, underscoring the life-saving value of incremental emissions reductions.
• Convergent evidence: Nolt’s analysis of average American lifetime emissions (~1840 t CO2e ≈ ~500 t C) implies ~0.5 of a death per person, consistent with the heuristic. Bressler’s estimate (~4434 t CO2 per death from heat alone) is of the same order of magnitude; including indirect pathways likely increases mortality per ton.
• Human climate niche: Each additional degree of warming could leave roughly one billion people outside the historical climate niche (SSP3), implying major mortality risks without migration/adaptation.
• Communication metric (millilife): 1 ton of fossil carbon burned ≈ 1 millilife destroyed; if an average future climate victim loses ~35 life-years, 1 millilife ~13 life-days. Example: an intercontinental round-trip flight (≈1 t C) "steals" ~13 days from a future person.
• Case examples: The Adani Carmichael mine’s reserves (~3 billion tons C) would correspond to ~3 million future deaths (range ~1–10 million). U.S. coal consumption in 2021 (~546 million tons coal) corresponds to ~400,000 future deaths (1000-ton rule; composition-adjusted), while current U.S. coal power air pollution already causes ~52,000 deaths/year, exceeding U.S. coal employment (~51,795 in 2016).

Translating emissions into human deaths provides a morally salient, comprehensible measure that directly addresses the research question of quantifying climate harms for energy policy. The 1000-ton rule, supported by convergent literature, ties cumulative carbon to temperature and temperature to mortality in a way that enables attribution and policy prioritization. Pro-rating responsibility by emissions clarifies liability and accountability and counters attribution challenges. Framing emissions as manslaughter-level harms supports aggressive interventions: rapid elimination of fossil fuel use, bans on deceptive advertising, explicit consumer warnings, legal mechanisms (liability, asset forfeiture, charter revocation), and economic redirection (taxation of fossil profits, mass retraining, accelerated renewables and efficiency deployment). The findings emphasize that even small emissions reductions save lives and that failing to achieve temperature targets should intensify, not relax, mitigation efforts. This approach centers equity, as most deaths will occur among poorer, vulnerable populations lacking adaptive capacity.

This review synthesizes evidence to approximate the human cost of carbon emissions and proposes the 1000-ton rule: roughly one future premature death per 1000 tons of fossil carbon burned (~3700 t CO2). Expressing emissions in human lives clarifies ethical stakes and prioritizes policies that rapidly cut emissions to zero. The work outlines immediate policy implications: accelerate energy efficiency and conservation, electrify end-uses, scale renewable energy, manage carbon waste via taxes and sequestration, and consider stronger measures (e.g., bans on extraction, charter revocations, liability regimes, consumer warnings). Future research should refine mortality estimates across causes and regions, model non-linearities beyond 2 °C, integrate DALY-based analyses, improve attribution methods, and detail implementation pathways to minimize sacrificed human lives during an accelerated decarbonization.

• Order-of-magnitude approach: The 1000-ton rule and the ~1 billion deaths estimate for ~2 °C are approximate and represent the central tendency of a broad (assumed log-normal) distribution; actual mortality could vary by several fold.
• Attribution challenges: Disaggregating direct vs. indirect causes (heat, famine, disease, conflict, migration) and assigning causality to specific emissions sources remain difficult.
• Non-linearities: Mortality may increase non-linearly with higher warming; the heuristic is most defensible below ~2 °C and may understate deaths at higher temperatures.
• Partial cause coverage: Some estimates (e.g., Bressler) include heat-related mortality only, excluding potentially larger indirect effects.
• Data uncertainty: Current death rates attributable to AGW are uncertain; WHO projections (250,000/year in 2030–2050 for select causes) are conservative and omit many pathways.
• Demographic dynamics: Future population size, age structure, and adaptive capacity changes (e.g., fertility declines, migration) affect mortality but are difficult to project reliably.
• DALY comparability: This study emphasizes deaths over DALYs; cross-study comparisons and funding analyses may require updated DALY frameworks and harmonization.
• Policy generalizability: Proposed strong policies may have context-specific feasibility and equity considerations requiring further evaluation and planning.