Study Overview: The Mortality Cost of Carbon

Released on July 29, 2021, a study led by R. Daniel Bressler, a PhD candidate at Columbia University’s Earth Institute, endeavors to quantify the human cost of carbon emissions. Bressler states, “This analysis illustrates the potential loss of lives due to decisions made by individuals, corporations, or governments. It makes the impact of these decisions more relatable and comprehensible.”

Is it feasible to measure such impacts?

Obtaining accurate, evidence-based figures is notoriously difficult, and any findings should be approached with caution. There’s no universal number to quantify these effects. For instance, during heat waves, the correlation with climate change can be established, but separating natural occurrences from anthropogenic factors presents significant challenges.

Similarly, indirect effects like crop failures leading to starvation, or fatalities from extreme weather events, complicate the picture. Thus, estimating these impacts requires a careful and reasonable approach.

What Metrics are Being Evaluated?

The study focuses on estimating the number of excess deaths attributable to temperature-related changes from 2020 to 2100, resulting from an additional metric ton of CO2 emissions. This is referred to as the Mortality Cost of Carbon (MCC).

The methodology involves assessing the mortality implications of climate change through various key public health studies. However, due to significant uncertainties, the primary conclusions rely on their central estimates. The paper examines direct temperature-related deaths—like heat strokes—while excluding potential fatalities from storms, floods, crop failures, infectious diseases, or conflict. Though these are anticipated consequences of climate change, quantifying them accurately remains elusive.

In essence, the study's findings may likely underestimate the true impacts of climate change.

Key Findings of the Study

The research concludes that if emissions continue unchecked, the MCC is calculated at 2.26×10^-4, or 0.000226 excess deaths per metric ton of CO2 emitted this century. To put this in perspective: for every 4,434 metric tons of CO2 added beyond 2020 emissions, one life will be lost.

While 4,434 may seem substantial, it's equivalent to the total emissions produced by 3.5 average Americans over a lifetime. The study elaborates that, on a global scale, this amount corresponds to the lifetime emissions of approximately 12.8 individuals, resulting in a theoretical loss of 0.08 lives per capita.

In more affluent nations like the UK, it would require the emissions of 9.4 individuals to account for similar excess mortality. In contrast, it would take 25.8 Brazilians (0.04 deaths per capita) or 146.2 Nigerians (0.01 deaths per capita). A few countries, including oil-rich Saudi Arabia, show even more alarming figures, with 0.33 deaths per capita attributed to their emissions.

In broader terms, an increase of 1 million metric tons over the 2020 baseline would correspond to an estimated loss of 226 lives. This volume of emissions equals the annual output from 216,000 passenger cars, 115,000 homes, or 35 commercial airliners.

The Implications of Our Emissions

The findings underscore a critical reality: emitting CO2 carries severe consequences. We are all aware of the financial ramifications—think of the costs associated with storms, floods, and heatwaves. However, the human toll, particularly in terms of premature deaths, is less widely recognized.

By 2100, failing to address climate change could lead to an estimated 83 million excess deaths.

Is this a realistic projection? The scenario is plausible under a "business as usual" approach. The study anticipates that, if current emission trends persist, global temperatures will exceed a rise of 2.1 degrees Celsius (3.8 degrees Fahrenheit) above preindustrial levels by 2050—the threshold beyond which the most severe climate consequences will occur. Under this scenario, temperatures could soar to 4.1 degrees Celsius (7.4 degrees Fahrenheit) by 2100, leading to the predicted 83 million excess deaths, primarily in the hottest and poorest regions of the world: Africa, the Middle East, and South Asia.

The first video discusses the alarming correlation between carbon emissions and potential future fatalities, emphasizing the urgent need for action.

Taking Action to Mitigate the Crisis

Conversely, if we act decisively to mitigate climate change and limit global warming to 2.4 degrees Celsius by 2100, we could prevent 74 million of these deaths, resulting in only 9 million fatalities.

Our species now stands at a crossroads, and the urgency for action has never been greater. With COP26 on the horizon, the time to make impactful choices is now.

Data and Code Availability

Further Reading

For more in-depth insights, the original paper in Nature Communications is available as Open Access: "The Mortality Cost of Carbon." Additionally, a related article in Scientific American, titled "Act on Climate Emergency Now to Prevent Millions of Deaths, Study Shows," elaborates on these findings.

The second video further explores the mortality implications of carbon emissions, providing vital context for the ongoing climate debate.