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Here's how many millions of lives climate action would save

Wednesday, August 25th 2021, 5:52 pm - Strong climate action now could prevent 74 million heat-related deaths due to climate change, a new study suggests.

As the world warms over the coming century, we’re used to estimating the costs in dollar terms. Now, a new report gives us a new way to think about the benefits of climate action, or costs of inaction: a projected body count.

And, whatever the emissions scenario, that body count will be in the millions.

The study, published in Nature Communications, aims at calculating what the researchers call the “mortality cost of carbon,” or the number of deaths linked to a particular level of emissions and their effect on global warming due to climate change. The researchers found that every 4,434 tonnes of CO2 added to the atmosphere by the end of the 21st Century results in the death of one person. Put another way, a million additional metric tonnes equates to 226 deaths.

“Based on the decisions made by individuals, businesses, or governments, this tells you how many lives will be lost, or saved,” lead author R. Daniel Bressler, a PhD candidate at Columbia University’s Earth Institute, said in a release from the institute. “It quantifies the mortality impact of those decisions. It brings this question down to a more personal, understandable level.”

That understanding becomes more ominous when those numbers are considered at a larger scale.

Bressler’s calculations are based on what happens if emissions continue at their current pace: 2.1°C higher than pre-industrial times by 2050 and 4.1°C by the end of the century. In that scenario, the death toll could be at least 83 million.

Bressler makes clear, however, that that figure relates only to deaths caused directly by excessive heat, such as heat stroke, and doesn’t take into account other expected climate change impacts such as crop failures and an increase in certain kinds of severe weather events – it could, he says, “be a vast underestimate.”


The study relates those per-person emissions to a wide range of human activity and demographic data, to bring the numbers even closer to real-world concepts.

The same million tonnes of emissions that would result in the deaths of 226 people by 2100 equate to the yearly emissions of 216,000 passenger vehicles, 115,000 homes, 35 commercial airliners, or one quarter of a coal-fired power plant, the Earth Institute says.

The 4,434 tonnes of emissions that would result in the death of a single person over that time scale equates to the lifetime emissions of 12.8 people. That figure, however, is the global average, and there’s a major spread between high-income countries and lower-income countries. Those emissions equate to those of 3.5 Americans, 8.5 Chinese, 9.4 Britons, 25.8 Brazilians, 34.8 Indians and 146.2 Nigerians.


The numbers certainly seem dire, something the researchers don’t try to play down. The Columbia release, for example, is bluntly titled “More Carbon Emissions Will Kill More People. Here's How Many.”

The study does, however, point the way to more concerted climate action. All those emissions come from somewhere, and can be brought down, by boosting renewable energy, electrifying power grids, and focussing on zero-emission vehicles.

In the best-case scenario, which the authors define as only a 2.4°C increase in average global temperatures by 2100, heat-related deaths due to climate change would be limited to 9 million. In that sense, climate action could be said to save 74 million lives.

Bressler says individuals, companies and communities should work on reducing their own emissions, but more crucial would be “large-scale policies such as carbon pricing, cap and trade, and investments in low-carbon technologies and energy storage.”

“My view is that people shouldn’t take their per-person mortality emissions too personally,” Bressler says. “Our emissions are very much a function of the technology and culture of the place that we live.”


While the pace at which the world is warming may sometimes seem to vary, no one can deny that the trend has been upward, and looks to stay on that trajectory without action.

Earlier in August, a report by the Intergovernmental Panel on Climate Change (IPCC) found average global temperatures were 1.09°C warmer in the last decade than during the Industrial Revolution, and global temperatures will keep on rising until mid-Century in even the most optimistic scenarios.


What that means is more, and hotter, extreme heat events, and so far, 2021 has certainly born that out.

Just days after the release of the new IPCC report, a weather station in Sicily reported a daytime high of 48.8°C, which, if confirmed, will mark the hottest temperature ever recorded in Europe. In the last days of June, the Interior B.C. village of Lytton shattered Canada’s all-time heat record for three days in a row, peaking at an astounding 49.6°C.

Worldwide, July may have been the hottest month ever recorded on Earth, according to data released by the U.S. National Oceanic and Atmospheric Administration.

Follow Daniel Martins on Twitter at @DFLCMartins

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