Climate crisis could kill 83 million people by 2100, study finds

The climate crisis would cause an estimated 83 million excess deaths by 2100, according to a new study.

The research paper, published on Wednesday, uses a new metric called the “mortality cost of carbon” to estimate the number of deaths caused by the emissions from putting one additional metric ton of carbon dioxide (CO2) into the atmosphere.

The study’s metric is based on temperatures reaching an average of 4.1C by 2100.

By adding 4,434 metric tons of CO2 in 2020, equivalent to lifetime emissions of 3.5 average Americans the study notes, “causes one excess death globally in expectation between 2020-2100”.

The carbon produced by Americans is far greater than in other countries - some 25 Brazilians or 146 Nigerians emit the equivalent amount of carbon over a lifetime, according to the peer-reviewed study published in journal, Nature Communications.

Additionally, the study assumes that on our current emissions trajectory by mid-century, average temperatures will surpass 2.1 degrees Celsius (3.8F) above the preindustrial era. This is the largely agreed-upon limit after which the worst consequences of the climate crisis will ramp up, according to the study’s release.

Daniel Bressler, the study’s author and Ph.D. student at Columbia University, told the Guardian that the estimates in deaths are likely an undercount because the model only factored in heat-related deaths. The climate crisis is also linked to rising mortality rates from air pollution, flooding, and fires.

Although the study looked at carbon emission from individuals, Mr Bessler said climate policies that affect businesses will have a greater impact than what each person can do.

“My view is that people shouldn’t take their per-person mortality emissions too personally,” he told the Guardian.

“There are a significant number of lives that can be saved if you pursue climate policies that are more aggressive than the business as usual scenario.”

This article has been updated