NEW YORK (BLOOMBERG) - A population equivalent to that of Germany - 83 million people - could be killed this century because of rising temperatures caused by greenhouse gas emissions, according to a new study that might influence how markets price carbon pollution.
The research from Columbia University's Earth Institute introduces a new metric to help companies and governments assess damages wrought by climate change. Accounting for the "mortality cost of carbon" could give polluters new reasons to clean up by dramatically raising the cost of emissions.
"Based on the decisions made by individuals, businesses or governments, this tells you how many lives will be lost or saved," said Mr Daniel Bressler from Columbia, whose research was published on Thursday (July 29) in the journal Nature Communications.
"It quantifies the mortality impact of those decisions" by reducing questions down "to a more personal, understandable level".
Adapting models developed by Yale University climate economist and Nobel Prize winner William Nordhaus, Mr Bressler calculated the number of direct heat deaths that will be caused by current global warming trajectories.
His calculations do not include the number of people who might die from rising seas, superstorms, crop failures or changing disease patterns affected by atmospheric warming. This means that the estimated deaths - which approximates the number of people killed in World War II - could still be a "vast underestimate", he said.
Every 4,434 tonnes of carbon spewed in 2020 into the earth's atmosphere will kill one person this century, according to the peer-reviewed calculations that see the planet warming by 4.1 deg C by 2100.
So far, the planet has warmed about 1.1 deg C, compared with pre-industrial times. The volume of pollution emitted over the lifetime of three average US residents is estimated to contribute to the death of another person.
Mr Bressler said the highest mortality rates can be expected in earth's hottest and poorest regions in Africa, the Middle East and South Asia.
The new metric could significantly affect how economies calculate the so-called social cost of carbon, which US President Joe Biden's administration set at US$51 (S$69) a tonne in February. That price on pollution, which complements carbon markets like the European Union's Emissions Trading System, helps governments set policy by accounting for future damages.
But the scale revealed by Mr Bressler's research suggests the social cost of carbon should be significantly higher, at about US$258 a tonne, if the world's economies want to reduce deaths caused by global warming.
A higher cost on carbon pollution could immediately induce larger emission cuts, which in turn could save lives. Capping global average temperature increase to 2.4 deg C by the end of the century, compared with modest emission reductions that would warm the planet by 3.4 deg C, could save 74 million people from dying of heat.
"People shouldn't take their per-person mortality emissions too personally," said Mr Bressler. Governments need to mobilise "large-scale policies such as carbon pricing, cap and trade and investments in low carbon technologies and energy storage".
