New Study Gives 150 Million Reasons to Reduce Carbon Emissions

The study looked at the human health benefits of holding global climate change to 1.5° Celsius (2.7° Fahrenheit) — the aspirational goal set by the Paris climate agreement. It found that taking significant steps to reduce carbon emissions in line with this goal would prevent more than 150 million premature deaths worldwide, largely through a decrease in air pollution.

The study looked at three different scenarios for carbon emissions reductions — one scenario where carbon emissions were reduced rapidly to keep the planet below 2° Celsius (3.6° Fahrenheit) by the end of the century, another where emissions were reduced less rapidly (but still enough to keep warming below 2°C by 2100), and a third where emissions were reduced rapidly enough to limit warming to 1.5°C.

Researchers then compared expected future emissions — and associated air pollution, like particulate matter and ozone — to expected public health impacts over the world.

Specifically, the study looked at how emissions reductions would benefit public health in the world’s largest urban areas. In six cities —  Moscow, Mexico City, Sao Paolo, Los Angeles, Puebla, and New York — between 320,000 and 120,000 premature deaths could be avoided by keeping global warming below 1.5°C.

The Indian cities of Kolkata and Delhi — both of which struggle with air pollution from energy and transportation — would see the greatest benefit, with up to 4.4 million and 4 million projected lives saved, respectively.

In total, 80 cities around the world would see more than 100,000 premature deaths prevented by rapid climate action meant to keep the world below 1.5°C of warming.

“Since air pollution is something we understand very well and have extensive historical data on, we can say with relatively high certainty how many people will die in a given city under each scenario,” Drew Shindell, lead author of the study and a professor of Earth Sciences at Duke University said in a press statement. “Hopefully, this information will help policymakers and the public grasp the benefits of accelerating carbon reductions in the near term, in a way that really hits home.”

The study adds to previous work Shindell has done on the subject of climate action and public health outcomes. In 2016, he authored a study that found that reducing U.S. climate emissions in line with a 2°C limit could prevent 175,000 pollution-related deaths by 2030 and generate health benefits around $250 billion.

That’s because climate policies aimed at reducing greenhouse gas emissions like carbon dioxide and methane often hold co-benefits for air pollution — forcing vehicles to become cleaner, for instance, or encouraging utilities to switch from polluting fuels like coal to cleaner sources like wind or solar.

Still, with the United States officially planning to exit the Paris agreement in 2020 — and with other nations also lagging behind on their individual climate pledges — achieving the most aspirational goal of the agreement seems increasingly unlikely.

A leaked report from the Intergovernmental Panel on Climate Change (IPCC) found that, absent “a rapid phase out of net global carbon dioxide (CO₂) emissions and deep reductions in non-CO₂ drivers of climate change such as methane,” the chance that the world will stay below 1.5°C is practically impossible. A different study, published in July of 2017, found that the world had roughly a 1 percent chance of remaining below 1.5°C of warming, and a 5 percent chance of remaining under 2°C.