A side benefit of climate action: Saving millions of lives

Source: Chelsea Harvey, E&E News reporter • Posted: Wednesday, March 21, 2018

Cutting carbon emissions as fast as possible isn’t just good for the climate, a new study suggests — it could also save tens of millions of lives.

The industrial sources that release greenhouse gases, such as power plants or automobiles, tend to produce other forms of air pollution, as well. And these emissions can have substantial impacts on human health. The World Health Organization estimates that about 3 million people suffer premature deaths every year because of exposure to outdoor air pollution, and indoor air pollution from cookstoves and other household activities may cause an additional 4 million deaths annually.

Reducing greenhouse gas emissions by curbing or altering industrial activities can reduce air pollution as a side effect. And the faster world nations take action, the greater the benefits will be. Research published yesterday in Nature Climate Change suggests that if world nations can reduce emissions quickly enough to meet the 2-degree Celsius climate target — without first overshooting it — as many as 153 million deaths worldwide could be prevented during this century.

That could be another incentive for world leaders to act quickly on climate change, the study’s authors say — perhaps an even greater motivator than the climate issue, itself. While the long-term impact of unmitigated climate change would also be devastating to human societies, “most people can relate more directly to preventing millions of premature deaths during the next few decades than to preventing a half a degree of warming in 80 years,” the authors write.

As world nations work to keep global temperatures within at least 2 C of their preindustrial levels — and within a more ambitious 1.5 C threshold, if possible — climate models suggest there are a variety of mitigation tactics they could use to meet those goals. Many model scenarios consistent with a 2 C target assume that emissions reduction efforts won’t initially be enough to keep global temperatures within those limits and that world leaders will have to employ special “negative emissions” technologies to bring temperatures back down again.

The few scenarios that don’t assume the use of negative emissions for a 2 C target would require urgent action to start reducing global carbon emissions immediately. Reaching a 1.5 C target would also require immediate reductions and may still call for negative emissions technology.

The new study focuses on these latter scenarios, assuming faster emissions reduction efforts that would allow the world to meet either a 2 C target with no negative emissions technology or even a 1.5 C target with some negative emissions.

Compared with scenarios that assume emissions fall at a slower rate, the accelerated reduction scenarios lead to greater and earlier declines in the number of deaths caused by pollution each year. These include deaths resulting from exposure to both fine particulate matter — tiny particles in the air that cause negative health effects when inhaled — and ozone, which is toxic in close contact with humans. The faster reduction efforts could bring ozone deaths down to nearly zero by the end of the century and would result in fewer than half as many deaths from particulate matter.

Altogether, the study suggests that the accelerated emissions reduction efforts would save about 153 million lives between 2020 and 2100. And about 40 percent of those would occur in the next four decades alone.

As it is, the pledges world nations have submitted under the Paris climate agreement are likely not strong enough to meet a 2 C climate target — at least not without the substantial use of negative emissions technology, which remains an unproven and highly uncertain tool in the arsenal. Numerous studies have warned of the potential consequences of allowing temperatures to exceed these limits, including catastrophic glacier melt and sea-level rise, extreme weather events, agricultural failures, and forced migrations.

But if these warnings are still not enough to spur stronger, faster action on climate change, the new study may provide an additional incentive. Even the unintended side effects of climate action can hold great benefits for human societies, and millions of lives could hang in the balance.