More than 500,000 lives could be saved globally each year by 2030 if the world took action to curb climate change, adding up to massive health benefits that far exceed the costs of forcing a reduction in fossil fuel emissions, a new study concludes.
The research, published Sunday in Nature Climate Change, said the benefits were especially striking for China, with its large population now exposed to some of the worst pollution in the world. The air quality and health benefits in East Asia in 2030 would amount to 10 to 70 times the cost of reducing greenhouse gas emissions, the researchers concluded. (See related, "Coal-Burning Shortens Lives in China, New Study Shows.")
It is the latest in a number of studies that have sought to underscore the health impact of climate change. With world leaders stymied on reaching a political agreement to curb fossil fuel emissions, much of this research seeks to quantify and make more tangible the costs of inaction. The new paper, written by a team led by Jason West, assistant professor of environmental sciences and engineering at the University of North Carolina Gillings School of Global Public Health, turns the equation around slightly: It seeks to quantify the benefits of action. (See related “Quiz: What You Don’t Know About Climate Change Science.”)
"Neglecting the air quality co-benefits misses an important component of the benefits of reducing greenhouse gas emissions," West said in an interview. "We show those benefits are large enough that they should be part of the analysis, and it should give extra motivation for people to think about why we should be taking action to slow climate change." (See related, "New U.S. Limits on Power Plant Pollution: Five Points.")
Carbon Price, Health Benefits
The study calculates the potential health impact based on one potential scenario for greenhouse gas mitigation that the Intergovernmental Panel on Climate Change (IPCC) uses in its latest assessment report—essentially, the scientific consensus statement on climate change—which will be made public Friday. The scenario (known prosaically, in typical IPCC fashion, as "Representative Concentration Pathway 4.5") is one in which nations establish a global price on carbon across all economic sectors through an efficiently functioning market. As a result, the atmospheric concentration of carbon dioxide would decrease by 2100 from a projected 760 parts per million (ppm) to 525 ppm. (Even though that would be an increase in atmospheric carbon from today's level of about 400 ppm, it would mark a substantial decrease in the current trajectory.) (See related, "Climate Milestone: Earth's CO2 Level Passes 400 ppm.")
Under such a scenario, fossil fuel use would decrease substantially; it would be replaced with nuclear and renewable energy, primarily wind power. Energy demand also would be curbed, and forest cover would be increased. The scenario assumes that the carbon emissions from nearly all electricity generated by fossil fuels and biofuels would be captured with carbon capture and geologic storage technology by 2100.
West and his team looked closely at just one set of health impacts of such a scenario: the benefits that would result from the substantial reductions in ozone and particulate matter, pollutants for which the link to respiratory disease and deaths is well established. (See related, "Five Reasons for Obama to Sell Climate Change as a Health Issue.") The researchers concluded that the average global benefits of avoided mortality from these pollutants would add up to $50 to $380 for every ton of carbon dioxide reduced by 2030, when a half million lives would be saved annually. That far exceeds the projected costs of those reductions, estimated to be from $0 to $33 per ton.
Looking Into the Future
If the world continued on this carbon reduction pathway, the number of lives saved by 2050 would increase to 1.3 million per year, and by 2100, to 2.2 million per year, the researchers projected. The health benefits would clearly exceed the costs in 2030 and in 2050. Even though the number of lives saved increases dramatically by 2100, it is less clear that the benefits outweigh the costs at that point in the projection. That's because the cost estimates for carbon mitigation become far greater in the distant future, when it assumed that there are no major technology breakthroughs and the cheapest measures—like energy efficiency—have been exhausted. Still, even in 2100, the health benefits calculated by the UNC team fall within the range of the lowest cost estimates for carbon mitigation.
"This is a very important kind of analysis, and I think more and more people are trying to figure out how best to do this," said Dan Greenbaum, president of Boston-based Health Effects Institute, who was not involved in the new study. "The impact of CO2 itself can seem quite abstract to people. This is a much more concrete way of showing what the other benefits are as you move away from coal-fired power plants."
Greenbaum noted that the researchers needed to look far into the future in their analysis, even though there are always uncertainties built into such long-term projections. The assumptions they've made "are not unreasonable ones," he said. Other studies may come up with lower projections on mortality due to air pollution in the distant future because of evidence that the number of deaths increase less rapidly at the higher levels of pollution seen in some Asian countries, he said. This was a key feature of the landmark Global Burden of Disease study published last year in The Lancet, in which Greenbaum participated. (See related, "Cookstove Smoke is 'Largest Environmental Threat,' Global Health Study Finds.")
The health benefits of climate mitigation in the UNC study are markedly higher than those calculated in previous studies that have attempted to tackle the issue. That's because the researchers sought to account for a number of influences not included in previous analyses, like the increase in economic activity (and value of life) in the future, the susceptibility to air pollution in certain populations, and the long-range transport of air pollution, affecting the health of people living "downwind." (See related, "Four Ways to Look at Global Carbon Footprints.")